Search Results (628)

The use of solar energy and semiconductor photocatalysts to reduce carbon dioxide (CO₂) into high-value fuels and chemicals is a promising approach to alleviate the current energy crisis and climate change. Layered double hydroxides (LDHs) are a special two-dimensional anionic clay material with a brucite-like structure. They have excellent properties such as adjustable layer cation types, interlayer anion types, and layer ratio. LDHs have been widely used in catalytic fields such as carbon dioxide reduction, water splitting, and ammonia synthesis, and are considered safe and green new photocatalysts. In recent years, researchers have conducted in-depth studies on the photocatalytic CO₂ reduction performance of hydrotalcite-like materials and have made certain progress. However, the low carrier mobility and low light utilization efficiency of pure LDHs greatly limit their catalytic reaction ability and further applications. More and more scientists are exploring methods based on regulating the structure of LDHs to improve the conversion efficiency and light utilization of products, such as changing the layer composition of LDHs, introducing vacancies in LDH structures, or coupling different types of semiconductors to construct heterojunctions. This article first summarizes the development history and structural properties of LDHs; Secondly, the mechanism of photocatalytic reduction of carbon dioxide was summarized; Thirdly, the application of LDH-based materials in photocatalytic reduction of CO₂ was classified and summarized. Although LDH-based photocatalysts have made significant progress in the field of photocatalytic reduction of CO₂, further exploration is still needed to investigate their photocatalytic active sites, mechanisms of action, synergistic mechanisms between components, and interfacial reaction mechanisms. Full article

The development of cost-effective, efficient, and visible-light-responsive photocatalysts for hydrogen evolution is pivotal for addressing global energy shortages and environmental degradation. In this context, non-precious metal cocatalysts have garnered significant attention for modifying semiconductor photocatalysts. Herein, a high-performance Co_0.85Se/g-C₃N₄ composite photocatalyst was successfully synthesized via a facile solvothermal method, where transition metal Co_0.85Se nanoparticles were grown on g-C₃N₄ nanosheets in situ. The optimized 6-Co_0.85Se/g-C₃N₄ composite exhibited a superior photocatalytic hydrogen evolution rate of 426 µmol·g⁻¹·h⁻¹ under visible light irradiation, which is approximately 53 times higher than that of pristine g-C₃N₄. Experimental characterizations revealed that the Co_0.85Se nanoparticles were well dispersed on the g-C₃N₄ nanosheets without obvious agglomeration, which significantly broadened the visible-light absorption range of the composite. Furthermore, photoelectrochemical measurements confirmed that the Co_0.85Se cocatalyst effectively accelerated charge separation and migration kinetics. Consequently, the construction of this heterojunction endows the composite with excellent photocatalytic performance. This work offers new insights into the design of efficient, non-precious metal-based photocatalysts for sustainable hydrogen production. Full article

Tetracycline hydrochloride (TCH) contamination poses serious environmental risks due to its persistence and bioaccumulation. Here we present an oxygen-vacancy-enriched BiVO₄/TiO₂ S-scheme heterojunction (5% BVO/TO) synthesized via a one-step solvothermal method. Under visible light (λ  >  420 nm), this composite achieves 78.8% TCH degradation in 80 min, outperforming TiO₂ (69.5%) and BiVO₄ (34.1%). Its rate constant (0.0198 min⁻¹) is 1.4 and 4.0 times higher than TiO₂ and BiVO₄, respectively, while retaining over 70% activity after four cycles. XPS and EPR confirm that oxygen vacancies serve as electron traps to suppress recombination, and UPS combined with DFT calculations validates directional electron transfer from BiVO₄ to TiO₂. Radical scavenging tests and in situ EPR reveal h⁺ > •OH > •O₂⁻ as the dominant reactive species. This study offers a robust design strategy for OV-enhanced S-scheme photocatalysts toward efficient, sustainable degradation of antibiotic pollutants. 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

Efficient interfacial charge transfer is crucial for improving the photocatalytic performance of semiconductor heterojunctions under visible-light irradiation. In this study, Bi₂WO₆/P25 heterojunction photocatalysts modified with 7,7,8,8-tetracyanoquinodimethane (TCNQ) were prepared to enhance visible-light photocatalytic activity. The optimized sample with a TCNQ mass ratio of 0.3% exhibited the highest activity for rhodamine B degradation, achieving a degradation rate approximately 6.0 times higher than that of pure Bi₂WO₆ and 1.7 times higher than that of the pristine Bi₂WO₆/P25 heterojunction. The degradation rates of phenol were 6.5 times and 2.3 times higher for Bi₂WO₆ and BP-5, respectively. The enhanced photocatalytic performance was mainly attributed to the modification of TCNQ, which enhanced the electron transfer from P25 to Bi₂WO₆, establishing a multi-stage electron transfer mechanism involving P25 → Bi₂WO₆ → TCNQ. This molecular surface modification strategy provides new insights for the rational design of high-performance photocatalytic materials. Full article

