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Cocatalysis plays an important role in enhancing the activity of semiconductor photocatalysts for solar water splitting. Compared to a single cocatalyst configuration, a cocatalytic system consisting of multiple components with different functions may realize outstanding enhancement through their interactions, yet limited research has been reported. Herein we describe the synergistic cocatalytic effect between carbon nanodots (CDots) and Co3O4, which promotes the photoelectrochemical water oxidation activity of the Fe2O3 photoanode with a 60 mV cathodically shifted onset potential. The C/Co3O4-Fe2O3 photoanode exhibits a photocurrent density of 1.48 mA cm−2 at 1.23 V (vs. reversible hydrogen electrode), 78 % higher than that of the bare Fe2O3 photoanode. The slow reaction process on the single CoIII-OH site of the Co3O4 cocatalyst, oxidizing H2O to H2O2 with two photogenerated holes, could be accelerated by the timely H2O2 oxidation to O2 catalyzed on CDots. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting using powered semiconductors as photocatalysts represents a promising strategy for clean, low-cost, and environmentally friendly production of H2 utilizing solar energy. The loading of noble-metal cocatalysts on semiconductors can significantly enhance the solar-to-H2 conversion efficiency. However, the high cost and scarcity of noble metals counter their extensive utilization. Therefore, the use of alternative cocatalysts based on non-precious metal materials is pursued. Nanosized MoS2 cocatalysts have attracted considerable attention in the last decade as a viable alternative to improve solar-to-H2 conversion efficiency because of its superb catalytic activity, excellent stability, low cost, availability, environmental friendliness, and chemical inertness. In this perspective, the design, structures, synthesis, and application of MoS2- based composite photocatalysts for solar H2 generation are summarized, compared, and discussed. Finally, this Review concludes with a summary and remarks on some challenges and opportunities for the future development of MoS2-based photocatalysts. [ABSTRACT FROM AUTHOR]

Platinum is a commonly used cocatalyst for improved charge separation and surface reactions in photocatalytic water splitting. It is envisioned that its practical applications can be facilitated by further reducing the material cost and improving the efficacy of Pt cocatalysts. In this direction, the use of atomically controlled Pd@Pt quasi-core-shell cocatalysts in combination with TiO2 as a model semiconductor is described. As demonstrated experimentally, the electron trapping necessary for charge separation is substantially promoted by combining a Schottky junction with interfacial charge polarization, enabled by the three-atomthick Pt shell. Meanwhile, the increase in electron density and lattice strain would significantly enhance the adsorption of H2O onto Pt surface. Taken together, the improved charge separation and molecular activation dramatically boost the overall efficiency of photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

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. Keywords: Piezocatalysis; cocatalysts; reactive oxidative species; hydrogen evolution EN Piezocatalysis cocatalysts reactive oxidative species hydrogen evolution 1 1 1 08/23/22 20220819 NES 220819 B The Cover Feature b highlights the key role of noble metal as cocatalysts for piezoelectricity-driven oxygen reduction and hydrogen evolution reactions. [Extracted from the article]

Atomic Layer Deposition (ALD) precise controlling ultra-thin platinum (Pt) modified Graphite carbon nitride (g-C 3 N 4) photocatalysts, which had been doped with gold nanoparticles (Au NPs) by photodeposition, were successfully synthesized. The experimental results showed that precise regulation of platinum decorated C 3 N 4 -Au(C 3 N 4 -Au/nPt (n is the number of Pt ALD cycles, 1 Å per cycle)) exhibited excellent photocatalytic degradation ability for Rhodamine B (RhB). Under simulated sunlight irradiation, the degradation rate of 10 mg/L RhB(100 mL) by 1.5 mg C 3 N 4 -Au/10Pt catalysts was 95.8% within 60 min that is much better than other photocatalysts for the degradation of RhB. The efficient degradation mechanism of RhB by C 3 N 4 -Au/10Pt photocatalysts was studied and the experiments demonstrated the ·O 2 – as main active species played an important role in the photocatalytic process. Local surface plasmon resonance (LSPR) of Au NPs and Schottky barrier between Pt clusters and g-C 3 N 4 may be the reasons for enhanced C 3 N 4 -Au/10Pt photocatalytic performances. Furthermore, the successive catalytic cycles revealed the excellent stability of C 3 N 4 -Au/10Pt photocatalyst. [ABSTRACT FROM AUTHOR]

Cocatalysts have been extensively used to promote water oxidation efficiency in solar-to-chemical energy conversion, but the influence of interface compatibility between semiconductor and cocatalyst has been rarely addressed. Here we demonstrate a feasible strategy of interface wettability modification to enhance water oxidation efficiency of the state-of-the-art CoOx/Ta3N5 system. When the hydrophobic feature of a Ta3N5 semiconductor was modulated to a hydrophilic one by in situ or ex situ surface coating with a magnesia nanolayer (2-5 nm), the interfacial contact between the hydrophilic CoOx cocatalyst and the modified hydrophilic Ta3N5 semiconductor was greatly improved. Consequently, the visible-light-driven photocatalytic oxygen evolution rate of the resulting CoOx/MgO(in)-Ta3N5 photocatalyst is ca. 23 times that of the pristine Ta3N5 sample, with a new record (11.3 %) of apparent quantum efficiency (AQE) under 500-600 nm illumination. [ABSTRACT FROM AUTHOR]

