Search Results (63)

The development of efficient visible-light-driven semiconductor photocatalysts is essential for scalable and sustainable green hydrogen production. Among ternary metal oxides, MV₂O₆ (M = Zn, Ni, Cu, Mn, Co, etc.) metavanadates have attracted considerable interest because of their narrow band gaps (~1.8–2.5 eV), strong visible-light absorption, and unique edge-sharing VO₆ octahedral framework that promotes charge separation. This review summarizes recent advances in the design, synthesis, and electronic engineering of MV₂O₆-based photocatalysts for solar water splitting. Since direct particulate overall water splitting has only been demonstrated for MnV₂O₆, whereas ZnV₂O₆, NiV₂O₆, and CuV₂O₆ have mainly been investigated as photoelectrodes, both particulate photocatalytic and photoelectrochemical (PEC) systems are critically examined. The review clearly distinguishes these two configurations, highlighting how PEC studies provide valuable insights into charge transport, interfacial processes, and reaction kinetics while recognizing the additional challenges associated with suspension-based photocatalysis. Fundamental crystal structures, electronic band alignments, and charge-transfer characteristics of MV₂O₆ compounds are discussed, followed by recent advances in synthesis strategies, including hydrothermal, sol–gel, and deep eutectic solvent (DES)-assisted methods, together with morphology and defect engineering. Particular attention is given to oxygen-vacancy formation and its influence on visible-light absorption and charge separation. Modification strategies, including elemental doping, cocatalyst loading, and the construction of Z-scheme and step-scheme (S-scheme) heterojunctions, are critically evaluated for improving photocatalytic efficiency. Finally, the review discusses the key challenges that limit practical applications, including unfavorable band-edge positions, rapid carrier recombination, sluggish surface reaction kinetics, photostability, and the need to establish composition–structure–activity relationships. Future perspectives emphasize rational materials design through advanced characterization, theoretical calculations, and scalable synthesis approaches to accelerate the development of efficient MV₂O₆ photocatalysts for solar-driven hydrogen production. Full article

The chronic overuse of antibiotics has accelerated the emergence of antibiotic-resistant bacteria, creating a global public health crisis as conventional therapies fail against multidrug-resistant pathogens spreading through water and food chains. Cadmium sulfide (CdS) has been established as an important visible-light-driven photocatalyst for antibacterial applications. This brief review systematically examines the structure–property relationships governing CdS-based antibacterial materials, including crystallographic polymorphs (cubic sphalerite and hexagonal wurtzite), morphological diversity from quantum dots to hierarchical architectures, and synthesis methodologies that critically influence particle size, crystallinity, and surface chemistry. The mechanisms of antibacterial action are elucidated, encompassing photocatalytic reactive oxygen species (ROS) generation, controlled Cd²⁺ ion release, and membrane disruption. A detailed tabulated analysis is presented across three material classes: pristine CdS, binary composites, and ternary Z-scheme heterostructures. Density functional theory (DFT) calculations and molecular docking simulations provide atomic-level insights into charge transfer dynamics and enzyme inhibition mechanisms. Finally, critical challenges, photocorrosion, toxicity, biocompatibility concerns, and scalability limitations are addressed. This review bridges fundamental materials science with antimicrobial applications to guide rational design of next-generation CdS-based antibacterial materials. Full article

The photoreduction of CO₂ is a growingly interesting research topic due to the intriguing possibility of producing solar fuels from a concerning pollutant. TiO₂ photocatalysts were the first materials used for this application, but since then, various strategies have been developed to optimise the catalytic performance and operating conditions to obtain competitive yield. This review presents the findings of the last decade of research on different semiconductors, TiO₂ and g-C₃N₄ and their composites. The main features of the reaction and its key issues are first overviewed, focusing on the effect of different reaction conditions on the performance and recalling the mechanism of the reaction. The strategies developed to overcome the challenges of this demanding reaction are described in the following paragraphs, including the use of dopants or co-catalysts, heterojunctions between different semiconductors and the use of electron transfer mediators. Finally, some unifying concepts are summarised, suggesting the calculation of the stored energy amount and the relative efficiency to allow a safer comparison between literature data collected under widely variable conditions and leading to different products. Full article

