Construction of 2D S-Scheme Heterojunction Photocatalyst

COF nanotubes/2D nanosheets heterojunction for superior photocatalytic bactericidal activity even at low concentration and weak light

Microbial fouling is a huge nuisance to equipment operation and human health. Two-dimensional (2D) photocatalytic materials such as g-C3N4, WSe2, and Ti3C2Tx, show immense potential for solar-driven eradication of microbial fouling. However, limited photon absorption and rapid photogenerated electron-hole recombination curtail their photocatalytic efficiency and availability, resulting in the necessity to operate at high concentration and strong light. Herein, three kinds of covalent organic frameworks (COF) nanotubes/2D nanosheets heterojunctions (COF-x) were flexibly constructed by in-situ growing COF nanotubes on g-C3N4, WSe2, and Ti3C2Tx nanosheet substrates via one-pot method. The internal electric field at the COF-x coupling interface enhanced the separation and migration of photogenerated charge pairs, contributing to the antimicrobial reactive oxygen species (ROS) produced by COF-x, which was 2.8-270 times more efficient than those of nanosheets. The bactericidal effect enhanced from 34.13 %∼41.68 % of pure nanosheets to over 99.86 % of COF-x at an ultra-low concentration of 2 µg/mL and a weak visible light of 15 mW/cm2. At a low concentration of 20 µg/mL, the bactericidal rate of COF-x achieved nearly 100 % within 6 h. COF-x also showed exceptional environmental stability and antimicrobial properties under heat, light, acid, alkali, and aqueous conditions, offering a new perspective in photocatalytic antimicrobial/antifouling.

Plasmon-mediated dual S-scheme charge transfer in Cu2-xS/In2S3/Bi2S3 hollow polyhedrons for efficient Photothermal-Assisted photocatalysis

Step-scheme (S-scheme) semiconductor junction has garnered considerable attention for its potential applications in photocatalytic energy conversion. However, the photocatalytic activity of S-scheme junctions is restricted by inadequate light absorption and low charge separation efficiency. Herein, a plasmon-mediated dual S-scheme junction is constructed by growing In2S3 and Bi2S3 nanoparticles on Cu2-xS hollow polyhedrons, exhibiting efficient photothermal-assisted photocatalysis. Due to the unique hollow polyhedron structure, the plasmon resonance, and the bandgap excitation, the Cu2-xS/In2S3/Bi2S3 hybrids show broad light absorption. Meanwhile, the plasmon-mediated dual S-scheme charge transfer, including the injection of plasmon-induced hot electrons from Cu2-xS to In2S3 and Bi2S3 as well as the transfer of plasmon-induced hot holes from the trap states of Cu2-xS to In2S3 and Bi2S3, enables the hybrids to have efficient charge separation. In addition, remarkable photothermal performance originates from the synergistic effect of plasmonic heating and lattice thermal vibration, which leads to a further increase in the local temperature and enhancement of charge transfer efficiency in the hybrids. As a result, the Cu2-xS/In2S3/Bi2S3 hybrids demonstrate outstanding performance in photothermal-assisted photocatalytic hydrogen generation, rivaling many similar photocatalysts. This work offers valuable insights for designing high-efficiency photocatalysts based on S-scheme junctions.

Enhancing built-in electric field via ZnIn2S4 nanosheet decorated with ZnS quantum dots photocatalyst for highly efficient hydrogen evolution

Two dimensional (2D) photocatalytic materials are desirable to achieve synergistic charge transfer and segregation. Here, we have developed 2D ZnIn2S4 nanosheet (3-4 nm) that generates more active sites for excellent photocatalytic activity. Further, we have fabricated ZnS quantum dots (QDs) and ZnS nanoparticles (NPs) embedded with ZnIn2S4 nanosheet in the form of ZnS QDs/ZnIn2S4 and ZnS NPs/ZnIn2S4 heterostructures prepared via one step hydrothermal method. The optimal ZnS QDs/ZnIn2S4 presents the hydrogen evolution rate (HER) of 4.5 mmol g-1 h-1 which was approximately 5 and 34 times higher than that of their counterparts as well as about 3 times more efficient than ZnS NPs/ZnIn2S4 heterostructure. The apparent quantum efficiency (AQE) of 21.2% was observed at 350 nm. The work functions determined through Ultraviolet photoelectron spectroscopy (UPS) elaborate the charge transfer mechanism. In situ KPFM validated the surface potential difference between the ZnS QDs and ZnIn2S4 interfaces estimated about 55 mV which was approximately 2 times higher than ZnS NPs/ZnIn2S4. Theoretical calculation confirms the significant reduction in Gibbs free energy about -0.6 eV. Electron paramagnetic resonance (EPR) spectra suggest the development of a novel S-scheme mechanism and provides a unique insight into the charge transfer, separation and the surface photovoltage of heterostructure photocatalysts.

Highly efficient photocatalytic removal of NO and synchronous inhibition of NO2via heterojunction formed by ZnAl-LDH and MXene-Ti3C2-derived TiO2@C

The key challenge in oxidizing NO using photocatalysis is controlling the selectivity of products to avoid the generation of toxic byproducts like NO2. Here, we propose regulating the generation of reactive oxygen species by constructing Type-II heterojunctions to facilitate the deep oxidation of NO to nitrates. Experimental characterization and Density functional theory (DFT) simulations demonstrate that the outstanding photocatalytic activity of heterojunction materials stems from their superior charge separation efficiency and stronger adsorption capacity for NO and O2 molecules, promoting the formation of reactive oxygen species. These results indicated that the best-performing sample, ZATC15, demonstrated an impressive NO removal efficiency of 65.43 %. However, the selectivity rate of NO2 was only 4.78 %, much lower compared to the NO2 selectivity rates of pure ZnAl-LDH (48.17 %) and TiO2@C (72.46 %). The intermediate and final products, the generation pathways of active free radicals (h+ and •O2-) and the mechanism behind the profound oxidation of NO were elucidated based on in-situ Fourier Transform Infrared Spectroscopy (in-situ FT-IR), Electron spin resonance (ESR), and capture experiment. This investigation will offer valuable insights for modifying LDH in order to effectively remove ppb-level NO through photocatalysis.

Preparation of Z-scheme AgI/Bi2Sn2O7 hybrids for profound CC/CO bonds cleavage in lignin β‑O‑4 ketone models

In the context of attaining carbon neutrality, photocatalytic cleavage of the CC/CO bonds between the β-O-4 structure into high-value products offers an environmentally friendly pathway. To simultaneously activate both CC and CO bonds for maximizing the utilization of lignin to yield high-value products requires the construction of highly active and selective photocatalysts. However, enhancing the efficiency and selectivity of photocatalysts for lignin degradation buffering unsuitable redox potential and rapid recombination of photogenerated carriers. Herein, we report that a direct Z-scheme heterojunction (AgI/Bi2Sn2O7) as confirmed by various characterizations. The construction of the Z-scheme AgI/Bi2Sn2O7 heterojunction was essential to efficiently separate the photoexcited carriers and then improve their redox capability. Due to its smart design, the lignin β-O-4 model compound was simultaneously activate both CC and CO bonds. Under solar illumination (AM1.5), the β-O-4 lignin molecule model achieved a conversion rate of 95.2 %, and the main product (guaiacol and p-anisaldehyde) yields were 87.6 % and 76.5 %, respectively. Mechanistic studies indicate that the efficient cleavage of CC/CO bonds mainly involved a photoexcited electron-hole-coupled redox mechanism. This finding offers insight into the high-performance charge transfer mechanism of heterogeneous interfaces, which could potentially inform the design of advanced photocatalytic systems in the depolymerisation of lignin.

