Synthesis of visible-light-activated CeO2-x/BiCrO3 photocatalysts with S-scheme mechanism: Effectual performances in detoxification of various antibiotics and organic pollutants.

In today's world, the development of an efficient water treatment strategy requires a prospective approach for the production of active and stable photocatalysts. The construction of heterojunctions with different semiconductors is a promising procedure for improving photocatalytic performances. In the present research, binary CeO2-x/BiCrO3 photocatalysts were synthesized using a hydrothermal route preceded by a calcination step. The CeO2-x/BiCrO3 (15%) photocatalyst proved its unique performance of 29.3, 11.4, 11.7, and 23.0 times better than CeO2 for photodegradation of respectively tetracycline hydrochloride (TCH), metronidazole (MET), azithromycin (AZM), and cephalexin (CPN), as antibiotic pollutants, upon visible light. The effective photocatalytic ability, which was caused by the impressive suppression of charge carriers, can be understood by the developed S-scheme mechanism. Moreover, the lower resistance of CeO2-x/BiCrO3 (15%) compared to CeO2, CeO2-x, and BiCrO3 against the charges transfer was another confirmation for boosted photocatalytic performance of the CeO2-x/BiCrO3 (15%) nanocomposite. Ultimately, the boosted activity, repeated utilization for five runs, and biocompatibility confirmation of the purified solution through pinto bean cultivation exhibited that CeO2-x/BiCrO3 photocatalysts could have the promising capability for detoxification of polluted water.

Dual S-scheme MoS2/ZnIn2S4/Graphene quantum dots ternary heterojunctions for highly efficient photocatalytic hydrogen evolution.

The layered chalcogenide ZnIn2S4 (ZIS) exhibits photo-stability and a tunable band gap but is limited in photocatalytic applications, such as hydrogen (H2) production, due to rapid carrier recombination and slow charge separation. To overcome these limitations, we have synthesized a ternary MoS2/ZIS/graphene quantum dots (GQDs) heterojunction, wherein MoS2 and GQDs are strategically attached to ZIS interlaced nanoflakes, enhancing light absorption across the 500-1500 nm range. This heterojunction benefits from dual S-scheme interfaces between MoS2-ZIS and ZIS-GQDs, establishing directed internal electric fields (IEFs). These IEFs accelerate the transfer of photoinduced electrons from the conduction bands of MoS2 and GQDs to the valence band of ZIS, promoting rapid recombination with holes and facilitating efficient catalytic reactions with plentiful photoinduced electrons stemmed from the conduction band of ZIS. As a result, the photocatalytic H2 production rate of the MoS2/ZIS/GQDs heterojunction is measured at 21.63 mmol h-1 g-1, marking an increase of 36.7 times over pure ZIS. This research provides valuable insights into designing novel heterojunctions for improved charge separation and transfer for solar energy conversion applications.

A novel photothermal-assisted FeNi2S4@Mn0.3C0.7S S-scheme heterojunction for enhanced photo-catalytic hydrogen evolution.

In addition to the intrinsic driving force of photocatalysis, the external thermal field from the photothermal effect can provide additional energy to the photo-catalytic system to improve the photo-catalytic hydrogen-evolution (PHE) efficiency. Herein, based on the results of density functional theory, we designed and constructed a hollow core-shell FeNi2S4@Mn0.3Cd0.7S (NFS@MCS) S-scheme heterojunction with a photothermal effect, thereby realising a significant enhancement of the PHE performance due to the thermal effect, S-scheme heterojunction and hollow core-shell morphology. As a light collector and heat source, the hollow NFS could absorb and convert photons into heat, resulting in the increased local temperature of photocatalyst particles. Moreover, the S-scheme charge path at the interface not only improved the carrier separation efficiency but also retained a higher redox potential. All these are favourable to increase the PHE activity. The PHE tests show that 0.5 %-NFS@MCS exhibits the highest PHE rate of 17.11 mmol·g-1·h-1, 7.7 times that of MCS. Moreover, through a combination of theoretical calculation and experimental evidence, the PHE mechanism of the NFS@MCS system is discussed and clarified in-depth.

A Tight-Connection g-C3N4/BiOBr (001) S-Scheme Heterojunction Photocatalyst for Boosting Photocatalytic Degradation of Organic Pollutants.

