Recently, triboelectric nanogenerators (TENGs) have been widely used for energy harvesting and self-powered sensing due to their significant and unique advantages. However, the intrinsic mechanisms that contribute to tribo-electricification (TE) between two materials remain as a subject of rigorous debate. In addition to predicting the qualitative charge transfer in solid-solid contacts based on the difference in the work functions of the two moieties constituting the interface, we argue that it is essential to obtain atomic-level, first principles, insights into the bonding properties, quantitative charge transfer, and the possible presence of a electrostatic potential barrier at the interface to fully understand the TE mechanism of a system. We have utilized dispersion-corrected density functional theory (DFT) calculations in this study to systematically investigate the TE potential of bare surface Ti3C2 and Ti3N2 2D MXene monolayers and their surface functionalized modifications Ti3C2R2 and Ti3N2R2 (where R = -O, -OH, or -F) in contact with Al(111). For these heterostructures, we have analyzed the adhesive energy of the interfaces, the nature of interaction through the electron localization function (ELF), and the charge distribution, which have revealed distinct characteristics of MXene/Al contacts for these monolayer/metal interfaces at their equilibrium distance and the changes in their properties under uniaxial pressure. Among all the metallic 2D MXene variants investigated in this study, we have determined that Ti3C2F2/Al and Ti3N2F2/Al interfaces show exceptional potential for TE.

Since their introduction by Sony in 1990, lithium-ion batteries (LIBs) have acquired a sizable market share. They have the best energy densities, a high open circuit voltage, a low self-discharge rate, no memory effect, and a slow loss of charge when not in use. These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications. They do, however, pose major safety issues since the conventional electrolytes are made of fluorinated salts dissolved in volatile organic solvents, the former being meta-stable at ambient temperature and the latter being flammable with a high vapour pressure. Thus, there is an urge to develop thermally and electrochemically stable non-fluorinated electrolytes to improve the safety and performance of batteries. Electrolytes based on ionic liquids (ILs) offer a range of advantages over traditional electrolytes including low volatility and high thermal and electrochemical stabilities, and can additionally be made fluorine-free and task-specific. In addition, the transport properties of ILs can be controlled by structural design of chemical functionalities to reduce the ionic interactions and enhance the ion mobilities.

This thesis is focussed on the development of new fluorine-free ILs and electrolytes for safer energy storage applications. An overview of synthesis, physicochemical and electrochemical characterizations of six different families of ILs and their structurally analogous electrolytes based on the aromatic heterocyclic rings, oligoether based aromatic and aliphatic carboxylates, oligoether phosphates and aromatic sulfonyl anions coupled with n- tetrabutylphosphonium-, imidazolium-, pyrrolidinium-based and alkali metal cations is presented. The structures and purity of the new anions, their intermediate products and the ILs are characterized by using multinuclear NMR, FTIR and mass spectrometry. These studies are further complemented by using NMR diffusometry to investigate the relative anion and anion mobilities and understand the possible interaction mechanisms between the oppositely charged ions within the ILs and the electrolytes, and especially, the influence of Li+ addition in the IL-based electrolytes. Among the synthesized ILs, the sulfonyl-based ILs revealed highest thermal stabilities, aromatic oligoether-based ILs showed the best electrochemical stabilities and aromatic sulfonyl -based ILs exhibited highest ionic conductivities. Some of the synthesized salts displayed promising performance as electrolytes in energy storage devices.

Five new n-tetrabutylphosphonium (P4444)+ cation based ionic liquids (ILs) with oligoether substituted aromatic carboxylate anions have been synthesized. The nature and position of the oligoether chain affect thermal stability (up to 330 ºC), phase behaviour (Tg < -55 ºC) and ion transport. Furthermore, with the aim of application in lithium batteries, electrolytes were created for two of the ILs by 10 mol% doping using the corresponding Li-salts. This affects the ion diffusion negatively, from being higher and equal for cations and anions to lower for all ions and unequal. This is due to the stronger ionic interactions and formation of aggregates, primarily between the Li+ ions and the carboxylate group of the anions. Electrochemically, the electrolytes have electrochemical stability windows up to 3.5 V, giving some promise for battery application.

We here present four new fluorine-free ionic liquids (ILs) based on the non-nutritive sweetener saccharinate (Sac) anion coupled with pyrrolidinium, imidazolium, and phosphonium cations and their thermal, physicochemical, and electrochemical properties. The pyrrolidinium cation-based material is a solid at room temperature, whereas the other three materials are room-temperature ionic liquids (RTILs). By infrared spectroscopy, we find the ionic interactions to be controlled by the distinct conformers of the Sac anion, which in turn are cation-dependent. (P4444)(Sac) shows the lowest glass transition temperature, (Tg), the highest thermal stability and ionic conductivity, and the widest electrochemical stability window, up to 6 V. As an electrolyte in a symmetric supercapacitor, it enabled a specific capacitance of 204 F g–1 at 1 mV s–1, an energy density of 53 Wh kg–1 and a power density of 300 W kg–1 at a current density of 0.1 A g–1, and the capacitor retained 81% of its initial capacitance after 10,000 cycles at 60 °C. Altogether, these fluorine-free electrolytes have electrochemical properties promising for application in supercapacitors operating at elevated temperatures over a wide voltage range. 

The immense progress of humanity on the technological, domestic, and industrial fronts comes at the cost of polluting the planet. Aquatic pollution is particularly dangerous since all life forms are directly linked to it. Each year tons of industrial and domestic pollutants make their way into aqueous systems. Efficient removal/degradation of these pollutants is of prime importance for the sustainable future. Among many technologies, photodegradation is an emerging and promising method for the successful removal of aqueous pollutants since it is powered by abundant solar light. The last decade had shown that carbon dots are among the most promising materials that can be utilized as an efficient tool to derive various solar-driven chemical reactions. Carbon dots possess unique photophysical and chemical properties such as light-harvesting over a broad-spectrum region, upconversion photoluminescence, photosensitizers, chemical inertness, and bivalent redox character, etc. The ease of synthesis of carbon dots at low cost also contributes hugely to their utilizations as an efficient photocatalyst for the degradation of aqueous pollutants. This review summarizes the recent progress made in the field of photodegradation of aqueous pollutants with the aid of carbon dots and their hybrids, highlighting the critical role carbon dots can play in the field. 