Since its discovery, methylalumoxane (MAO) has become of great importance as a cocatalyst in homogeneous olefin polymerization. The working principles of single-site polymerization catalysts are well-understood, but those of the cocatalyst MAO itself are not. Thus far structural and functional investigations have yielded limited insights and often give contradicting results. MAO's complex nature is due to multiple equilibria between undefined oligomers and 'free' trimethylaluminum. Fundamental studies do not clearly portray the molecular structure, and the exact functioning of MAO remains a topic of debate. This comprehensive overview starts with the historical background of MAO and then focuses on its synthesis and large-scale production, structural characterization, properties, and different roles in the activation of olefin polymerization catalysts. Also given is an overview of potential modifications, immobilization on surfaces, and other alternative applications that have been reported for MAO. [ABSTRACT FROM AUTHOR]

• The noble-metal-free CuII/CuI was used as cocatalysts via transient CuII/CuI centers. • The non-traditional LLCMT pathway was formed as a novel charge transfer channel. • The Cu species transient center can enhance the charge carriers separation efficiency. The earth-abundant copper species anchored on the -NH 2 of NH 2 -MIL-101(Fe) as noble-metal-free cocatalysts via transient CuII/CuI centers were obtained via a convenient synthesis technique to achieve excellent photocatalytic hydrogen evolution performance in the dye sensitization system. The prepared sample 6Cu-NM-101 exhibited the best hydrogen evolution activity of 5770.96 μ mol·g−1·h−1, which was 4.06 times higher than the original NH 2 -MIL-101(Fe). A series of characterization tests, especially the CV and the Auger Cu LMM, demonstrated that the transient CuII/CuI center played a significant part in the novel ligand to linker metal charge transfer (LLMCT) process. In other words, the electrons could transfer from the lowest unoccupied molecular orbital (LUMO) energy level of the excited state Eosin Y (EY*) to the transient CuII/CuI center to further accelerate the carrier transfer and separation rate. Our work provided a more convenient and effective strategy to prepare various earth-abundant metal ions based on MOFs as low-cost cocatalysts via transient metal centers to boost the photocatalytic hydrogen evolution performance. [ABSTRACT FROM AUTHOR]

• In-situ formed bifunctional catalyst g-C3N4/CN/CoP with efficient electron transfer rates. • Uniformly distributed noble-metal-free CoP as an ideal substitute for precious metal. • Excellent photocatalytic and electrocatalytic hydrogen evolution performance and stability. Developing an efficient, robust and low-budget bifunctional material for hydrogen evolution is a daunting challenge, which has attracted plenty of researchers' interest. Herein, we report the non-noble metal bifunctional g-C 3 N 4 /CN/CoP catalysts in situ formed for both photocatalytic and electrocatalytic hydrogen production through a convenient phosphorization process. It was found that the optimal g-C 3 N 4 (90)/CN300/CoP3 composite not only had the best photocatalytic hydrogen production rate (29.78 mmol·g−1·h−1) in the dye sensitization system, but also had an excellent electrocatalytic hydrogen evolution activity, with an overpotential of 221 mV at 10 mA·cm−2. The XRD, FT-IR, TG, et al. confirm the close contact between ZIF-Co and g-C 3 N 4 in the ideal g-C 3 N 4 /ZIF-Co precursor could expediently achieve the uniformly distributed CoP to accelerate electron transfer and reduce the recombination rate of charge. This work can provide a novel strategy to fabricate non-noble metal dual-functional materials for photocatalytic and electrocatalytic hydrogen production to solve energy crises and environmental further. [ABSTRACT FROM AUTHOR]

A new strategy has been put forward to improve the performance of photocatalytic H 2 evolution of tantalate-based catalysts through designing solid solutions Bi 1− x In x TaO 4 combined with CdS, among which the solid solutions Bi 1− x In x TaO 4 ( x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0) were firstly synthesized by the citrate method using cheap and environment-friendly Ta 2 O 5 . The experimental results reveal that the Bi 0.5 In 0.5 TaO 4 solid solution shows the best photocatalytic performance among the Bi 1− x In x TaO 4 solid solutions. And in the absence of noble metals, the 30% CdS/Bi 0.5 In 0.5 TaO 4 (30CBITO) catalyst exhibits good photocatalytic hydrogen evolution from water splitting with a rate of H 2 production of 511.75 μmol h −1 g −1 under simulated sunlight irradiation. And the rate of hydrogen evolution does not markedly change for 60 h. Their compositions, structures and morphologies were characterized by UV–vis diffusion reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). A photocatalytic enhancement mechanism was put forward to elucidate the superior photocatalytic activity and long-term stability of the heterostructured CdS/Bi 0.5 In 0.5 TaO 4 composites. [ABSTRACT FROM AUTHOR]

