Search Results (488)

The vast majority of photocatalysts find it difficult to consistently and stably exhibit high performance due to the variability of sunlight intensity within a day, as well as the high energy consumption of artificial light sources. In this study, mechanoluminescent Sr₂MgSi₂O₇:Eu,Dy phosphors is combined with NiS@g-C₃N₄ composite to construct a ternary heterogeneous photocatalytic system, denoted as NCS. In addition to the enhanced separation efficiency of photogenerated charge carriers by the formation of a heterojunction, the introduction of Sr₂MgSi₂O₇:Eu,Dy provides an ultra-driving force for the photocatalytic reactions owing to its mechanoluminescence-induced excitation. Results show that the degradation rate of RhB increased significantly in comparison with pristine g-C₃N₄ and NiS@g-C₃N₄, indicating the obvious advantages of the ternary system for charge separation and migration. Moreover, the additional photocatalytic activity of NCS under ultrasound stimulation makes it a promising all-weather photocatalyst even in dark environments. This novel strategy opens up new horizons for the synergistic combination of light-driven and ultrasound-driven heterogeneous photocatalytic systems, and it also has important reference significance for the design and application of high-performance photocatalysts. Full article

Intermediate-band photovoltaics promise single-junction efficiencies that exceed the Shockley and Queisser limit, yet viable material platforms and device geometries remain under debate. Here, we perform comprehensive two-dimensional device-scale simulations using Silvaco Atlas TCAD to analyze p-i-n In_0.20Ga_0.80N solar cells in which the intermediate band is supplied by In_0.35Ga_0.65N quantum dots located inside the intrinsic layer. Quantum-dot diameters from 1 nm to 10 nm and areal densities up to 116 dots per period are evaluated under AM 1.5G, one-sun illumination at 300 K. The baseline pn junction achieves a simulated power-conversion efficiency of 33.9%. The incorporation of a single 1 nm quantum-dot layer dramatically increases efficiency to 48.1%, driven by a 35% enhancement in short-circuit current density while maintaining open-circuit voltage stability. Further increases in dot density continue to boost current but with diminishing benefit; the highest efficiency recorded, 49.4% at 116 dots, is only 1.4 percentage points above the 40-dot configuration. The improvements originate from two-step sub-band-gap absorption mediated by the quantum dots and from enhanced carrier collection in a widened depletion region. These results define a practical design window centred on approximately 1 nm dots and about 40 dots per period, balancing substantial efficiency gains with manageable structural complexity and providing concrete targets for epitaxial implementation. Full article

The transition to clean and renewable energy sources is critically dependent on efficient hydrogen production technologies. This review surveys recent advances in photocatalytic water splitting, focusing on MNb₂O₆ nanomaterials, which have emerged as promising photocatalysts due to their tunable band structures, chemical robustness, and tailored morphologies. The objectives of this work are to (i) encompass the current synthesis strategies for MNb₂O₆ compounds; (ii) assess their structural, electronic, and optical properties in relation to photocatalytic performance; and (iii) elucidate the mechanisms underpinning enhanced hydrogen evolution. Main data collection methods include a literature review of experimental studies reporting bandgap measurements, structural analyses, and hydrogen production metrics for various MNb₂O₆ compositions—especially those incorporating transition metals such as Mn, Cu, Ni, and Co. Novelty stems from systematically detailing the relationships between synthesis routes (hydrothermal, solvothermal, electrospinning, etc.), crystallographic features, conductivity type, and bandgap tuning in these materials, as well as by benchmarking their performance against more conventional photocatalyst systems. Key findings indicate that MnNb₂O₆, CuNb₂O₆, and certain engineered heterostructures (e.g., with g-C₃N₄ or TiO₂) display significant visible-light-driven hydrogen evolution, achieving hydrogen production rates up to 146 mmol h⁻¹ g⁻¹ in composite systems. The review spotlights trends in heterojunction design, defect engineering, co-catalyst integration, and the extension of light absorption into the visible range, all contributing to improved charge separation and catalytic longevity. However, significant challenges remain in realizing the full potential of the broader MNb₂O₆ family, particularly regarding efficiency, scalability, and long-term stability. The insights synthesized here serve as a guide for future experimental investigations and materials design, advancing the deployment of MNb₂O₆-based photocatalysts for large-scale, sustainable hydrogen production. Full article