It is known that when an n-type semiconductor and a p-type semiconductor (i.e., a p–n junction) are connected, an intrinsic electric field is formed due to the diffusion motion of majority carriers. The direction of this intrinsic electric field in the p–n junction runs from the n-type to the p-type semiconductor (n→p). If the migration directions of photogenerated charge carriers in the conduction band (CB) and valence band (VB) of the two contacting semiconductors align with the direction of the intrinsic electric field in the heterojunction, band-to-band transfer occurs. In experiments using TiO₂-based composite photocatalysts, the heterojunction catalyst forms a structure analogous to a p–n junction relative to CdS/TiO₂; however, due to differing carrier concentrations, TiO₂ exhibits a p-type character while CdS shows an n-type character. Under the influence of the intrinsic electric field, photogenerated electrons migrate to the p-type TiO₂ surface, while holes migrate to the n-type CdS surface. The migration directions of photogenerated electrons and holes in the CB and VB of both CdS and TiO₂ match those observed in a typical p–n junction, confirming that the photocarrier migration mechanism in TiO₂-dominated CdS/TiO₂ systems follows a band-to-band transfer mechanism. When CdS serves as the dominant component, rapid recombination occurs between electrons in TiO₂’s CB and holes in CdS’s VB, resulting in significant electron accumulation in TiO₂’s CB and substantial hole generation in CdS’s VB. Electrons in the CB of TiO₂, which carries a higher negative potential, reduce O₂ to •O₂⁻, while holes in the VB of CdS, possessing a higher positive potential, generate •OH⁻, thereby enhancing photocatalytic activity; thus, the photoexcited carrier transfer mechanism follows Scheme Z. Full article

Pharmaceutical residues in wastewater pose persistent ecological and public health risks, creating an urgent need for efficient and sustainable remediation technologies. MXene-based photocatalysts have attracted growing interest owing to their high electrical conductivity, tunable surface chemistry, abundant active sites, and excellent charge-transfer capability. This review summarizes recent advances in MXene-based photocatalytic systems for pharmaceutical wastewater treatment and renewable energy production. Key topics include pharmaceutical degradation pathways, reactive oxygen species generation, ecotoxicological implications, and the multifunctional roles of MXenes as conductive supports, electron mediators, and cocatalysts. Interfacial engineering strategies, including Z-scheme, S-scheme, and Schottky heterojunctions, are discussed with respect to light absorption, charge separation, and interfacial redox reactions. Practical considerations, such as reactor design, life cycle assessment, and techno-economic feasibility, are also addressed. Finally, current challenges and future directions are highlighted, particularly scalable fluorine-free synthesis, improved oxidative stability, and machine learning-assisted material design. This review provides a concise framework for developing stable, efficient, and scalable MXene-based photocatalytic platforms for pharmaceutical wastewater remediation and sustainable energy generation. Full article

Hydrogen peroxide (H₂O₂) is an important green oxidant, and developing efficient visible-light-driven routes for its synthesis is highly desirable. Herein, a CN/Zn_V-ZCS composite photocatalyst was constructed by coupling g-C₃N₄ (CN) with Zn-vacancy-containing ZnCdS (Zn_V-ZCS) for photocatalytic H₂O₂ production. The optimized CN/Zn_V-10 delivered 44.58 mmol g⁻¹ H₂O₂ within 60 min under 425 nm LED irradiation, outperforming pristine CN, ZCS, Zn_V-ZCS, and vacancy-free CN/ZCS, with good cycling stability. Trapping and EPR results identify O₂ as the key electron acceptor and ·O₂⁻ as an important intermediate. Structural characterization and XPS results indicate successful Zn-vacancy introduction, intimate heterointerface formation, and interfacial electron redistribution. Combined VB-XPS, photoelectrochemical, and reactive-species analyses suggest that Zn vacancies are favorable for O₂ adsorption/activation, whereas the CN/Zn_V-ZCS heterointerface promotes charge separation and migration. Based on the available evidence, a Z-scheme interfacial charge-transfer pathway is established in the CN/Zn_V-ZCS system. Full article