It is fundamental to uncover adsorption properties of metal oxide nanoclusters as cocatalysts on semiconductor surface and charge transfer mechanisms at the interface to understand experimentally observed improvement of photocatalytic activity. This work presents first-principle calculation on RuO nanoclusters as an example of cocatalysts adsorbed at rutile TiO (110) and anatase TiO (101) surfaces, determines the most stable adsorption configurations and elucidates the binding nature of ruthenium oxide clusters on TiO surfaces. Our results demonstrate that, for the same cluster size, adsorption energy of RuO cluster on rutile surface is larger than that on anatase surface due to more interfacial bonds formed between cluster and surface. The adsorption of RuO clusters on rutile (110) surface rather than anatase (101) surface brings noticeable contributions of cluster-related states in the top of valence bands. Upon light irradiation, electron transfer from ruthenium oxide cluster to surface increases the possibility of spatially separating photoinduced electron and hole, which is beneficial to the enhancement of photocatalytic activity. The present study may be helpful for understanding the enhanced photocatalytic activity by loading appropriate cocatalysts on the surface of semiconductor. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dye-sensitization strategy is proposed to enable Fe-MOFs for H 2 production; • Dye sensitization can elevate the quasi-Fermi levels of Fe-MOFs under light irradiation; • Experimental and theoretical results reveal the refined band structure of Fe-MOFs; • Pt deposition can further enhance the photocatalytic activity of dye-sensitized Fe-MOFs. Fe-based metal-organic frameworks (MOFs) have shown promising applications in photocatalysis, yet they are incapable of photocatalytic H 2 production due to their inappropriate conduction band (CB) position and large overpotential for H 2 evolution. Herein, we present a facile strategy enabling the photocatalytic H 2 production over Fe-based MOFs through dye sensitization. A combination of characterization techniques with theoretical simulation reveals that dye sensitization can effectively inject energetic electrons into Fe-MOFs and elevate their quasi-Fermi level under light irradiation, overcoming the surface overpotential for H 2 production from water. Furthermore, deposition of Pt nanoparticles on Fe-MOFs can lower the overpotential for H 2 evolution toward further enhanced photocatalytic activity. This work provides insights into MOF band structure engineering at electronic level, and proves a concept that harnesses MOF materials for targeted photocatalytic applications they are originally not fit for. [ABSTRACT FROM AUTHOR]

Earth-abundant nickel hydroxide (Ni(OH) 2)-based cocatalysts, by virtue of its bargain price, simple synthesis and diverse structure, have attracted increasing research interest in the field of solar-to-fuels conversion. Herein, we intend to afford a concise review on the recent progress regarding the promising applications of nickel hydroxide-based cocatalyst for photocatalytic H 2 production and CO 2 reduction. In particular, the roles of nickel hydroxide-based cocatalysts for promoting photocatalytic activities are systematically discussed. Furthermore, the future prospects and current challenges on constructing high-performance Ni(OH) 2 -based cocatalysts are proposed, which are expected to stimulate ongoing studies to unlock the potential of Ni(OH) 2 -based cocatalysts in various photocatalytic application. [Display omitted] • Applications of Ni(OH) 2 -based cocatalysts in photocatalysis are summarized. (68 characters). • Roles of Ni(OH) 2 -based cocatalysts for promoting photocatalytic activities are discussed. (80 characters). • Current challenges on constructing high-performance Ni(OH) 2 -based cocatalyst are proposed. (82 characters). • Future feasible opportunities about the Ni(OH) 2 -based cocatalysts are presented. (72 characters). [ABSTRACT FROM AUTHOR]

The copolymerization of carbon dioxide and propylene oxide to generate poly (propylene carbonate) (PPC) were efficiently catalyzed by zinc adipate (ZnAA) in the presence of various tertiary amines as cocatalyst. The influences of temperature, pressure as well as cocatalyst concentration on the copolymerization were studied. The ZnAA/4,4′-methylenebis ( N,N-dimethylaniline) composite catalyst shows reasonable high polymer productivity (>280 g polymer/g zinc), high selectivity (>95 %, PPC/cyclic carbonate), especially considerable high molecular weight (Mn > 250 k). Because of the high molecular weight, the as-prepared PPC exhibits apparently improved thermal properties as contrast to the one reported elsewhere previously. Furthermore, the effects of the steric and electronic properties of various tertiary amine derivatives on cocatalytic performance have also been discussed. The experimental results suggest that the tertiary amine cocatalysts with the rigid and bulky aromatic structure are more favorable for the copolymerization. [ABSTRACT FROM AUTHOR]

Artificial photoreduction of CO 2 is vital for the sustainable development of human beings via solar energy storage in stable chemicals. This process involves intricate light-matter interactions, but the role of incident light intensity in photocatalysis remains obscure. Herein, the influence of excitation intensity on charge kinetics and photocatalytic activity is investigated. Model photocatalysts include the pure graphitic carbon nitride (g-C 3 N 4 ) and g-C 3 N 4 loaded with noble/non-noble-metal cocatalysts (Ag, TiN, and CuO). It is found that the increase of light intensity does not always improve the electron utilization. Overly high excitation intensities cause charge carrier congestion and changes the recombination mechanism, which is called the light congestion effect. The electron transport channels can be established to mitigate the light-induced effect via the addition of cocatalyst, leading to a nonlinear growth in the reaction rate with increasing light intensity. From experiments and simulations, it is found that the light intensity and active site density should be collectively optimized for increasing the energy conversion efficiency. This work elucidates the effect of light intensity on photocatalytic CO 2 reduction and emphasizes the synergistic relationship of matching the light intensity and the photocatalyst category. The study provides guidance for the design of efficient photocatalysts and the operation of photocatalytic systems., (© 2022 Wiley-VCH GmbH.)