The rapid recombination of photoinduced charge carriers in semiconductors remains a significant challenge for their practical application in photocatalysis. This study presents the design of a step-scheme (S-scheme) heterojunction composed of carbon nitride (g-C₃N₄) and nickel-based metal–organic framework (Ni-MOF) to achieve enhanced charge separation. The establishment of an S-scheme charge transfer configuration at the interface of the Ni-MOF/g-C₃N₄ heterostructure plays a pivotal role in enabling efficient charge carrier separation, and hence, high CO₂ photoreduction efficiency with a CO evolution rate of 1014.6 µmol g⁻¹ h⁻¹ and selectivity of 95% under simulated solar illumination. CO evolution represents an approximately 3.7-fold enhancement compared to pristine Ni-MOF. Density functional theory (DFT) calculations, supported by in situ irradiated X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) experimental results, confirmed the establishment of a well-defined and strongly bonded interface, which improves the charge transfer and separation following the S-scheme mechanism. This study sheds light on MOF-based S-scheme heterojunctions as fruitful and selective alternatives for practical CO₂ photoreduction. Full article

The use of semiconductors for photocatalytic degradation of organic pollutants has garnered considerable attention as a promising solution to environmental challenges. Compared to TiO₂, BiPO₄ exhibits superior photocatalytic activity. However, its large band gap restricts its light absorption to the UV region. One effective technique for extending BiPO₄’s absorption wavelength into the visible spectrum is the construction of the heterostructure. This study aimed to synthesize monodisperse BiPO₄ nanorods via a solvothermal approach and fabricate BiPO₄/g-C₃N₄ heterojunctions with varying loadings through in situ deposition. Tetracyclines were employed as the target pollutant to evaluate the photocatalytic performance and stability of the prepared materials. The results indicated that 5 wt% of composite exhibited better photocatalytic performance than single catalysts, which showed the highest photodegradation efficiency of approximately 98% for tetracyclines. The prepared bi-photocatalyst presented favorable stability under sunlight irradiation, the photocatalytic activity of which remained almost unchanged after four cycles. The enhanced photocatalytic activity was attributed to the synergistic effect. Additionally, the possible degradation mechanism was elucidated utilizing the semiconductor energy band theory. Overall, this work presents new perspectives on synthesizing innovative and efficient visible-light-driven photocatalysts. It also offers a mechanistic analysis approach by integrating theoretical calculations with experimental observations. Full article

Graphitic carbon nitride (g-C₃N₄) is emerging as one of the most promising non-metallic semiconductors for the degradation of pollutants in water by photocatalytic processes. Its exceptional reduction–oxidation (redox) potentials and adequate band gap of approximately 2.7 eV give it the ability to absorb in the visible light range. However, the characteristic sensitivity to light absorption is limited, leading to rapid recombination of electron–hole pairs. Therefore, different strategies have been explored to optimize this charge separation, among which the formation of heterostructures based on g-C₃N₄ is highlighted. This review addresses recent advances in photocatalysis mediated by g-C₃N₄ heterostructures, considering the synthesis methods enabling the optimization of the morphology and active interface of these materials. Next, the mechanisms of charge transfer are discussed in detail, with special emphasis on type II, type S, and type Z classifications and their influence on the efficiency of photodegradation. Subsequently, the progress in the application of these photocatalysts for the degradation of water pollutants, such as toxic organic dyes, pharmaceutical pollutants, pesticides, and per- and polyfluoroalkyl substances (PFAS), are analyzed, highlighting both experimental advances and remaining challenges. Finally, future perspectives oriented towards the optimization of heterostructures, the efficiency of synthesis methods, and the practical application of these in photocatalytic processes for environmental remediation. Full article

Lithium–sulfur (Li-S) batteries are hindered by the sluggish electrochemical kinetics and poor reversibility of lithium polysulfides (LiPSs), which limits their practical energy density and cycle life. In order to address this issue, a novel Ni₃N/Nb₄N₅ heterostructure was synthesized via electrospinning and nitridation as a functional coating for polypropylene (PP) separators. Adsorption experiments were conducted in order to ascertain the heterostructure’s superior affinity for LiPSs, thereby effectively mitigating their shuttling. Studies of Li₂S nucleation demonstrated the catalytic role of the substance in accelerating the deposition kinetics of Li₂S. Consequently, Li-S cells that employed the Ni₃N/Nb₄N₅-modified separator were found to achieve significantly enhanced electrochemical performance, with the cells delivering an initial discharge capacity of 1294.4 mAh g⁻¹ at 0.2 C. The results demonstrate that, after 150 cycles, the cells retained a discharge capacity of 796.2 mAh g⁻¹, corresponding to a low capacity decay rate of only 0.25% per cycle. In addition, the rate capability of the cells was found to be improved in comparison to control cells with NiNb₂O₆-modified or pristine separators. Full article