The construction of Z-scheme heterojunctions is regarded as one of the most effective modification strategies for photocatalysts. However, how to improve the interfacial charge transfer efficiency to further enhance the photocatalytic activity remains an urgent issue to be addressed. In this study, sulfur vacancy-enriched ZnIn₂S₄/MoS₂ Z-scheme heterojunctions (V-ZIS/MS) containing interfacial Mo-S bonds was successfully synthesized using a hydrothermal method. The V-ZIS/2%MS showed the highest hydrogen evolution rate, achieving 19.21 ± 0.78 mmol·g⁻¹·h⁻¹ under visible light and 112.89 ± 10.98 mmol·g⁻¹·h⁻¹ under full-spectrum illumination, which are 5.07 and 4.41 times higher than ZIS (3.79 ± 0.79 mmol·g⁻¹·h⁻¹) and V-ZIS (4.36 ± 0.98 mmol·g⁻¹·h⁻¹) under visible light, respectively, outperforming most reported ZIS-based photocatalysts. This is because the composite of V-ZIS and MS enhanced its light absorption performance. More importantly, the formation of Mo-S bonds at the V-ZIS/MoS₂ interface facilitated efficient charge transfer and reduced interfacial resistance, leading to significantly improved photocatalytic activity. Cycling experiments further demonstrate that V-ZIS/2%MS exhibits considerable photocatalytic stability. X-ray diffraction analysis before and after the reaction further confirmed the structural stability of the catalyst. This work provides a certain reference for the preparation of high-performance ZIS-based photocatalysts. Full article

Defect engineering in semiconductor heterojunctions offers a promising route for enhancing the selectivity of photocatalytic CO₂ conversion. In this work, a ZnS/gel-derived TiO₂ photocatalyst featuring sulfur vacancies introduced via hydrazine hydrate (N₂H₄) treatment is developed. XRD, HRTEM, and XPS analyses confirm the formation of a crystalline heterointerface and a defect-rich ZnS surface, enabling effective interfacial electronic modulation. The optimized ZnS/gel-derived TiO₂-0.48 composite achieves CH₄ and CO yields of 6.76 and 14.47 μmol·g⁻¹·h⁻¹, respectively, with a CH₄ selectivity of 31.8% and an electron selectivity of 65.1%, clearly outperforming pristine TiO₂ and the corresponding single-component catalysts under identical conditions. Photoluminescence quenching, enhanced photocurrent response, and reduced charge-transfer resistance indicate significantly improved interfacial charge separation. Mott–Schottky analysis combined with optical bandgap measurements reveals pronounced interfacial charge redistribution in the composite system. Considering the intrinsic band structure of ZnS and gel-derived TiO₂, a Z-scheme-compatible interfacial charge migration model is proposed, in which photogenerated electrons with strong reductive power are preferentially retained on ZnS, while holes with strong oxidative capability remain on gel-derived TiO₂. This charge migration pathway preserves high redox potentials, facilitating multi-electron CO₂ methanation and water oxidation. Density functional theory calculations further demonstrate that sulfur vacancies stabilize *COOH and *CO intermediates and reduce the energy barrier for *COOH formation from +0.51 eV to +0.21 eV, thereby promoting CO₂ activation and CH₄ formation. These results reveal that sulfur vacancies not only activate CO₂ molecules but also regulate interfacial charge migration behavior. This work provides a synergistic strategy combining defect engineering and interfacial electronic modulation to enhance selectivity and mechanistic understanding in CO₂-to-CH₄ photoconversion. Full article

Currently, continuous population growth and unsustainable industrialization have caused ongoing water pollution, with harmful consequences for human health and the environment. Persistent organic pollutants (dyes, active pharmaceutical compounds, pesticides, etc.) are discharged into water from various industrial, agricultural, and domestic activities. Therefore, wastewater treatment through sustainable technologies is imperative, representing a great and real challenge for worldwide research. Photocatalysis, an innovative and green technology, uses advanced oxidation processes in the presence of a photocatalyst, usually a semiconductor with expanded light absorption ability and high conductivity for photogenerated charge carriers. Molybdenum disulfide (MoS₂) is an n-type semiconductor with different morphologies, variable bandgap energies (Eg = 1.1–2.63 eV), and numerous applications. Although pristine MoS₂ exhibits special structural and optoelectronic properties, its photocatalytic activity can be further improved through various strategies, and constructions with the heterojunctions construction with other semiconductors being frequently pursued. This review extensively studies the recent research (the last 4 years) on MoS₂ and MoS₂-based heterojunction (I-type, II-type, Z-scheme, S-scheme) photocatalysts for degrading organic contaminants under simulated and sunlight irradiation in wastewater treatment. Even if in a relatively short time (a few years) valuable studies have been reported on this topic, there are still numerous challenges facing future research. Full article