Anti-perovskites A₃SnO (A = Ca, Sr, and Ba) are an important class of materials due to the emergence of Dirac cones and tiny mass gaps in their band structures originating from an intricate interplay of crystal symmetry, spin-orbit coupling, and band overlap. This provides an exciting playground for modulating their electronic properties in the two-dimensional (2D) limit. Herein, we employ first-principles density functional theory (DFT) calculations by combining dispersion-corrected SCAN + rVV10 and mBJ functionals for a comprehensive side-by-side comparison of the structural, thermodynamic, dynamical, mechanical, electronic, and thermoelectric properties of bulk and monolayer (one unit cell thick) A₃SnO anti-perovskites. Our results show that 2D monolayers derived from bulk A₃SnO anti-perovskites are structurally and energetically stable. Moreover, Rashba-type splitting in the electronic structure of Ca₃SnO and Sr₃SnO monolayers is observed owing to strong spin-orbit coupling and inversion asymmetry. On the other hand, monolayer Ba₃SnO exhibits Dirac cone at the high-symmetry Γ point due to the domination of band overlap. Based on the predicted electronic transport properties, it is shown that inversion asymmetry plays an essential character such that the monolayers Ca₃SnO and Sr₃SnO outperform thermoelectric performance of their bulk counterparts.

Ceria-doped titania photocatalysts (ceria loading 0.25–5.0 wt%) were synthesized by hydrothermal methods for water remediation. Nanotubes (CeTNTx) and nanoparticles (CeTNPx) were obtained. Ceria doping was applied to tune the electronic properties of nanostructured titania, boosting its photocatalytic activity. CeTNT nanostructures contained anatase as the only titania phase, whereas the CeTNP series consisted of both anatase and rutile polymorphs. The Ce addition induced a decrease in the energy gap, allowing enhancement of visible light harvesting. The photodegradation of methylene blue, MB, in aqueous solution was chosen to study the influence of the morphology and the ceria loading on the photocatalytic response, under UV and solar light. Both CeO₂–TiO₂ nanoparticles and nanotubes were found to be very active under UV light. The highest MB degradation rates were obtained for the 0.25 wt% CeO₂ doping, for both nanotubes and nanoparticles (0.123 and 0.146 min⁻¹, respectively), able to photodegrade completely the dye after 120 min. The two samples are stable after a 3-cycle reusability test. The photo-response under simulated solar light confirmed that doping titania with ceria allows harvesting visible light absorption, enhancing its photoactivity. A maximum efficiency of 85% under simulated sunlight at a degradation rate of 0.054 min−1 was obtained. Transient photoluminescence confirmed that MB acts as a charge scavenger for the composite system. These results pointed out ceria-doped titania nanostructures as a promising class of photocatalysts for the degradation of dyes and other hazardous organic compounds in wastewater.

Optimizing electrocatalytic activity and recognizing the most reactive sites for oxygen evolution reaction (OER) electrocatalysts are valuable to the order of renewable power. In this research article, we explored an innovative in-situ annealing technique for constructing iron carbide nanoparticles (Fe3C NPs) encapsulated via nitrogen and phosphorous doped bamboo-shape carbon nanotubes (NP-CNTs) for OER. Interestingly, the constructed Fe3C NPs@NP-CNT-800 composite exhibited remarkable electrochemical operation and offered a stable current density of 10 mA/cm2 at a lower overpotential (280 mV) in an alkaline solution. Furthermore, an innovative Fe3C NPs@N,P-CNT-800 hybrid surpassed the standard RuO2 electrocatalyst in terms of OER performance and showed negligible degradation in chronoamperometric (21 h) and chronopotentiometry (3000 cycles) analyses. The remarkable performance and stability are ascribed to the Fe3C NPs, novel tubular bamboo-like morphology of its carbon materials, and heteroatom doping, which contribute to the electrochemical interfaces, large surface area, active catalytic sites, and rapid charge transfer kinetics.

Transition metal carbides, nitrides, and carbonitrides (MXenes) have become an appealing framework for developing various energy applications. MXenes with van der Waals (vdW) interactions are facile, highly efficient, affordable, and self-assembled features that improve energy density. MXenes exhibit large surface area, high electric conductivity, and excellent electrochemical characteristics for various energy applications. This review summarizes and emphasizes the current developments in MXene with improved performance for energy storage or conversion devices, including supercapacitors (SCs), various types of rechargeable batteries (RBs), solar cells, and fuel cells. We discuss the crystal structures of MXenes properties of MXenes and briefly discuss them for different types of energy applications. Finally, the critical outlook and perspective for the MXene progress for applications in energy applications are also described.

Potential anchoring materials in lithium–sulfur batteries help overcome the shuttle effect and achieve long-term cycling stability and high-rate efficiency. The present study investigates the two-dimensional nanosheets B2C4P2 and B3C2P3 by employing density functional theory calculations for their promise as anchoring materials. The nanosheets B2C4P2 and B3C2P3 bind polysulfides with adsorption energies in the range from −2.22 to −0.75 and −2.43 to −0.74 eV, respectively. A significant charge transfer occurs from the polysulfides, varying from −0.74 to −0.02e and −0.55 to −0.02e for B2C4P2 and B3C2P3, respectively. Upon anchoring the polysulfides, the band gap of B3C2P3 reduces, leading to enhanced electrical conductivity of the sulfur cathode. Finally, the calculated barrier energies of B2C4P2 and B3C2P3 for Li2S indicate fast diffusion of Li when recharged. These enthralling characteristics propose that the nanosheets B2C4P2 and B3C2P3 could reduce the shuttle effect in Li–S batteries and significantly improve their cycle performance, suggesting their promise as anchoring materials.

One often proposed route to improved energy density for lithium-ion batteries is to use alloy anodes, such as silicon, able to store large amounts of lithium. Mechanical instability caused by the large expansion and contraction associated with (de)lithiation, and hence bad cyclability, has, however, so far hindered progress. As proof-of-concept of a remedy, we here present BiSbSe1.5Te1.5, a medium high-entropy alloy with improved cycling stability for conversion-alloying (de)lithiation reactions. We attain five to twenty times more stable cycles than previously reported for comparable metal-Se and -Te-based anodes, with a very good reversible capacity (464 mAh g−1) for up to 110 cycles- and this without using any carbonaceous materials to create a composite. Altogether, this highlights how alloy engineering and increased entropy materials can stabilize conversion-alloying electrodes.

