Search

As cocatalysts play important roles in enhancing the catalytic performance, designing and fabricating highly active cocatalysts is an effective approach to improving photocatalytic H2 production. In this work, transition metal phosphides (including Fe2P, Co2P, and Ni2P) with nanoscale structures are synthesized by the solvothermal method, which can largely enhance the photocatalytic activity and stability of CdS nanorods as cocatalysts. By optimizing the synthesis and reaction conditions, 10% Co2P/CdS achieved the highest H2 production, about 29.24 mmol·g–1·h–1 in the lactic acid solution, which was 21.5 and 3.0 times higher than that of CdS (1.36 mmol·g–1·h–1) and 1% Pt/CdS (9.63 mmol·g–1·h–1), respectively. Testing by many characterizations, not only the reasons for different activities for TMPs/CdS but also the enhanced reasons of Co2P/CdS are explored. The results indicated that the non-noble metal Co2P cocatalyst not only enhanced the visible light absorption of CdS but also promoted the effective separation of photogenerated charge carriers. This work contributes to the further development of TMPs as low-cost and highly active cocatalysts for CdS-based photocatalysts. [ABSTRACT FROM AUTHOR]

Photosynthesis converts solar energy, carbon dioxide, and water into biomass, offering a renewable energy and chemical source. Biomass photo(electro)refining (BPeR) emerges as a sustainable alternative to petrochemicals for fuel and chemical production. However, BPeR faces challenges due to photocatalyst limitations, necessitating the integration of cocatalysts. Cocatalysts significantly impact the efficiency, selectivity, and durability of BPeR reactions, yet their roles require systematic elucidation and understanding. This review explores how cocatalysts impact the carbon bond functionalization, cleavage, and formation in biomass and its derivatives. It discusses their crucial roles in charge carrier generation, separation, and transportation, particularly in catalyzing surface reactions such as hydrogen‐involved reactions, generation, and manipulation of oxygen or carbon radicals, and the C─C/O/H bond transformations. Additionally, it outlines challenges and prospects for developing cocatalysts to enhance BPeR efficiency and durability, boosting the viability of biomass as a sustainable source of energy and materials. [ABSTRACT FROM AUTHOR]

An innovative charge self-regulation strategy is proposed to construct a strongly interacting 2D/2D ReS 2 -MoS 2 in-plane hetero-cocatalyst, which collectively enables the activation of H 2 O molecules and subsequent H 2 evolution. [Display omitted] • A in-plane 2D/2D ReS 2 -MoS 2 hetero-catalyst was developed via molten salt methods. • H 2 -evolution rate of TiO 2 can be greatly improved by ReS 2 -MoS 2 hetero-cocatalyst. • The high activity of ReS 2 -MoS 2 was due to the formed Re(4−δ)+ and S(2−δ)− sites. • A charge self-regulation mechanism of ReS 2 -MoS 2 was proposed. The rationally designing and constructing atomic-level heterointerface of two-dimensional (2D) chalcogenides is highly desirable to overcome the sluggish H 2 O-activation process toward efficient solar-driven hydrogen evolution. Herein, a novel in-plane 2D/2D molybdenum disulfide-rhenium disulfide (ReS 2 -MoS 2) heterostructure is well-designed to induce the charge self-regulation of active site by forming electron-enriched Re(4−δ)+ and electron-deficient S(2−δ)− sites, thus collectively facilitating the activation of adsorbed H 2 O molecules and its subsequent H 2 evolution. Furthermore, the obtained in-plane heterogenous ReS 2 -MoS 2 nanosheet can powerfully transfer photoexcited electrons to inhibit photocarrier recombination as observed by advanced Kelvin probe measurement (KPFM), in-situ X-ray photoelectron spectroscopy (XPS) and femtosecond transient absorption spectroscopy (fs-TAS). As expected, the obtained ReS 2 -MoS 2 /TiO 2 photocatalyst achieves an outperformed H 2 -generation rate of 6878.3 μmol h−1 g−1 with visualizing H 2 bubbles in alkaline/neutral conditions. This work about in-plane 2D/2D heterostructure with strong free-electron interaction provides a promising strategy for designing novel and efficient catalysts for various applications. [ABSTRACT FROM AUTHOR]

Energy demand worldwide demands clean, cheap, and renewable energy. Through the use of photoelectrochemical (PEC) conversion, solar energy can be transformed into chemical energy. Bismuth vanadate (BiVO4), a material exhibiting visible light activity, favourable conduction band edge energies, and ease of synthesis, has become increasingly popular in recent years. In BiVO4, charge carriers recombine rapidly, which adversely affects the PEC performance and stability. There have been several strategies developed to mitigate these deficiencies, including novel heterojunctions, doping with metals, coupling with cocatalysts, interface modification and modifying morphology. To achieve the best results, it is required to develop PEC devices with exceptional cost‐to‐efficiency ratios and long‐term durability. This review also examines novel yet commercially viable applications for BiVO4‐based photoanodes. Lastly, we discuss the challenges and perspectives facing PEC water splitting systems based on BiVO4. [ABSTRACT FROM AUTHOR]

Transition metal carbides, including both MXene and non‐MXene metal carbides, have enjoyed a soaring reputation in recent years. Benefitting from their intriguing physical and chemical characteristics, they shine in multifarious research fields and currently, they have emerged as promising nanomaterials for photocatalysis in energy and environmental science. Herein, based on the recent theoretical research and experimental studies, a systematic and comprehensive review of the expeditious advances of metal carbides and their nano‐architectures in the flourishing arena of photocatalysis is presented. The fundamental mechanism involved in photocatalysis with metal carbides serving as semiconductors or cocatalysts is thoroughly discussed. Besides, we highlight the main synthetic strategies of MXene and non‐MXene metal carbides and unravel the structural properties of the as‐obtained metal carbides via different fabrication routes to establish and elucidate their intriguing role in ameliorating photocatalytic activity. Moreover, the state‐of‐the‐art advancements of metal carbides in diverse photocatalytic applications, including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, and carbon dioxide reduction reaction, are summarized. In particular, insights into the structure–activity relationship of metal carbide in photocatalysis are elucidated. Finally, this review concludes with the ongoing challenges and perspectives on the future directions of metal carbides in the realm of photocatalysis. [ABSTRACT FROM AUTHOR]

Subnanocluster (SNC) cocatalysts are considered to be promising cocatalysts for photocatalytic hydrogen evolution reaction (HER) due to their rich surface-active sites and high atom utilization efficiency. Herein, a reductant-mediated in situ growth of the atomic clusters procedure is developed to synthesize SNC-Cu serving as advanced cocatalysts on TiO2 nanoparticles for HER. The optimized SNC-Cu/TiO2 catalyst, with 1.8 wt % metal mass loading, exhibits a remarkable hydrogen evolution rate of 6832 μmol g–1 h–1, which is ca. 25-fold that of bare TiO2 (273 μmol g–1 h–1 and comparable to that of 1 wt % Pt-modified TiO2 (7754 μmol g–1 h–1). Meanwhile, decent photostability and recyclability are also certified via a 20 h durability test. Comprehensive electron microscopy and spectroscopy characterizations unveil that the outstanding performance of SNC-Cu/TiO2 can be attributed to accelerated charge separation/transfer and suppressed photoinduced electron–hole recombination. Furthermore, in situ X-ray photoelectron spectroscopy and first-principle calculations reveal that the electron-localized SNC-Cu, with its abundant surface sites, facilitates *H adsorption and desorption, thus enhancing the HER activity significantly. This work highlights the promising potential of constructing noble-metal-free SNCs in semiconductors for photocatalytic HER. [ABSTRACT FROM AUTHOR]