The efficient separation of photogenerated charge carriers and strong oxidizing properties can improve photocatalytic performance. Here, we combine the construction of a tightly connected S-scheme heterojunction with the exposure of an active crystal plane to prepare g-C3N4/BiOBr for the degradation of high-concentration organic pollutants. This strategy effectively improves the separation efficiency of photogenerated carriers and the number of active sites. Notably, the synthesized g-C3N4/BiOBr displays excellent photocatalytic degradation activity towards various organic pollutants, including methylene blue (MB, 90.8%), congo red (CR, 99.2%), and tetracycline (TC, 89%). Furthermore, the photocatalytic degradation performance of g-C3N4/BiOBr for MB maintains 80% efficiency under natural water quality (tap water, lake water, river water), and a wide pH range (pH = 4-10). Its excellent photocatalytic activity is attributed to the tight connection between g-C3N4 and BiOBr in the S-scheme heterojunction interface, as well as the exposure of highly active (001) crystal planes. These improve the efficiency of the separation of photogenerated carriers, and maintain their strong oxidation capability. This work presents a simple approach to improving the separation of electrons and holes by tightly combining two components within a heterojunction.

Directional Electron Transfer in CuInS2/Mo2S3 S-Scheme Heterojunctions for Efficient Photocatalytic Hydrogen Production.

The photocatalytic conversion of solar energy to hydrogen is a promising pathway toward clean fuel production, yet it requires advancement to meet industrial-scale demands. This study demonstrates that the interface engineering of heterojunctions is a viable strategy to enhance the photocatalytic performance of CuInS2/Mo2S3. Specifically, CuInS2 nanoparticles are incorporated into Mo2S3 nanospheres via a wet impregnation technique to form an S-scheme heterojunction. This configuration facilitates directional electron transfer, optimizing electron utilization and fostering efficient photocatalytic processes. The presence of an S-scheme heterojunction in CuInS2/Mo2S3 is corroborated by in situ irradiation X-ray photoelectron spectroscopy and density functional theory analyses, which confirm the directional movement of electrons at the interface of heterojunction. Comprehensive characterization of the heterojunction photocatalyst, including phase, structural, and photoelectric property assessments, reveals a significant specific surface area and light absorption capability. These attributes augment the number of active sites available in CuInS2/Mo2S3 for proton reduction reactions. This study offers a pragmatic approach for designing metal sulfide-based photocatalysts via strategic interface engineering, potentially advancing the field toward sustainable hydrogen production.

Bifunctional CdS-MoO2 catalysts for selective oxidation of lactic acid coupled with photocatalytic H2 production.

The persistent hurdles of charge rapid recombination, inefficient use of light and utilization of sacrificial reagents have plagued the field of photocatalytic hydrogen evolution (PHE). In this research, tiny MoO2 nanoparticles of 10 nm in diameter were prepared through a straightforward solvothermal approach with a specific ratio of oleylamine and oleic acid as stabilizers. The critical factor in the synthesis process was found to be the ratio of oleylamine to oleic acid. Moreover, a two-phase interface assembly method facilitated the uniform deposition of MoO2 onto CdS nanorods. Due to the localized plasmonic-thermoelectric effect on the surface of MoO2 along with its abundant oxygen vacancies, the composite catalyst exhibited outstanding photo-utilization efficiency and an abundance of active sites. The CdS-MoO2 composite displayed a unique photochemical property in transforming lactic acid into pyruvic acid and generating hydrogen simultaneously. After exposure to artificial sunlight for 4 h, significant values of 4.7 and 3.7 mmol⋅g-1⋅h-1 were achieved for hydrogen production and pyruvic acid formation, respectively, exceeding CdS alone by 3.29 and 4.02-fold, while the selectivity of pyruvic acid was 95.68 %. Furthermore, the S-Scheme electron transport mechanism in the composites was elucidated using Electron Paramagnetic Resonance (EPR) spectroscopy, radical trapping experiments, energy band structure analysis, and the identification of critical intermediates in the process of selective oxidation. This work sheds light on the design and preparation of high-performance photocatalysts for biorefining coupled with efficient hydrogen evolution.