Abstract: Surface modification of cocatalysts has been extensively tested efficient to promote photocatalytic water splitting of semiconductor oxides, but its influence on an oxysulfide photocatalyst is limited. In this work, various metals and metal oxides, formed under different preparation conditions and using several deposition methods, were examined as cocatalysts to investigate their effects on the H2 and O2 evolution rates of a 1wt% Ag-modified Sm2Ti2S2O5 catalyst with an absorption edge of ca. 600nm. The photocatalytic rate of H2 evolution was found to strongly depend on the species, existing state and dispersion of the deposited metals, with the highest rate of 949μmolh−1 achieved by using 1wt% impregnated Rh combined with H2 reduction at 623K for 1h. The order of H2 activity of the deposited metals was Rh>Pt>Pd>Ir. IrO2 colloid cocatalysts promoted O2 evolution more strongly than other oxides deposited by impregnation. The pH environment during the synthesis of IrO2 colloids is an important factor in determining the final O2 evolution rate and a suitable pH region (8–9.5) was finally suggested. So far, the optimized apparent quantum efficiencies of H2 and O2 evolution have reached ca. 2.6% and 3.3% at 440nm, respectively. [Copyright &y& Elsevier]

[Display omitted] • Cocatalysts in TiO2-based photocatalysts are highlighted for solar hydrogen production. • Design strategies of cocatalysts in TiO2-based photocatalysts are presented systematically. • Enhancements are attributed to manipulating the charge separation and surface reactions. • Challenges and perspectives of cocatalysts in TiO2-based photocatalysts are proposed. TiO 2 -based photocatalysts have been maintained as the most prominent candidate for solar-driven hydrogen (H 2) evolution over the past decades. However, poor separation of generated electron-hole pairs has been considered the bottle-neck issue, restricting the TiO 2 activity. Coupling a TiO 2 photocatalyst to cocatalyst(s) turns out to be the ideal strategy to suppress the charge recombination and offer robust active centres, boosting the H 2 evolution performance. This review aims at providing the frontier investigations of cocatalysts-integrated TiO 2 for photo-induced H 2 evolution. Four types of cutting-edge development of cocatalysts, including metal (noble metal, non-noble metal, bimetallic), metal sulfides and metal phosphides, 2D-MXenes, and dual materials-based cocatalysts, have been successfully highlighted and discussed. The systematically provided cocatalysts, which remarkably promote the charge separation and facilitate the surface reactions, bring out a roadmap to inspire the preparation of superior TiO 2 -based materials for H 2 evolution shortly. We expect this review could provide enriched information to tailor the TiO 2 supported active sites of cocatalysts for highly photo-induced H 2 evolution. [ABSTRACT FROM AUTHOR]

Br and ultra-fine dispersed RhO x nanoparticles were decorated on the ultrathin 2D g-C 3 N 4 to induce high separation efficiency of photo-induced electrons and holes, resulting in high performance of degradation 10 ppm BPA within 9 min under visible light condition. [Display omitted] • Ultrafine RhO x nanoparticles (∼2 nm) were prepared on g-C 3 N 4. • The ultrathin g-C 3 N 4 largely shorten the migration distance of h+–e– pair. • Dual cocatalysts Br and RhO x can respectively promote the transfer of electrons and holes. • CN-Br 0.12 /2%RhO x exhibits the fastest degradation rate among CN-based photocatalysts. g-C 3 N 4 (CN), which shows enormous potential for photocatalysis, has long been studied, but still exhibits an unsatisfactory degradation rate. Herein, dual cocatalysts, Br and ultrafine RhO x nanoparticles, were constructed on ultrathin CN for synergetic photocatalysis. Ultrathin CN increased the exciton separation efficiency, while cocatalysts Br and RhO x can accelerated electron and hole transfer simultaneously, maximizing the photocatalytic degradation performance of CN. This CN-Br 0.12 /2%RhO x degraded 10 ppm bisphenol A (BPA) in 9 min, which represents the fastest degradation rate reported to date. This excellent performance was also demonstrated by a larger photocurrent response, higher separation efficiency, and faster transfer rate for electron–hole pairs than CN. This work obtained an enhanced electron–hole separation efficiency and migration rate by combing ultrathin CN with dual-channel cocatalysts, leading to the best photocatalytic degradation performance reported for CN. [ABSTRACT FROM AUTHOR]