In recent decades, photocatalysis technology, a typical mild and environmentally friendly technique, can use sunlight to drive the oxidation/reduction reactions on the surface of catalysts. However, single semiconductor materials can hardly meet the requirements of photocatalytic application due to the low availability of visible light, quick e− − h+ recombination, and the insufficiency of active sites. Cocatalysts are often introduced to solve the above problems. Among the numerous cocatalysts, NiS cocatalysts exhibit excellent properties, such as superior chemical stability, suitable band structure, and larger specific surface area, which can improve the photocatalytic efficiency of various semiconductors. Herein, the research progress of NiS cocatalysts in photocatalysis is reviewed. First, the structure of NiS and several common preparation methods are briefly introduced. Second, the NiS cocatalytic principle about how to achieve the effective separation of photogenerated carriers is introduced. Third, the methods to optimize the catalytic activity of NiS are mainly summarized. At the same time, the review summarizes the research progress of composite photocatalysts based on NiS cocatalyst. Finally, the review discusses the existing challenges and obstacles of NiS‐based photocatalytic systems and proposes feasible improvements and ideas to meet the future requirements of practical applications. [ABSTRACT FROM AUTHOR]

Cocatalyst depositing on photocatalysts with the oxidation of sacrificial reagents (photodeposition) has been widely used because of its simplicity. In most cases, alcohols are used as sacrificial reagents during photodeposition; however, the optimal types have yet to be fully investigated. In this study, methanol (MeOH) and triethanolamine (TEOA) are used as sacrificial reagents to prepare Pt‐ or Au‐deposited titanium dioxide. The use of different sacrificial reagents changes the deposition process. Pt deposited in the presence of MeOH and Au deposited in the presence of TEOA show higher cocatalytic activity. In this study, it is suggested that the consideration and selection of sacrificial reagents in terms of their reactivity with the cocatalyst are important for the development of optimal cocatalyst‐supported photocatalysts. [ABSTRACT FROM AUTHOR]

Oxygen vacancies in oxygen evolution cocatalysts (OECs) can significantly improve the photoelectrochemical (PEC) water splitting performance of photoanodes. However, OECs with abundant oxygen vacancies have a poor stability when exposing to the highly-oxidizing photogenerated holes. Herein, we partly fill oxygen vacancies in a MnCo2Ox OEC with N atoms by a combined electrodeposition and sol-gel method, which dramatically improves both photocurrent density and stability of a BiVO4 photoanode. The optimized N filled oxygen vacancy-rich MnCo2Ox/BiVO4 photoanode (3 at.% of N) exhibits an outstanding photocurrent density of 6.5 mA·cm−2 at 1.23 VRHE under AM 1.5 G illumination (100 mW·cm−2), and an excellent stability of over 150 h. Systematic characterizations and theoretical calculations demonstrate that N atoms stabilize the defect structure and modulate the surface electron distribution, which significantly enhances the stability and further increases the photocurrent density. Meanwhile, other heteroatoms such as carbon, phosphorus, and sulfur are confirmed to have similar effects on improving PEC water splitting performance of photoanodes. [ABSTRACT FROM AUTHOR]

Abstract Transition metal carbides, including both MXene and non‐MXene metal carbides, have enjoyed a soaring reputation in recent years. Benefitting from their intriguing physical and chemical characteristics, they shine in multifarious research fields and currently, they have emerged as promising nanomaterials for photocatalysis in energy and environmental science. Herein, based on the recent theoretical research and experimental studies, a systematic and comprehensive review of the expeditious advances of metal carbides and their nano‐architectures in the flourishing arena of photocatalysis is presented. The fundamental mechanism involved in photocatalysis with metal carbides serving as semiconductors or cocatalysts is thoroughly discussed. Besides, we highlight the main synthetic strategies of MXene and non‐MXene metal carbides and unravel the structural properties of the as‐obtained metal carbides via different fabrication routes to establish and elucidate their intriguing role in ameliorating photocatalytic activity. Moreover, the state‐of‐the‐art advancements of metal carbides in diverse photocatalytic applications, including hydrogen evolution reaction, oxygen evolution reaction, overall water splitting, and carbon dioxide reduction reaction, are summarized. In particular, insights into the structure–activity relationship of metal carbide in photocatalysis are elucidated. Finally, this review concludes with the ongoing challenges and perspectives on the future directions of metal carbides in the realm of photocatalysis.

Cocatalyst depositing on photocatalysts with the oxidation of sacrificial reagents (photodeposition) has been widely used because of its simplicity. In most cases, alcohols are used as sacrificial reagents during photodeposition; however, the optimal types have yet to be fully investigated. In this study, methanol (MeOH) and triethanolamine (TEOA) are used as sacrificial reagents to prepare Pt‐ or Au‐deposited titanium dioxide. The use of different sacrificial reagents changes the deposition process. Pt deposited in the presence of MeOH and Au deposited in the presence of TEOA show higher cocatalytic activity. In this study, it is suggested that the consideration and selection of sacrificial reagents in terms of their reactivity with the cocatalyst are important for the development of optimal cocatalyst‐supported photocatalysts.

Cobalt carbides are emerging as promising materials for various magnetic and catalytic applications. However, exploring dedicated cobalt carbides with optimal catalytic properties via adjusting phase compositions remains a significant challenge. Herein, three different cobalt carbides, Co x C (Co2C-Co3C), Co2C-Co, and Co3C, were successfully prepared using a facile one-pot green method. The phase compositions of cobalt carbides could be easily controlled by varying the cobalt-based precursors and carbon sources. More remarkably, three different cobalt carbides could serve as reduction cocatalysts decorated CdS for improved hydrogen production under visible light. Intriguingly, the obtained Co3C/CdS nanocomposite displayed the highest photocatalytic hydrogen evolution activity among the three composites and superior photocatalytic stability. This work provides a fundamental approach to tuning the photocatalytic properties of cobalt carbides for energy conversion fields. [ABSTRACT FROM AUTHOR]

Photocatalytic H 2 evolution and dye degradation using a semiconductor photocatalytic system are considered to be the most appropriate techniques for solving current energy crises and environmental issues. However, the effective separation and utilization of photoexcited charge carriers is the bottleneck of a photocatalytic system. To tackle this problem, we report an efficient photocatalytic system of CdS nanowires (NWs) electrostatically self-assemble on the Nb 2 C MXene cocatalyst. The synthesized CdS/Nb 2 C composites indicate that the CdS NWs are homogeneous and uniformly distributed on the accordion type Nb 2 C MXene cocatalyst, which was confirmed via different characterization techniques such as SEM, TEM, HRTEM, and elemental mapping. Furthermore, the electrochemistry analysis, PL, TRPL, EPR, and UV DRS spectra indicate the synthesized CdS/Nb 2 C composites exhibit appreciable enhancement in the separation of photoexcited charge carriers and transfer ability by inhibiting the annihilation factor and improving the light absorption. Therefore, the photocatalytic H 2 evolution efficiency of the optimized CdS/Nb 2 C composite reveals 2.53 mmol g−1 h−1, which was 5.34 times superior to CdS NWs. Moreover, the optimized sample manifested efficient stability even after five consecutive cycles and has an apparent quantum efficiency (AQE) of 3.69% with monochromatic light at 420 nm. Furthermore, the optimized CdS/Nb 2 C composite also manifests superior performance for photocatalytic degradation of Rhodamine B (RhB), which was a 99% degradation of RhB under light illumination for 20 min, much higher than pristine CdS NWs. This study shows that Nb 2 C MXene can be used as a potential noble metal free cocatalyst in a photocatalytic system to overcome environmental and energy crises. [Display omitted] • CdS nanowires anchored on Nb 2 C MXene through electrostatic self-assembly method. • Nb 2 C MXene as an efficient cocatalyst for photocatalytic applications. • Schottky junction was developed between CdS nanowires and Nb 2 C MXene. • CdS/Nb 2 C composite exhibited enhanced photocatalytic H 2 production. • Highly efficient RhB degradation by CdS/Nb 2 C composite. [ABSTRACT FROM AUTHOR]

