This study reveals the critical chemical and physical roles of ultrasound in enhancing contact-electro-catalysis (CEC), using the methane (CH4) oxidation process as a model system. By integrating density functional theory (DFT), ab initio molecular dynamics (AIMD), and targeted experiments, we demonstrate for the first time that ultrasonic treatment significantly modifies the solid material’s (i.e. CEC catalyst) surface chemistry and morphology, leading to enhanced catalytic performance. FTIR and Raman spectroscopy analyses reveal distinct molecular-level changes in the tested solid material (i.e. fluorinated ethylene propylene (FEP)) following ultrasonication, specifically the formation of C–H bonds, aligning closely with theoretical spectra predictions. Additionally, ultrasound induces substantial physical alterations, tripling the surface roughness of FEP, and significantly elevating fluoride ion concentrations in the surrounding solution, indicating pronounced C–F bond cleavage. AIMD simulations further elucidate that ultrasound-generated radicals initiate homogenous catalytic pathways by cleaving C–H bonds in CH4, identifying this as a critical mechanistic step previously unclarified. Those induced structural defects in FEP could also simultaneously enhance heterogeneous catalytic activity. Our findings establish a comprehensive mechanistic framework that resolves prior ambiguities in ultrasound-assisted CEC processes, offering robust theoretical and experimental foundations for advancing CEC catalytic efficiency and guiding future CEC catalyst development.

The incorporation of 2D materials into memristive devices has boosted advancements in non-volatile memory (NVM), and other related applications including brain inspired neuromorphic systems, artificial intelligence (AI)-machine learning (ML), optoelectronics, photonics, implementing arithmetic operations, and hybrid CMOS architectures. These advancements have taken place among limitations on silicon-based flash and surging data demands, stimulating the research of innovative materials and architectures, particularly for the next generation memory devices. This comprehensive review expands upon the cutting-edge developments in 2D material-based memristors, including their fabrication techniques, performance evaluation, fundamental properties, diverse applications, further challenges in their modernization, and future road map. By emphasizing the distinct characteristics of 2D materials, we reviewed their memristive behavior and highlighted the major contributions by leading researchers over the years. Focus of this review is on the incorporation of graphene (derivatives of graphene), transition metal dichalcogenides (TMDs), and other 2D materials (like MXenes and nanocomposites) in various memristive architectures. The review paper systematically explored the specific roles of graphene and other 2D materials in memristor devices including their use as electrodes, active layers, barrier layers, interfacial layers, and tunnel layers. The major challenges faced by the 2D material based memristor technology hindering their advancement have been critically reviewed including the scalability, yield, hardware implementation, performance enhancement, fabrication techniques, material/device engineering, and commercialization of these devices. Workable solutions to those problems along with the clear and comprehensive road map of future directions for addressing these hurdles have been recommended to unlock the full potential of this transitional technology. This review provides an authoritative resource and compelling rationale for researchers working towards metamorphic memristor solutions by emphasizing the imperative role of 2D materials.

The long-term intelligent machine condition monitoring system is essential in improving maintenance costs and decision-making. Triboelectric nanogenerator (TENG) has a great advantage in developing self-powered machine condition monitoring. The main issues preventing TENG for such applications are poor integration to machine components, limited operational range, and weak durability. In this work, durable non-contact TENG energy harvester adaptive is designed to mechanical shafts for harvesting rotational energy. The harvester is designed to automatically switch to the non-contact mode by using centrifugal force to avoid manual switching while operating over a wide range of speeds of 0–2000 rpm. The designed TENG generates a high output of up to 25 mW with excellent stability for >20 days of continuous operation and exhibits a high-power density of 286 W m−3. Moreover, a self-powered long-term continuous condition monitoring system is developed from a TENG sensor, energy harvester, and wireless module. The developed system successfully sends possible machine fault frequency every 74 min to the cloud and accessible anywhere. This is the only TENG design reported in the literature that can fully power a Wi-Fi module to send data. Hence, the result promises the practical application of the system in developing internet of things (IoT) in the Industry.

Two-dimensional (2D) systems serve as promising platforms for engineering nanoscale devices and for exploring emergent quantum phenomena. The recent experimental realization of AlSb in a double-layer honeycomb (DLHC) configuration confirms the prior theoretical predictions that traditional semiconductors are stable in DLHC configurations at the ultrathin limit and paves the way for systematic exploration of structurally robust DLHC materials. In this work, we have studied In-based InA (A = P, As, Sb, or Bi) in wurtzite, zincblende, DLHC, and AA configurations and found that all the pristine InA structures energetically prefer the DLHC structure. The Z2 topological invariant number calculation showed that the pristine case is topologically trivial. Furthermore, using the energetically favored configuration, we tailored a Janus In2AB (A and B = P, As, Sb, or Bi) that breaks the inversion symmetry. Topological property calculations under the hybrid HSE06 functional reveal that three out of six compounds (In2PSb, In2AsSb, and In2BiSb) exhibit nontrivial topology with system band gaps of 527, 456, and 649 meV, respectively. The presence of gapless edge states further confirmed the nontrivial topological property of these compounds. Moreover, In2PSb also showed a significant isotropic Rashba splitting, with a Rashba parameter of αR = 1.45 eV Å. These materials with nontrivial topology and Rashba-like splitting might have meaningful applications in spintronics. 

