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.

Ultraviolet (UV) photodetectors (PDs) are essential for a range of applications, such as space exploration, radiation monitoring, electronics manufacturing, etc. Zinc oxide (ZnO), a wide-bandgap n-type semiconductor, demonstrates high sensitivity to UV light, making it a promising material for UV PDs. This study investigates the impact of rare-earth (RE) doping–especially (lanthanum (La), neodymium (Nd), and dysprosium (Dy)–on the photodetection performance of ZnO based UV PDs. Hydrothermally synthesized RE: ZnO nanostructures were incorporated into fabricated RE: ZnO-Cu2O UV PDs, leading to significant performance enhancements. We present a detailed analysis of structural, morphological, and optoelectrical properties. Results show that RE incorporation transforms ZnO nanoparticles morphology into flake-like structures and increases charge carrier density (confirmed by Mott-Schottky measurements). These modifications yield enhanced photocurrent efficiency and charge carrier density, leading to superior photodetection capabilities. The RE-doped configuration also demonstrates improved response and decay times in UV photodetection studies. This study underscores the potential of RE doping to markedly enhance the performance of ZnO-based UV-PDs.

Thermally-activated delayed fluorescence (TADF) materials have received significant attention for their ability to harvest both singlet and triplet excitons via reverse intersystem crossing (rISC), enabling near 100% internal quantum efficiency without relying on scarce heavy-metal complexes. While TADF emitters are largely used in organic light-emitting diodes (OLEDs), their implementation in organic light-emitting transistors (OLETs), a device platform that uniquely combines transistor switching and light emission, remains relatively underexplored. In this work, we fabricated and investigated the integration of 2CzPN, a blue-emitting TADF molecule, doped into the high-triplet-energy host DPEPO in different architectures to explore their potential for efficient and colour-tunable light emission. We explored multilayer heterostructures which include (or not) an electron transport layer, and we found that an approximate 10 wt% doping of 2CzPN in the DPEPO host yielded optimal performance in all cases. However, two-layer devices (no electron transport layer) exhibited intrinsic emission, typical of 2CzPN, while the addition of the electron transport layer led to both a redshift of the emission (green emission) and the onset of an additional spectral contribution due to the formation of interfacial exciplexes at the emissive layer/e-transport interface. Our results demonstrate the dual advantage of TADF emitters in field-effect devices: efficient triplet harvesting and tunable emission via interface engineering, thus suggesting the importance of optimizing both emitter design and device architecture for high-performance, color-tunable organic transistors.

We present a systematic investigation on the structural and physical features of a series of ternary Prussian blue analogues (t-PBAs) based on cobalt, nickel, and iron (Co/Ni ratio varied from 0 to 1), coupled with the study of their electrochemical performance as potential supercapacitors. The materials are prepared through the well-established coprecipitation method in water, proving it as a robust approach for a fine on demand modulation of their composition. The increase of the Co content rules the extent of crystallite sizes, as well as the strength of the bond in the iron-cyanide ligand, through internal charge exchange between these two transition metal ions. The relative amount of Co and Ni, on the other hand, significantly affects their electrochemical behavior: the formal potentials, the current generated under voltage scanning, the resistance to long bias solicitations, and the characteristics of galvanostatic charge–discharge are all affected by this parameter. A mixed charge storage control mechanism is observed for both capacitive and diffusive processes for the entire batch. The supercapacitive behavior is investigated as well, showing no obvious dependence on material composition, although fairly good performance in terms of capacitance and capacitance retention is recorded.

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.

Rationalizing material features according to the adopted synthetic strategy, aiming then to tune them on demand, is among the most relevant purposes of investigation in materials science. Herein, the systematic analysis of the dependence of graphitic carbon nitride (g-C3N4) physical characteristics on the decomposition temperature of urea, rationalizing the impact of synthetic temperature on several characteristics of the materials (degree of N–H condensation, carbon vs nitrogen content, structural parameters, photoluminescence lifetime, surface area, pores volume), is discussed. g-C3N4 nanostructures are fabricated by thermal decomposition of urea at different temperatures under ambient atmosphere, obtaining an almost ideal stoichiometry (C/N = 0.72) when setting the temperature at 600 °C. The samples show structural, textural, compositional, and optical differences directly depending on the fabrication temperature: specific surface area, pore volume and size, intralayer distance, and speed of radiative recombination of photogenerated charges are proportionally enhanced by increasing the synthesis temperature. The role played by all the physicochemical features of the prepared samples in promoting the catalytic degradation of Rhodamine B is investigated, highlighting their synergistic role in enhancing the catalytic efficiency. Significant differences in the dye degradation are recorded when using either UV or solar simulated light, demonstrating that Rhodamine B photosensitization rules the process.

Binary and ternary composites of BiOI with NH2-MIL-101(Fe) and a functionalized biochar were synthesized through an in situ approach, aimed at spurring the activity of the semiconductor as a photocatalyst for the removal of ciprofloxacin (CIP) from water. Experimental outcomes showed a drastic enhancement of the adsorption and the equilibrium (which increased from 39.31 mg g–1 of bare BiOI to 76.39 mg g–1 of the best ternary composite in 2 h time), while the kinetics of the process was not significantly changed. The photocatalytic performance was also significantly enhanced, and the complete removal of 10 ppm of CIP in 3 h reaction time was recorded under simulated solar light irradiation for the best catalyst of the investigated batch. Catalytic reactions supported by different materials obeyed different reaction orders, indicating the existence of different mechanisms. The use of scavengers for superoxide anion radicals, holes, and hydroxyl radicals showed that although all these species are involved in CIP photodegradation, the latter play the most crucial role, as also confirmed by carrying out the reaction at increasing pH conditions. A clear correlation between the reduction of BiOI crystallite sizes in the composites, as compared to the bare material, and the material performance as both adsorbers and photocatalyst was identified. 

Cu2O is a narrow band gap material serving as an important candidate for photoelectrochemical hydrogen evolution reaction. However, the main challenge that hinders its practical exploitation is its poor photostability, due to its oxidation into CuO by photoexcited holes. Here, we thoroughly minimize the photo-oxidation of Cu2O nanowires by growing a thin layer of the TiO2 protective layer and an amorphous layer of the VOx cocatalyst using magnetron sputtering and atomic layer deposition, respectively. After optimization of the protective and the cocatalyst layers, the photoelectrode exhibits a current density of −2.46 mA/cm2 under simulated sunlight (100 mW/cm2) at 0.3 V versus reversible hydrogen electrode, and its performance is stable for an extended illumination time. The chemical stability and the good performance of the engineered photoelectrode demonstrate the potential of using earth-abundant materials as a light-harvesting device for solar hydrogen production.

Hierarchical nanostructures have attracted considerable research attention due to their applications in the catalysis field. Herein, we design a versatile hierarchical nanostructure composed of NiMoO4 nanorods surrounded by active MoS₂ nanosheets on an interconnected nickel foam substrate. The as-prepared nanostructure exhibits excellent oxygen evolution reaction performance, producing a current density of 10 mA cm⁻² at an overpotential of 90 mV, in comparison with 220 mV necessary to reach a similar current density for NiMoO₄. This behavior originates from the structural/morphological properties of the MoS₂ nanosheets, which present numerous surface-active sites and allow good contact with the electrolyte. Besides, the structures can effectively store charges, due to their unique branched network providing accessible active surface area, which facilitates intermediates adsorptions. Particularly, NiMoO₄/MoS₂ shows a charge capacity of 358 mAhg⁻¹ at a current of 0.5 A g⁻¹ (230 mAhg⁻¹ for NiMoO₄), thus suggesting promising applications for charge-storing devices.