The inception of high-entropy alloy promises to push the boundaries for new alloy design with unprecedented properties. This work reports entropy stabilisation of an octonary refractory, HfMoNbTaTiVWZr, high-entropy thin film metallic glass, and derived nitride films. The thin film metallic glass exhibited exceptional ductility of ≈60% strain without fracture and compression strength of 3 GPa in micro-compression, due to the presence of high density and strength of bonds. The thin film metallic glass shows thermal stability up to 750 °C and resistance to Ar-ion irradiation. Nitriding during film deposition of HfMoNbTaTiVWZr thin film of strong nitride forming refractory elements results in deposition of nanocrystalline nitride films with compressive strength, hardness, and thermal stability of up to 10 GPa, 18.7 GPa, and 950 °C, respectively. The high amount of lattice distortion in the nitride films leads to its insulating behaviour with electrical conductivity as low as 200 S cm−1 in the as-deposited film. The design and exceptional properties of the thin film metallic glass and derived nitride films may open up new avenues of development of bulk metallic glasses and the application of refractory-based high entropy thin films in structural and functional applications.

Ionic liquids (ILs) are room temperature molten salts that possess preeminent physicochemical properties and have shown great potential in many applications. However, the use of ILs in surface-dependent processes, e.g. energy storage, is hindered by the lack of a systematic understanding of the IL interfacial microstructure. ILs on the solid surface display rich ordering, arising from coulombic, van der Waals, solvophobic interactions, etc., all giving near-surface ILs distinct microstructures. Therefore, it is highly important to clarify the interactions of ILs with solid surfaces at the nanoscale to understand the microstructure and mechanism, providing quantitative structure–property relationships. Atomic force microscopy (AFM) opens a surface-sensitive way to probe the interaction force of ILs with solid surfaces in the layers from sub-nanometers to micrometers. Herein, this review showcases the recent progress of AFM in probing interactions and microstructures of ILs at solid interfaces, and the influence of IL characteristics, surface properties and external stimuli is thereafter discussed. Finally, a summary and perspectives are established, in which, the necessities of the quantification of IL–solid interactions at the molecular level, the development of in situ techniques closely coupled with AFM for probing IL–solid interfaces, and the combination of experiments and simulations are argued.

Utilizing iron silicate copper slag as supplementary cementitious material (SCM) is a means to improve resource efficiency and lower the carbon dioxide emissions from cement production. Despite multiple studies on the performance of these slags in SCM applications, the variations in cooling procedure, grinding, and methods for evaluating reactivity limit the ability to assess the influence of chemical composition on reactivity from the literature data. In this study, a methodology was developed to synthesize iron silicate slags, which were then evaluated for their inherent reactivity using the R-3 calorimeter-based experiments. The results demonstrated that laboratory-scale granulation produced the same reactivity as industrially granulated slag. Furthermore, a synthesized triplicate sample showed high repeatability. Based on these two aspects, this method can be used to systematically study the influence of chemical composition on the inherent reactivity of iron silicate slags while producing results that are directly translatable to industrial slags.

The study investigates the impact of incorporating Ni and Cu into the lattice of ZnO nanoparticles (NPs) to enhance their anticancer and antioxidant properties. Characterization techniques including pXRD, FTIR, UV–visible absorption spectroscopy, FESEM, and EDAX confirm the successful synthesis and structural modifications of Ni/Cu-ZnO NPs. Anticancer activity against breast cancer (MDA) and normal skin (BHK-21) cells reveals dose-dependent cytotoxicity, with Ni/Cu-ZnO NPs exhibiting higher efficacy against MDA cells while being less harmful to BHK-21 cells. Morphological studies corroborate these findings. Additionally, antioxidant assays using TAC, FRAP, and DPPH assay demonstrate the superior antioxidant activity of Ni/Cu-ZnO NPs matched to pure ZnO. Overall, the synergistic effect of Ni and Cu incorporation leads to improved therapeutic potential, making Ni/Cu-ZnO NPs promising candidates for cancer therapy and antioxidant applications.Molecular docking recreations were performed using Auto Dock Vina software to gain more insights and validate the observed biological activities of un-doped ZnO and bi-metal doped ZnO NPs, we investigated the interaction and binding affinities of pure ZnO and bimetallic metal co-doped ZnO for their antioxidant and anticancer studies. Ni/Cu-ZnO have shown good antioxidants and exhibited remarkable anticancer activities.

Li-ion batteries (LIBs) are widely used nowadays. Because of their limited lifetimes and resource constraints in manufacturing them, it is essential to develop effective recycling routes to recover their valuable elements. This study focuses on the pyrometallurgical recycling of black mass (BM) from a mixture of different LIBs. In this study, the high-temperature behavior of two types of mixed BM is initially examined. Subsequently, the effect of mechanical activation on the BM reduction kinetics is investigated. Finally, hematite is added to the BM to first be reduced by the excess graphite in the BM and second to form an Fe-based alloy containing Co and Ni. This study demonstrates that mechanical activation does not necessarily affect the kinetics of BM high-temperature behavior. Furthermore, it demonstrates that alloy-making by the addition of hematite is a successful method to simultaneously utilize the graphite in the BM and recover Co and Ni, regardless of the LIB type.

The increased demand for Li-ion batteries has prompted the scientific community to improve recycling routes in order to reuse the valuable materials in batteries. After their end-of-life, the batteries are collected, discharged, and mechanically disintegrated, generating plastic and metallic streams that are recycled directly; this leaves behind a small particle size fraction known as black mass (BM). BM is composed mainly of graphite and Li-metal complex oxides. Pyrometallurgy is a route known for recycling of BM, in which identifying the BM’s behavior at high temperatures is essential. In this study, two types of BM are characterized in two fractions of 150–700 µm and smaller than 150 µm. The thermal behavior of the BM is studied with thermal analysis techniques. The analyses demonstrate that the mineralogical and morphological properties of the two fractions do not significantly differ, while the amounts of C and organic materials might vary. When the BM was thermally treated, the binders decomposed until a temperature of 500 ℃ was reached, where the volatilization of hydrocarbons was observed, although F mostly persisted in the BM. The Li-metal oxide was partially reduced to lower oxides and Li carbonate at ⁓ 600 ℃, and the main mass loss was caused by carbothermic reduction immediately thereafter. As the products of this process, metallic Co and Ni phases were formed, and part of the graphite remained unreacted. Regarding the Li behavior, it was observed that in the presence of Al, AlLiO2 is the most likely composition to form, and it changes to LiF by increasing the F concentration in the composition.

In this study we present and discuss p-n heterostructures for photodetection. The hybrid structures consist of CeO2:ZnO-Cu2O, featuring different concentrations of CeO2, fabricated by using hydrothermal co-growth for CeO2 and ZnO, and sputtering deposition for Cu2O. As the concentration of CeO2 in the ZnO pristine nanorods was increased, the structural, optical and functional features of the materials showed relevant changes, in terms of crystalline domains and optical bandgap. After Cu2O deposition, the ternary materials were tested as UV photodectors, showing very good performance in terms of fast response and decay times. Specifically, we found that the CeO2:ZnO-Cu2O devices maintain a stable current under light irradiation, whose value was dependent on the CeO2 amount incorporated in the ZnO 1D nanostructures. Among all tested configurations, the 5.5 % hybrid CeO2:ZnO-Cu2O exhibits the highest current efficiency, accompanied by rapid rise and decay times. Our investigation suggests that the CeO2:ZnO-Cu2O configuration holds great potential for optoelectronic applications, particularly in the development of UV photodetectors.