To date, two‐dimensional (2D) β‐ketoenamine‐linked covalent organic frameworks (COFs) have exhibited tremendous potential in visible light photocatalysis due to their broad absorption and favorable stability provided by the linkage. Here, with 1,3,5‐triformylphloroglucinol as the stationary building block, various COFs can be constructed to address different challenges. To inspire state‐of‐the‐art advancements toward photocatalysis, in this Concept article, the rational design of 2D β‐ketoenamine‐linked COFs is summarized. First, the dimension of engineering the linker is considered to improve the activity of the COFs. The photocatalysis could be extended by inserting a functional group to the other building block. Second, the other dimension of integrating cocatalysts like transition metals or 2,2,6,6‐tetramethylpiperidine‐N‐oxyl with β‐ketoenamine‐linked COFs could further expand the potential in photocatalytic reactions. These prior accomplishments establish that the rational design of 2D β‐ketoenamine‐linked COFs is instrumental in improving the photocatalytic activity, laying the foundation for future explorations. [ABSTRACT FROM AUTHOR]

Photocatalytic technology is considered as one of effective approaches to address increasingly serious problems of environment and energy. To boost the photocatalytic efficiency, the innovative cocatalysts have been extensively explored and investigated in recent years. Mo2C MXene as a new two‐dimensional layer cocatalyst is gained increasing attentions for promoting photocatalytic performance owing to high specific surface area, excellent hydrophilic surface, outstanding metallic conductivity, and flexible adjustability of Mo sites. However, compared with the traditional Ti3C2 MXene cocatalyst, Mo2C MXene has not been fully investigated and systematically summarized in the published articles in the photocatalytic field. In this review, the recent advances about synthesis, modification, photocatalytic applications, and our outlook of the Mo2C MXene cocatalyst are comprehensively summarized. First, the synthetic methods of Mo2C MXene are introduced, including top‐down route and down‐top route. Moreover, four modification strategies (constructing heterojunction, doping heteroatom, controlling morphology, and modifying termination) of Mo2C MXene are illustrated. Subsequently, the photocatalytic applications of Mo2C MXene cocatalyst in H2 production, CO2 reduction, and pollutants degradation are thoroughly discussed. Finally, the crucial challenges and important outlooks of Mo2C MXene cocatalysts for photocatalytic solar‐to‐fuel conversion are proposed to deliver novel insights and design high‐efficiency Mo2C MXene cocatalyst‐modified photocatalysts. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting by semiconductors is a promising technology to produce clean H2 fuel, but the efficiency is restrained seriously by the high overpotential of the H2-evolution reaction together with the high recombination rate of photoinduced charges. To enhance H2 production, it is highly desirable yet challenging to explore an efficient reductive cocatalyst and place it precisely on the right sites of the photocatalyst surface to work the proton reduction reaction exclusively. Herein, the metalloid NixP cocatalyst is exactly positioned on the Z-scheme Cd0.5Zn0.5S/NiTiO3 (CZS/NTO) heterostructure through a facile photodeposition strategy, which renders the cocatalyst form solely at the electron-collecting locations. It is revealed that the directional transfer of photoexcited electrons from Cd0.5Zn0.5S to NixP suppresses the quenching of charge carriers. Under visible light, the CZS/NTO hybrid loaded with the NixP cocatalyst exhibits an optimal H2 yield rate of 1103 μmol h−1 (i.e., 27.57 mmol h−1 g−1), which is about twofold of pristine CZS/NTO and comparable to the counterpart deposited with the Pt cocatalyst. Besides, the high apparent quantum yield (AQY) of 56% is reached at 400 nm. Further, the mechanisms of the cocatalyst formation and the H2 generation reaction are discussed in detail. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting by semiconductors is a promising technology to produce clean H2 fuel, but the efficiency is restrained seriously by the high overpotential of the H2-evolution reaction together with the high recombination rate of photoinduced charges. To enhance H2 production, it is highly desirable yet challenging to explore an efficient reductive cocatalyst and place it precisely on the right sites of the photocatalyst surface to work the proton reduction reaction exclusively. Herein, the metalloid NixP cocatalyst is exactly positioned on the Z-scheme Cd0.5Zn0.5S/NiTiO3 (CZS/NTO) heterostructure through a facile photodeposition strategy, which renders the cocatalyst form solely at the electron-collecting locations. It is revealed that the directional transfer of photoexcited electrons from Cd0.5Zn0.5S to NixP suppresses the quenching of charge carriers. Under visible light, the CZS/NTO hybrid loaded with the NixP cocatalyst exhibits an optimal H2 yield rate of 1103 μmol h−1 (i.e., 27.57 mmol h−1 g−1), which is about twofold of pristine CZS/NTO and comparable to the counterpart deposited with the Pt cocatalyst. Besides, the high apparent quantum yield (AQY) of 56% is reached at 400 nm. Further, the mechanisms of the cocatalyst formation and the H2 generation reaction are discussed in detail.

This research introduces a pioneering approach to solar water splitting technology, utilizing an innovative, highly efficient immersed system. The system incorporates a flexible array of electrochemical and photoelectrochemical cells, powered by high‐performance III‐V triple‐junction cells. Remarkably, this method significantly boosts the solar‐to‐hydrogen (STH) conversion efficiency, reaching a record 20.7% under 1 sun illumination, employing earth‐abundant catalysts operating at ambient temperature. These findings highlight extensive scope for further optimization, including minimizing optical transmission losses, mitigating shading effects, and reducing the overpotential of the electrochemical cells, thereby augmenting the STH efficiency to an estimated 28%. Through a comprehensive techno‐economic analysis, a levelized cost of hydrogen (LCOH) of 8.3 USD kg−1 is estimated, forecasting the potential for a reduction to a competitive 1.8 USD kg−1 with improved efficiency, increased capacity factors, and decreased production costs. A sensitivity analysis emphasizes the significant influence of factors such as III‐V cell cost, electrolyzer membrane cost and capacity factor on the LCOH. Overall, this study signifies crucial progress toward a highly efficient and economically viable solar water splitting solution, promising a sustainable route for hydrogen production. [ABSTRACT FROM AUTHOR]

Poly (triazine imide) (PTI/Li+Cl−), one of the crystalline versions of polymeric carbon nitrides, holds great promise for photocatalytic overall water splitting. In principle, the photocatalytic activity of PTI/Li+Cl− is closely related to the morphology, which could be reasonably tailored by the modulation of the polycondensation process. Herein, we demonstrate that the hexagonal prisms of PTI/Li+Cl− could be converted to hexagonal nanosheets by adjusting the binary eutectic salts from LiCl/KCl or NaCl/LiCl to ternary LiCl/KCl/NaCl. Results reveal that the extension of in‐plane conjugation is preferred, when the polymerisation was performed in the presence of ternary eutectic salts. The hexagonal nanosheets bears longer lifetimes of charge carriers than that of hexagonal prisms due to lower intensity of structure defects and shorter hopping distance of charge carriers along the stacking direction of triazine nanosheets. The optimized hexagonal nanosheets exhibits a record apparent quantum yield value of 25 % (λ=365 nm) for solar hydrogen production by one‐step excitation overall water splitting. [ABSTRACT FROM AUTHOR]