Photocatalytic decomposition of water to produce hydrogen and the degradation of organic pollutants are among the most ideal strategies for addressing energy shortages and environmental pollution. Moreover, constructing organic–inorganic heterojunctions based on surface interactions is one of the most effective strategies for enhancing photocatalytic activity. In this work, a novel II-type polyimide/zinc sulfide (PI/ZnS) heterojunction photocatalyst was successfully synthesized for the first time through a simple hydrothermal method. The influence of PI in the PI/ZnS composite material was systematically studied. The 1PI/ZnS composite shows the highest rate (587.7 μmol/g/h) of photocatalytic water splitting for hydrogen production, which is approximately 19% higher than the value of ZnS (492.5 μmol/g/h), and it is 34.6 times the PI value (16.95 μmol/g/h). The degradation efficiency of the 3 PI/ZnS composite is nearly 35.5 times that of PI and nearly 1.9 times that of ZnS. The enhancement in the photocatalytic activity of the PI/ZnS photocatalyst is mainly attributed to the dense interface and II-type heterojunction between the PI and ZnS, which effectively improves the spatial separation efficiency of photogenerated carriers. This study demonstrates that the nanostructured II-type heterojunction in the PI/ZnS composite can significantly improve the photocatalytic performance of polyimide photocatalysts. 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

The Z-scheme Ag₂MoO₄/BiOCl heterojunction with oxygen vacancies was successfully fabricated at a low temperature via a simple in situ precipitation method. The morphological, structural, and optical characteristics of the Ag₂MoO₄/BiOCl heterojunction were systematically examined. The optimized synthesized Ag₂MoO₄/BiOCl heterojunction achieved a removal rate of 80.44% for ciprofloxacin within 180 min of simulated solar irradiation, which was 3.27 and 1.90 times higher than that of pure Ag₂MoO₄ and BiOCl, respectively. The fabricated Z-scheme heterojunction and oxygen vacancies optimize the electron transfer route, enhancing the separation efficiency of photogenerated electrons and holes. Moreover, the active species trapping experiments and ESR analyses demonstrated that holes were the primary reactive species involved in the photocatalytic process. It was hypothesized that the Ag₂MoO₄/BiOCl heterojunction adhered to a Z-scheme mechanism for charge transfer. The straightforward approach opened up novel avenues for the synthesis of efficient BiOCl-based photocatalysts aimed at environmental remediation. Full article

Solar-driven photocatalysis has attracted increasing interest as an efficient and environmentally friendly approach for the mineralization of pollutants. In this work, carbon-doped g-C₃N₄/V_oBiOBr composites rich in oxygen vacancy (denoted as CCN/V_oBOB) were prepared by combining calcination with a solvothermal method, using glucose as the carbon source. The obtained composites were comprehensively characterized by XRD, TEM, and XPS to investigate their crystal structure, morphology, and surface chemical states, and their photocatalytic activity was evaluated through the degradation of organic pollutants. Among the prepared samples, 3.2 wt% CCN/V_oBOB exhibited the best photocatalytic performance, reaching 98% degradation of Rhodamine B (RhB) and 95% degradation of Methylene Blue (MB) within 90 min, which was significantly superior to that of V_oBOB and g-C₃N₄/V_oBOB. This enhanced activity can be attributed mainly to the synergistic effects of oxygen vacancy, carbon doping, and heterojunction construction. Their combined action not only regulates the band structure of V_oBOB effectively, but also greatly inhibits the recombination of photogenerated electron–hole pairs. These results were further supported by UV-Vis DRS and transient photocurrent measurements. Radical trapping experiments indicated that superoxide radicals (O₂⁻) were the dominant active species during the reaction. In addition, density functional theory (DFT) calculations provided further evidence for the above conclusions. On the basis of both experimental observations and theoretical analysis, a reasonable photocatalytic reaction mechanism was proposed. This work offers a useful strategy for designing highly efficient photocatalysts through the synergistic integration of oxygen vacancy, nonmetal doping, and heterojunction engineering, and thus promotes the application of photocatalytic technology in pollutant degradation. Full article

Formaldehyde (HCHO), a prevalent indoor air pollutant released from furniture and building materials, poses significant health risks due to its carcinogenic nature. In this study, a binary cuprous oxide–titanium dioxide (Cu₂O–TiO₂) composite photocatalyst was synthesized via a hydrothermal method to enable efficient visible-light-driven degradation of gaseous formaldehyde at ambient temperature. The structural, morphological, and optical properties of the as-prepared catalysts were characterized using XRD, SEM, TEM, EDX, and UV-Vis spectroscopy. While pristine Cu₂O exhibited a formaldehyde degradation efficiency of approximately 68% under white light illumination, the incorporation of TiO₂ markedly enhanced the photocatalytic performance. Among the different mass ratios tested, the Cu₂O–TiO₂ (1:1) composite demonstrated the highest activity, achieving 83% degradation of formaldehyde within 240 min under white light. Enhanced performance is attributed to the formation of a heterojunction that reduces the effective bandgap, promotes charge separation, and suppresses electron–hole recombination. Additionally, the generation of carbon dioxide and water as end products confirmed complete mineralization. The catalyst also showed good reusability, retaining over 81% efficiency after five cycles. This work presents a cost-effective, stable, and visible-light-active Cu₂O–TiO₂ heterojunction photocatalyst with strong potential for indoor air purification applications. Full article