Interestingly, it opens the door for the development of the 2D materials family, which includes different classes of 2D materials. Among them, transition metal dichalcogenides (TMDs) and transition metal carbide MXenes (TMCs) have emerged. TMDs have unique layered structures, low cost, and are composed of earth abundant elements, but their poor electronic conductivity, poor cyclic stability, their structural and morphological changes during electrochemical measurements hinder their practical use. Recently, TMC MXenes have garnered attention in the 2D material world, but the issue of restacking and aggregation limits their direct use in large-scale energy conversion and storage. To address these challenges, hetero structures based on conductive TMCs MXenes and electrochemically active TMDs have emerged as a promising solution. However, understanding the solid/solid interface in heterostructured materials remains a challenge. To tackle this, 2D single component crystals with high capacity, low diffusion barrier, and good electronic conductivity are highly sought. The emergence of transition metal carbo-chalcogenides (TMCCs) has provided a potential solution, as these 2D nanosheets consist of TM2X2C, where TM represents transition metal, X is either S or Se, and C atom. This new class of 2D materials serves as a remedy by avoiding the challenges related to solid/solid interfaces often encountered in heterostructures. This review focuses on the latest developments in TMCCs, including their synthetic strategies, surface/interface engineering, and potential application in batteries, water splitting, and other electro-catalytic processes. The challenges and future perspectives of the design of TMCCs for electrochemical energy conversion and storage are also discussed.

Designing an efficient electrocatalyst for the oxygen evolution reaction (OER) in alkaline media is highly needed but very challenging task. Herein, we used organic polyelectrolytes such as (carboxymethyl cellulose) CMC and polyacrylamide polymers for the growth of Co₃O₄ nanostructures by aqueous chemical growth method. The morphology and composition studies were performed on scanning electron microscopy (SEM), energy dispersive X-ray (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) techniques. The structural properties and the surface chemistry of the Co₃O₄ electrocatalysts were correlated to the OER performance, and the enhancement mechanism with respect to pristine Co₃O₄ was observed to be specifically related to the polyelectrolyte templating role.

Co₃O₄@CMC composites displayed reduced crystallite size, producing OER overpotential as low as 290 mV at 10 mAcm⁻² in 1.0 KOH and Tafel slope of 71 mVdec⁻¹, suggesting fast transfer of intermediates and electrons during water electrolysis. On the other hand, the use of polyacrylamide and its different templating mechanism resulted in similar crystallite size, but preferential exposed faces and larger surface vacancies content, as demonstrated by HR-TEM and XPS, respectively. Consistently, this material displays cutting-edge OER performance, such as overpotential of 260 mV at 10 mAcm⁻² and a low Tafel slope of 63 mVdec⁻¹. The proposed strategy for the preparation of Co₃O₄ nanostructures in the presence of CMC and polyacrylamide is facile, mass production, thus it could equally contributed towards the realization of hydrogen energy. Therefore, these nanostructures of Co₃O₄ can be regarded as an alternative and promising materials for the different electrochemical applications including fuel cells, metal air batteries, overall water electrolysis and other energy storage devices.

Ion transport measures and details as well as physico-chemical and electrochemical properties are presented for a small set of structurally flexible pyrrolidinium (Pyrr) and morpholinium (Morph) cation-based ionic liquids (ILs), all with oligoether phosphate-based anions. All have high thermal stabilities, low glass transition temperatures, and wide electrochemical stability windows, but rather moderate ionic conductivities, whereas both the anions and the cations of the Pyrr-based ILs diffuse faster than those of the Morph-based ILs. Overall the former ILs have significantly more promise as high-temperature supercapacitor electrolytes, rendering a specific capacitance of 164 F g−1 at 1 mV s−1, a power density of 241 W kg−1 and a specific energy density of 30 Wh kg−1 at 90 °C in a symmetric graphite supercapacitor.

Starting from spent coffee grounds, the use of coffee-derived biochar (CB) as a flame retardant (FR) additive was explored following a waste-to-wealth approach. CB was employed alone and in combination with ammonium polyphosphate (APP) and a ternary (Si-Ti-Mg) mixed oxide to enhance the thermal, fire, and mechanical performances of a bisphenol A diglycidyl ether (DGEBA)-based epoxy resin modified with (3-aminopropyl)-triethoxysilane (APTES) and cured with a cycloaliphatic amine hardener. The presence of silicon-modified epoxy chains guaranteed the uniform distribution of CB throughout the resin. The combined FR action of fillers (CB, APP, and Si-Ti-Mg oxide) and the acidic characteristics of hybrid epoxy moieties enabled the achievement of a no dripping UL 94-V-0 classification for epoxy resin containing 20 wt% CB and 1 wt% of phosphorus loading, significantly increasing the flexural modulus (by ∼15%). Although it is not self-extinguishing, compared to pristine resin, the silicon-modified epoxy nanocomposite filled only with CB exhibited a remarkable decrease in the peak of heat release rate (pHRR) (by ∼65%) and a beneficial smoke suppressant effect with a notable decrease (∼11%) in the total smoke production. Cone calorimetry tests, pyrolysis combustion flow calorimetry analysis, and microscopy measurements helped to outline the combined mode of action of CB, APP, and Si-Ti-Mg oxide in the flame retardation of the hybrid epoxy resin, highlighting a strong FR action in the condensed phase, with the formation of a stable aromatic ceramic char, as well as the smoke suppressant character due to the basic nature of the ternary metal oxide and the ability of porous biochar to adsorb the generated gases.