An Atypical Heterojunction in Favor of Conversion of CO2 and Sunlight into C2H4

Current heterojunction semiconduction assemblies, including type I, II, Z-Scheme, and S-Scheme constructures, enable the utilization of longer-wavelength sunlight for photocatalytic conversions. However, such benefits are often achieved at the expense of either the redox potentials of the conduction and valence bands or the quantum yield due to additional electron-hole recombination across the heterojunction interface. Herein, an atypical type II heterojunction constituted of Au/TiO2/MFU-4l is reported that demonstrates outstanding catalytic performance in photocatalytic reduction of carbon dioxide (CO2) to ethylene (C2H4) through tuning up-converting of holes in MFU-4l component raised from full-spectrum solar irradiation. Anchored to the edge of cube MFU-4l with a TiO2 cover layer, aurum ions (Au+)supported by aurum (Au) nanoparticles enables such a reverse hole-transfer event through leveraging the Ti-O-•-Au+/0-•-O-Zn potential, which significantly accelerates the hole-dominated oxidative desaturation of C-C intermediates from CO2 reduction into C═C bond products. The catalyst efficiently converts CO2 to C2H4 with more than 90% selectivity and a yield of 107.0 µmol g-1 h-1 under simulated sunlight. Electron paramagnetic resonance (EPR) experiments directly observe the holes formed in visible-light excited MFU-4l moiety of Au/TiO2/MFU-4l that are fused into TiO2 component's holes, thereby generating more hydroxyl radicals (•OH) than that TiO2 is excited alone under ultraviolet (UV) carbon dioxide (CO2) light of the same intensity.

Construction of a thiophene-based conjugated polymer/TP-PCN S-scheme to enhance visible-light-driven photocatalytic activity: Promotion of wound healing in super-resistant bacterial infections

S-scheme heterojunctions have garnered significant attention in the field of photocatalytic antimicrobials due to their superior charge separation efficiency and higher redox capacity. In this study, an innovative linear conjugated polymer (PCO) was combined with fragmented carbon nitride (TP-PCN) to create PCO/TP-PCN organic-organic S-scheme heterojunctions, which markedly enhanced the photocatalytic antimicrobial performance. The composite (PCO-7/TP-PCN) demonstrated the ability to combat bacterial infections under visible light irradiation, effectively eradicating approximately 2.16 × 107 cfu/ml MRSA within 6 min. This exceptional photocatalytic performance can be attributed to the successful formation of an S-scheme heterojunction between PCO and TP-PCN, as well as the interaction of surface functional groups of PCO-7/TP-PCN with bacteria. Results from UV-Vis-NIR DRS and in situ-XPS experiments indicated a significant enhancement in carrier transport rate through the establishment of a built-in electric field and energy band bending at the interface. In vitro and in vivo experiments further demonstrated that PCO-7/TP-PCN not only exhibited potent antimicrobial activity under visible light irradiation but also promoted angiogenesis to inhibit inflammatory responses. Therefore, it can be concluded that this organic-organic S-scheme heterojunction photocatalyst holds great potential for development as a promising new generation of efficient antimicrobial materials, which could aid in preventing bacterial infection of wounds and ensuring effective wound healing.

Charge-transfer dynamics in S-scheme photocatalyst

Natural photosynthesis represents the pinnacle that green chemistry aims to achieve. Photocatalysis, inspired by natural photosynthesis and dating back to 1911, has been revitalized, offering promising solutions to critical energy and environmental challenges facing society today. As such, it represents an important research avenue in contemporary chemical science. However, single photocatalytic materials often suffer from the rapid recombination of photogenerated electrons and holes, resulting in poor performance. S-scheme heterojunctions have emerged as a general method to enhance charge transfer and separation, thereby greatly improving photocatalytic efficiencies. This Perspective delves into the electron transfer dynamics in S-scheme heterojunctions, providing a comprehensive overview of their development and key characterization techniques, such as femtosecond transient absorption spectroscopy, in situ irradiated X-ray photoelectron spectroscopy and Kelvin probe force microscopy. By addressing a critical research gap, this work aims to trigger further understanding and advances in photo-induced charge-transfer processes, thereby contributing to green chemistry and the United Nations sustainable development goals.

Highly selective conversion of NO to NO3-through radical modulation over UiO-66-67-NH2 S-scheme heterojunction

Semiconductor photocatalysis presents significant potential for reducing low concentrations of NO, yet achieving efficient and selective conversion of NO to NO3-while suppressing toxic NO2 release remains challenging. Here, a UiO-66-67-NH2 S-scheme heterojunction, synthesized by integrating UiO-66-NH2 and UiO-67-NH2, generate ·O2- as the sole active species for efficient NO to NO3-conversion under visible light. The photocatalytic performance evaluation indicates that the optimized UiO-66-67-NH2 efficiently and selectively converts NO to NO3-. The photocatalytic NO removal efficiency reaches 78 %, which is 2.2 times and 3.4 times higher than that of the individual UiO-66-NH2 and UiO-67-NH2, respectively. Experimental results and DFT calculations reveal that charge redistributions within the heterojunction creates an internal electric field, facilitating effective charge separation. The selective adsorption of O2 and NO at the Zr sites facilitates of ·O2- generation and NO enrichment, while the -NH2 sites suppress the formation of ·OH and 1O2, inhibiting NO2 release. The rate-determining step, reaction between *NO2 and *O is energetically favored in the heterojunction, accelerating NO3- formation. This study provides valuable insights into designing photocatalysts for environmental remediation by controlling reactive oxygen species and NO removal.

Interface Engineering, Charge Carrier Dynamics, and Solar-Driven Applications of Halide Perovskite/2D Material Heterostructured Photocatalysts

Halide perovskites (HPs), renowned for their intriguing optoelectronic properties, such as robust light absorption coefficient, long charge transfer distance, and tunable band structure, have emerged as a focal point in the field of photocatalysis. However, the photocatalytic performance of HPs is still inhibited by rapid charge recombination, insufficient band potential energy, and limited number of surface active sites. To overcome these limitations, the integration of two-dimensional (2D) materials, characterized by shortened charge transfer pathways and expansive surface areas, into HP/2D heterostructures presents a promising avenue to achieve exceptional interfacial properties, including extensive light absorption, efficient charge separation and transfer, energetic redox capacity, and adjustable surface characteristics. Herein, a comprehensive review delving into fundamentals, interfacial engineering, and charge carrier dynamics of HP/2D material heterostructures is presented. Numerous HP/2D material photocatalysts fabricated through diverse strategies and interfacial architectures are systematically described and categorized. More importantly, the enhanced charge carrier dynamics and surface properties of the HP/2D material heterostructures are thoroughly investigated and discussed. Finally, an analysis of the challenges faced in the development of HP/2D photocatalysts, alongside insightful recommendations for potential strategies to overcome these barriers, is provided.

Recent advances and perspectives of Li-O2 batteries

Aprotic Li-O2 batteries have emerged as a promising next-generation energy storage technology due to their high theoretical specific energy. However, the sluggish cathode reaction kinetics, undesired parasitic reactions, and severe lithium dendrites result in large overvoltages and poor cycling stability for Li-O2 batteries. Considerable efforts have been dedicated to designing cathode materials, optimizing electrolytes and stabilizing lithium anodes. Despite these advancements, fundamental understanding for improving performance remains insufficient. Herein, this review discusses recent advancements on cathode catalysts, semiconductor photocathodes, singlet oxygen (1O2) quenchers, and electrolytes in Li-O2 batteries, and provides perspectives on the remaining challenges and future development for Li-O2 batteries.

Building Ultrathin MOL/MOL S-Scheme Heterostructures toward Boosted Photocatalytic Charge Kinetics for Efficient H2 Evolution

Photocatalytic efficiencies highly depend on the kinetic behaviors of photogenerated electrons in catalysts. Herein, based on the promising metal-organic frameworks (MOFs), we design and build an advantageous architecture of ultrathin MOF-layer (metal-organic layers [MOL]) heterojunctions by a facile pH-adjusted electrostatic assembling of pre-exfoliated porphyrinic and pyrene-based MOLs. Such an architecture constitutes an S-scheme junction to drive interfacial charge separation, features ultrathin structures to shorten charge transfer distances, and maximizes accessible metal sites to facilitate terminal charge reaction, thoroughly promoting the charge kinetics in materials. The resulting MOL/MOL composites perform a significantly enhanced catalytic activity for visible-light-driven H2 evolution, 8.5 and 106 times that of individual MOLs. Further fine-tuning into more reactive metal nodes achieves an optimal H2 production (2027 µmol h-1 g-1) with a high apparent quantum yield of 2.75% without additional cocatalysts, ranking among state-of-the-art activities from all-MOF photocatalysts. This work demonstrates an accessible and universal methodology to realize a superior ultrathin MOL/MOL heterojunction architecture toward accelerated charge kinetics, providing valuable insights for the development of efficient photocatalyst systems for solar-to-chemical energy conversions.