• The semi-metallic 1 T′ phase MoReS 3 is distributed on g-C 3 N 4 nanotubes to construct 1 T′-MoReS 3 /g-C 3 N 4 composite. • The 1 T′-MoReS 3 /g-C 3 N 4 composite is highly active for water splitting to produce hydrogen at 2671 μmol h−1 g−1. • The porous g-C 3 N 4 nanotubes with hollow structure promote the light scattering and the transport of photoexcited carrier. • The semi-metallic 1 T′ phase MoReS 3 show a synergistic effect of 1 T′-MoS 2 and 1 T′-ReS 2 with better electrical conductivity. In this paper, we for the first time report that semi-metallic 1T′-MoReS 3 acts as cocatalyst loading on the g-C 3 N 4 nanotubes (NTs) through a solvothermal reaction process for photocatalytic hydrogen evolution. 1T′-MoReS 3 /g-C 3 N 4 composites with 7 wt% 1T′-MoReS 3 exhibit an expressively enhanced photocatalytic hydrogen evolution activity (2671 μmol·g−1·h−1), better than g-C 3 N 4 NTs (61 μmol·g−1·h−1), 1T′-MoS 2 /g-C 3 N 4 composites (2207 μmol h−1 g−1) and 1T′-ReS 2 /g-C 3 N 4 composites (1600 μmol h−1 g−1). According to the DFT calculation and experimental data, the enhanced photocatalytic activity of 1T′-MoReS 3 /g-C 3 N 4 composites is ascribed to the advantages as follows: 1) The porous g-C 3 N 4 NTs with hollow structure possess short charge transfer distance and large surface area, promoting the light scattering and the transport of photoexcited carriers; 2) 1T′-MoReS 3 as cocatalysts show a synergistic effect of 1T′-MoS 2 and 1T′-ReS 2 with better electrical conductivity, boosting the electron transfer process; 3) After loading 1T′-MoReS 3 cocatalysts, 1T′-MoReS 3 /g-C 3 N 4 composites show an improved light absorption and photoelectrochemical performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Evidencing the role of different oxidation states of Pt cocatalyst loaded onto BVO. • Control of photoreduction time ends up in different content of Pt0/PtO x onto BVO. • PtO x species improve the apparent quantum efficiency of BiVO 4 compared to only Pt0. • Pt/PtO x shows a 58-fold increase in photodegradation rate constant vs. pristine BVO. • PtO x act as traps for the photoexcited electrons in the CB of BVO. Monoclinic bismuth vanadate (BVO) has gained attention as a low-cost and promising visible light photocatalyst but suffers from fast charge carrier recombination. The present study reports the controlled photoreduction deposition of different Pt-based co-catalysts on the surface of BVO to address this drawback and brings a detailed discussion on the role of the oxidation state of Pt in determining the photoactivity of the photocatalysts. Results evidenced the presence of both metallic Pt and Pt oxides on the surface of BVO, with proportions that depended on the photoreduction time. The photocatalytic activity towards degradation of three model dyes revealed that platinum oxides (PtO x , x = 1 or 2) or a mixture of Pt0/PtO x species act out as better cocatalysts than Pt0, with an almost 4-fold higher apparent quantum yield for the optimized sample. The enhanced photoactivity of BVO/Pt/PtO x photocatalysts was attributed to their improved visible light absorption and enhanced charge carrier separation than pristine BVO or BVO/Pt. This study provides important insight into and a better understanding of the general photodeposition strategy employed to prepare semiconductor/metal (photo)catalysts on one hand and highlights the role of the oxidation state of deposited metal in determining the properties of composite (photo)catalysts on the other. [ABSTRACT FROM AUTHOR]

A set of structurally modulated salicylaldimine cobalt(II) complexes have been synthesized and utilized them for ethylene oligomerizations in combination with various organoaluminum cocatalysts. All catalyst systems yielded α-olefins with butenes as major product. The catalytic activity and product distribution were affected by the catalytic structure and reaction conditions. The formation of active species in these complexes under oligomerization conditions was investigated by UV-VIS spectroscopy and the results matched well with oligomerization results. [ABSTRACT FROM AUTHOR]

Low-cost transition-metal chalcogenides (MS x ) are demonstrated to be potential candidate cocatalyst for photocatalytic H 2 generation. However, their H 2 -generation performance is limited by insufficient quantities of exposed sulfur (S) sites and their strong bonding with adsorbed hydrogen atoms (SH ads ). To address these issues, an efficient coupling strategy of active-site-enriched regulation and electronic structure modification of active S sites is developed by rational design of core-shell Au@NiS 1+ x nanostructured cocatalyst. In this case, the Au@NiS 1+ x cocatalyst can be skillfully fabricated to synthesize the Au@NiS 1+ x modified TiO 2 (denoted as TiO 2 /Au@NiS 1+ x ) by a two-step route. Photocatalytic experiments exhibit that the resulting TiO 2 /Au@NiS 1+ x (1.7:1.3) displays a boosted H 2 -generation rate of 9616 µmol h -1 g -1 with an apparent quantum efficiency of 46.0%  at 365 nm, which is 2.9 and 1.7 times the rate over TiO 2 /NiS 1+ x and TiO 2 /Au, respectively. In situ/ex situ XPS characterization and density functional theory calculations reveal that the free-electrons of Au can transfer to sulfur-enriched NiS 1+ x to induce the generation of electron-enriched S δ - active centers, which boosts the desorption of H ads for rapid hydrogen formation via weakening the strong SH ads bonds. Hence, an electron-enriched S δ - -mediated mechanism is proposed. This work delivers a universal strategy for simultaneously increasing the active site number and optimizing the binding strength between the active sites and hydrogen adsorbates., (© 2021 Wiley-VCH GmbH.)

• Zn 0.5 Cd 0.5 S nanocrystals were synthesized through a one-pot solvothermal method using N-Methyl pyrrolidone. • 2D/0D Ni/Zn 0.5 Cd 0.5 S heterostructures were fabricated via a solution phase route. • Ni/Zn 0.5 Cd 0.5 S showed much higher photocatalytic H 2 production performance than Pt/Zn 0.5 Cd 0.5 S. • Ni nanosheets serve as cost-effective and high-efficient cocatalyst to boost the charge separation on Zn 0.5 Cd 0.5 S. [Display omitted] Ni-based precious-metal-free cocatalysts have attracted copious attention due to their nature-friendly and cost-effectiveness compared with platinum (Pt) during photocatalytic H 2 evolution. However, the typical morphologies and structures of Ni-based cocatalysts (e.g., Ni) focus on the zero-dimensional (0D) nanoparticles. Herein, we demonstrate a two-dimensional (2D) nickel nanosheets cocatalyst decorated Zn 0.5 Cd 0.5 S nanocrystals that pays attention to visible-light-motivated photocatalytic H 2 generation. By rationally introducing Ni nanosheets to modify Zn 0.5 Cd 0.5 S nanoparticles, a series of unique 2D/0D Ni/Zn 0.5 Cd 0.5 S nanohybrids with different Ni contents were synthesized. The optimized Ni-5%/Zn 0.5 Cd 0.5 S composite possesses a high H 2 production rate of 5930 μmol h−1 g−1 upon visible-light (λ > 420 nm) illumination, which was about 33.7 and 15.4-fold more elevated than those of Zn 0.5 Cd 0.5 S nanocrystals, and Pt/Zn 0.5 Cd 0.5 S, respectively. Combining photoelectrochemical (PEC) and photoluminescence (PL) studies, the conspicuous enhancement in photocatalytic H 2 generation was stemmed from the Ni nanosheets cocatalyst act as an electron-transfer layer to extract photoexcited electrons from Zn 0.5 Cd 0.5 S and offer enormous reaction sites for H 2 production. This work verifies Ni nanosheets' capability for photocatalytic water splitting. The Ni/Zn 0.5 Cd 0.5 S composed of magnetic metal and ternary metal sulfide can be extended to other photocatalytic applications, such as dyes degradation and CO 2 reduction. [ABSTRACT FROM AUTHOR]