This study explores the possibility of using various silsesquioxane precursors such as (3-aminopropyl) triethoxysilane (APTES), methyltrimethoxysilane (MTMS), and tetraethyl orthosilicate (TEOS) to produce silsesquioxane-bacterial cellulose nanofibre (bCNF) aerogels. Each precursor allowed to customize the aerogel properties, leading to unique properties suitable for various applications requiring lightweight insulative materials. When utilizing APTES as the silsesquioxane precursor, an aerogel capable of over 90% recovery after compression was formed, making them suitable for flexible applications. When MTMS was used as the precursor, the aerogel retained some compression recovery (80%) but had the added property of superhydrophobicity with a contact angle over 160° due to the presence of CH3 functional groups, enabling water-repellence. Finally, TEOS allowed for excellent thermal insulative properties with a low Peak Heat Release Rate (PHRR), making it a promising candidate for fire-resistant applications. The customization of these aerogel materials was attributed to a combination of the chemical composition of the silsesquioxane precursors and the morphology of the coated bacterial cellulose nanofibres (bCNF), such as CH3 groups found in MTMS enabled for superhydrophobicity. Differences in morphology, such as uniform and smooth silsesquioxane coatings when using APTES or a “pearl-necklace” morphology using TEOS, enabled either compression recovery and flexibility or low thermal conduction. This investigation of silsesquioxane-bCNF provides a good understanding of the importance of the choice of precursor effect on insulating aerogel properties.

Tandem solar cells combining perovskite and CIGS have rapidly gained prominence as highly efficient photovoltaic devices. Recent advancements in enhancing their efficiency in-volve adjusting the thickness of distinct layers with tunable bandgaps, demonstrating superior performance compared to al-ternative tandem solar cells. The upper cell, employing perovskite material chosen for its excellent light absorption coefficient and optoelectronic properties, collaborates with the bottom CIGS cell, characterized by a tunable bandgap and low thermal requirements, contributing significantly to overall efficiency improvement. Through numerical simulations conducted with wxAMPS software, our proposed model, which incorporates a 3μm thick perovskite absorber layer as the upper cell and a 3.5μm thick CIGS absorber layer as the lower cell, demonstrated outstanding power conversion efficiency of 40.0209%, Voc of 1.8675 V, Jsc of 23.2146 mA/cm2, and FF of 92.3152

The use of a wide range of methods for incorporating nitrogen atoms on robust catalysts has given rise to fundamental advances in the field of energy conversion and storage. Recently, nitrogen incorporation has proven to be able to fine-tune the electron densities of exposed active sites to create high-performance electrocatalysts. The preservation of a strong interface between the local atomic coordination of nitrogen atoms on bare carbon, single metal atoms, transition metal oxides, metal chalcogenides, and MXenes during synthesis plays an important role in producing an efficient electrocatalysts. In addition, the ability of nitrogen atoms to bind with carbon or metal atoms can be influenced by processing conditions. In this regard, this review is the first comprehensive overview of the range of synthetic strategies to form nitrogen incorporated catalysts and assess their chemical, structural, physical electronic property modification and their influence on electrocatalytic ORR, OER, and HER performance. This review will describe how specific strategies have been utilized to realise effective electrocatalytic systems, including the energy conversion of nitrogen incorporated catalysts, structural coordination, and material optimization. Finally, the main challenges to be considered in future investigations in order to initiate new research efforts in this promising research area are discussed.

Previous investigations on anti-/de-icing techniques have primarily focused on mild laboratory conditions, which have limited practical applicability due to their short service life. Consequently, there is an urgent demand for the development of durable anti-/de-icing technologies capable of withstanding complex environmental conditions. In this research endeavour, we have successfully formulated a hydrophobic coating based on graphene. To circumvent the challenges associated with environmentally unfriendly organic solvents, we utilized a graphene water slurry as the foundational material and subsequently incorporated a poly (vinyl alcohol)-water solution. The resulting solution was subjected to in situ polymerization of a siloxane urea crosslinked polymer, yielding the desired coating solution. Following a solution spraying and drying process, the ultimate product obtained was the hydrophobic conductive graphene (HCG) siloxane Coating. The HCG siloxane Coating exhibits a conductivity of 66 S/m, enabling it to melt ice droplets within a mere 10 s, whereas conventional coatings require 20–500 s for the same task. A comprehensive field test conducted during an entire winter period on a high mountain situated within the Arctic Circle in Finland demonstrated the excellent anti-icing properties of the developed coating when subjected to approximately 310 W/m2 power. Furthermore, the coating exhibited satisfactory de-icing performance under approximately 570 W/m2 power, successfully removing ice accumulations within approximately 10 min. Throughout the field test, temperatures frequently plummeted to −20 °C, accompanied by wind speeds reaching up to 12 m/s. Material characterization revealed that the micro-nano structure of the coating surface, which engenders favourable hydrophobic behaviour, was primarily attributed to the phase separation resulting from hydrophilic and hydrophobic interactions. Moreover, the semi-interpenetrating structure formed by the polyvinyl alcohol molecular chains and in-situ polymerized siloxane urea ensured the coating's strength.

Spent pot lining (SPL) is a hazardous solid waste generated after overhauling the aluminum electrolytic cell. SPL contains carbon resources with high graphitization and toxic impurities, such as NaF, Na₃AlF₆, and CaF₂. These toxic substances are difficult to remove from graphite completely. This study introduces an innovative method of oxidation-expansion acid leaching (OEAL) to eliminate impurities inside the graphitized carbon. For such a purpose, typical purification methods (conventional leaching, flotation-acid leaching) were investigated and compared to OEAL. The experimental outcomes indicated that the process efficiency for removing SPL impurities by various methods had the following sequence from high to low: OEAL > flotation-acid leaching > conventional leaching. The maximum SPL impurities removal rate by conventional leaching and flotation-acid leaching was 89.65 %, while it was 99.36 % with the OEAL method. For understanding fundamental aspects of the SPL impurity removal, their rejection mechanisms in the examined methods were systematically studied by different instrumentals and chemical analysis techniques. As a result of the reaction between H⁺ and residuals during OEAL process, the distance between graphitized carbon layers expands. This expansion resulted in a qualitative improvement in the SPL impurity removal by OEAL, making SPL one of the graphite or graphene oxide resources.

Prussian blue analogues (PBAs) have recently emerged as effective materials in different functional applications, ranging from energy storage to electrochemical water splitting, thence to more “traditional” heterogeneous catalysis. Their versatility is due to their open framework, compositional variety, and fast and efficient internal charge exchange, coupled with a self-healing ability that makes them unique. This review paper presents and discusses the findings of the last decade in the field of the catalytic and photocatalytic application of PBAs in water remediation (via the degradation of organic pollutants and heavy metal removal) and the catalytic oxidation of organics and production or organic intermediates for industrial synthesis. Analysis of the catalytic processes is approached from a critical perspective, highlighting both the achievements of the research community and the limits still affecting this field.