Preparation of ZnIn2S4/MoS2-SA Photocatalyst Gel for Wastewater Treatment: Photocatalytic Performance and Solar Interfacial Evaporation

With the rapid advancement of industrialization, wastewater pollution has become an increasingly severe environmental issue. The integration of photocatalysis with solar interfacial evaporation technology, which leverages the abundant and clean energy of solar power, has drawn growing attention as effective solutions to this problem. In this study, MoS2 nanosheets with low-dimensional and controllable morphology were successfully grown on layered ZnIn2S4 using a simple template method, resulting in a novel nanoflower heterojunction photocatalyst. This photocatalyst was then combined with sodium alginate, and aerogels were fabricated through directional freezing technology. The ZnIn2S4/MoS2 photocatalytic aerogel demonstrated excellent photocatalytic performance under visible light, efficiently degrading various pollutants such as rhodamine B(RhB)(30 min, 99%), methyl orange(MO)(30 min, 99%), tetracycline(TC)(1h, 88%), and other antibiotics and dyes. Notably, the degradation efficiency for tetracycline remained at 88% even after five cycles of use, highlighting the aerogel's strong reusability and stability across different pollutants. Additionally, the current aerogel composite exhibits an evaporation rate of up to 1.984 kg m-2 h-1 and a photothermal conversion efficiency of 95.5%. These results demonstrate that the ZnIn2S4/MoS2 photocatalytic aerogel is a promising candidate for sustainable water treatment, with broad applicability and stable photocatalytic degradation efficiency and interfacial evaporation efficiency under different polluted environments.

Light-Driven Low-Temperature and Near-Unity Conversion of Ester on a Perovskite Derivative Photothermal Catalyst via Photon-Bismuth Triggered Hotspot

Solar-driven photothermal chemical transformations are regarded as green processes to reduce energy consumption and are expected to utilize unique light-induced activation mechanisms to improve reaction kinetics. Halide perovskites and their derivatives, due to unique optoelectronic properties and compositional flexibility, are allowed for the precise regulation of energy band structures and surface electronic states, showing potentials as photoactivated catalysts with photo-thermal synergistic effects. However, the photothermal catalytic performance of halide perovskites is still unsatisfied with low conversion (<0.2%). Herein, Cs3BixSb2- xBr9 is designed as a novel and effective photothermal catalyst for light-driven degradation of ester under room temperature, achieving a near-unity conversion of ≈99% without external heating. Photothermal catalytic process shows the remarkable enhancementup to 796% and 200% compared with that in the single thermocatalysis or photocatalysis. The stable catalyst shows superior light-driven cyclic performance, as well. Mechanistic studies combined with in situ characterizations and theoretical calculations show that photon-bismuth hotspot with the synergy of photoinduced charge transfer process (photochemistry) significantly reduce the activation energy, light-to-heat effects (thermochemistry) elevate the local temperature, and bismuth active site promotes the C─O bond activation (surface adsorption), which together contribute to excellent solar-driven conversion efficiency on the perovskite derivative.

A bi-functional S-scheme cobalt-porphyrin conjugated polymer/C3N4 heterojunction for cooperative CO2 reduction and tetracycline degradation

The design of bifunctional photocatalysts for the removal of contaminants and the reduction of CO2 is of significant practical importance in addressing pollution and energy challenges. However, the photocatalytic efficiency is limited by the inadequate redox ability, high carrier recombination rate, and insufficient reactive sites of existing photocatalysts. Herein, a 2D/2D S-scheme heterojunction composed of cobalt-porphyrin conjugated polymer nanoflakes and C3N4 nanosheets (CoPor-DBE/CN) was rationally synthesized, exhibiting matched redox ability and favorable CO2 adsorption properties. The layered structure and functional groups of CoPor-DBE/CN provide numerous active sites, thereby enhancing the separation and transfer of charge carriers as well as the adsorption of reactants. Under visible light illumination, the optimized 50CoPor-DBE/CN hybrid achieved a CO production rate of 16.7 μmol g-1 h-1 and a tetracycline removal rate of 93.8%, which are significantly higher than those of the individual CN material. By employing X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), and photo-irradiated Kelvin probe force microscopy (KPFM), we demonstrate that the transfer of charge carriers within the CoPor-DBE/CN system follows the S-scheme heterojunction mechanism. This work offers a promising blueprint for the design of multifunctional S-scheme photocatalysts aimed at the simultaneous efficient reduction of CO2 and degradation of organic pollutants.

Nanoconfinement Effects in Electrocatalysis and Photocatalysis

Recently, the enzyme-inspired nanoconfinement effect has garnered significant attention for enhancing the efficiency of electrocatalysts and photocatalysts. Despite substantial progress in these fields, there remains a notable absence of comprehensive and insightful articles providing a clear understanding of nanoconfined catalysts. This review addresses this gap by delving into nanoconfined catalysts for electrocatalytic and photocatalytic energy conversion. Initially, the effect of nanoconfinement on the thermodynamics and kinetics of reactions is explored. Subsequently, the primary and secondary structures of nanoconfined catalysts are categorized, their properties are outlined, and typical methods for their construction are summarized. Furthermore, an overview of the state-of-the-art applications of nanoconfined catalysts is provided, focusing on reactions of hydrogen and oxygen evolution, oxygen reduction, carbon dioxide reduction, hydrogen peroxide production, and nitrogen reduction. Finally, the current challenges and future prospects in nanoconfined catalysts are discussed. This review aims to provide in-depth insights and guidelines to advance the development of electrocatalytic and photocatalytic energy conversion technology by nanoconfined catalysts.

Ultrafast electron transfer at the ZnIn2S4/MoS2 S-scheme interface for photocatalytic hydrogen evolution

The performance of any photocatalyst relies on its solar harvesting and charge separation characteristics. Fabricating the S-scheme heterostructure is a proficient approach for designing next-generation photocatalysts with improved redox capabilities. Here, we integrated ZnIn2S4 (ZIS) and MoS2 nanosheets to develop a unique S-scheme heterostructure through an in situ hydrothermal technique. The designed ZIS/MoS2 heterostructure showcased a 2.8 times higher photocatalytic H2 evolution rate than pristine ZIS nanosheets. The steady-state optical measurements revealed enhanced visible light absorption and reduced charge recombination in the heterostructure. Transient absorption (TA) spectroscopy revealed the interfacial electron transfer from ZIS to MoS2. The X-ray photoelectron and electron/hole quenching TA spectroscopic measurements collectively confirmed the integration of both semiconductors in an S-scheme manner, facilitating enhanced H2 production in the case of the heterostructure. This study highlights the importance of in-depth spectroscopic investigations in advancing the photocatalytic performance of S-scheme heterostructure-based photocatalysts.

In situ engineered Ce2O2S/CeO2 nanofibrous heterojunctions for photocatalytic H2O2 synthesis via S-scheme charge separation

Photocatalytic H2O2 synthesis offers an efficient and sustainable means to convert solar energy into chemical energy, representing a forefront and focal point in photocatalysis. S-scheme heterojunctions demonstrate the capability to effectively separate photogenerated electrons and holes while possessing strong oxidation and reduction abilities, rendering them potential catalysts for photocatalytic H2O2 synthesis. However, designing S-scheme heterojunction photocatalysts with band alignment and close contact remains challenging. Here we report Ce2O2S/CeO2 multiphase nanofibrous prepared via an in situ sulphuration/de-sulphuration strategy. This in situ process enables intimate contact between the two phases, thereby shortening the charge transfer distance and promoting charge separation. The interfacial electronic interaction and charge separation were investigated using in situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. The work function difference enables Ce2O2S to donate electrons to CeO2 upon combination, resulting in the formation of an internal electric field (IEF) at interfaces. This IEF, along with bent energy bands, facilitates the separation and transfer of photogenerated charge carriers via an S-scheme pathway across the Ce2O2S/CeO2 interfaces. The Ce2O2S as the reduction photocatalyst exhibits significant O2 adsorption and activation along with a low energy barrier for the H2O2 production. The optimal Ce2O2S/CeO2 nanofibers heterojunction demonstrate enhanced photocatalytic H2O2 production of 2.91 mmol g-1h-1, 58 times higher than that of pristine CeO2 nanofibers. This investigation provides valuable insights for the rational design and preparation of intimate contact nanofibrous heterojunctions with efficient solar H2O2 synthesis.