Amorphous CuO is considered as an excellent cocatalyst, owing to its large surface area and superior conductivity compared with its crystalline counterpart. The current work demonstrates a facile method to prepare amorphous CuO, which is grown on the surface of graphitic carbon nitride (g-C 3 N 4 ) and is then applied for the photocatalytic degradation of tetracycline hydrochloride. The prepared CuO/g-C 3 N 4 composite shows higher photocatalytic activities compared with bare g-C 3 N 4 . Efficient charge transfer between g-C 3 N 4 and CuO is confirmed by the photocurrent response spectra and photoluminescence spectra. This work provides a facile approach to prepare low-cost composites for the photocatalytic degradation of antibiotics to safeguard the environment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zhao, Zada, Yang, Pan, Wang, Yan, Xu and Qi.)

Photocatalytic hydrogen (H2) production by water splitting provides an alternative to fossil fuels using clean and renewable energy, which gives important requirements about the efficiency of photocatalysts, co-catalysts, and sacrificial agents. To achieve higher H2 production efficiencies from water splitting, the study uses different metals such as yttrium (Y), praseodymium (Pr), magnesium (Mg), Indium (In), calcium (Ca), europium (Eu), and terbium (Tb) doped lanthanum iron oxide (LaFeO3) perovskites. They were synthesized using a co-precipitate method in a citric acid solution, which was loaded with the rhodium chromium oxide (RhCrOx) cocatalysts by an impregnation method along with a detailed investigation of photocatalytic hydrogen evolution performance. Photoluminescence (PL) and UV–Vis diffuse reflectance spectra (DRS) measured the rate of electron–hole recombination for RhCrOx/Pr-LaFeO3 photocatalysts, and X-ray powder diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), and X-ray photoelectron spectra (XPS) analyzed their characteristics. The experimental results obtained show that the samples with 0.5 wt.% RhCrOx loading and 0.1 M Pr-doped LaFeO3 calcined at a temperature of 700 °C (0.1Pr-LaFeO3-700) exhibited the highest photocatalytic H2 evolution rate of 127 µmol h−1 g−1, which is 34% higher photocatalytic H2 evolution performance than undoped LaFeO3 photocatalysts (94.8 μmol h−1 g−1). A measure of 20% of triethanolamine (TEOA) enabled a high hole capture capability and promoted 0.1-Pr-LaFeO3-700 to get the highest H2 evolution rate. [ABSTRACT FROM AUTHOR]

Over the past few decades, graphitic carbon nitride (g-C 3 N 4 ) has arisen much attention as a promising candidate for photocatalytic hydrogen evolution reaction (HER) owing to its low cost and visible light response ability. However, the unsatisfied HER performance originated from the strong charge recombination of g-C 3 N 4 severely inhibits the further large-scale application of g-C 3 N 4 . In this case, the utilization of cocatalysts is a novel frontline in the g-C 3 N 4 -based photocatalytic systems due to the positive effects of cocatalysts on supressing charge carrier recombination, reducing the HER overpotential, and improving photocatalytic activity. This review summarizes some recent advances about the high-performance cocatalysts based on g-C 3 N 4 toward HER. Specifically, the functions, design principle, classification, modification strategies of cocatalysts, as well as their intrinsic mechanism for the enhanced photocatalytic HER activity are discussed here. Finally, the pivotal challenges and future developments of cocatalysts in the field of HER are further proposed., (© 2021 Wiley-VCH GmbH.)

The development and optimization of sonosensitizers for elevating intratumoral reactive oxygen species (ROS) are definitely appealing in current sonodynamic therapy (SDT). Given this, branched vanadium tetrasulfide (VS 4 ) nanodendrites with a narrower bandgap (compared with the most extensively explored sonosensitizers) are presented as a new source of sonosensitizer, which allows a more effortless separation of sono-triggered electron-hole pairs for ROS generation. Specifically, platinum (Pt) nanoparticles and endogenous high levels of glutathione (GSH) are rationally engineered to further optimize its sono-sensitized performance. As cocatalyst, Pt is conducive to trapping electrons, whereas GSH, as a natural hole-scavenger, tends to capture holes. Compared with the pristine VS 4 sonosensitizer, the GSH-Pt-VS 4 nanocomposite can greatly prolong the lifetime of the charge and confer a highly efficacious ROS production activity. Furthermore, such nanoplatforms are capable of reshaping tumor microenvironments to realize ROS overproduction, contributed by overcoming tumor hypoxia to improve SDT-triggered singlet oxygen production, catalyzing endogenic hydrogen peroxide into destructive hydroxyl radicals for chemodynamic therapy, and depleting GSH to amplify intratumoral oxidative stress. All these combined effects result in a significantly efficient tumor suppression outcome. This study enriches sonosensitizer research and proves that sonosensitizers can be rationally optimized by charge separation engineering strategy., (© 2021 Wiley-VCH GmbH.)