Understanding competitive adsorption behaviors and pore-filling mechanisms of multicomponent gas mixtures in metal–organic frameworks (MOFs) is essential for advancing gas separation technologies. This study explores the adsorption dynamics of CO2, CH4, and N2 in MIL-101(Cr), demonstrating how its unique topological structure determines adsorption capacity and governs competitive interactions. Pure CO2 and N2 exhibit edge-to-center pore-filling sequences, while CH4 fills from the center outward. In mixed gas systems, CH4 dominates by reshaping the spatial distribution and filling sequence of CO2 and N2, while its own adsorption remains stable. Excess CO2 or CH4 inhibits competing gases from accessing adsorption sites, whereas excess N2 enhances CH4 adsorption, revealing a nuanced interplay of competitive effects. Furthermore, these interactions influence gas mobility, with excess molecules reducing the self-diffusion coefficients of other gases while increasing their own. This work also introduces a novel computational framework that integrates molecular-scale simulations with process-scale modelling to predict breakthrough curves of gas mixtures with high accuracy. The proposed two-stage adsorption process highlights MIL-101(Cr)’s exceptional potential for purifying CH4 from coal bed methane and biogas under ambient conditions. These findings underscore the utility of MIL-101(Cr) and computational innovations for sustainable energy applications and greenhouse gas mitigation.

Driven by the potential applications of ionic liquid (IL) flow for charging graphene-based surfaces in many emerging technologies, recent research efforts have focused on understanding ion dynamics and structuring at IL–graphene interfaces. Here, graphene colloid probe (GrP) atomic force microscopy (AFM) was used to probe the dynamics and ion structuring of 1-butyl-3-methylimidazolium tetrafluoroborate at graphene surfaces under various bias voltages. In particular, the AFM-measured nanofriction provides a good measure of the dynamic properties of the ILs at graphene surfaces. Compared with the IL at the unbiased graphene surface (0 V), the charged graphene surfaces with either negative (–1, –2 V) or positive (+1, +2 V) voltages favor a reduction in the friction coefficient by the IL. A higher magnitude of the bias voltage applied on the graphene surface with either sign (–2 or +2 V) results in a smaller friction coefficient than that at –1 and +1 V. In combination with the AFM-probed contact stiffness, adhesion forces, and ion structuring force curves with an ion orientational distribution according to molecular dynamics (MD) simulations, we discovered that the unbiased graphene surface (0 V) possesses randomly structured IL ions and that the graphene colloid probe is more likely to become stuck, resulting in more energy dissipation to contribute to a larger friction coefficient. Biasing of the graphene surface under either negative or positive voltages resulted in uniformly arranged ions, which produced a more ordered ion structure and, thus, a smoother sliding plane to reduce the friction coefficient. Electrochemical impedance spectroscopy (EIS) for the IL with graphene as an electrode demonstrated a greater ionic conductivity in the IL paired with the biased graphene than in the unbiased one, implying faster ion movement at the charged graphene, which is beneficial for reducing the friction coefficient.

With growing environmental concerns and resource depletion, developing green lubricants is essential. This study presents a lignosulfonate (LS)-based hydrogel grease, synthesized via a one-step, eco-friendly process at room temperature. Ammonium persulfate (APS) initiated polymerization and crosslinking, with ferric chloride (FeCl₃) as a secondary crosslinker. The 15 % LS hydrogel reduced the coefficient of friction (COF) by 37.5 % and wear volume by 31.25 % compared to the 0 % LS sample. A chemically adsorbed tribofilm, rich in oxygen and sulfur, formed on worn surfaces, enhancing lubrication and wear resistance. This study highlights LS hydrogels as promising green lubricants, offering improved tribological performance and environmental sustainability.

The requirement for sustainable and environmentally friendly materials has led to the exploration of lignin as a potential candidate for protective coatings in various industrial applications. Recent researches demonstrate the feasibility of lignin-based coatings for enhancing wear and corrosion resistance. The lignin improved the coating’s barrier properties and prevented corrosive electrolytes from contacting the metal. The lignin additives also functionalised wear resistance coating. This review points out the improvements in using lignin extraction to produce high-quality materials suitable for corrosion and wear resistance coating purposes. However, the application of lignin in coatings faces significant challenges, primarily due to its heterogeneous and complex nature, which complicates the attainment of uniform and reliable coating qualities. Moreover, it emphasises the need for further studies on lignin to harness lignin’s potential. Future research needs include the development of standardised methods for lignin characterisation and modification, the exploration of novel lignin-based composites and the evaluation of lignin coatings in real-world applications. This review probes into the burgeoning field of lignin-based coatings, evaluating their potential for wear and corrosion resistance, and discusses the current state of research, challenges and future directions in this promising area.

Triboelectric nanogenerators (TENGs) generate electricity through contact electrification. However, the output power is limited by several factors across materials, device design, and mechanical systems. This article aims to analyze several strategies for enhancing the outputs of TENGs across four key aspects: (1) The fundamentals of charge generation to establish effective strategies for designing or selecting tribo-materials, including recent practical approaches to surface and bulk modifications; (2) structural designs that maximize TENG output; (3) the output enhancement strategies tailored to different types of mechanical energy for practical applications; and (4) mechanical systems that effectively modulate external mechanical energy to increase TENG output. Finally, we provide a future outlook, highlighting open opportunities and remaining challenges for TENGs.