Optimizing Light Dynamics: Designing A Ni-MOF Functionalized g-C3N4 Type II Heterostructure and a Ti3C2 MXene Schottky Junction for Efficient Photocatalytic H2 Production.

The photocatalytic production of hydrogen (H2) from water is a vital avenue towards sustainable energy and addressing global environmental challenges. To maximize efficiency, harnessing the synergistic effects of multiple co-catalysts is essential, as these interactions can significantly enhance performance. In this study, we introduce a ternary heterojunction composed of a nickel-imidazole framework (Ni-MOF), graphitic carbon nitride (CN), and Ti3C2 MXene (TC), employing solvothermal and wet impregnation methods, featuring a well-designed Type II heterojunction and a noble metal-free Schottky junction for efficient hydrogen evolution. The Type II heterojunction between Ni-MOF and CN minimizes charge carrier recombination and promotes photogenerated electron generation, while TC as an electron acceptor enhances electron capture, increases participation in surface reactions, and augments active sites. Consequently, the Ni-MOF/CN/TC hybrid catalyst achieves outstanding photocatalytic hydrogen evolution under visible light, with a peak production rate of 1044.46 µmol/g over 3 hours, surpassing CN by 13 fold and Ni-MOF/CN by 50%. This work provides insights into MXene-based ternary systems, emphasizing the potential for enhanced light absorption and efficient charge separation, making it a promising platform for photocatalytic applications.

Unraveling the synergism mechanistic insight of O-vacancy and interfacial charge transfer in WO3-x decorated on Ag2CO3/BiOBr for photocatalysis of water pollutants: Based on experimental and density functional theory (DFT) studies.

Photocatalysis has been widely used as one of the most promising approaches to remove various pollutants in liquid or gas phases during the last decade. The main emphasis of the study is on the synergy of vacancy engineering and heterojunction formation, two widely used modifying approaches, to significantly alter photocatalytic performance. The vacancy-induced Ag2CO3/BiOBr/WO3-x heterojunction system has been fabricated using a co-precipitation technique to efficiently abate methylene blue (MB) dye and doxycycline (DC) antibiotic. The as-fabricated Ag2CO3/BiOBr/WO3-x heterojunction system displayed improved optoelectronic characteristic features because of the rational combination of dual charge transferal route and defect modulation. The Ag2CO3/BiOBr/WO3-x system possessed 97% and 74% photodegradation efficacy for MB and DC, respectively, with better charge isolation and migration efficacy. The ternary photocatalyst possessed a multi-fold increase in the reaction rate for both MB and DC, i.e., 0.021 and 0.0078 min-1, respectively, compared to pristine counterparts. Additionally, more insightful deductions about the photodegradation routes were made possible by the structural investigations of MB and DC using density functional theory (DFT) simulations. This study advances the understanding of the mechanisms forming visible light active dual Z-scheme heterojunction for effective environmental remediation.

Defect-mediated Fermi level modulation boosting photo-activity of spatially-ordered S-scheme heterojunction.

Spatially-ordered S-scheme photocatalysts are intriguing due to their enhanced light harvesting, spatially isolated redox sites, and strong redox abilities. Nonetheless, heightening the performance of S-scheme photocatalysts via controllable defect engineering is still challenging to now. In this work, multi-armed MoSe2/CdS S-scheme heterojunction with intimate Mo-S bond coupling and adjustable Se vacancies (VSe) and Mo5+ concentrations was constructed, which consisted of few- or even single-layered MoSe2 growing on the {11-20} facets of wurtzite CdS arms. The S-scheme charge transmission mechanism of MoSe2/CdS heterojunction was validated by density functional theory calculation combined with in situ photo-irradiated X-ray photoelectron spectroscopy, surface photovoltage, and radical measurements. Moreover, the Fermi level gap between CdS and MoSe2 was enlarged by regulating the contents of donor (VSe) and acceptor (Mo5+) impurities with synthesis temperature, which strengthens the built-in electric field and carriers transfer driving force of MoSe2/CdS composites, contributing to an outstanding H2 evolution activity of 52.62 mmol·g-1·h-1 (corresponding to an apparent quantum efficiency of 34.8 % at 400 nm) under visible-light irradiation (λ > 400 nm), 25.8 times that of Pt-loaded CdS counterpart and a substantial amount of reported CdS-containing photocatalysts. Our study results are anticipated to facilitate the rational design of advanced semiconductor nanostructures for efficient solar conversion and utilization.