The escalating threat of ever-increasing urban heat islands presents a significant global challenge regarding energy usage. Hence, the passive daytime solar radiative cooling technique relying on cooling materials is considered an innovative strategy to mitigate this issue without the utilization of any external energy. However, typical solar reflective cooling materials tend to have a bright white appearance, hence prompting an interest in aesthetic-colored reflective coolers with the requisite properties. However, achieving a balance between properties and appearance remains challenging. The present work establishes the synthesis of La2W2O9 and La2W1.86M0.14O9 (M = Co, Cu, Zn, and Fe) radiative cooling pigments showcasing high near-infrared reflectance via a solution combustion route. Doping with different ions results in a tunable hue, enabling the preparation of coated surfaces with variable colors. The nano-pigments exhibited a pure triclinic phase of LaW2O9 with the P1 space group. Doped transition metal chromophores were successfully substituted into the LaW2O9 lattice without altering its initial structure. The best performing La2W1.86Fe0.14O9 cooling nano-pigment exhibits a relatively high near-infrared reflectance of around 97.8% with International Commission on Illumination chroma color coordinates L* = 62.77, a* = 19.34, and b* = 19.79. Interestingly, the thermal conductivity of the prepared pigments was found to be 0.07–0.08 W m−1 K−1, which is relatively smaller than conventional roofing materials, implying their advantage in cooling systems. Thanks to the high reflectance and low thermal conductivity of the synthesized pigments, a decrease in the interior temperature was recorded, ranging from 7 to 10 °C under infrared-light illumination for up to 60 minutes. Furthermore, building energy simulation results indicate that 17.54 kW h m−2 of electricity can be saved annually if the colored La2W1.86Fe0.14O9 nano-pigment is employed. The aforementioned results demonstrated the efficacy of the prepared La2W1.86M0.14O9 (M = Co, Cu, Zn, and Fe) cooling nano-pigments as passive daytime solar radiative cooling materials to mitigate urban heat islands and achieve energy sustainability.

Fire retardants, although can impart fire-safety in polymeric composites, are detrimental to the mechanical properties. Biochar can be used, in conjunction with fire retardants, to create a balance between fire-safety and mechanical performance. It is possible to thermally dope fire retardants into the pores of biochar to make it functionalised. Thus, the current work is intended in identifying a composite having the combination of the most desirable fire retardant, bioplastic, and a suitable processing method. A comparison was made between two fire retardants (lanosol and ammonium polyphosphate), bioplastics (wheat gluten and polyamide 11), and composite processing methods (compression and injection moulding). It was found that wheat gluten containing ammonium polyphosphate-doped biochar made by compression moulding had the best fire-safety properties with the lowest peak heat release rate (186 kW/m2), the highest fire performance index (0.6 m2s/kW), and the lowest fire growth index (1.6 kW/ms) with acceptable mechanical properties compared to the corresponding neat bioplastic. Thus, for gluten-based polymers, the use of ammonium polyphosphate thermally doped into biochar processed by compression moulding is recommended to both simultaneously improve fire-safety and conserve the mechanical strength of the resulting biocomposites.

MoO₂ nanocrystals were prepared by solvothermal treatment of a Mo chloromethoxide at 250 °C in oleic acid. The monoclinic MoO2 phase, with a mean crystallite size of 29 nm, formed through reduction of molybdenum bronzes. The as-prepared MoO₂ nanocrystals were free from organics, allowing their use in photodegradation tests of organic pollutants (methylene blue, rhodamine B, paracetamol), without any preliminary purification treatment of the nanocrystals. It was found that MoO₂ was an efficient adsorbent of methylene blue (43 mg g^-1 for 1.5 × 10⁻⁴ M concentration) in the dark and an efficient photodegradation catalyst under visible light (all methylene blue removed from the solution after 240 min). From the analysis of the combined photodegradation tests of rhodamine B and paracetamol, it was clarified that direct sensitization was responsible for photodegradation. This finding was related to the work function value of metallic MoO₂, placed at more negative values if compared with other metallic materials.

A one-step side-by-side 3D printing method is proposed to construct linear lithium-, sodium-, and zinc-ion full batteries with high electrochemical performance. The inks of the battery components present shear thinning characteristics and can be printed on different substrates. This approach to design high performance linear full batteries is a general strategy.

Despite the fact that solid-state electrolytes have attracted broad research interests, the limited ion transfer and high interface impedance restrain their application in high-performance batteries with high cyclic stability and power density. Here, a new quasi-solid-state polymer electrolyte containing lightweight semiconducting hydrogenated borophene (HB) nanosheets, ionic liquids, and poly (ethylene oxide) is reported. The cyclic overpotential of the Li-Li symmetrical battery is about 65 mV lower than that of HB-free quasi-solid-state electrolyte, demonstrating the lower interface impedance. The interaction between lithium-ion and ethylene-oxide chains decreases owing to the existence of HB nanosheets and ionic liquids, which facilitates lithium-ion diffusion. The lithium bis(trifluoromethanesulfonyl)imide molecule surface adsorption at the HB nanosheets enhances the dissociation of lithium ions, and thus the matched lithium iron phosphate/Li full cell delivers the acceptable rate performance up to 5C. This work provides a new filler candidate to enhance the ionic conductivity of quasi-solid-state electrolytes that may facilitate to construct the high-performance HB nanosheets and ionic liquids-based lithium metal batteries.

Herein, a novel sulfur-doped carbon material has been synthesized via a facile and sustainable single-step pyrolysis method using lignin-sulfonate (LS), a by-product of the sulfite pulping process, as a novel carbon precursor and zinc chloride as a chemical activator. The sulfur doping process had a remarkable impact on the LS-sulfur carbon structure. Moreover, it was found that sulfur doping also had an important impact on sodium diclofenac removal from aqueous solutions due to the introduction of S-functionalities on the carbon material’s surface. The doping process effectively increased the carbon specific surface area (SSA), i.e., 1758 m2 g−1 for the sulfur-doped and 753 m2 g−1 for the non-doped carbon. The sulfur-doped carbon exhibited more sulfur states/functionalities than the non-doped, highlighting the successful chemical modification of the material. As a result, the adsorptive performance of the sulfur-doped carbon was remarkably improved. Diclofenac adsorption experiments indicated that the kinetics was better described by the Avrami fractional order model, while the equilibrium studies indicated that the Liu model gave the best fit. The kinetics was much faster for the sulfur-doped carbon, and the maximum adsorption capacity was 301.6 mg g−1 for non-doped and 473.8 mg g−1 for the sulfur-doped carbon. The overall adsorption seems to be a contribution of multiple mechanisms, such as pore filling and electrostatic interaction. When tested to treat lab-made effluents, the samples presented excellent performance.