In situ photo‐deposition of both Pt and CoOx cocatalysts on the facets of poly (triazine imide) (PTI) crystals has been developed for photocatalytic overall water splitting. However, the undesired backward reaction (i.e. water formation) on the noble Pt surface is a spontaneously down‐hill process, which restricts their efficiency to run the overall water splitting reaction. Herein, we demonstrate that the efficiency for photocatalytic overall water splitting could be largely promoted by the decoration of Rh/Cr2O3 and CoOx as H2 and O2 evolution cocatalysts, respectively. Results reveal that the dual cocatalysts greatly extract charges from bulk to surface, while the Rh/Cr2O3 cocatalyst dramatically restrains the backward reaction, achieving an apparent quantum efficiency (AQE) of 20.2 % for the photocatalytic overall water splitting reaction. [ABSTRACT FROM AUTHOR]

Nanocluster-modified semiconductor-based photocatalysts have been identified as a vital area of research in the area of photocatalytic hydrogen evolution from water. However, the existing ligand protection strategy for synthesizing ultrasmall metal nanoclusters remains confined to a few metals, including Au, Ag, Cu, and their alloys. In this investigation, we describe a facile solution-phase reduction synthesis method for the production of L -cysteine-protected Ru nanoclusters. Our findings demonstrate that these novel Ru nanoclusters function as cocatalysts, which notably increase the photocatalytic activity and photostability of CdS photocatalysts. Moreover, the hybrid CdS photocatalyst modified with Ru nanoclusters exhibits superior activity and stability relative to photoinduced Ru nanoparticles/CdS composite photocatalysts. The simplicity of the synthesized metal nanocluster cocatalyst and its effectiveness in enhancing photocatalyst activity, while reducing the use of precious metals, present new avenues for the development of advanced photocatalysts. • Ru nanocluster cocatalysts synthesized by solution-phase reduction. • Ru NCs exhibit ultrasmall size and remarkable resistance to aggregation. • Ru NCs/CdS exhibit a higher H 2 -evolution rate than CdS and Ru NPs/CdS. • The hydrogen production rate of Ru NCs/CdS is high, reaching 29.4 mmol/g/h. [ABSTRACT FROM AUTHOR]

Photocatalysis, which performed under mild conditions by utilizing solar energy, has become a desirable technology to convert methane into highly valuable chemicals, such as methanol, ethane, and other hydrocarbons. However, pristine photocatalysts still suffer from the low utilization efficiency of solar light and the high recombination rate of photogenerated charge carriers, which exhibit the low activity and selectivity for photocatalytic methane conversion. Loading cocatalysts on photocatalysts is an attractive strategy to manipulate the products' yield and selectivity of photocatalytic methane conversion due to the enhanced charge carrier separation efficiency, extended light absorption and promoted reactant adsorption/desorption kinetics. This review discusses the recent achievements of the cocatalysts for photocatalytic methane conversion reactions. Moreover, the challenges and perspectives for the development of efficient cocatalysts are presented. This review provides considerable guidelines for the design and construction of efficient cocatalysts for photocatalytic methane conversion reactions. [ABSTRACT FROM AUTHOR]

Developing highly efficient and low-cost noble-metal-free cocatalysts is significant for visible-light photocatalytic water splitting. Herein, 2H phase MoSe 2 nanosheets were successfully synthesized via a solvent-assisted hydrothermal method and used as cocatalysts to construct heterostructure with hexagonal Cd 0·7 Zn 0·3 S nanoparticles. This well-designed heterostructure will significantly shorten the distance of charge migration to achieve efficient electron transfer between Cd 0·7 Zn 0·3 S and MoSe 2. As expected, the optimized composites exhibited excellent photocatalytic hydrogen evolution (PHE) activity (3363.4 μmol g−1 in 5 h), which was 3.3 times than that of pristine Cd 0·7 Zn 0·3 S, and higher than that of 1%Pt–Cd 0.7 Zn 0.3 S. Based on electrochemical and photoluminescence results, the enhanced activity could be attributed to the lower overpotential (−0.27 V) and superior carrier separation of Cd 0·7 Zn 0·3 S/MoSe 2 heterojunction. Meanwhile, 2H–MoSe 2 nanosheets with large specific surface area can afford highly active Se-edge sites to absorb the protons for boosting hydrogen evolution. Moreover, Cd 0·7 Zn 0·3 S/MoSe 2 photocatalysts also displayed a long-term stability without apparent debasement. This work provides new inspiration that transition metal dichalcogenides (TMDCs) as cocatalysts are promising to effectively enhance the PHE performance of sulfide solid solutions. [Display omitted] • 2H–MoSe 2 cocatalyst was used to construct novel heterostructure with hexagonal Cd 0·7 Zn 0·3 S. • The well-designed heterostructure achieves efficient interfacial charge transfer and separation. • MoSe 2 nanosheets with large specific surface area could provide abundant Se-edge sites. • The optimized MS-CZS heterojunction exhibits superior PHE activity than bare CZS and 1%Pt-CZS. [ABSTRACT FROM AUTHOR]

Focusing on the degradation of organic dyes in wastewater, a novel titania composite nanofiber small area film photocatalyst with improvedphotocatalytic activity using strontium ions and graphite as dual cocatalysts has been synthesized by electrospinning and hydrothermal methods.Morphology control, doping causing crystal defect engineering (strontium ion doping), and heterojunction building (graphite surface modification) strategies are simultaneously applied to the synthetic design of new photocatalysts.In degradation tests of rhodamine B, methyl orange, methylene blue, and malachite green, the degradation rate constants were 2.57, 2.85, 3.06, or 3.54 times higher than those of pure titania, respectively.The composite nanofiber small area film exhibited excellent recyclability in fourrecycling tests.The improved photocatalytic activity of titania composite nanofiber small area film is attributed to the morphology of the nanofibers with the addition of more reaction sites, dopingwith more crystal defects, and heterojunctions providing channels for the transfer of photogenerated carriers.Design solutions with the synergistic effects of multiple strategies inform the use of titania in industrial applications. [ABSTRACT FROM AUTHOR]

Piezocatalysis has great potential in the field of new energy. Developing robust piezocatalyst with high hydrogen evolution reaction (HER) performance is of great significance but still challenging. Here, the hydrothermal-synthesized (Bi 0.5 Na 0.5)TiO 3 (BNT) cubes are demonstrated to the excellent piezocatalytic HER performance. Based on the strong piezoelectric property, the BNT cubes allow an efficient water splitting by the action of ultrasonic vibration, with a H 2 yield of 0.38 mmol g−1 h−1 and a H 2 O 2 yield of 0.25 mmol g−1 h−1. To further improve the piezoelectric HER efficiency, Ag and CoO x nanoparticles are employed as the cocatalysts through photochemical decoration. Consequently, the HER performance of BNT cubes is significantly enhanced. These cocatalysts provide the unique channels for charge transfer, thus increase the charge separation efficiency, thereby enhancing the piezocatalytic HER performance. This work not only demonstrates the eco-friendly BNT is a promising and superior piezocatalyst for new-energy applications, but also provides a rational strategy to enhance the piezocatalytic performance. [ABSTRACT FROM AUTHOR]

The bis(imino)pyridyl iron‐based ethylene oligomerization catalysts have the advantages of mild reaction conditions, high activity and high selectivity to linear α‐olefins. However, barriers, such as high polymer content in the product mixture and large methylaluminoxane (MAO) dosage, are still limitations for the development of these systems at the industrial scale. In this study, new cocatalysts are prepared by the reaction of alkylaluminums with urea and its derivatives, and successfully used to activate iron‐based catalysts. It is found that the type and molar ratio of alkylaluminum and urea have significant influence on the performance of the cocatalysts. The activity of the preferred triisobutylaluminum/urea activated systems reaches more than 3.0 × 108 g (mol‐Fe)−1 h−1, and the polymer content can be controlled to be less than 2 wt.%. Notably, the catalytic system exhibits good high temperature stability, the activity can still reach 1.0 × 108 g (mol‐Fe)−1 h−1 even at 120 °C. Further 1H NMR studies show that alkylaluminum can react with the NH moieties of urea, forming complex alkylaluminum clusters, even aluminoxane‐like structures. This study offers a promising family of cocatalysts, making it possible to simultaneously improve their performance and reduce their cost. [ABSTRACT FROM AUTHOR]