Recent Advances of Indium-Based Sulfides in Photocatalytic CO2 Reduction

Urgent and significant, the mitigation of greenhouse effects and the preservation of the Earth's ecological environment are paramount concerns. Photocatalytic carbon dioxide (CO2) reduction technology holds immense promise as it directly harnesses renewable solar energy to convert CO2 into hydrocarbon fuels and valuable chemical products. Indium (In)-based sulfides have garnered significant attention in the realm of fundamental research on CO2 photocatalytic conversion. The photocatalytic performance exhibited by In-based materials is attributed to the appropriate bandgap (E g), unique electronic states, tunable atomic structure, and superior optoelectronic properties. Notably, In-based metal sulfides also show excellent potential for addressing challenges related to photocorrosion and carrier recombination. This paper highlighted the key structural features and commonly employed synthesis techniques of In-based metal sulfides. Furthermore, it summarized effective modification strategies aimed at optimizing the photocatalytic performance of these materials. A particular focus was placed on exploring the intricate structure-activity relationships, encompassing the influence of heterostructure construction, element doping, defect engineering, and co-catalyst modification on enhancing photocatalytic efficiency. Finally, the article identified the current challenges and outlined the promising future directions for In-based photocatalysts, hoping to provide valuable references for researchers.

Unique NiCo bimetal boosting 98% CH4 selectivity and high catalysis stability for photothermal CO2 hydrogenation

A highly dispersed NiCo alloy catalyst derived from NiCo bimetallic-organic framework nanosheets was synthesized for efficient photothermal catalysis for CO2 hydrogenation to methane. The NiCo bimetal catalyst achieves a CH4 production rate of 55.60 mmol g-1 h-1 with only a 18.82% decline in performance after 86 hours under atmospheric pressure at selected 290 °C and continuous flow reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveals the synergistic and complementary roles of light and heat in photothermal catalysis. The thermochemical process drives the reverse water-gas shift reaction to form a *CO intermediate, a key intermediate for the formation of CH4, and light irradiation-generating strong near field from the surface plasma resonance of NiCo bimetals promotes the subsequent *CO hydrogenation step to form *CHO, the rate-determining step for the hydrogenation of CO2 into CH4. Meanwhile, density functional theory (DFT) calculations suggest that the NiCo bimetallic catalyst can also lower the energy barrier of *CO hydrogenation, facilitating the formation of *CHO.

Direct Synthesis of Topology-Controlled BODIPY and CO2-Based Zirconium Metal-Organic Frameworks for Efficient Photocatalytic CO2 Reduction

Boron dipyrromethene (BODIPY)-based zirconium metal-organic frameworks (Zr-MOFs) possess strong light-harvesting capabilities and great potential for artificial photosynthesis without the use of sacrificial reagents. However, their direct preparation has not yet been achieved due to challenges in synthesizing suitable ligands. Herein, we reported the first successful direct synthesis of BODIPY-based Zr-MOFs, utilizing CO2 as a feedstock. By controlling synthetic conditions, we successfully obtained two distinct Zr-MOFs. The first, CO2-Zr6-DEPB, exhibits a face-centered cubic (fcu) topology based on a Zr6(μ3-O)4(μ3-OH)4 node, while the second, CO2-Zr12-DEPB, features a hexagonal closed packed (hcp) topology, structured around a Zr12(μ3-O)8(μ3-OH)8(μ2-OH)6 node. Both MOFs demonstrated excellent crystallinity, as verified through powder X-ray diffraction and high-resolution transmission electron microscopy analyses. These MOF catalysts displayed suitable photocatalytic redox potentials for the reduction of CO2 to CO using H2O as the electron donor in the absence of co-catalyst or toxic sacrificial reagent. Under light irradiation, CO2-Zr12-DEPB and CO2-Zr6-DEPB offered high CO yields of 16.72 and 13.91 μmol g-1 h-1, respectively, with nearly 100 % selectivity. CO2 uptake and photoelectrochemical experiments revealed key insights into the mechanisms driving the different catalytic activities of the two MOFs. These BODIPY and CO2-based, light-responsive Zr-MOFs represent a promising platform for the development of efficient photocatalysts.

Designed 2D/2D F-doped TiO2@ZnIn2S4 heterojunction for efficient photo-utilization hydrogen generation

Comprehending the catalytic reaction implementation for heterostructure photocatalysts is crucial by scrutinizing the spatial separation and transfer process of photoexcited charges at nanoscale junctions. Herein, we fabricated the F-doped TiO2/ZnIn2S4-based S-scheme heterostructure using a direct liquid-assembly method. The optimum hydrogen evolution rate (HER) of ∼ 1.58 mmol g-1h-1 was acquired for 30-F3T@ZIS, which was about 15 and 2 times superior to the pristine F-doped TiO2 and ZnIn2S4, respectively. The interaction between F-doped TiO2 and ZnIn2S4 facilitated the charge transfer from ZIS to F3T which was confirmed through XPS. UV-vis spectroscopy and Mott-Schottky validated that F-doped TiO2 and ZnIn2S4 retain the suitable energy band alignment for the S-scheme heterostructure. In situ, KPFM and EPR analysis revealed that F-doped TiO2 and ZnIn2S4 possess a spontaneous photoelectrochemical response, and their junction significantly improves the internal electric field by separating photoexcited charge carriers. This work provides a conclusive experimental and theoretical validation for an internal electric field and charge flow direction in non-noble-metal-based heterostructure photocatalysts.

Co Nanoparticles on MnO: Electron Transfer through Ohmic and S-Scheme Heterojunction for Photocatalytic Hydrogen Evolution

The photocatalytic hydrolysis method represents a significant potential solution to the dual challenges of energy security and environmental sustainability. The selection of suitable photocatalytic materials and systems is of paramount importance for the successful implementation of photocatalytic hydrogen production technology. In this study, in situ reduction of Co nanoparticles on MnO was successfully performed by calcining MnCo-PBA. Furthermore, graphdiyne (GDY) was successfully introduced by physical agitation. The introduction of GDY reduced Co/MnO agglomeration and made the Co/MnO/GDY catalyst exhibit high activity in hydrogen production, with an optimum production rate of 2117.33 μmol·g-1·h-1, which was 4.88 and 2.67 times higher than that of GDY and Co/MnO, respectively. The results of the photoelectrochemical test indicate that the composite catalyst has a better photogenerated carrier separation efficiency. In situ X-ray photoelectron spectroscopy, density functional theory calculations, and electron paramagnetic resonance were used to investigate the electron transfer mechanism during the photocatalytic process, confirming the presence of an S-scheme heterojunction and an ohmic junction, which enhance the separation of photogenerated carriers. The GDY-based heterojunction catalyst constructed in this study has the potential to significantly enhance the hydrogen production activity of bimetallic catalysts.

Reducing Intrinsic Carrier Recombination in Au/CuTCPP(Fe) Schottky Junction Through Spin Polarization Manipulation for Sensitive Photoelectrochemical Biosensing

Schottky junctions have been widely applied to facilitate charge carrier separation through the formation of an internal electric field (IEF). However, the notably restricted spatial distribution of the IEF weakens the promotion of intrinsic carrier separation. In this study, we unveil that Au nanoparticles (NPs) in the Au/CuTCPP(Fe) Schottky junction can manipulate the spin polarization of CuTCPP(Fe) to inhibit inner carrier recombination. Experimental investigations and theoretical calculations reveal that the introduction of Au NPs leads to an increased population of spin-polarized electrons, effectively suppressing inner charge carrier recombination in CuTCPP(Fe) by employing the spin mismatch between spin-polarized photoexcited carriers. Moreover, as a typical active site for the oxygen reduction reaction, the oxygen adsorption configuration on spin-polarized Fe single-atom sites in Au/CuTCPP(Fe) is further optimized, resulting in boosted interfacial reactions. Leveraging the thiocholine-induced poisoning of the active sites and the magnetic-enhanced photoelectric response, Au/CuTCPP(Fe) is harnessed to develop a photoelectrochemical biosensing platform for organophosphorus pesticides. This work offers a promising method for manipulating the spin polarization of semiconductors in heterojunctions to mitigate intrinsic charge carrier recombination.