Nanoarchitectonics of S-Scheme Heterojunction Photocatalysts: A Nanohouse Design Improves Photocatalytic Nitrate Reduction to Ammonia Performance.

Photocatalytic nitrate reduction reaction (NitRR) is a promising route for environment remediation and sustainable ammonia synthesis. To design efficient photocatalysts, the recently emerged nanoarchitectonics approach holds great promise. Here, we report a nanohouse-like S-scheme heterjunction photocatalyst with high photocatalytic NitRR performance. The nano-house has a floor of plate-like metal organic framework-based photocatalyst (NH2-MIL-125), on which another photocatalyst Co(OH)2 nanosheet is grown while ZIF-8 hollow cages are also constructed as the surrounding wall/roof. Experimental and simulation results indicate that the positively charged, highly porous and hydrophobic ZIF-8 wall can modulate the environment in the nanohouse by (i) NO3- enrichment / NH4+ discharge and (ii) suppression of the competitive hydrogen evolution reaction. In combination with the enhanced electron-hole separation and strong redox capability in the NH2-MIL-125@Co(OH)2 S-scheme heterjunction confined in the nano-house, the designed photocatalyst delivers an ammonia yield of 2454.9 µmol g-1 h-1 and an apparent quantum yield of 8.02% at 400 nm in pure water. Our work provides new insights into the design principles of advanced photocatalytic NitRR photocatalyst.

In situ construction of Ag/Bi2O3/Bi5O7I heterojunction with Bi-MOF for enhance the photocatalytic efficiency of bisphenol A by facet-coupling and s-scheme structure.

In this study, Ag/Bi2O3/Bi5O7I with s-scheme heterostructures were successfully synthesized in situ by nano-silver modification of CUA-17 and halogenated hydrolysis.The growth rate of Bi2O3 crystals was effectively controlled by adjusting the doping amount of Ag, resulting in the formation of a facet-coupling heterojunctions. Through the investigation of the microstructure and compositional of catalysts, it has been confirmed that an intimate facet coupling between the Bi2O3 (120) facet and the Bi5O7I (312) facet, which provides robust support for charge transfer. Under visible light irradiation, the AgBOI.3 heterojunction photocatalyst exhibited an outstanding degradation rate of 98.2% for Bisphenol A (BPA) with excellent stability. Further characterization using optical, electrochemical, impedance spectroscopy, and electron spin resonance techniques revealed significantly enhanced efficiency in photogenerated charge separation and transfer, and confirming the s-scheme structure of the photocatalyst. Density functional theory calculations was employed to elucidate the mechanism of BPA degradation and the degradation pathway of BPA was investigated by LC-MS. Finally, the toxicity of the degradation intermediates was evaluated using T.E.S.T software.

S-scheme homojunction of 0D cubic/2D hexagonal ZnIn2S4 for efficient photocatalytic reduction of nitroarenes.

The targeted conversion of toxic nitroarenes to corresponding aminoarenes presents significant promise in simultaneously addressing environmental pollution concerns and producing value-added fine chemicals. In this study, we synthesize a 0D/2D ZnIn2S4 homojunction (CH-ZnIn2S4) by in situ growth of cubic ZnIn2S4 (C-ZnIn2S4) quantum dots onto the surface of ultrathin hexagonal ZnIn2S4 (H-ZnIn2S4) nanosheets for photocatalytic reduction of nitroarenes to aminoarenes using water as a hydrogen donor. The optimal performance of photocatalytic nitro reduction over the 0D/2D CH-ZnIn2S4 homojunction reaches 96.1% within 20 min of visible light irradiation, which is 2.45 and 1.52 times than that of C-ZnIn2S4 (39.3%) and H-ZnIn2S4 (63.3%), respectively. The improved photocatalytic performance can be attributed to the formation of a step-type S-scheme homojunction, characterized by identity chemical composition and natural lattice matching. The configuration enables continuous band bending and a low energy barrier of charge transportation, benefiting the charge transfer across the interface while maximizing their redox capabilities. Furthermore, the 2D structure of H-ZnIn2S4 nanosheets offers abundant surface sites to immobilize the 0D C-ZnIn2S4 that provides ample exposed active sites with low overpotential for HER, thereby ensuring high hydrogenation reduction activity of nitroarenes. The study is expected to inspire further interest in the reasonable design of homojunction structures for efficient and sustainable photocatalytic redox reactions.