BiVO4 is a highly promising material for Photoelectrochemical (PEC) water splitting photoanodes due to its narrow band gap value (~2.4 eV) and its ability to efficiently absorb visible light. However, the short hole migration distance, severe surface complexation, and low carrier separation efficiency limit its application. Therefore, in this paper, BiVO4 was modified by loading CoOOH cocatalyst on the rare earth element Nd-doped BiVO4 (Nd-BiVO4) photoanode. The physical characterization and electrochemical test results showed that Nd doping will cause lattice distortion of BiVO4 and introduce impurity energy levels to capture electrons to increase carrier concentration, thereby improving carrier separation efficiency. Further loading of surface CoOOH cocatalyst can accelerate charge separation and inhibit electron–hole recombination. Ultimately, the prepared target photoanode (CoOOH-Nd-BiVO4) exhibits an excellent photocurrent density (2.4 mAcm−2) at 1.23 V versus reversible hydrogen electrode potential (vs. RHE), which is 2.67 times higher than that of pure BiVO4 (0.9 mA cm−2), and the onset potential is negatively shifted by 214 mV. The formation of the internal energy states of rare earth metal elements can reduce the photoexcited electron–hole pair recombination, so as to achieve efficient photochemical water decomposition ability. CoOOH is an efficient and suitable oxygen evolution cocatalyst (OEC), and OEC decoration of BiVO4 surface is of great significance for inhibiting surface charge recombination. This work provides a new strategy for achieving effective PEC water oxidation of BiVO4. [ABSTRACT FROM AUTHOR]

Cocatalyst engineering with non‐noble metal nanomaterials can play a vital role in low‐cost, sustainable, and large‐scale photocatalytic hydrogen production. This research adopts slow carburization and simultaneous hydrocarbon reduction to synthesize carbon‐encapsulated Mo/Mo2C heterostructure nanoparticles, namely Mo/Mo2C@C cocatalyst. Experimental and theoretical investigations indicate that the Mo/Mo2C@C cocatalysts have a nearly ideal hydrogen‐adsorption free energy (ΔGH*), which results in the accelerated HER kinetics. As such, the cocatalysts are immobilized onto organic polymer semiconductor g‐C3N4 and inorganic semiconductor CdS, resulting in Mo/Mo2C@C/g‐C3N4 and Mo/Mo2C@C/CdS catalysts, respectively. In photocatalytic hydrogen evolution application under visible light, the Mo/Mo2C@C with g‐C3N4 and CdS can form the Schottky junctions via appropriate band alignment, greatly suppressing the recombination of photoinduced electron‐hole pairs. The surface carbon layer as the conducting scaffolds and Mo metal facilitates electron transfer and electron‐hole separation, favoring structural stability and offering more reaction sites and interfaces as electron mediators. As a result, these catalysts exhibit high H2 production rates of 2.7 mmol h−1 g−1 in basic solution and 98.2 mmol h−1 g−1 in acidic solution, respectively, which is significantly higher than that of the bench‐mark Pt‐containing catalyst. The proposed cocatalyst engineering approach is promising in developing efficient non‐noble metal cocatalysts for rapid hydrogen production. [ABSTRACT FROM AUTHOR]

The application of photoelectrochemical (PEC) water splitting is limited by the sluggish surface oxygen evolution reaction (OER) kinetics. OER kinetics can be effectively improved through cocatalyst engineering. However, the tardy transfer process and serious recombination of carriers are the key factors restricting the cocatalyst development. Taking BiVO4 as an example, a Co-modified heme film rich in large conjugated ring structures is introduced onto the photoanode surface using a solvothermal method. This film functions as an efficient cocatalyst. It considerably reduces the surface overpotential, promotes the transfer of photogenerated holes, and boosts the kinetics of OER by specifically affecting the formation of OOH*. Simultaneously, the formed Co-O-V bonds induce strong interaction at the photoanode/cocatalyst interfaces, reducing the recombination of photogenerated carriers. Consequently, the onset potential of the optimized photoanode decreases from 0.45 to 0.07 V and the photocurrent density at 1.23 V versus reversible hydrogen electrode boosts to 5.3 mA cm-2. This work demonstrates a facile strategy for designing cocatalysts to obtain rapid hole transfer capability and reduced carrier recombination for improved PEC performance. [ABSTRACT FROM AUTHOR]

Suppressing the amount of carbon dioxide in the atmosphere is an essential measure toward addressing global warming. Specifically, the photocatalytic CO2 reduction reaction (CRR) is an effective strategy because it affords the conversion of CO2 into useful carbon feedstocks by using sunlight and water. However, the practical application of photocatalyst‐promoting CRR (CRR photocatalysts) requires significant improvement of their conversion efficiency. Accordingly, extensive research is being conducted toward improving semiconductor photocatalysts, as well as cocatalysts that are loaded as active sites on the photocatalysts. In this review, we summarize recent research and development trends in the improvement of cocatalysts, which have a significant impact on the catalytic activity and selectivity of photocatalytic CRR. We expect that the advanced knowledge provided on the improvement of cocatalysts for CRR in this review will serve as a general guideline to accelerate the development of highly efficient CRR photocatalysts. [ABSTRACT FROM AUTHOR]

Electron density regulation of active sites can realize an optimal hydrogen‐binding strength, whereas the underlying regulation mechanism is still indistinct. Herein, a new concept of antibonding‐orbital occupancy state is first proposed to unveil the fundamental influence mechanism of electron density on the SeHads bond strength for achieving first‐rank adsorption energy toward atomic hydrogen by constructing Se‐enriched surrounding to form electron‐deficient Se(2‐δ)‐ active sites in ReSe2+x nanodots. To this end, the Se‐rich ReSe2+x nanodots (0.3–1 nm) can be dexterously fabricated onto the TiO2 to prepare Se‐rich ReSe2+x/TiO2 by an ingenious one‐step photosynthesis route. In a surprise, a large number of visual H2 bubbles are continuously produced on the resultant ReSe2+x/TiO2(0.7 wt.%) with an ultrahigh rate of 12 490.4 µmol h−1 g−1 and an apparent quantum efficiency of 60.0%, which is 5.0 times higher than that of traditional ReSe2/TiO2, even comparable with benchmark Pt/TiO2(0.7 wt.%). In situ/ex situ XPS characterizations coupled with density functional theory (DFT) calculations corroborate that a Se‐enriched environment can induce the formation of electron‐deficient Se(2‐δ)− and then reduce its antibonding‐orbital occupancy state, thus increasing the stability of H 1s‐p antibonding and accordingly reinforcing the SeHads bonds. This holistic study identifies the dominant role of antibonding‐orbital occupancy states in the optimization of hydrogen‐binding energy. [ABSTRACT FROM AUTHOR]

Atom transfer radical polymerization (ATRP) is one of the most powerful methods to prepare well‐defined (co)polymers. Cu‐catalyzed ATRP methods are most commonly used because of the excellent control and tunable catalytic activities via ligand functionalization. This minireview summarizes the development of Cu‐catalyzed ATRP in the presence of cocatalysts, which are used to regenerate CuI complex activators during polymerizations. Fundamentals of Cu‐based ATRP catalysts are first introduced, followed by the discussion of different types of cocatalysts in different Cu‐catalyzed ATRP methods. Recent developments of photochemical cocatalysts for oxygen‐tolerant ATRP and ATRP using long‐wavelength irradiation are highlighted, which significantly expand the applications of Cu‐catalyzed ATRP. Methods to study the properties of cocatalysts and their roles in Cu‐catalyzed ATRP are discussed, with an outlook for the future development of cocatalysts. [ABSTRACT FROM AUTHOR]