In this work, we have demonstrated a prompt anodic electrochemical exfoliation of graphite into graphene sheets (GS) in aqueous media. For the synthesis of GS, a constant potential of +10 V has been applied between two identical graphite sheets in 0.1 M aqueous ammonium sulfate. The exfoliated GS were characterized via standard analytical tools such as Fourier transform infra red spectroscopy (FT-IR), X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy with energy dispersive spectrum (FE-SEM with EDS). Further, the electrochemical performance of GS coated Ni foam (GS/Ni foam) was assessed by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques in 2 M KOH. The quasi-rectangular shaped voltammograms and charge-discharge curves in a three-electrode system evidenced the double-layer capacitance of GS and GS/Ni foam which exhibited maximum specific capacitance of 84.8 and 40. 8 F/g at 2 mV/s, and 0.1 A/g of current density, respectively. Moreover, the symmetric two-electrode performance of GS/Ni foam was also examined, which showed good energy density (3.03 Wh/kg) and power density (562.5 W/kg). This study proves that the anodically exfoliated GS can act as a good symmetric supercapacitor in KOH.

Deep eutectic solvents (DES) are considered as a green non-toxic electrolyte for the replacement of cyanide based toxic electrolytes towards the electrodeposition of noble metal and alloy nanoparticles on conducting surfaces. In this work, ruthenium nanoparticles (RuNPs) are electrochemically synthesized over cathodically treated stainless-steel mesh (CSS) by applying the cathodic current of −15 mA/cm² using ruthenium chloride and deep eutectic mixture consists of choline chloride/urea as electrolyte. The resulting material is abbreviated as RuNPs@CSS and are characterized by surface analytical tools such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning elctron microscopy with energy dispersive spectrum (FE-SEM with EDS). Further, the electrocatalytic hydrogen evolution reaction (HER) activity of RuNPs@CSS is accessed and compared with state of art Pt electrode using open circuit potential (OCP), linear sweep voltammetry (LSV), Tafel plot and electrochemical impedance spectroscopy (EIS) measurements in 0.5 M H₂SO₄. The calculated HER's onset potential and over potential @ −10 mA/cm² of RuNPs@CSS are about −0.0273 and −0.0657 V vs. RHE, which are very close to the bare Pt values. The EIS results suggested that, RuNPs@CSS possess excellent conductivity, which decrease the charge transfer resistance and enhances the HER. This study proved that the electrodeposited RuNPs@SS is better replacement for Pt based electrocatalysts towards acidic HER.

The separation of rare earth elements (REEs) has been a persistent challenge in the industrial sector. Despite the development of numerous adsorption materials for rare earth element separation, achieving high adsorption capacity and superior separation selectivity from these materials simultaneously has proven difficult. In this study, we synthesized a nanocomposite material called CoFeM@Be_IIM by combining bentonite clay&apos;s good adsorption capacity with cobalt ferrite&apos;s superior magnetic separation performance (CoFe2O4) and ion-imprinted materials’ high target separation selectivity (IIMs). We used surface ion-imprinting technique to create the material. The ion-imprinted material has a maximum adsorption capacity of 87.6 mg/g for Gd(III), with a selectivity of Gd/La ≈ 28.6, Gd/Nd ≈ 22.6, and Gd/Y ≈ 15.2. The Gd(III)-CoFeM@Be_IIM showed good reusability for up to five cycles. Our work presents a new magnetic ion-imprinted nano-adsorbent as a reliable and effective solution for recovering and utilizing REEs from industrial wastewater.

Rare earth metals (REEs) are crucial for modern industries and technological development. Their extraction from non-renewable primary sources has almost reached its threshold due to excessive global demand. An effectual approach for REEs recovery is recycling secondary sources governed by separation materials. In this work, a novel glutenin-based Na-bentonite (Gle@Na_Bex:y) composite was produced via the in-situ hydrothermal route followed by a subsequent freeze-drying process. Additionally, a possible production route for the composites was proposed. The novel Gle@Na_Bex:y composites were characterized with Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area, and zeta potential (ZP) measurements. FTIR results complemented with SEM images and XRD measurements confirmed the successful incorporation of glutenin into the Na-bentonite clay. The separation of REEs from aqueous solution was used as a model system to demonstrate the material’s ability for selective metal recovery. The best conditions (T, pH, time) for REE sorption were assessed using equilibrium batch adsorption experiments. The kinetics of REE adsorption were effectively explained by a pseudo-second-order model; all the adsorption equilibrium data followed the Langmuir model. Thermodynamic investigations revealed that the adsorption is endothermic and spontaneous, and the adsorption of REEs occurred through a chemisorption process. The sorption mechanism of REE ions was investigated using molecular modelling. The results of this study demonstrate the feasibility of utilizing Gle@Na_Be50:50 composite as an efficient material for REEs removal. The maximum adsorption capacities of Y³⁺, La³⁺, and Nd³⁺ achieved with Gle@Na_Be_50:50, were 76.87, 56.71, and 74.61 mg/g, respectively. This work offers a new route for engineering, valuable composite materials for the separation of REEs from diverse sources.

Rare earths (REs) incorporated in glasses, mostly in the form of RE3+ ions, have several applications such as lasers and optical amplifiers, spectral conversion layers for solar cells, light emitters and sensors. In this context, both the composition and the structural properties of the glass, as well as the dopant concentration play an important role in determining the optical properties and the efficiency of the system. Usually, the concentration of REs is small, below 1 at%, to avoid clustering and optical quenching. In this paper, we report the case of sol–gel Eu-doped silica–soda glass films. The addition of soda to silica can reduce RE clustering and precipitation, according to molecular dynamic simulations, but brings structural instabilities to the network. Here, sodium was varied from 10 to 30 at% and Eu from 0 to 8 at%. It was shown that Eu plays a significant role in the stabilization of the matrix, improving the transparency, the refractive index and the thickness of the films. The increase of Eu concentration provides a decrease of site symmetry and an increase of quantum efficiency (QY), reaching 71% for the highest 8 at% Eu doping, with remarkable absence of concentration quenching.

Copper oxide nanostructures have great potential use in a plethora of nanotechnology applications including nanoelectronics, photovoltaics, sensors, electrochemistry, and pharmacology. In the present work we show how hierarchically nano‐structured copper oxide and hydroxide may be prepared through self‐assembly from CuSO4 salt and silicate solutions using the chemobrionic growth process of a chemical garden. Procedures were explored using the cupric salt in either solid (pellet and seed growth methods) or liquid phase (fluid injection techniques). Self‐assembling nanostructures were characterized by means of environmental scanning electron microscopy (ESEM) with energy‐dispersive X‐ray spectroscopy (EDX) analysis, micro‐Raman spectroscopy and X‐ray diffraction. Our results show the formation of crystalline aggregates of copper oxide and hydroxide in complex hierarchical nanostructured forms including fans, flowers, petals, skeins, lentils, and sheaves. Analytical methods corroborate that these nanostructures may be selected in shape and chemical composition with the reaction conditions.