Rationally Designed S-Scheme CeO2/g-C3N4 Heterojunction for Promoting Visible Light Driven CO2 Photoreduction into Syngas.

Exploring low-cost visible light photocatalysts for CO2 reduction to produce proportionally adjustable syngas is of great significance for meeting the needs of green chemical industry. A S-Scheme CeO2/g-C3N4 (CeO2/CN) heterojunction was constructed by using a simple two-step calcination method. During the photocatalytic CO2 reduction process, the CeO2/CN heterojunction can present a superior photocatalytic performance, and the obtained CO/H2 ratios in syngas can be regulated from 1:0.16 to 1:3.02. In addition, the CO and H2 production rate of the optimal CeO2/CN composite can reach 1169.56 and 429.12 µmol g-1 h-1, respectively. This superior photocatalytic performance is attributed to the unique S-Scheme photogenerated charge transfer mechanism between CeO2 and CN, which facilitates rapid charge separation and migration, while retaining the excellent redox capacity of both semiconductors. Particularly, the variable valence Ce3+/Ce4+ can act as electron mediator between CeO2 and CN, which can promote electron transfer and improve the catalytic performance. This work is expected to provide a new useful reference for the rational construction of high efficiency S-Scheme heterojunction photocatalyst, and improve the efficiency of photocatalytic reduction of CO2, promoting the photocatalytic reduction of CO2 into useful fuels.

0D/1D CuWO4/Mn0.3Cd0.7S S-scheme heterojunctions for full-spectrum bifunctional photocatalytic degradation and hydrogen production.

Integrating photocatalytic oxidation for pollutant removal with hydrogen production via photocatalysis presents a promising approach for sustainable water purification and renewable energy generation, circumventing the sluggish multi-electron transfer inherent in photocatalytic water oxidation. This study introduces novel zero-/one-dimensional (0D/1D) CuWO4/Mn0.3Cd0.7S step-scheme (S-scheme) heterojunctions that exhibit exceptional bifunctional capabilities in photocatalytic degradation and hydrogen production under full-spectrum illumination. The degradation efficiency for tetracycline (TC) using 5 %-CuWO4/Mn0.3Cd0.7S reaches 94.3 % and 94.5 % within 60 min and 6 h, respectively, under ultraviolet-visible (UV-Vis) and near-infrared (NIR) light. Notably, these 0D/1D CuWO4/Mn0.3Cd0.7S S-scheme heterojunctions demonstrate superior hydrogen production, achieving rates of 12442.03 µL g-1h-1 and 2418.54 µL g-1h-1 under UV-Vis light and NIR light irradiation, respectively-these rates are 2.3 times and 55.2 times higher than that of Mn0.3Cd0.7S alone. This performance enhancement is attributed to the intrinsic dimensional effects, transitions of transition metal d-d orbitals, and S-scheme hole/electron (h+/e-) separation characteristics. Additionally, experimental results and density functional theory (DFT) calculations have clarified the modulation of electronic configurations, band alignment, and interfacial interactions via 0D/1D S-scheme heterojunction engineering. This study sheds light on the electron transfer mechanism within S-scheme heterojunction and enhances the effectiveness, economy, and sustainability of recalcitrant pollutant removal and hydrogen production.

Recent advances in photocatalytic removal of antiviral drugs by Z-scheme and S-scheme heterojunction.

The possible impact of antivirals on ecosystems and the emergence of antiviral resistance are the reasons for concern about their environmental release. Consequently, there has been a significant increase in curiosity regarding their presence in both organic and synthetic systems in recent years. The primary objective of this review is to address the void of information regarding the global presence of antiviral drugs in both wastewater and natural water sources. Photocatalytic degradation of pollutants is an eco-friendly, cost-effective method that effectively addresses environmental degradation. The development of efficient photocatalysts remains a significant issue in accelerating the degradation of pollutants, especially when employing solar light. Thus, the development of Z-scheme and S-scheme semiconductor heterojunctions has emerged as a viable method to improve light absorption and enhance the redox capability of photocatalysts. The principles of Z-scheme and S-scheme are reviewed extensively. The degradation route and occurrence of antiviral are discussed briefly. Finally, a short preview of the degradation of antiviral using Z-scheme and S-scheme is also highlighted.