TiO2–based photocatalysis system for splitting water into hydrogen offers a sustainable and green technology to produce clean hydrogen energy. However, pristine TiO2 still exists inherent shortcomings restricting its practical applications. Herein, the impact of postprocessing approaches of protonic titanate on engineering of oxygen vacancy and photocatalytic hydrogen evolution of TiO2−x is studied. Subsequently, interfacial cocatalysts are successfully involved in the optimized TiO2−x for enhanced photocatalytic hydrogen evolution. TiO2−x with the highest photocatalytic hydrogen evolution performance of 3112.09 μmol g−1 h−1, denoted as TiO2–C, is selected to adjust the interface with Cu and MoS2 respectively. Cu–TiO2–C and MoS2–TiO2–C composites are synthesized to enhance the separation ability of photogenerated electron‐hole pairs and significantly improve the photocatalytic hydrogen evolution performance. The photocatalytic hydrogen evolution rates of 5 wt% Cu–TiO2–C and 40 wt% MoS2–TiO2–C are 9225.75 and 5765.48 μmol g−1 h−1, respectively. It is proved that different postprocessing methods can tune the content of oxygen vacancy in TiO2−x and regulate the photocatalytic hydrogen evolution performance of TiO2−x materials. The interface regulation of the cocatalyst also contributes to the separation of photogenerated electron‐hole pairs and serves as active sites to enhance hydrogen evolution performance.

Abstract The application of photoelectrochemical (PEC) water splitting is limited by the sluggish surface oxygen evolution reaction (OER) kinetics. OER kinetics can be effectively improved through cocatalyst engineering. However, the tardy transfer process and serious recombination of carriers are the key factors restricting the cocatalyst development. Taking BiVO4 as an example, a Co‐modified heme film rich in large conjugated ring structures is introduced onto the photoanode surface using a solvothermal method. This film functions as an efficient cocatalyst. It considerably reduces the surface overpotential, promotes the transfer of photogenerated holes, and boosts the kinetics of OER by specifically affecting the formation of OOH*. Simultaneously, the formed CoOV bonds induce strong interaction at the photoanode/cocatalyst interfaces, reducing the recombination of photogenerated carriers. Consequently, the onset potential of the optimized photoanode decreases from 0.45 to 0.07 V and the photocurrent density at 1.23 V versus reversible hydrogen electrode boosts to 5.3 mA cm−2. This work demonstrates a facile strategy for designing cocatalysts to obtain rapid hole transfer capability and reduced carrier recombination for improved PEC performance.

Severe surface photocarrier recombination and poor electronic conductivity are the major factors behind the sluggish photoelectrochemical water oxidation kinetics of the ZnFe2O4 photoanode. Here, the CeOx catalyst overlayer has been coupled with the reduced ZnFe2O4 nanorods (NRs) to reduce the surface charge recombination on the photoanode significantly. The density functional theory (DFT) studies indicate that the oxygen vacancy defect‐rich CeOx catalyst constructs a favorable band alignment with ZnFe2O4 promoting rapid photocarrier separation and serves as a conducting photocarrier transfer pathway accelerating the hole transportation toward the electrode/electrolyte interface. The ZnFe2O4/CeOx nano‐heterostructure photoanode exhibits a current density of 0.64 mA cm−2 at 1.23 V versus RHE under AM 1.5 G illumination, which corresponds to >167% increase over that of the ZnFe2O4 NRs photoanode. The CeOx coupling reduces the onset potential cathodically by 180 mV over the ZnFe2O4 NRs photoanode. The ZnFe2O4/CeOx nano‐heterostructure photoanode also exhibits excellent charge transfer efficiency (≈64% at 1.23 V vs RHE) and photostability. The results indicate the superior catalytic performance of oxygen vacancy defect‐rich CeOx in the PEC process. This work demonstrates the multifunctional role of CeOx as a surface passivation overlayer, hole transfer layer, and efficient oxygen evolution reaction catalyst. [ABSTRACT FROM AUTHOR]

Semiconductor-based photocatalytic water splitting is a promising technology to convert solar energy into chemical energy. However, the photocatalytic performance is seriously limited by the low photo-generated charge separation efficiency and high interfacial reaction resistance. Here, a hollow double-shell stacked CdS@ZnIn 2 S 4 system was firstly constructed. The Pt and Co 3 O 4 nanoparticles (NPs) as the hydrogen evolution and the hydrogen peroxide production cocatalysts were loaded on the inner surface and outer surface of CdS@ZnIn 2 S 4 to obtain a novel Pt/CdS@ZnIn 2 S 4 /Co 3 O 4 photocatalyst. Compared with the CdS@ZnIn 2 S 4 and dual cocatalysts randomly incorporated CdS@ZnIn 2 S 4 /(Pt+Co 3 O 4) sample, this well-designed photocatalyst shows high photocatalytic performance with hydrogen evolution rate and H 2 O 2 production rate reached 8.53 mmol g−1 h−1 and 5.26 mmol g−1 h−1, respectively, which are 3.8 and 1.8 times higher than those of CdS@ZnIn 2 S 4 sample. The enhanced photocatalytic performance can be attributed to the formation of compact heterojunction structure between the ultrathin double shells, which can promote the separation of electron-hole pairs due to its built-in field effect. Besides, the synergistic effect of spatially separated dual cocatalysts are beneficial to the migration of the photo-generated charges to the opposite direction and the suppression of the reverse reaction. This work would pave a way to design unique structure and high-performanced photocatalyts towards photocatalytic water splitting. [Display omitted] • A unique double-shell stacked Pt/CdS@ZnIn 2 S 4 /Co 3 O 4 photocatalyst was constructed. • The heterojunction formed between double shells promotes the charge separation. • The spatially separated dual co-catalysts can reduce reaction energy barrier. • The sample shows high hydrogen evolution and hydrogen peroxide production activity. [ABSTRACT FROM AUTHOR]

Charge‐enhanced chiral thioureas were used in the organocatalysis of the Friedel–Crafts alkylation of indole with trans‐β‐nitrostyrene and the oxa‐Pictet–Spengler reaction of tryptophol and benzaldehyde. The effects of substoichiometric Brønsted acidic additives on the reaction conversions and enantiomeric ratios of these transformations were examined, and the role of these species in the mechanism of the latter reaction was explored using variable time normalization kinetics to elucidate the reaction order of the catalyst, cocatalyst, and reagents. A proposed pathway for the oxa‐Pictet–Spengler cyclization that involves matched and mismatched catalyst and cocatalyst pairs and an off‐cycle racemization of the latter species is provided. [ABSTRACT FROM AUTHOR]

Abstract Severe surface photocarrier recombination and poor electronic conductivity are the major factors behind the sluggish photoelectrochemical water oxidation kinetics of the ZnFe2O4 photoanode. Here, the CeOx catalyst overlayer has been coupled with the reduced ZnFe2O4 nanorods (NRs) to reduce the surface charge recombination on the photoanode significantly. The density functional theory (DFT) studies indicate that the oxygen vacancy defect‐rich CeOx catalyst constructs a favorable band alignment with ZnFe2O4 promoting rapid photocarrier separation and serves as a conducting photocarrier transfer pathway accelerating the hole transportation toward the electrode/electrolyte interface. The ZnFe2O4/CeOx nano‐heterostructure photoanode exhibits a current density of 0.64 mA cm−2 at 1.23 V versus RHE under AM 1.5 G illumination, which corresponds to >167% increase over that of the ZnFe2O4 NRs photoanode. The CeOx coupling reduces the onset potential cathodically by 180 mV over the ZnFe2O4 NRs photoanode. The ZnFe2O4/CeOx nano‐heterostructure photoanode also exhibits excellent charge transfer efficiency (≈64% at 1.23 V vs RHE) and photostability. The results indicate the superior catalytic performance of oxygen vacancy defect‐rich CeOx in the PEC process. This work demonstrates the multifunctional role of CeOx as a surface passivation overlayer, hole transfer layer, and efficient oxygen evolution reaction catalyst.