The efficient degradation of antibiotics in pharmaceutical wastewater remains a critical challenge against environmental contaminants. Conventional photocatalysts face potential limitations such as narrow visible-light absorption, rapid carrier recombination, and reliance on precious metal cocatalysts. This review investigates the coordination structure of MXene as a cocatalyst to synergistically enhance photocatalytic antibiotic degradation efficiency and the coordination structure modification mechanisms. MXene’s tunable bandgap (0.92–1.75 eV), exceptional conductivity (100–20,000 S/cm), and abundant surface terminations (-O, -OH, -F) enable the construction of Schottky or Z-scheme heterojunctions with semiconductors (Cu₂O, TiO₂, g-C₃N₄), achieving 50–70% efficiency improvement compared to pristine semiconductors. The “electron sponge” effect of MXene suppresses electron-hole recombination by 3–5 times, while its surface functional groups dynamically optimize pollutant adsorption. Notably, MXene’s localized surface plasmon resonance extends light harvesting from visible (400–800 nm) to near-infrared regions (800–2000 nm), tripling photon utilization efficiency. Theoretical simulations demonstrate that d-orbital electronic configurations and terminal groups cooperatively regulate catalytic active sites at atomic scales. The MXene composites demonstrate remarkable environmental stability, maintaining over 90% degradation efficiency of antibiotic under high salinity (2 M NaCl) and broad pH range (4–10). Future research should prioritize green synthesis protocols and mechanistic investigations of interfacial dynamics in multicomponent wastewater systems to facilitate engineering applications. This work provides fundamental insights into designing MXene-based photocatalysts for sustainable water purification. Full article

Photocatalytic technology offers significant potential for pollutant remediation through efficient, cost-effective mineralization but faces inherent limitations, including catalyst agglomeration and rapid charge recombination. To address these challenges, we developed activated carbon-modified porous graphitic carbon nitride (APCN) synthesized through the co-polycondensation of dicyandiamide with NH₄Cl and fir-wood-derived activated carbon (AC). The incorporated AC effectively prevented the agglomeration of carbon nitride frameworks, thereby enhancing the specific surface area (S_BET) of APCN. This matrix was subsequently composited with hydrothermally prepared (1T/2H) mixed-phase MoS₂ through ultrasonication, forming a MoS₂/APCN heterostructure. Characterizations including Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and N₂ adsorption–desorption isotherms (BET) confirmed that MoS₂ was successfully loaded onto APCN via an ultrasonic synthesis method. The composite exhibited outstanding photocatalytic activity, degrading 95.5% RhB in 40 min (pH = 7) and 97.4% in 25 min (pH = 3.5), with 87.3% efficiency retention after four cycles (pH = 7). Crucially, AC enhanced visible-light absorption and functioned as an electron-mediating component. Photoelectrochemical analyses and radical-trapping experiments confirmed a direct Z-scheme charge transfer mechanism, wherein conductive AC accelerates electron transport and suppresses carrier recombination. This study establishes both an efficient RhB degradation photocatalyst and a sustainable strategy for valorizing agricultural waste in advanced material design. Full article

A high-performance Z-scheme heterojunction photocatalytic compound, ZnBiGdO₄/SnS₂ (ZS), was prepared for the first time using a microwave-assisted solvothermal method. ZS significantly improved the separation efficiency of photoinduced carriers and effectively broadened the response range to visible light through the unique mechanism of the Z-type heterojunction. Therefore, ZS exhibited an excellent photocatalytic performance during the degradation process of tinidazole (TNZ). Specifically, the removal rate of TNZ by ZS reached 99.63%, and the removal rate of total organic carbon (TOC) reached 98.37% with ZS as catalyst under visible light irradiation (VLIN). Compared to other photocatalysts, the photocatalytic performance of ZS was significantly better than that of ZnBiGdO₄, SnS₂, or N-doped TiO₂ (N-T). The removal rate of TNZ by ZS was 1.12 times, 1.26 times, or 2.41 times higher than that by ZnBiGdO₄, SnS₂, or N-T, respectively. The mineralization efficiency of TNZ for TOC with ZS as a catalyst was 1.15 times, 1.28 times, or 2.57 times higher than that with ZnBiGdO₄, SnS₂, or N-T as a catalyst, respectively. Free radical scavenging experiments and the electron paramagnetic resonance experiments confirmed that ZS could generate multiple reactive species such as hydroxyl radicals (•OH), superoxide anions (•O₂⁻), and photoinduced holes (h⁺) during the photocatalytic degradation process of TNZ. The photocatalytic degradation performance of ZS on TNZ under VLIN was evaluated, concurrently, the reliability, reproducibility, and stability of ZS were verified by five cycle experiments. This study explored the degradation mechanism and degradation pathway of TNZ with ZS as a catalyst under VLIN. This study not only provides new ideas for the design and preparation of Z-type heterojunction photocatalysts but also lays an important foundation for the development of efficient environmental remediation technologies for TNZ pollution. Full article