S-scheme heterojunction phthalocyanine/TiO2 photoelectrochemical sensor for innovative glutathione detection.

A novel photoelectrochemical sensor, employing an S-scheme heterojunction of phthalocyanine and TiO2 nanoparticles, has been developed to enable highly sensitive determination of glutathione. By integrating the favorable stability, environmental benignity, and electronic properties of the TiO2 matrix with the unique photoactivity of phthalocyanine species, the designed sensor presents a substantial linear dynamic range and a low detection limit for the quantification of glutathione. The sensitivity is attributed to efficient charge transfer and separation across the staggered heterojunction energy levels, which generates measurable photocurrent signals. Systematic variation of phthalocyanine content reveals an optimal composition that balances light harvesting capacity and electron-hole recombination rates. The incorporation of phosphotungstic acid (PTA) in sample preparation effectively minimizes interference from compounds like L-cysteine and others. Consequently, this leads to an improvement in accuracy through the reduction of impurity levels. Appreciable photocurrent enhancements are observed upon introduction of both oxidized and reduced glutathione at the optimized composite photoanode. Coupled with advantageous features of photoelectrochemical transduction such as simplicity, cost-effectiveness, and resistance to fouling, this sensor holds great promise for practical applications in complex biological media.

Anisotropic Dual S-Scheme Heterojunctions Mimic Natural Photosynthetic System for Boosting Photoelectric Response.

The design of heterojunctions that mimic natural photosynthetic systems holds great promise for enhancing photoelectric response. However, the limited interfacial space charge layer (SCL) often fails to provide sufficient driving force for the directional migration of inner charge carriers. Drawing inspiration from the electron transport chain (ETC) in natural photosynthesis system, we developed a novel anisotropic dual S-scheme heterojunction artificial photosynthetic system composed of Bi2O3-BiOBr-AgI for the first time, with Bi2O3 and AgI selectively distributed along the bicrystal facets of BiOBr. Compared to traditional semiconductors, the anisotropic carrier migration in BiOBr overcomes the recombination resulting from thermodynamic diffusion, thereby establishing a potential ETC for the directional migration of inner charge carriers. Importantly, this pioneering bioinspired design overcomes the limitations imposed by the limited distribution of SCL in heterojunctions, resulting in a remarkable 55-fold enhancement in photoelectric performance. Leveraging the etching of thiols on Ag-based materials, this dual S-scheme heterojunction is further employed in the construction of photoelectrochemical sensors for the detection of acetylcholinesterase and organophosphorus pesticides.

Fabrication of close-contact S-scheme Cr2Bi3O11-Bi2O3/Fe3O4@porous carbon microspheres based on in-situ reaction: Enhanced photo-Fenton wastewater treatment.

Low photo-induced carrier recombination rate, exceptional light absorption, and advantageous recycling performance are crucial attributes of semiconductor photocatalyst for wastewater purification. Herein, based on in-situ reaction, close-contact S-scheme bismuth chromate/bismuth oxide/ferroferric oxide@porous carbon microspheres (Cr2Bi3O11-Bi2O3/Fe3O4@PCs) (F-CBFP) was fabricated using alginates as precursor. Due to the abundance of functional groups on the porous carbon (PCs), Bi2O3 and Cr2Bi3O11 nanoparticles (NPs) are in situ deposited onto the highly conductive 3D magnetic porous Fe3O4@PCs microsphere surface, which not only form tight interfacial contacts and reduces interfacial potential barriers but also prevent agglomeration or shedding of the NPs during photocatalytic reactions. Moreover, density functional theory (DFT) calculations further confirm that the formation of a robust built-in electric field (BIEF) within F-CBFP prompts photo-induced electrons in the conduction band (CB) of Bi2O3 to combine with holes in the valence band (VB) of Cr2Bi3O11, effectively constructing a S-scheme heterojunction system. Also, Fe3O4 can act as a Fenton catalyst, activating the H2O2 generated by Cr2Bi3O11 under illumination. In wastewater treatment, the obtained F-CBFP shows remarkable photo-Fenton degradation (towards methyl orange (97.8 %, 60 min) and tetracycline hydrochloride (95.3 %, 100 min)) and disinfection performance (100 % E. coli inactivation), and exceptional cyclic stability.