Developing new renewable, carbon-neutral fuels to diminish the amount of released CO 2 in the atmosphere and to solve global challenges such as global warming and climate change is significant. Among them, hydrogen (H 2) is attracting much attention due to its high energy density, ease of transportation, and multiple means of production. To meet the global demand of H 2, photocatalytic water splitting is one of the most promising methods for large scale production. Herein, Al-doped SrTiO 3 photocatalyst (Al–SrTiO 3) was prepared by a molten flux method. Then, plasmonic metal nanoparticles (Au, Cu, Pt), and cocatalysts Rh/Cr 2 O 3 and CoOOH were selectively deposited onto the reductive and oxidative active sites of Al–SrTiO 3 using multi-step photodeposition-impregnation methods for water splitting and H 2 production under UV-rays, UV–Vis. Light, and visible light (λ ≥ 400 nm). Our results showed that, compared with Pt and Cu loaded Al–SrTiO 3 photocatalyst supported with Rh/Cr 2 O 3 and CoOOH cocatalysts, Au-loaded samples showed the highest H 2 production efficiency under both UV (920 μmol/h - EQE = 41% at 365 nm) and UV–Vis (100.5 μmol/h) rays. In addition, the amount of evolved H 2 decreased by increasing the weight ratio of Au nanoparticles (NPs) due to the overlap between Au NPs and Rh/Cr 2 O 3 cocatalyst. Although Au 0.3 wt%-loaded sample showed high activity under both UV and UV–Vis. Rays, it exhibited almost no efficiency under visible light because of the large bandgap of Al–SrTiO 3 (3.1 eV) and the poor absorption in the visible region. Visible light absorption was then enhanced by increasing the loaded amount of Au NPs and by separating Au NPs and Rh/Cr 2 O 3 cocatalyst responsible for H 2 evolution by combining both photodeposition and impregnation methods. Under visible light, Rh/Cr 2 O 3 -loaded Al–SrTiO 3 with 4 wt % Au NPs showed the highest H 2 evolution efficiency (41 μmol/3 h). This was attributed to the efficient hot electron transfer from Au NPs to Al–SrTiO 3 then to RhCr 2 O 3 , resulting in charge separation needed for efficient H 2 generation. Proposed reaction mechanism of water splitting and H 2 production by the prepared cocatalysts and Au NPs-loaded Al–SrTiO 3 under different light sources. [Display omitted] • Al doped SrTiO 3 perovskite photocatalyst was prepared by a molten flux method. • Al–SrTiO 3 was loaded with plasmonic NPs, RhCr 2 O 3 , CoOOH cocatalysts for HE and OE. • Cocatalyst distribution on active sites of the main photocatalyst was controlled. • Water splitting and H 2 production was evaluated under UV, UV–Vis, and visible light. • Visible light active system was developed for H 2 evolution with no sacrificial agents. [ABSTRACT FROM AUTHOR]

The development of phase engineering still confronts challenges including controlled synthesis of desired phase structures and unraveling of inner mechanism for phase‐dependent applications. Herein, taking CoSe2 as a prototype, a facile wet‐chemical method is developed to synthesize metastable orthorhombic phase CoSe2 (o‐CoSe2). In the meantime, stable cubic phase CoSe2 (c‐CoSe2) can be prepared by phase transition from o‐CoSe2 using a general annealing approach. It is demonstrated that CoSe2 exhibits distinct phase‐dependent hydrogen evolution performance in photo‐ and electrocatalysis. In electrocatalytic reaction, o‐CoSe2 shows an overpotential of 300 mV better than c‐CoSe2 (365 mV) at –10 mA cm‐2 in acid solution. Unlike electrocatalysis, as cocatalyst in photocatalytic hydrogen evolution, c‐CoSe2/TiO2 exhibits a roughly 4.5‐folds higher hydrogen evolution rate (12.001 µmol h‐1) than o‐CoSe2/TiO2 (2.601 µmol h‐1). Combined with comprehensive theoretical and experimental analysis, it has been proposed that appropriate hydrogen adsorption ability of o‐CoSe2 contributes to efficient electrocatalysis, whilst fast interfacial charge migration between TiO2 photo‐harvester and c‐CoSe2 cocatalyst is the dominating factor for photocatalysis. This article demonstrates the feasibility of improving catalytic activity of CoSe2 by phase engineering, and also, provides guidance into unmasking the relationship between phase structure and hydrogen evolution catalysis. [ABSTRACT FROM AUTHOR]

Piezocatalysis in aqueous medium has shown great potential for various applications, however the efficiency of piezocatalytic nanoparticles is harmed by the limited utilization of piezoelectric charge and the lack of active catalytic interface. In this study, BaTiO3@Metal (BTO@M, M=Pt, Pd and Au) hetero‐nanostructures were synthesized by using a piezodeposition method. The deposited metal cocatalysts significantly promote the separation and migration of piezogenerated charge, consequently enhancing the piezocatalytic reactions on different metal cocatalyst interfaces. Specifically, BTO@Au under ultrasonic vibrations exhibited most efficient generation of reactive oxidative species via a two‐electron reduction pathway in the presence of dissolved oxygen, while BTO@Pt showed promoted hydrogen evolution in the absence of oxygen. The metal‐piezoelectric hetero‐nanostructures proposed in this work highlight the key role of noble metal as cocatalysts for piezoelectricity‐driven oxygen reduction and hydrogen evolution reactions, which could further advance piezocatalysis in the field of clean energy, water disinfection and biomedicine. [ABSTRACT FROM AUTHOR]

Carbon neutrality has become an urgent mission for the future of mankind. Powering the world with renewable energy from solar CO2 reduction represents a promising way to accomplish this target. Photoelectrochemical (PEC) CO2 reduction, integrating the merits of photocatalysis and electrocatalysis, offers an intriguing and effective approach to realizing solar fuel production and CO2 mitigation in one shot. To stimulate research efforts in PEC CO2 reduction, a comprehensive review of recent advances in this field is presented, with a special emphasis on the general design motives for the assembly of highly efficient PEC cells. First, basic principles and evaluating parameters of PEC CO2 reduction cells are introduced. Then, recent innovative PEC cells with highly active photocathodes for CO2 reduction to different target chemicals are highlighted and the material designing principles are discussed. In addition, the representative self‐biased PEC CO2 reduction cells including the tandem and artificial‐leaf configurations are also addressed. Finally, this review is concluded with remarks on the present achievements in PEC CO2 reduction to different chemicals, pointing out some effective strategies to promote the efficiencies for solar fuel production. A vision of the challenges and opportunities for how to forward PEC CO2 reduction research is further provided. [ABSTRACT FROM AUTHOR]

In this paper, the semi-metallic 1T’ phase rhenium disulfide (ReS2) nanosheets (NSs) as cocatalysts are loading on the graphitic carbon nitride (g-C3N4) nanotubes (NTs) for photocatalytic hydrogen (H2) production. The as-prepared 1T′-ReS2/g-C3N4 composites present expressively enhanced photocatalytic activity. The 1T′-ReS2/g-C3N4 composite with 12 wt% 1T′-ReS2 exhibits the best photocatalytic H2 evolution performance (2275 μmol h−1 g−1), about 37 times of g-C3N4 NTs, 4 times of 2H-ReS2/g-C3N4 NTs, 6.7 times of 1T-ReS2/g-C3N4 NTs and 1.2 times of Pt/g-C3N4 NTs. Meanwhile, the apparent quantum yield (AQE) values of 1T′-ReS2/g-C3N4 (12 wt%) using 50 mg photocatalyst are 6.44% and 3.45% under light at λ = 370 nm and 456 nm, respectively. The activity tests and the DFT calculations prove that 1T′-ReS2/g-C3N4 composites have the following advantages: 1) The hollow porous g-C3N4 nanotubes are beneficial for improving the absorption and utilization of light, and the migration of photoexcited electrons; 2) After loading 1T′-ReS2 nanosheets on the g-C3N4 nanotubes, the 1T′-ReS2/g-C3N4 composites show the enhanced light absorption and fast carriers transfer, proving that the conductive 1T′-ReS2 nanosheets as cocatalysts could facilitate g-C3N4 nanotubes to generate more photoexcited charges, promote the carrier migration and separation, and supply abundant active sites for photocatalysis.