Promoted Photocatalytic H2 Production of 0D/2D CeO2 Nanoparticles and N-Defects Graphitic Carbon Nitride S-Scheme Heterojunction

Incorporating two-phase heterojunctions with matching band structures represents a promising strategy for developing photocatalysts with enhanced efficiency. This work prefers a novel approach that employs a template-assisted strategy based on a porous structured UCCN@CeO2 0D/2D S-scheme heterojunction. The proposed method aims to improve photocatalytic activity by harnessing the synergistic effects of monodispersed CeO2 nanoparticles and ultrathin N-defect CN nanosheets. The catalyst demonstrates a remarkable photocatalytic hydrogen evolution rate, reaching an impressive value of 5.59 mmol h-1 g-1 when subjected to simulated sunlight irradiation. Furthermore, the photocatalyst maintains a substantial activity level, yielding 2.35 mmol h-1 g-1 under visible light (≥400 nm). The significant improvement in the photocatalytic performance of the UCCN@CeO2 catalyst is attributed to the unique structural design and effective charge separation facilitated by the S-scheme mechanism. Kelvin probe force microscopy, theoretical calculations, and femtosecond transient absorption spectroscopy affirm the efficient charge transportation across the catalyst interface. Additionally, electron spin resonance spectroscopy measurements further support the charge transfer pathway in the S-scheme. This research presents an innovative approach for designing and developing CN-based catalysts featuring S-scheme heterojunctions, aiming to improve their efficiency and practical use in photocatalytic applications.

Synergetic efficiency: in situ growth of a novel 2D/2D chemically bonded Bi2O3/Cs3Bi2Br9 S-scheme heterostructure for improved photocatalytic performance and stability

Adverse reactions caused by waterborne contaminants constitute a major hazard to the environment. Controlling the pollutants released into aquatic systems through water degradation has been one of the major concerns of recent research. Bismuth-based perovskites have exhibited outstanding properties in the field of photocatalysis. Nonetheless, many proposed bismuth-based perovskites still suffer from stability problems. The present study investigated a unique bismuth-based metal-co-sharing composite of 2D Bi2O3/Cs3Bi2Br9 nanosheet perovskite synthesized via a modified anti-solvent reprecipitation method. Several samples were prepared using different ratios of Bi2O3 and Cs3Bi2Br9. The optimal composite sample was found to be BO/CBB 28%, where 2D stacked nanosheets of Cs3Bi2Br9 showed remarkable interaction with Bi2O3 due to its optimal Bi co-sharing, as displayed in the FE-SEM and HRTEM images. However, further increasing the percentage led to greater agglomeration, hindering the photocatalytic degradation efficiency. The average size and optical band gap energy of the optimal sample were 42.5 nm and 2.46 eV, respectively. The photocatalytic degradation of MB using the optimal sample reached ∼92% within 60 min with a catalyst dosage of 10 mg L-1. With an increase in catalyst concentration to 40 mg L-1, MB removal reached almost ∼96% within 60 min under visible light owing to the enhanced stability, facilitating efficient charge separation. This paper presents an improved composite with optimal ratios of 2D Bi2O3/Cs3Bi2Br9 nanosheets that demonstrated good stability and enhanced photocatalytic performance in comparison with pure Bi2O3 and Cs3Bi2Br9. This study also sheds light on the significance of metal co-sharing and the pivotal role it plays in enhancing the S-scheme charge transfer and the internal electric field between the two components.

Enabling Interfacial Lattice Matching by Selective Epitaxial Growth of CuS Crystals on Bi2WO6 Nanosheets for Efficient CO2 Photoreduction into Solar Fuels

Photocatalytic CO2 reduction serves as an important technology for value-added solar fuel production, however, it is generally limited by interfacial charge transport. To address this limitation, a two-dimensional/two-dimensional (2D/2D) p-n heterojunction CuS-Bi2WO6 (CS-BWO) with highly connected and matched interfacial lattices was designed in this work via a two-step hydrothermal tandem synthesis strategy. The integration of CuS with BWO created a robust interface electric field and provided fast charge transfer channels due to the work function difference, as well as highly connected and matched interfacial lattices. The p-n heterojunction combination promoted the electron transfer from the Cu to Bi sites, leading to the coordination of Bi sites with high electronic density and low oxidation state. The Bi sites in the BWO nanosheets facilitated the adsorption and activation of CO2, and the generation of high-coverage key intermediate b-CO3 2-, while CuS (CS) acted as a broad light-harvesting material to provide abundant photoinduced electrons that were injected into the conduction band of BWO for CO2 photoreduction reaction. Remarkably, the p-n heterojunction CS-BWO exhibited average CO and CH4 yields of 33.9 and 16.4 μmol g-1 h-1, respectively, which were significantly higher than those of CS, BWO, and physical mixture CS-BWO samples. This work provided an innovative design strategy for developing high-activity heterojunction photocatalyst for converting CO2 into value-added solar fuels.

Heterogeneous Interface Engineering of 2D Black Phosphorus-Based Materials for Enhanced Photocatalytic Performance

Photocatalysis has garnered significant attention as a sustainable approach for energy conversion and environmental management. 2D black phosphorus (BP) has emerged as a highly promising semiconductor photocatalyst owing to its distinctive properties. However, inherent issues such as rapid recombination of photogenerated electrons and holes severely impede the photocatalytic efficacy of single BP. The construction/stacking mode of BP with other nanomaterials decreases the recombination rate of carriers and extend its functionalities. Herein, from the perspective of atomic interface and electronic interface, the enhancement mechanism of photocatalytic performance by heterogeneous interface engineering is discussed. Based on the intrinsic properties of BP and corresponding photocatalytic principles, the effects of diverse interface characteristics (point, linear, and planar interface) and charge transfer mechanisms (type I, type II, Z-scheme, and S-scheme heterojunctions) on photocatalysis are summarized systematically. The modulation of heterogeneous interfaces and rational regulation of charge transfer mechanisms can enhance charge migration between interfaces and even maximize redox capability. Furthermore, research progress of heterogeneous interface engineering based on BP is summarized and their prospects are looked ahead. It is anticipated that a novel concept would be presented for constructing superior BP-based photocatalysts and designing other 2D photocatalytic materials.

Hollow TiO2@TpPa S-Scheme Photocatalyst for Efficient H2O2 Production Through 1O2 in Deionized Water Using Phototautomerization

Hydrogen peroxide (H2O2) production through photocatalytic O2 reduction reaction (ORR) is a mild and cost-efficient alternative to the anthraquinone oxidation strategy. Of note, singlet state oxygen (1O2) plays a crucial role in ORR. Herein, a hollow TiO2@TpPa (TOTP) S-scheme heterojunction by the Schiff base reactions involving 1,3,5-triformylphloroglucinol (Tp) and paraphenylenediamine (Pa) for efficient photocatalytic H2O2 production in deionized water has been developed. Upon irradiation, rapid phototautomerization of TaPa from enol to keto form expands π-electron delocalization, facilitating effective conversion of the triplet excited state and consequent generation of 1O2. This mechanism is supported by time-resolved electron paramagnetic resonance (EPR) spectral analysis. Additionally, density functional theory calculations, in situ irradiated X-ray photoelectron spectroscopy, and femtosecond transient absorption spectroscopy reveal superior separation of photogenerated carriers in the TOTP S-scheme composites. In deionized water, the TOTP2.4 S-scheme heterojunction exhibits exceptional H2O2 production activity, yielding 891 µmol g-1 h-1, underscoring the critical role of 1O2 in the process. This research offers insights into the S-scheme heterojunctions and emphasizes the pivotal role of 1O2 in enhancing H2O2 production efficiency.