• The amorphous NiS 1+ x nanoclusters with sulfur-rich property were anchored onto TiO 2. • The amorphous NiS 1+ x nanoclusters possess abundant active S sites for H 2 evolution. • H 2 -evolution rate of TiO 2 can be greatly enhanced by sulfur-rich NiS 1+ x nanoclusters. • The synthetic route can be extended to construct various metal sulfide cocatalysts. Transition-metal sulfides have been proved to be a favorable candidate for high-efficiency cocatalyst for photocatalysts, but the major bottlenecks remains lacking sufficient active sites for interfacial H 2 -generation reactions. In this article, the sulfur-rich NiS 1+x nanoclusters with abundant active unsaturated S sites are homogeneously anchored on TiO 2 particles by a facile S 2 O 3 2−-mediated photodeposition route. The as-synthesized NiS 1+x /TiO 2 (1 wt%) photocatalyst achieves the boosted H 2 evolution rate of 264.42 μmol h-1 as well as shows an outstanding stability and repeatability. The sulfur-rich NiS 1+x nanoclusters can not only act as an outstanding cocatalyst to effectively accelerate the electron migration from TiO 2 to NiS 1+x nanoclusters, but also provide numerous active unsaturated S sites to promote interfacial H 2 -generation reaction, thereby promoting the photocatalytic H 2 -production rate of the NiS 1+x /TiO 2 photocatalysts. Particularly, the present method can be extended to construct other metal sulfides (AgS x , CoS x or CuS x) to evidently promote the photocatalytic H 2 -evolution activity. [ABSTRACT FROM AUTHOR]

Cobalt incorporated sulfur-doped graphitic carbon nitride with bismuth oxychloride (Co/S-gC 3 N 4 /BiOCl) heterojunction is prepared by an ultrasonically assisted hydrothermal treatment. The heterojunction materials have employed in photoelectrochemical (PEC) water splitting. The PEC activity and stability of the materials are promoted by constructing an interface between the visible light active semiconductor photocatalyst and cocatalysts. The photocurrent density of Co-9% S-gC 3 N 4 /BiOCl has attained 393.0 μA cm -2 at 1.23 V vs. RHE, which is 7-fold larger than BiOCl and ~3-fold higher than 9% S-gC 3 N 4 /BiOCl. The enhanced PEC activity can be attributed to the improved electron-hole charge separation and the boosted charge transfer is confirmed by photoluminescence (PL) and electrochemical impedance spectroscopy (EIS) analysis. The fabricated Co/S-gC 3 N 4 /BiOCl nanohybrid material has exhibited high stability of up to 10,800 s (3 h) at 1.23 V vs. RHE during PEC water splitting reaction and the obtained photo-conversion efficiency is 3.7-fold greater than S-gC 3 N 4 /BiOCl and 17-fold higher than BiOCl. The FESEM and HRTEM images have revealed the formation of heterojunction interface between S-gC 3 N 4 and BiOCl and the elemental mapping has confirmed the presence of cobalt over S-gC 3 N 4 /BiOCl. The heterojunction interface has facilitated the photo-excited charge separation and transport across the electrode/electrolyte interface and also the flat-band potential, which is confirmed by Mott-Schottky analysis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Pt/CdS/7.5Co-Pi photoelectrode was prepared for improving PEC water splitting. • Design and fabrication of Pt/CdS/Co-Pi photoanode for efficient PEC water splitting. • Pt serves as an electron capture layer to collect electron to facilitate water reduction. • Co-Pi used as cocatalysts to accelerate the surface water oxidation in Pt/CdS/Co-Pi. • It can provide a promising guidelines for photoanodes to realize efficient PEC water splitting. The recombination of electron-hole pairs and the slow surface catalytic reactions have been deemed as the core problem affecting the efficiency of photoelectrochemical (PEC) performance. Here we synthesized hexagonal CdS photoanode on FTO substrate by hydrothermal method. Cobalt-phosphate (Co-Pi) and Pt cocatalysts were simultaneously decorated on the inner and outer surfaces of CdS (denoted as Pt/CdS/Co-Pi), which showed efficient charge separation/transfer performance on account of trapping the electrons with Pt and transferring holes with Co-Pi. As a result, the Pt/CdS/7.5Co-Pi photoanode showed a maximum photo-current of 5.05 mA/cm−2 at 0.28 V vs RHE under solar simulated illumination, which was 8.3 times higher than that of pure CdS photoanode. This work presents a promising guideline to design and fabricate an eco-friendly and sunlight-driven photoanode for the PEC water-splitting system. [ABSTRACT FROM AUTHOR]