Anchoring ZnIn2S4 nanosheets on cross-like FeSe2 to construct photothermal-enhanced S-scheme heterojunction for photocatalytic H2 evolution.

Rational design of the morphology and heterojunction to accelerate the separation of electron-hole pairs has played an indispensable role in improving the photocatalytic hydrogen evolution. ZnIn2S4 (ZIS) has aroused considerable attention in solar-to-chemical energy conversion due to its remarkable photoelectrical properties and relatively negative energy band, whereas it still suffers from the severe photogenerated carrier recombination and catalyst aggregation. Herein, guided by density functional theory calculations, the constructed FeSe2@ZnIn2S4 (FS@ZIS) heterojunction model has a hydrogen Gibbs free energy closer to zero compared with pure ZIS and FS, which is beneficial for hydrogen adsorption and desorption on the photocatalyst surface. Therefore, a novel cross-like core-shell FS@ZIS Step-scheme (S-scheme) heterojunction was synthesized successfully by in-situ growing ZIS nanosheets on the surface of cross-like FS. The structure with cross-like core-shell morphology not only inhibits the agglomeration of ZIS to increase specific surface area, but also provides a tight interface with S-scheme heterojunction. Moreover, the S-scheme heterojunction with a tight interface can effectively separate electron-hole pairs, leaving photoinduced charges with higher potentials. Furthermore, FS@ZIS-20 possesses exceptional photothermal capabilities, enabling the conversion of optical energy from visible and near infrared light to heat, thereby further enhancing the photocatalysis reaction. As a result, the cross-like core-shell FS@ZIS S-scheme heterojunction exhibits an excellent photocatalytic hydrogen evolution rate (7.640 mmol g-1 h-1), which is 24 times higher than that of pure ZIS (0.319 mmol g-1 h-1) under visible and near infrared light. Furthermore, employing more in-depth density functional theory calculations further investigates the charge transfer pathway of the FS@ZIS S-scheme heterojunction. This work provides insights into the construction of S-scheme heterojunctions with core-shell structure and photothermal effect for photocatalytic evolution hydrogen.

Simultaneously Utilizing Excited Holes and Electrons for Piezoelectric-Enhanced Photoproduction of H2O2 from S-Scheme 2D S-Doped VOx/g-C3N4 Nanostructures.

2D/2D step-scheme (S-scheme) piezo-photocatalysts for the production of fine chemicals, such as hydrogen peroxide (H2O2), have attracted significant attention of global scientists owing to the efficiency in utilizing surface piezoelectric effects from 2D materials to overcome rapid charge recombination in photocatalytic processes. In this research, we reported the fabrication of 2D S-doped VOx deposited on 2D g-C3N4 to produce H2O2 via the piezo-photocatalytic process with high production yields at 20.19 mmol g-1 h-1, which was 1.75 and 4.87 times higher than that from solely piezo-catalytic and photocatalytic H2O2 generation. The finding pointed out that adding sulfur (S) to VOx can help to improve the catalytic outcomes by modifying the electronic properties of pristine VOx. In addition, when coupled with g-C3N4, the presence of S limits the formation of graphene in the VOx/g-C3N4 composites, causing shielding effects and pushing the cascade reactions toward water generation in the materials. Besides, the research also sheds light on the charge transport between g-C3N4 and S-VOx under irradiation and how the composites work to trigger the formation of H2O2. The presence of S in the composite systems enhances charge transfer between two semiconductors by strengthening the internal electric fields (IEF) to drive electrons moving in one direction, as demonstrated by density functional theory (DFT) calculations. Moreover, the formation of H2O2 significantly relies on the reduction of oxygen to generate oxygenic radical species at the g-C3N4 sites. Meanwhile, S-VOx provides oxidative sites in the composites to oxidize water molecules to directly or indirectly generate H2O2 or O2, which will further participate in the reactions to produce the final products. This study confirms the validation of S-scheme piezo-photocatalysts, thus encouraging further research on developing heterojunction materials with high catalytic efficiency, which can be used in practical conditions.