Porous fluorine-cerium nanosheets anchored with FeOOH quantum dots for synergistic enhanced visible-light-driven photo-Fenton degradation of phenol

The utilization of two-dimensional (2D) materials to construct heterogeneous catalysts provides opportunities for environmental remediation, while the incorporation of porous structures can further enhance catalytic performance. In this work, a porous 2D FeOOH/fluorine-cerium (F-Ce) nanosheet composite was designed and synthesized by a simple impregnation-precipitation method. The unique 2D porous structure of F-Ce promoted the high dispersion of FeOOH quantum dots (QDs) (∼1.4 nm) and their tight integration to form S-scheme heterojunctions. This structure offered a greater number of active sites, and significantly improved the capacity of light absorption and the separation and migration efficiency of photogenerated carriers, thus improving catalytic activity. This catalyst achieved a phenol removal rate of 98.1 % within 20 min during the photo-Fenton reaction, which significantly surpasses pure FeOOH (32.9 %) and F-Ce (21.7 %) alone. In particular, the optimized 14FeOOH/F-Ce catalyst achieved more than 95.0 % degradation efficiency within a remarkably short period of 5 min. Mott Schottky and in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) studies demonstrated that the S-scheme charge transfer mechanism of this heterojunction synergistically enhanced the catalytic activity of the Fenton-like reaction. This study provides valuable insights for designing efficient 2D porous heterojunction catalysts for visible-light-driven Fenton applications.

Unveiling Charge Carrier Dynamics at Organic-Inorganic S-Scheme Heterojunction Interfaces: Insights From Advanced EPR

Understanding charge carrier transfer at heterojunction interfaces is critical for advancing solar energy conversion technologies. This study utilizes continuous wave (CW), pulse, and time-resolved (TR) electron paramagnetic resonance (EPR) spectroscopy to explore the radical species formed at the TAPA (tris(4-aminophenyl)amine)-PDA (Terephthaldicarboxaldehyde)/ZnIn2S4 (TP/ZIS) heterojunction interface. CW and pulse EPR identify stable radical defects localized near the interface, accessible to water molecules. Time-resolved EPR reveals a photoinduced electron transfer from TP to ZIS, leading to the generation of spin-correlated radical pairs under light irradiation, signifying efficient charge carrier separation and spatial transfer within the S-scheme heterojunction. This electron transfer mechanism, confirmed through in situ X-ray photoelectron spectroscopy and femtosecond transient absorption spectroscopy, suppresses undesirable carrier recombination, extending charge carrier lifetimes. These findings provide novel insights into the transport direction of charge carriers at the S-scheme heterojunction interface, offering valuable guidance for designing highly efficient and stable organic-inorganic heterojunction photocatalysts for solar energy applications.

Improved hydrogen production performance of an S-scheme Nb2O5/La2O3 photocatalyst

Addressing the intricate challenge of simultaneously improving the separation of photoinduced electron-hole pairs and enhancing redox potentials to produce hydrogen fuel demands the rational design of S-scheme heterojunction photocatalysts. Herein, we used a hydrothermal process to integrate Nb2O5 nanorods and La2O3 nanosheets to design an Nb2O5/La2O3 S-scheme system for photocatalytic hydrogen production under simulated sunlight illumination. Notably, the optimal hydrogen production performance of Nb2O5/La2O3 (the molar ratio of Nb2O5 to La2O3 is 0.4% and denoted as 0.4NbO-LaO) reached 2175 μmol h-1 g-1, which is 14.5 and 15.9 times superior in comparison with those of pure Nb2O5 and La2O3, respectively. In addition, repeated experiments verify the strong stability of the 0.4NbO-LaO photocatalyst. The S-scheme mechanism, verified by the in situ XPS method, plays a crucial role in producing hydrogen with a significantly higher yield than pure Nb2O5 and La2O3. This design approach offers an innovative avenue to widen the scope of S-scheme photocatalysts for solar fuel production.

Zeeman Effect-Boosted Spin-Polarized Band Splitting in Diluted Magnetic Photocatalysis Semiconductors for Efficient CO2 Photoreduction

Magnetic field regulation is an effective strategy to improve the photocatalytic activity of magnetic semiconductor photocatalysts, but it is not suitable for widely used nonmagnetic photocatalytic semiconductors. Here, we report a Zeeman effect-driven spin-polarized band splitting phenomenon in diluted magnetic semiconductors that show efficient photocatalytic CO2 reduction under visible-light irradiation. A flexible Ni2+-doped BaTiO3 nanofiber film is used as the diluted magnetic semiconductor model to prove this concept. The interstitial Ni2+ dopant induces the spin-polarized bands in Ni-BaTiO3 nanofibers to split under light excitation, generating spin-excited electrons and holes. This Zeeman effect induced by the magnetic field is more obvious since it intensifies the spin-polarized band splitting and generates more spin-excited electrons and holes, suppressing the carrier recombination and extending the carrier lifetime for CO2 photoreduction. As a result, the evolution rates of CO and CH4 are as high as 86.47 and 96.06 μmol/g/h under a small magnetic field of 50 mT. The proposed mechanism of Zeeman effect-driven spin-polarized band splitting is feasible to improve the CO2 photoreduction efficiency of broadly applied diluted magnetic semiconductors.

Tuning interfacial charge transport via Ti-O-Sn bonds for efficient CO2 conversion

Here, the clever design of forming an ohmic contact between SnS2 and MXene can regulate interfacial electron transport through Ti-O-Sn chemical bonds. This fast directional charge transport kinetics is attributed to the built-in electric field formed by the ohmic contact. As expected, the photoreduction CO2 activity of the optimized SSTC-5 catalyst is 10.4 times that of the original SnS2.

Organic-inorganic complex S-scheme photocatalyst resorcinol-formaldehyde resins/Bi2O2CO3 with enhanced photocatalytic H2O2 production

Herein, resorcinol formaldehyde resins/Bi2O2CO3 S-scheme heterojunctions are constructed via in situ polymerization. The composites displayed an improved separation efficiency of photo-induced carriers and the H2O2 production rate achieved 1178.08 μmol h-1 g-1, marking 47.18 times over that of Bi2O2CO3 under simulated solar illumination.

Optimizing photocatalytic hydrogen evolution performance by rationally constructing S-scheme heterojunction to modulate the D-band center

The research in the field of photocatalysis has progressed, with the development of heterojunctions being recognized as an effective method to improve carrier separation efficiency in light-induced processes. In this particular study, CuCo2S4 particles were attached to a new cubic CdS surface to create an S-scheme heterojunction, thus successfully addressing this issue. Specifically, owing to the higher conduction band and Fermi level of CuCo2S4 compared to CdS, they serve as the foundation and driving force for the formation of an S-scheme heterojunction. Through in-situ X-ray photoelectron spectroscopy and electron paramagnetic resonance analysis, the direction of charge transfer in the composite photocatalyst under light exposure was determined, confirming the charge transfer mechanism of the S-scheme heterojunction. By effectively constructing the S-scheme heterojunction, the d-band center of the composite photocatalyst was adjusted, reducing the energy needed for electron filling in the anti-bonding energy band, promoting the transfer of photogenerated carriers, and ultimately enhancing the photocatalytic hydrogen production. performance. After optimization, the hydrogen evolution activity of the composite photocatalyst CdS-C/CuCo2S4-3 reached 5818.9 μmol g-1h-1, which is 2.6 times higher than that of cubic CdS (2272.3 μmol g-1h-1) and 327.4 times higher than that of CuCo2S4 (17.8 μmol g-1h-1), showcasing exceptional photocatalytic activity. Electron paramagnetic resonance and in situ X-ray photoelectron spectroscopy have established a theoretical basis for designing and constructing S-scheme heterojunctions, offering a viable method for adjusting the D-band center to enhance the performance of photocatalytic hydrogen evolution.

Dual Near-Infrared-Response S-Scheme Heterojunction with Asymmetric Adsorption Sites for Enhanced Nitrogen Photoreduction

Photocatalytic nitrogen reduction reaction (PNRR) holds immense promise for sustainable ammonia (NH3) synthesis. However, few photocatalysts can utilize NIR light that carries over 50% of the solar energy for NH3 production with high performance. Herein, a dual NIR-responsive S-scheme ZnCoSx/Fe3S4 heterojunction photocatalyst is designed with asymmetric adsorption sites and excellent PNRR performance. The heterojunction possesses a hollow-on-hollow superstructure: Fe3S4 nanocrystal-modified ZnCoSx nanocages as building blocks assemble into spindle-shaped particles with a spindle-like cavity. Both Fe3S4 and ZnCoSx are NIR active, allowing efficient utilization of full-spectrum light. Moreover, an S-scheme heterojunction is constructed that promotes charge separation. In addition, the Fe/Co dual-metal sites at the interface enable an asymmetric side-on adsorption mode of N2, favoring the polarization and activation of N2 molecules. In combination with the promoted mass transfer and active site exposure of hollow superstructure, a superior PNRR performance is achieved, with a high NH3 evolution rate of 2523.4  µmol g-1 h-1, an apparent quantum yield of 9.4% at 400 nm and 8% at 1000 nm, and a solar-to-chemical conversion efficiency of 0.32%. The work paves the way for the rational design of advanced heterojunction catalysts for PNRR.