The aim of this study was to investigate the biomimetic precipitation processes that follow the chemical-garden reaction of brines of CaCl2 and sulfate salts with silicate in alkaline conditions under a Mars-type CO2-rich atmosphere. We characterize the precipitates with Environmental Scanning Electron Microscope micrography, micro-Raman spectroscopy, and X-ray diffractometry. Our analysis results indicate that self-assembled carbonate structures formed with calcium chloride can have vesicular and filamentary features. With magnesium sulfate as a reactant a tentative assignment with Raman spectroscopy indicates the presence of natroxalate in the precipitate. These morphologies and compounds appear through rapid sequestration of atmospheric CO2 by alkaline solutions of silica and salts.

Perchlorates have been found widespread on the surface of Mars, their origin and degradation pathways are not understood to date yet. We investigate here, from a theoretical point of view, the potential redox processes that take place in the interaction of Martian minerals such as olivine, with anhydrous and hydrated perchlorates. For this theoretical study, we take as mineral substrate the (1 0 0) surface of forsterite and calcium perchlorate salt as adsorbate. Our DFT calculations suggests a reduction pathway to chlorate and chlorite. When the perchlorate has more than 4 water molecules, this mechanism, which does not require high-temperature or high energy sources, results in parallel with the oxidation of the mineral surface, forming magnesium peroxide, MgO2, and in the formation of ClO3, which through photolysis is known to form ClO-O2. Because of the high UV irradiance that reaches the surface of Mars, this may be a source of O2 on Mars. Our results suggest that this process may be a natural removal pathway for perchlorates from the Martian regolith, which in the presence of atmospheric water for salt hydration, can furthermore lead to the production of oxygen. This mechanism may thus have implications on the present and future habitability of the Martian surface.

This study investigates the impact of powder aging on the degradation of AlSi10Mg powder during processing in laser powder bed fusion. Powder aging as result of handling, continuous storage and recycling is a fundamental concern for aluminum alloys as it introduces oxygen to the feedstock material. In this work, the analysis of the powder properties, affected by laser exposure and the aging procedure, showed a change of chemical and morphological characteristics of the powders in virgin and aged conditions. The oxygen content in the powders appeared to have a significant effect on the powders' surface appearance and light absorbance, gradually deteriorating the processability of the powders with the increase of oxygen level. Optical microscopy and X-ray computed tomography were used to analyze the porosity distribution in the printed part samples, identifying the origin, size and location of the pores. A direct relationship between the pore occurrence in final parts and the oxygen content in the powders was observed, revealing a higher degree of porosity in the aged powder sample (6.5%) in comparison with the virgin state (3.16%). The evolution of mechanical properties in the part samples after laser processing and powder aging was also studied, demonstrating a rapid decrease of ultimate tensile strength and elongation from virgin condition to aged.

The processing of multicomponent (Ti_0.25V_0.25Zr_0.25Hf_0.25)B₂ ultra-high temperature hexagonal transition metal diboride in dual-phase and single-phase microstructures and investigation of oxidation behavior in the air at 1000 and 1500 °C are reported. The dual-phase diboride is a metastable phase composed of Hf-Zr-rich and Ti-V-rich phases that undergo phase transformation to a single-phase high-entropy diboride after thermal annealing. At 1000 °C, a B₂O₃ layer was formed on the material's surface, and the oxidation kinetics followed a para-linear behavior. At 1500 °C, a porous oxide layer was formed, facilitating oxygen diffusion and reaction with the diboride, resulting in linear oxidation kinetics. The prediction of the lifetime of the materials during high-temperature oxidation suggested that the high-entropy material outperforms the dual-phase diboride, making it most suitable for related applications. The superior performance of the high-entropy single-phase diboride was associated with the high-entropy and sluggish diffusion effects.

Transition metal borides have a unique combination of high melting point and high chemical stability and are suitable for high temperature applications (>2000 °C). A metastable dual-phase boride (Ti_0.25V_0.25Zr_0.25Hf_0.25)B₂ with distinct two hexagonal phases and with an intermediate entropy formation ability of 87.9 (eV/atom)⁻¹ as calculated via the density functional theory (DFT) was consolidated by pulsed current sintering. Thermal annealing of the sintered dual-phase boride at 1500 °C promoted the diffusion of metallic elements between the two boride phases leading to chemical homogenization and resulted in the stabilization of a single-phase high-entropy boride. Scanning electron microscopy, in situ high temperature x-ray diffraction, and simultaneous thermal analysis of the as-sintered and annealed high-entropy borides showed the homogenization of a dual-phase to a single-phase. The experimentally obtained single-phase structure was verified by DFT calculations using special quasirandom structures, which were further used for theoretical investigations of lattice distortions and mechanical properties. Experimentally measured mechanical properties of the single-phase boride showed improved mechanical properties with a hardness of 33.2 ± 2.1 GPa, an elastic modulus of 466.0 ± 5.9 GPa, and a fracture toughness of 4.1 ± 0.6 MPa m^1/2.

Mitigation of greenhouse gas emissions, especially CO2, highlights the critical demand for efficient CO2 capture technologies. This is due to their essential role in climate change and their profound impact on global ecosystems and human well-being. Activated carbons have emerged as promising candidates for CO2 capture due to their availability, cost-effectiveness, and tunable properties. In this study, activated carbons were synthesized from sawdust carbonized at various temperatures within the 700–1100 °C range and subsequently activated using CO2. Comprehensive characterization was conducted through SEM, FESEM, XRD, TGA, and FTIR techniques to assess the properties. The results reveal that carbonization at 1000 °C yielded an activated carbon with a hierarchical and microporous structure, featuring surface area, pore volume, and pore size of 1651.34 m2/g, 0.69 cm³/g, and <1.76 nm, respectively. Remarkably, this activated carbon exhibited promising CO2 uptake of 9.2 mmol/g at 25 °C and 1 bar. Moreover, a remarkable recyclability over 10 cycles demonstrates its potential for practical CO2 capture applications. Furthermore, the synthesized activated carbon exhibited high selectivity for CO2 over N2 (85/15 v/v), reaching 40.2 at 1 bar and 25 °C. These findings underscore the viability of the as-prepared activated carbon as a desired candidate for efficient and selective CO2 capture, contributing to the ongoing efforts to mitigate the impact of anthropogenic CO2 emissions to the environment.