This work presents the improvement of the electro-optical response of n-type crystalline silicon via dip-coated graphene oxide (GO) thin films. GO was deposited on Si/SiO₂ by immersion, and the resulting heterostructures were characterized by cyclic voltammetry measurements and Raman spectroscopy. Raman analysis revealed a slight but measurable broadening (~0.7 cm⁻¹) of the Si TO phonon mode at 514 cm⁻¹, indicating local interfacial strain. Cyclic voltammetry measurements showed a substantial increase in photocurrent in comparison to pristine silicon substrates. These effects are attributed to a GO-induced p-type inversion layer and enhanced interfacial charge transfer. The results suggest that GO can serve as a functional interfacial layer for improving silicon-based optoelectronic and photoelectrochemical devices. Full article

The synthesis of graphitic carbon nitride (g-C₃N₄) coupled with tin sulfide (SnS) has been identified as an effective method for improving the photocatalytic and electrochemical performance of SnS, a promising material for environmental and energy-related applications. In this study, we focused on how g-C₃N₄ influences the structural, optical, electrochemical, and functional properties of SnS. XRD and FTIR confirmed the formation of SnS/g-C₃N₄ heterostructure, while surface morphology analysis by SEM showed proper dispersion of SnS particles over g-C₃N₄ with a good interface contact. The SnS/g-C₃N₄ composite itself demonstrated improved photocatalytic performance, with the degradation rate of methylene blue reaching approximately 94% under visible light irradiation compared to the moderate activity of SnS. This enhancement can be credited to the successful charge carrier separation enabled by the type II heterojunction created between SnS and g-C₃N₄. Moreover, the composite presented improved electrochemical activity with a specific capacitance of 1340 F·g⁻¹ at a scan rate of 10 A·g⁻¹ and good cycling stability, where the capacitance was 92% after 5000 cycles. As such, these SnS/g-C₃N₄ composites suggest the specific application of this class of material in photocatalytic degradation as well as energy storage, putting forward new effective resolutions to environmental and energy issues. Full article

Recent advancements in biomarker technology have revolutionized diagnostic and monitoring applications, yet their potential in food quality assessment remains largely untapped. Herein, we report a breakthrough in gas-sensitive nanocomposite engineering through the design of α-Fe₂O₃-NiO heterostructures synthesized via a single-step hydrothermal protocol. The introduction of NiO led to increased oxygen vacancies and active sites, thereby reducing the sensor’s operating temperature. Additionally, the P-N heterojunction structure promoted the redistribution of electrons and hole, thus enhancing its conductivity. The optimized sensor exhibited high sensitivity (75.5% at 100 ppm), fast response/recovery (20 s/92 s), and perfect selectivity for NH₃ at room temperature. In the end, based on this sensor and combined with a Programmable Logic Controller (PLC), a rapid and nondestructive meat spoilage detection system was constructed to reflect the degree of spoilage of meat with the help of NH₃ concentration, providing a valuable strategy for the application of biomarker detection in the food industry. Full article

Triethylamine (TEA), a volatile organic compound (VOC), has important applications in industrial production. However, TEA has an irritating odor and potential toxicity, making it necessary to develop sensitive TEA gas sensors with high efficiency. This study focused on preparing LaFeO₃ nanoparticles modified by SnS₂ nanosheets (SnS₂/LaFeO₃ composite) using a hydrothermal method together with sol–gel technique. According to the comparison results of the gas-sensing performance between pure LaFeO₃ and SnS₂/LaFeO₃ composite with varying composition ratios, 5% SnS₂/LaFeO₃ sensor had a sensitivity for TEA that was 3.2 times higher than pure LaFeO₃ sensor. The optimized sensor operates at 140 °C and demonstrates strong stability, selectivity, and long-term durability. Detailed analyses revealed that the SnS₂ nanosheets enhanced oxygen vacancy (O_V) content and carrier mobility through heterojunction formation with LaFeO₃. This study provides insights into improving gas-sensing performance via p-n heterostructure design and proposes a novel LaFeO₃-based material for TEA detection. Full article