Polarization-Induced Internal Electric Field-Dominated S-Scheme KNbO3-CuO Heterojunction for Photoreduction of CO2 with High CH4 Selectivity

The polarization-induced internal electric field (IEF) in ferroelectric materials could promote photogenerated charge transfer across the heterojunction interface, but the effect of polarization-induced IEF on the mechanism of photogenerated charge transfer is ambiguous. In this study, a KNbO3-CuO heterojunction was synthesized by depositing copper oxide (CuO) onto KNbO3. Incorporating CuO broadens the light absorption of KNbO3, thereby enhancing the dissociation of the photogenerated charges. The results show that the polarization-induced IEF in KNbO3 determines that the charge transport mechanism in the KNbO3-CuO heterojunction follows the S-scheme. Owing to the S-scheme heterojunctions and efficient CO2 capture and activation by CuO, the CH4 production rate of KNbO3-CuO increased by nearly 26 times compared to KNbO3. Additionally, the CH4 selectivity of KNbO3-CuO could reach up to 97.80%. This research offers valuable insights into enhancing the photogenerated charge separation and constructing heterojunctions.

MoSe2-Sensitized Water Splitting Assisted by C60-Dendrons on the Basal Surface

To facilitate water splitting using MoSe2 as a light absorber, we fabricated water-dispersible MoSe2/C60-dendron nanohybrids via physical modification of the basal plane of MoSe2. Upon photoirradiation, the mixed-dimension MoSe2/C60 (2D/0D) heterojunction generates a charge-separated state (MoSe2⋅+/C60⋅-) through electron extraction from the exciton in MoSe2 to C60. This process is followed by the hydrogen evolution reaction (HER) from water in the presence of a sacrificial donor (1-benzyl-1,4-dihydronicotinamide) and co-catalyst (Pt-PVP). The apparent quantum yields of the HER were estimated to be 0.06 % and 0.27 % upon photoexcitation at the A- and B-exciton absorption peaks (λmax=800 and 700 nm), respectively.

Step-Scheme SnO₂/Zn₃In₂S₆ Catalysts for Solar Production of Hydrogen Peroxide From Seawater

Photocatalytic generation of H₂O₂, involving both oxygen reduction and water oxidation without sacrificial agents, necessitates maximized light absorption, suitable band structure, and efficient carrier transport. Leveraging the redox capacity this study designs and constructs a step-scheme heterostructured SnO₂/Zn₃In₂S₆ catalyst for H₂O₂ production from seawater under ambient conditions for the first time. This photocatalyst demonstrates a remarkable H₂O₂ production rate of 43.5 µmol g⁻¹ min⁻¹ without sacrificial agents, which can be increased to 80.7 µmol g⁻¹ min⁻¹ with additional O₂ injection. Extensive in situ and ex situ characterizations, supported by theoretical calculations, reveal efficient carrier transport and robust redox ability, enabling complete photosynthesis of H₂O₂ at the oxidation and reduction sites in the S-scheme SnO₂/Zn₃In₂S₆ heterojunction. Furthermore, it is hypothesized that substituting SnO₂ with other semiconductors such as TiO₂, WO₃, and BiVO₄ can all form S-scheme and the results confirm the feasibility of such catalyst design. Additionally, it demonstrates the recycling and further utilization of the H₂O₂ produced. These findings offer new insights into the design of heterostructure catalyst architectures and present new opportunities for H₂O₂ production from seawater at ambient conditions without sacrificial agents.

Efficient Preparation of S-Scheme Ag/AgBr/BiOBr Heterojunction Photocatalysts and Implications for Degradation of Carbendazim: Mechanism, Pathway, and Toxicology

Carbendazim (CBZ), as a highly effective benzimidazole fungicide, has a good control effect on various crops caused by fungi. However, excessive use of CBZ in water, atmosphere, soil, and crops has serious effects. The efficient degradation of CBZ is an effective way to reduce its toxic effect. In this work, the type of S-scheme Ag/AgBr/BiOBr heterojunction photocatalyst was effectively prepared by a simple one-step solvothermal in situ method and first applied to the mineralization and degradation of CBZ. The effects of the molar ratio of AgBr to BiOBr, catalyst dosage, CBZ concentration, pH value of the original solution, and inorganic salt ions on the photocatalytic degradation performance of CBZ were comprehensively studied. The results showed that, under visible light irradiation, 0.9-Ag/AgBr/BiOBr (0.9-AAB) exhibited the best photocatalytic degradation performance (88.9%) against the concentration at 10 mg/L of CBZ in original solutions with pH of 10. However, the degradation effect was also good at pH 7. After 90 min, the degradation efficiency reached 86.0%, corresponding to a TOC removal efficiency of 84.0%. The results indicate that the main active species are 1O2 and •O2- free radicals according to the free radical quenching experiments and electron spin resonance spectra. Combined with the XPS characterization results, the electron transfer mechanism of the S-scheme heterojunction was deeply revealed. Additionally, the degradation pathway of CBZ was proposed through both the intermediate identification and the theoretical calculation derived from the DFT Fukui index. Finally, the toxicity of CBZ and the degradation intermediates were predicted based on the T.E.S.T.

Full-spectrum plasmonic semiconductors for photocatalysis

Localized surface plasmon resonance (LSPR) of noble metal nanoparticles can focus surrounding light onto the particle surface to boost photochemical reactions and solar energy utilization. However, the rarity and high cost of noble metals limit their applications in plasmonic photocatalysis, forcing researchers to seek low-cost alternatives. Recently, some heavily doped semiconductors with high free carrier density have garnered attention due to their metal-like LSPR properties. However, plasmonic semiconductors have complex surface structures characterized by the presence of a depletion layer, which poses challenges for active site exposure and hot carrier transfer, resulting in low photocatalytic activity. In this review, we introduce the essential characteristics and types, synthesis methods, and characterization techniques of full-spectrum plasmonic semiconductors, elucidate the mechanism of full-spectrum nonmetallic plasmonic photocatalysis, including the local electromagnetic field, hot carrier generation and transfer, the photothermal effect, and the solutions for the surface depletion layer, and summarize the applications of plasmonic semiconductors in photocatalytic environmental remediation, CO2 reduction, H2 generation, and organic transformations. Finally, we provide a perspective on full-spectrum plasmonic photocatalysis, aiming to guide the design and development of plasmonic photocatalysts.

Photothermal-assisted S-scheme heterojunction of NiPS3 nanosheets modified ZnIn2S4 microspheres for promoting photocatalytic hydrogen evolution

Exploring high-efficiency photocatalysts for solar hydrogen (H2) generation through water splitting is of great significance for addressing both energy shortage and environmental contamination. In this work, a facile self-assembly strategy was developed to couple NiPS3 nanosheets (NPS NSs) with ZnIn2S4 (ZIS) microspheres to synthesize NPS NSs/ZIS (NPS/ZIS) composites, featuring a characteristic of S-scheme charge transfer mechanism. The NPS/ZIS composites possess broad-spectrum light absorption property, improved photothermal effect and efficient charge transfer, showcasing exceptional solar-to-chemical energy conversion capability for visible-light-driven photocatalytic hydrogen evolution (PHE). The photothermal effect derived from NPS NSs loading can facilitate charge carrier transfer across the interfaces and surface reaction kinetics. By carefully adjusting the mass ratio of NPS NSs, the optimized 4-NPS/ZIS exhibits excellent stability and significantly improved PHE activity (1827.6 μmol⋅g-1⋅h-1) in water, which is 18.4 times higher than that of bare ZIS (99.4 μmol⋅g-1⋅h-1). Furthermore, the 4-NPS/ZIS also shows the high PHE efficiency of 312.2 μmol⋅g-1⋅h-1 in seawater. Diverse characterization results reveal that the remarkably enhanced PHE performance primarily arises from the synergistic effect of S-scheme heterostructure, heightened light harvesting capacity, and enhanced photothermal effect. On the basis of density functional theory (DFT) simulations and experimental verifications, a possible PHE mechanism via the S-scheme heterojunction with photothermal assistance in NPS/ZIS is proposed. This study serves as inspiration for the development of novel photothermal-assisted S-scheme photocatalysts, paving the way for efficient and sustainable green energy production.