Addressing global energy and environmental issues calls for the development of effective photocatalysts capable of enabling solar-driven water splitting, a key route toward sustainable hydrogen generation. In this work, we conducted a detailed density functional theory (DFT) study on three bilayer van der Waals (vdW) heterojunctions, Ga₂SSe/GaP, Ga₂SSe/PtSSe, and Ga₂SSe/SnSSe, each explored in four distinct stacking configurations, with Ga₂SSe serving as the base monolayer. We assessed their structural stability, electronic properties, and optical responses to determine their suitability for photocatalytic water splitting. The analysis showed that Ga₂SSe/GaP and Ga₂SSe/SnSSe exhibit type-II band alignment, while Ga₂SSe/PtSSe displays a type-I alignment. Electrostatic potential profiles and Bader charge calculations identified SeGa₂S/SSnSe and SeGa₂S/SeSnS as direct Z-scheme systems, offering efficient charge carrier separation and robust redox potential. For effective water splitting, the band edges must straddle the water redox potentials. Our results indicate that configurations A and B in Ga₂SSe/GaP, along with C and D in Ga₂SSe/SnSSe, fulfill this requirement. These four configurations also exhibit strong absorption in both the visible and ultraviolet spectral ranges. Notably, configurations C and D of Ga₂SSe/SnSSe achieve high solar-to-hydrogen (STH) efficiencies, reaching 38.44% and 21.75%, respectively. Overall, our findings suggest that these direct Z-scheme heterostructures are promising candidates for water splitting photocatalysis. Full article

The development of high-performance photocatalysts is vital for combating water pollution and microbial contamination. In this study, visible-light-active Z-scheme heterojunction nanocomposites composed of Co₃O₄ and Nb₂O₅ (CNNC) were synthesized via co-crystallization and subsequent high-pressure annealing to enhance photocatalytic and antimicrobial performance. Structural and optical analyses via XRD, FESEM, TEM, XPS, and PL confirmed the heterojunction formation between porous Co₃O₄ nanoparticles (CONP) and columnar orthorhombic Nb₂O₅ nanoparticles (NONP). The CNNC exhibited significantly improved photocatalytic activity, achieving degradation efficiencies of 95.1% for methylene blue, 72.6% for tetracycline, and 90.0% for Congo red within 150 min. Kinetic studies showed that CNNC’s rate constants were 367% and 466% of those of CONP and NONP, respectively. Moreover, CNNC demonstrated a strong antibacterial effect on Staphylococcus aureus and Escherichia coli with ZOI values of 9.3 mm and 6.8 mm, respectively. Mechanistic analysis revealed that the Z-scheme charge-transfer pathway improved charge separation and reduced electron–hole recombination, contributing to the promoted photocatalytic efficiency. The nanocomposite also showed robust stability and recyclability over five times. These results highlight the promise of CNNC as a bifunctional, visible-light-driven photocatalyst for pollutant decomposition and microbial control. Full article

Two-dimensional direct Z-scheme photocatalysts have emerged as highly promising photocatalysts for solar-driven water splitting owing to their effective separation of photogenerated carriers and strong redox abilities. This study focuses on the theoretical prediction of promising Z-scheme photocatalysts for solar-driven water splitting based on M₂X/BiOY (M = Ag, Au; X = S, Se; Y = Cl, Br, I) heterojunctions using first-principles calculations. All M₂X/BiOY heterojunctions possess staggered band alignments, Z-scheme carrier migration, and suitable band edges for overall water splitting. Optical absorption spectra indicate that these heterojunctions exhibit significantly extended solar absorption in the visible and near-infrared regions. Moreover, the interfacial built-in electric fields of (0.46–0.72 V/Å) point from M₂X to BiOY, promote photogenerated carrier separation, and enhance redox overpotentials, thereby improving photocatalytic performance. These results suggest that M₂X/BiOY heterojunctions are promising Z-scheme photocatalysts for solar-driven water splitting and are expected to be experimentally prepared and realized in the near future. Full article