The structural parameters and electronic structures of Sc- and Y-based nitride semiconductors that adopted hexagonal BN-like atomic sheets were investigated with calculations based on density functional theory (DFT). A hybrid exchange-correlation functional and spin–orbit coupling were employed for studies on the band structures. A strong variation in the band gap type, as well as the width, was revealed not only between the monolayer and bulk materials but also between the multilayer systems. An exceptionally wide range of band gaps from 1.39 (bulk) up to 3.59 eV (three layers) was obtained for two-dimensional materials based on ScN. This finding is related to two phenomena: significant contributions of subsurface ions into bands that formed a valence band maximum and pronounced shifts in conduction band positions with respect to the Fermi energy between the multilayer systems. The relatively low values of the work function (below 2.36 eV) predicted for the few-layer YN materials might be considered for applications in electron emission. In spite of the fact that the band gaps of two-dimensional materials predicted with hybrid DFT calculations may be overestimated to some extent, the electronic structure of homo- and heterostructures formed by rare earth nitride semiconductors seems to be an interesting subject for further experimental research. Full article

Slight changes in potassium levels can affect health. Therefore, rapid, reliable, and quantitative determination of potassium ion content is important for medical diagnosis. AlGaN, as a semiconductor material with good biocompatibility, has many advantages in the development of new potassium ion sensors. Understanding the adsorption behavior of a specific ion on the AlGaN surface and the eventual effect on AlGaN/GaN’s heterostructure interface is the key to obtaining high-performance nitride sensors. In this paper, we calculated the changes in the density of states and energy bands of the material after AlGaN adsorbed potassium ions through first-principles simulation. Combined with two-dimensional device simulation software, the changes in device performance caused by the changes in material properties are presented. The simulation results show that the adsorption of a single potassium ion can cause a current change in the order of milliamperes, providing a theoretical reference for the subsequent development of high-sensitivity potassium ion sensors. Full article

Utilizing renewable energy for green hydrogen production via electrolyzed seawater is a promising technology for the future. However, undesired chlorine evolution and the corrosive nature of seawater are crucial challenges for direct seawater splitting technology. In this work, heterojunctions of CoS₂/FeS₂ encapsulated in N-doped carbon nanocubes (denoted as CoS₂/FeS₂@NC) were designed by proposing the synchronous pyrolysis and vulcanization of polydopamine-coated coordination polymers. Such a synthetic strategy was demonstrated to be effective in increasing the favorable exposure of active sites, moderately regulating electronic structure, and remarkably facilitating charge transfer due to the controllable generation of unique core–shell structures with suitable carbon shells, leading to the excellent bifunctional electrocatalytic performance and enhanced stability of electrocatalysts. As a result, CoS₂/FeS₂@NC can be revealed as a superior water splitting catalyst, possessing a small voltage of 1.75 V and requiring 100.0 mA cm⁻² in 1 M KOH alkaline solution and 1.80 V for alkaline seawater media, with satisfactory long-term stability. This work presents fresh strategies for designing core–shell heterostructures and developing green technology for hydrogen production. Full article

In order to solve the self-heating problem of power electronic devices, this paper adopts a nonequilibrium molecular dynamics approach to study the thermal transport regulation mechanism of the aluminum nitride/graphene/silicon carbide heterogeneous interface. The effects of temperature, size, and vacancy defects on interfacial thermal conductivity are analyzed by phonon state density versus phonon participation rate to reveal their phonon transfer mechanisms during thermal transport. It is shown that the interfacial thermal conductance (ITC) increases about three times when the temperature increases from 300 K to 1100 K. It is analyzed that the increase in temperature will enhance lattice vibration, enhance phonon coupling degree, and thus increase its ITC. With the increase in the number of AlN-SiC layers from 8 to 28, the ITC increases by about 295.3%, and it is analyzed that the increase in the number of AlN-SiC layers effectively reduces the interfacial scattering and improves the phonon interfacial transmission efficiency. The increase in the number of graphene layers from 1 layer to 4 layers decreases the ITC by 70.3%. The interfacial thermal conductivity reaches a minimum, which is attributed to the increase in graphene layers aggravating the degree of phonon localization. Under the influence of the increase in graphene single and double vacancy defects concentration, the ITC is slightly reduced. When the defect rate reaches about 20%, the interfacial thermal conductance of SV (single vacancy) and DV (double vacancy) defects rises back to 5.606 × 10⁻² GW/m²K and 5.224 × 10⁻² GW/m²K, respectively. It is analyzed that the phonon overlapping and the participation rate act at the same time, so the heat-transferring phonons increase, increasing the thermal conductance of their interfaces. The findings provide theoretical support for optimizing the thermal management performance of heterostructure interfaces. Full article