BiVO4 is a highly promising material for Photoelectrochemical (PEC) water splitting photoanodes due to its narrow band gap value (~2.4 eV) and its ability to efficiently absorb visible light. However, the short hole migration distance, severe surface complexation, and low carrier separation efficiency limit its application. Therefore, in this paper, BiVO4 was modified by loading CoOOH cocatalyst on the rare earth element Nd-doped BiVO4 (Nd-BiVO4) photoanode. The physical characterization and electrochemical test results showed that Nd doping will cause lattice distortion of BiVO4 and introduce impurity energy levels to capture electrons to increase carrier concentration, thereby improving carrier separation efficiency. Further loading of surface CoOOH cocatalyst can accelerate charge separation and inhibit electron–hole recombination. Ultimately, the prepared target photoanode (CoOOH-Nd-BiVO4) exhibits an excellent photocurrent density (2.4 mAcm−2) at 1.23 V versus reversible hydrogen electrode potential (vs. RHE), which is 2.67 times higher than that of pure BiVO4 (0.9 mA cm−2), and the onset potential is negatively shifted by 214 mV. The formation of the internal energy states of rare earth metal elements can reduce the photoexcited electron–hole pair recombination, so as to achieve efficient photochemical water decomposition ability. CoOOH is an efficient and suitable oxygen evolution cocatalyst (OEC), and OEC decoration of BiVO4 surface is of great significance for inhibiting surface charge recombination. This work provides a new strategy for achieving effective PEC water oxidation of BiVO4.

Sustainable and highly efficient non‐noble metal catalysts could facilitate the realization of closed‐loop and carbon‐neutral hydrogen (H2) economy via low‐cost electrocatalytic (EC) or photocatalytic (PC) H2 evolution reaction (HER) from water. Herein, molybdenum carbide (MoC) quantum dots onto N‐doped porous carbon are in situ synthesized and immobilized, resulting in a bifunctional catalyst MoC@NC. Density functional theory calculation suggests that the targeted catalyst has a suitable Gibbs free‐energy (ΔGH*) for the adsorption of atomic hydrogen, which is beneficial to both EC and PC HERs. For EC HER, the as‐prepared MoC@NC catalyst delivers a low overpotential of 160 mV at −10 mA cm−2 and a remarkable H2 evolution rate in alkaline electrolytes. For PC HER, MoC@NC couple with 2D graphitic carbon nitride (g‐C3N4), which significantly reduces the PC HER energy barrier and enhances the separation efficiency of photogenerated carriers, and consequently, achieves an outstanding photocatalytic H2 evolution rate of 1709 µmol h−1 g−1, which is 213‐fold of that of pure g‐C3N4. This study paves a new avenue for developing sustainable non‐noble metal catalysts for both EC and PC HERs. [ABSTRACT FROM AUTHOR]

The effective separation of photogenerated electrons and holes is the key to improve photocatalytic activity in hydrogen evolution reaction (HER). However, the mechanism of photoinduced charge transfer between the cocatalyst and the semiconducting heterojunction in a single nanocrystal is vague at present. Herein, the relationships between the crafted cocatalyst and the constructed semiconducting heterojunction in a single nanocrystal were verified. Manipulating these relationships will improve the performance of visible light-driven hydrogen evolution. As a model, we used CuInS2 (CIS) nanocrystals (NCs) modified by the cocatalyst platinum (Pt) NCs and the semiconductor cadmium sulfide (CdS), forming the ternary heterostructured NCs (HNCs). Under visible light irradiation, the photocatalytic activity in hydrogen evolution of Pt-CIS/CdS HNCs is 6.38 and 1.76 times higher than those of pristine CIS NCs and CIS/CdS HNCs, respectively. Transient absorption measurements certified that the high photocatalytic activity in the HER was attributed to the photoinduced electron transfer from the defect-mediated trap state in CIS to the cocatalyst Pt, which was superior to the direct Z-scheme heterojunction between CIS and CdS. This research paves a route for the design of a suitable cocatalyst and the formation of heterostructured semiconducting NCs for boosting the photocatalytic activity in solar energy conversion. [ABSTRACT FROM AUTHOR]

Improved photogenerated carrier separation efficiency is of importance for improving photocatalytic activity. Herein, the photocatalytic CO2 reduction of a 3D/0D ZnIn2S4/NiS ohmic‐junction photocatalyst under simulated sunlight is studied. The ZnIn2S4–2%NiS sample has the best excellent photoreduction CO2 performance facilitated by triethanolamine (TEOA) reagents, the ZnIn2S4–2%NiS sample with a CO yield of 12.63 μmol g−1 h−1, which is two times that for pure ZnIn2S4 (6.37 μmol g−1 h−1). It is demonstrated that NiS nanoparticles not only improve the efficiency of electron generation and charge separation by constructing a tight contact ohmic‐junction, but also act as a cocatalyst to extend the photoreaction range and lower the reaction barrier, which effectively accelerates the photocatalytic reduction reaction. Additionally, the 3D structure of ZnIn2S4 has an excellent specific surface area that facilitates the dispersion of NiS. The generation, separation, and migration of photogenerated electron holes are studied from the kinetics perspective through transient photocurrent response, linear sweep voltammetry curve and photoluminescence spectroscopy. In situ Fourier transform infrared spectroscopy is applied to study the CO2 photoreduction process. Herein, the important role of cocatalyst and ohmic‐junction in improving photocatalytic activity is revealed and a new idea for the construction of efficient photocatalysts is provided. [ABSTRACT FROM AUTHOR]

This review focused to the discussion of the results from recent research in a promising area of the complex processing of lignocellulosic biomass: reductive catalytic fractionation (RCF). The effect catalysts, co-catalysts, solvents, sources of hydrogen, and the nature of lignocellulosic raw materials on the selectivity in the production of monomeric lignin products is considered. Heterogeneous catalysts are mainly used in RCF processes, which allows the reductive depolymerization of lignin to obtain low molecular weight compounds while maintaining the carbohydrate components of the biomass. Of the considered catalysts based on platinum group and transition metals, those containing Pd, Pt, Ru, and Ni have the highest activity. The nature of the metal also affects the composition of the resulting products. For example, ruthenium catalysts produce 4-propyl guaiacol as the main product, while ones based on Ni and Pd yield 4-propanol guaiacol. Catalysts containing Mo, due to their lower hydrogenation activity, give monolignols or their esterified derivatives of while preserving the carbohydrate components of lignocellulosic biomass. However, bifunctional catalysts that contain both acidic and metallic active sites are the most efficient in RCF processes. Acid sites contribute to the breaking of etheric β-O-4 bonds, while metal sites catalyze reduction of the resulting intermediate compounds. An important aspect of selecting suitable catalysts for the RCF process is their reusability. The use of a ferromagnetic catalyst or a basket for the catalyst solves the problem of separating it from products of the process. [ABSTRACT FROM AUTHOR]