Surface Epitaxial Growth of 2D/2D Bi2O2S/CdS Heterojunction Photoanodes and Their Photoelectrochemical Properties

Constructing high catalytic activity heterojunctions to compensate for the shortcomings of single catalysts has promoted the development of semiconductor catalysts in photoelectrochemical (PEC) water splitting. In this case, the 2D/2D Bi2O2S/CdS composite was successfully constructed by an in situ surface epitaxial growth method. At 1.23 V vs RHE, the catalytic activity of Bi2O2S/CdS with a 2D/2D heterojunction is the highest, and the current density of the Bi2O2S/CdS photoanode is 3.46 mA/cm2. Compared with the Bi2O2S photoanode (0.59 mA/cm2), the performance has been improved by 5.86 times. In electrochemical impedance spectroscopy testing, the arc radius of 2D/2D Bi2O2S/CdS is smaller than that of Bi2O2S, indicating faster charge-transfer kinetics. The data show that the 2D/2D heterojunction with surface-surface contact successfully enhances the catalytic activity of Bi2O2S, greatly elevating the efficiency of charge separation and migration. This study provides a method to enhance the PEC activity in type-I heterojunction photoelectrodes, promoting the application of Bi2O2S-based materials in photoelectrochemistry.

Strong Built-In Electric Field-Assisted ZnO/ZnIn2S4 S-Scheme Heterostructure to Promote Photocatalytic Hydrogen Production

Photocatalysis is an eco-friendly and significant perspective for generating hydrogen. Our study investigated the ZnO/ZnIn2S4 heterojunction photocatalytic system prepared through hydrothermal technique. Accordingly, the ZnIn2S4 nanofibers loaded with 11 mol % ZnO exhibited the hydrogen evolution rate of about 1998 μmol g-1 h-1, which was 2.6 times higher than the pristine ZnIn2S4. In situ electron paramagnetic resonance results proved the S-scheme photocarrier transport route, and in situ KPFM further characterized the internal electric field between ZnO and ZnIn2S4. The development of S-scheme heterojunctions allows for the spatial segregation and transport of charges by preserving photoexcited holes and electrons with a tremendous redox potential. Furthermore, the photoelectrochemical analysis demonstrated that the S-scheme heterojunction could also be employed for the separation of photoexcited species.

Ultrafast Hole Trapping in Te-MoTe2-MoSe2/ZnO S-Scheme Heterojunctions for Photochemical and Photo-/Electrochemical Hydrogen Production

Te-MoTe2-MoSe2/ZnO S-scheme heterojunctions are engineered to ascertain the advanced redox ability in sustainable HER operations. Photo-physical studies have established the steady state transfer of photo-induced charge carriers whereas an improved transfer dynamics realized by state-of-art ultrafast transient absorption and irradiated-XPS analysis of optimized 5wt% Te-MoTe2-MoSe2/ZnO heterostructure. 2.5, 5, and 7.5wt% Te-MoTe2-MoSe2/ZnO photocatalysts (2.5MTMZ, 5MTMZ and 7.5MTMZ) exhibited 2.8, 3.3, and 3.1-fold higher HER performance than pristine ZnO with marvelous apparent quantum efficiency of 35.09%, 41.42% and 38.79% at HER rate of 4.45, 5.25, and 4.92 mmol/gcat/h, respectively. Electrochemical water splitting experiments manifest subdued 583 and 566 mV overpotential values of 2.5MTMZ and 5MTMZ heterostructures to achieve 10 mA cm-2 current density for HER, and 961 and 793 mV for OER, respectively. For optimized 5MTMZ photocatalyst, lifetime kinetic decay of interfacial charge transfer step is evaluated to be 138.67 ps as compared to 52.92 ps for bare ZnO.

A compendium of all-in-one solar-driven water splitting using ZnIn2S4-based photocatalysts: guiding the path from the past to the limitless future

Photocatalytic water splitting represents a leading approach to harness the abundant solar energy, producing hydrogen as a clean and sustainable energy carrier. Zinc indium sulfide (ZIS) emerges as one of the most captivating candidates attributed to its unique physicochemical and photophysical properties, attracting much interest and holding significant promise in this domain. To develop a highly efficient ZIS-based photocatalytic system for green energy production, it is paramount to comprehensively understand the strengths and limitations of ZIS, particularly within the framework of solar-driven water splitting. This review elucidates the three sequential steps that govern the overall efficiency of ZIS with a sharp focus on the mechanisms and inherent drawbacks associated with each phase, including commonly overlooked aspects such as the jeopardising photocorrosion issue, the neglected oxidative counter surface reaction kinetics in overall water splitting, the sluggish photocarrier dynamics and the undesired side redox reactions. Multifarious material design strategies are discussed to specifically mitigate the formidable limitations and bottleneck issues. This review concludes with the current state of ZIS-based photocatalytic water splitting systems, followed by personal perspectives aimed at elevating the field to practical consideration for future endeavours towards sustainable hydrogen production through solar-driven water splitting.

MgCr2O4/MgIn2S4 Spinel/Spinel S-Scheme Heterojunction: A Robust Catalyst for Photothermal-Assisted Photocatalytic CO2 Reduction

Photocatalytic CO2 reduction technology has engaged significant attention due to its high efficiency, high selectivity, and environmental friendliness. However, its application is severely restrained by issues such as low separation efficiency of photogenerated carriers and a limited light absorption range. This work proposes an innovative MgCr2O4/MgIn2S4 magnesium-based spinel/spinel heterostructure photocatalyst to improve the photocatalytic CO2 reduction efficiency through the synergistic contributions of S-scheme heterojunction and photothermal effect. On the one hand, the unique S-scheme charge transfer mechanism enables the effective separation of photogenerated carriers. On the other hand, the photothermal effect allows an accelerated charge migration by increasing the reaction center temperature. Moreover, the abundant oxygen vacancies serve as electron traps and CO2 adsorption sites, unifying reaction and adsorption sites and substantially improving catalytic efficiency. Under UV-vis and UV-vis-NIR illumination, the average CO yields of the MgCr2O4/MgIn2S4 composite are 8.03 and 15.62 μmol g-1 h-1, respectively, greatly higher than those of pure MgCr2O4 and MgIn2S4 samples. Furthermore, the fabricated photocatalyst demonstrates excellent performance and structure stability. Therefore, this work may offer a new strategy for designing efficient and stable photocatalysts.

High-Throughput Computational Study and Machine Learning Prediction of Electronic Properties in Transition Metal Dichalcogenide/Two-Dimensional Layered Halide Perovskite Heterostructures

Heterostructures formed by transition metal dichalcogenides (TMDs) and two-dimensional layered halide perovskites (2D-LHPs) have attracted significant attention due to their unique optoelectronic properties. However, theoretical studies face challenges due to the large number of atoms and the need for lattice matching. With the discovery of more 2D-LHPs, there is an urgent need for methods to rapidly predict and screen TMDs/2D-LHPs heterostructures. This study employs first-principles calculations to perform high-throughput computations on 602 TMDs/2D-LHPs heterostructures. Results show that different combinations exhibit diverse band alignments, with MoS2 and WS2 more likely to form type-II heterostructures with 2D-LHPs. The highest photoelectric conversion efficiency of type-II structures reaches 23.26%, demonstrating potential applications in solar cells. Notably, some MoS2/2D-LHPs form type-S structures, showing promise in photocatalysis. Furthermore, we found that TMDs can significantly affect the conformation of organic molecules in 2D-LHPs, thus modulating the electronic properties of the heterostructures. To overcome computational cost limitations, we constructed a crystal graph convolutional neural network model based on the calculated data to predict the electronic properties of TMDs/2D-LHPs heterostructures. Using this model, we predicted the bandgaps and band alignment types of 9,360 TMDs/2D-LHPs heterostructures, providing a comprehensive theoretical reference for research in this field.