• Mechanism for the stability of Cu2O photocathode in for PEC water splitting is explored. • Self-oxidation caused by accumulation of photogenerated holes is the main reason for Cu2O photocorrosion. • FeOOH as a hole transfer layer (HTL) can suppress the self-photooxidation of Cu2O photocathode. • Total PEC activity can be accomplished after FeOOH/Cu 2 O activated with Pt co-catalyst. Photocorrosion of Cu 2 O photoelectrode regarded as a serious factor extremely restricts its photoactivity. So far, nonetheless, there are few comprehensive reports on the mechanism affecting the stability of Cu 2 O photocathode in photoelctrochemical (PEC) water splitting. In this work, we firstly explore the influence mechanism for the stability of Cu 2 O photocathode, revealing that self-oxidation caused by accumulation of photogenerated holes is the main reason to the occurrence of Cu 2 O photoelectrode photocorrosion. By knowing the dominant deactivation mode of Cu 2 O photoelectrode, we firstly select FeOOH as a hole transfer layer (HTL) to promote the extraction of photogenerated holes from the bulk of bare Cu 2 O photoelectrode and thus suppress the self-photooxidation of Cu 2 O. Furthermore, restraint of photocorrosion combined with increase in its total photoelectrochemistry activity can be accomplished after the surface of FeOOH/Cu 2 O photoelectrode activated with Pt co-catalyst. This work provides a novel strategy and method for improving the stability of photoelectrodes due to self-redox reactions. [ABSTRACT FROM AUTHOR]

A metal-complex-modified graphitic carbon nitride (g-C 3 N 4 ) bulk heterostructure is presented here as a promising alternative to high-cost noble metals as artificial photocatalysts. Theoretical and experimental studies of the spectral and physicochemical properties of three structurally similar molecules Fo-D , Pt-D , and Pt-P confirm that the Pt(II) acetylide group effectively expands the electron delocalization and adjusts the molecular orbital levels to form a relatively narrow bandgap. Using these molecules, the donor-acceptor assemblies Fo-D @ CN , Pt-D @ CN , and Pt-P @ CN are formed with g-C 3 N 4 . Among these assemblies, the Pt(II) acetylide-based composite materials Pt-D @ CN and Pt-P @ CN with bulk heterojunction morphologies and extremely low Pt weight ratios of 0.19% and 0.24%, respectively, exhibit the fastest charge transfer and best light-harvesting efficiencies. Among the tested assemblies, 10 mg Pt-P @ CN without any Pt metal additives exhibits a significantly improved photocatalytic H 2 generation rate of 1.38 µmol h -1 under simulated sunlight irradiation (AM1.5G, filter), which is sixfold higher than that of the pristine g-C 3 N 4 ., Competing Interests: The authors declare no conflict of interest., (© 2021 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Efficient charge separation and utilization are critical factors in photocatalysis. Herein, it is demonstrated that the complete spatial separation of oxidation and reduction cocatalysts enhances the efficacy of charge separation and surface reaction. Specifically, a Pt@NH 2 -UiO-66@MnO x (PUM) heterostructured photocatalyst with Pt and MnO x as cocatalysts is designed for the optimization of the NH 2 -UiO-66 photocatalyst. Compared with the pristine NH 2 -UiO-66, Pt@NH 2 -UiO-66 (PU), and NH 2 -UiO-66@MnO x (UM) samples, the PUM sample exhibits the highest hydrogen production activity. As cocatalysts, Pt favors trapping of electrons, while MnO x tends to collect holes. Upon generation from NH 2 -UiO-66, electrons and holes flow inward and outward of the metal-organic framework photocatalyst, accumulating on the corresponding cocatalysts, and then take part in the redox reactions. The PUM photocatalyst greatly prolongs the lifetime of the photogenerated electrons and holes, which favors the electron-hole separation. Furthermore, the PUM sample facilitates overall water splitting in the absence of sacrificial agents, thereby demonstrating its potential as a modification method of MOF-type semiconductors for the overall water-splitting reaction., (© 2020 Wiley-VCH GmbH.)

Exploiting spontaneous polarization of ferroelectric materials to achieve high charge separation efficiency is an intriguing but challenging research topic in solar energy conversion. This work shows that loading high work function RuO 2 cocatalyst on BiFeO 3 (BFO) nanoparticles enhances the intrinsic ferroelectric polarization by efficient screening of charges to RuO 2 via RuO 2 /BFO heterojunction. This leads to enhancement of the surface photovoltage of RuO 2 /BFO single nanoparticles nearly 3 times, the driving force for charge separation and transfer in photocatalytic reactions. Consequently, efficient photocatalytic water oxidation is achieved with quantum efficiency as high as 5.36 % at 560 nm, the highest activity reported so far for ferroelectric materials. This work demonstrates that, unlike low photocurrent density in film-based ferroelectric devices, high photocatalytic activity could be achieved by regulating the ferroelectric spontaneous polarization using appropriate cocatalyst to enhance driving force for efficient separation and transfer of photogenerated charges in particulate ferroelectric semiconductor materials., (© 2020 Wiley-VCH GmbH.)

Understanding the origin of formation and active sites of oxygen evolution reaction (OER) cocatalysts is highly required for solar photoelectrochemical (PEC) devices that generate hydrogen efficiently from water. Herein, we employed a simple pH-modulated method for in situ growth of FeNi oxyhydroxide ultrathin layers on BiVO 4 photoanodes, resulting in one of the highest currently known PEC activities of 5.8 mA cm -2 (1.23 V RHE , AM 1.5 G) accompanied with an excellent stability. More importantly, both comparative experiments and density functional theory (DFT) studies clearly reveal that the selective formation of Bi-O-Fe interfacial bonds mainly contributes the enhanced OER activities, while the construction of V-O-Ni interfacial bonds effectively restrains the dissolution of V 5+ ions and promotes the OER stability. Thereby, the synergy between iron and nickel of FeNi oxyhydroxides significantly improved the PEC water oxidation properties of BiVO 4 photoanodes., (© 2020 Wiley-VCH GmbH.)