Bismuth tungstate (Bi₂WO₆) is a typical bismuth-based visible-light-responsive semiconductor photocatalyst that has attracted significant attention in the fields of environment remediation and energy conversion. In this paper, to address the issues of high photogenerated carrier recombination rate and limited visible-light-response range of Bi₂WO₆, various modification strategies are highlighted, including morphology control, element doping, heterojunction construction, carbon material compositing, and coupling with functional materials such as metal–organic frameworks (MOFs), covalent organic frameworks (COFs), or conductive polymers. Furthermore, the structure–activity relationships are discussed. On this basis, the latest application progress of Bi₂WO₆-based photocatalysts in fields such as pollutant degradation, antibacterial activity, and energy conversion and storage is summarized. Finally, prospects are put forward regarding the existing shortcomings and future development directions in the application of Bi₂WO₆-based photocatalysts, aiming to provide a systematic theoretical reference for the design and application of high-performance Bi₂WO₆-based photocatalysts. Full article

The structural, electronic, optical, transport and photocatalytic properties of the BTe/PtS₂ vdW heterojunction are investigated by the density functional theory approach. The results reveal that applying the tensile effect can significantly impact the material’s properties. The bandgap values of BTe, PtS₂ and BTe/PtS₂ vdW heterojunction are 1.599 eV, 1.756 eV and 1.19 eV, respectively. The bandgap decreases as the percentage of applied tensile effect increases. Moreover, the photocatalytic water decomposition of BTe/PtS₂ vdW heterojunction is significantly broadened in the pH range compared with that of the two monolayers. In conclusion, the BTe/PtS₂ vdW heterojunction can be used as an efficient photocatalytic material for optoelectronic devices and photocatalysis. Full article

The objective of this study is to develop a nanosized, visible-light-responsive photocatalyst with magnetic separability and recyclability for repeated use. Spinel ferrite nanoparticles, which are environmentally friendly, are promising candidates for achieving this goal. Spinel ferrite nanoparticles were synthesized via a low-temperature hydrothermal method to investigate their microstructural characteristics, magnetic properties, and photocatalytic performance. Initially, four ternary spinel ferrite (MFe₂O₄, where M = Mg, Mn, Co, and Zn) nanoparticles were compared in terms of their physical properties and photodegradation efficiencies of organic dye methylene blue (MB). Among them, the MgFe₂O₄ and ZnFe₂O₄ samples exhibited superior photocatalytic activity compared to the MnFe₂O₄ and CoFe₂O₄ samples. Subsequently, a systematic investigation of the Zn–Mg ferrite system (Zn_1−xMg_xFe₂O₄, x = 0 to 0.8 in increments of 0.2) was carried out. The results revealed that the x = 0.8 samples achieved the highest photodegradation efficiency of 99 for a 10 MB aqueous solution under visible-light irradiation for 90 min. This improved performance is attributed to formation of a heterojunction of Zn–Mg nanoferrite/Fe₂O₃, which promotes light harvesting and prevents photogenerated charge recommendation, thus significantly improving photocatalytic activity. Full article

The extensive use of oxytetracycline (OTC) poses significant threats to aquatic ecosystems, necessitating efficient removal strategies. While photocatalytic technology is a promising approach, single catalysts, like UiO-66-NH₂ and Bi₂MoO₆, suffer from rapid photogenerated carrier recombination and narrow light absorption. To address this, a Z-scheme heterojunction photocatalyst, Bi₂MoO₆/UiO-66-NH₂, was synthesized via a solvothermal method to enhance OTC degradation. Characterization results showed that the composite expanded visible-light absorption and improved electron-hole separation. Under simulated sunlight, the optimized composite (BUN80) achieved an OTC removal efficiency of 87.68% within 120 min under optimized conditions. The catalyst retained photocatalytic activity over five consecutive cycles, although a decrease in removal efficiency was observed. Radical trapping experiments indicated that h⁺ and •O₂⁻ were the main reactive species, and a proposed Z-scheme charge transfer pathway was suggested based on band structure analysis and photoelectrochemical results. LC-MS analysis identified 17 intermediate products, and ECOSAR-based toxicity prediction suggested a decreasing trend in aquatic toxicity during the degradation process. These findings indicate that Bi₂MoO₆/UiO-66-NH₂ is a promising photocatalyst for OTC degradation in water. Full article