H2 Evolution Reaction Activity Research Articles

Enriched edge sites of ultrathin Ni3S2/NiO nanomeshes promote surface reconstruction for robust electrochemical water splitting

Developing highly efficient nonnoble bifunctional electrocatalysts for both the H2 evolution reaction (HER) and O2 evolution reaction (OER) is essential but challenging for overall water splitting (OWS). Ni based catalysts are proved as promising candidates for water splitting, which usually undergo surface reconstruction by transforming into nickel oxyhydroxides as active sites. Although evidence suggests that the reconstruction originates from the exchange of surface lattice oxygen with the OH- in the electrolyte under electric field, modulating the reconstruction of Ni based catalysts remains a great challenge. Herein, we propose an edge sites enrichment strategy to promote the active phase evolution. The one-step synthesized ultrathin Ni3S2/NiO nanomeshes exhibited an ultrathin porous structure which contain abundant edge sites and Ni3S2/NiO in-plane interface sites. Owing to the unique structure, Ni3S2/NiO nanomeshes possessed an affinity feature to proton and OH-, resulting in a faster reconstruction from Ni3S2 to Ni(OH)2 than Ni3S2 bulk which subsequently converted into γ-NiOOH and a lower adsorption barrier for H*. Consequently, the Ni3S2/NiO nanomeshes exhibited outstanding OER activity (300 mV at 200 mA cm−2) and unexpected HER activity (73 mV at 10 mA cm−2) in 1.0 M KOH. Remarkably, the nanomeshes achieved an ultralow voltage of 1.41 V at 10 mA cm−2 with excellent stability for overall water splitting, which prevailed over most of the reported catalysts. Moreover, the nanomeshes performed a H2 yield of 900 µmol/h in a solar-assisted water splitting system with a H2 minimum sales price of $1.77/kg, much lower than that of the commercial catalyst ($7.18/kg). This work sets a new benchmark of monometallic bifunctional catalysts for industrial water splitting and provides new insights into the synthesis of 2D nanomeshes.

Highly dispersed PtO over g-C3N4 by specific metal-support interactions and optimally distributed Pt species to enhance hydrogen evolution rate of Pt/g-C3N4 photocatalysts

Understanding the fundamental chemistry of metal-support interactions during catalyst preparation is essential to develop a highly efficient Pt/g-C3N4 photocatalyst for the H2 evolution reaction (HER). In this study, we prepared Pt/g-C3N4 photocatalysts via a loading process of different Pt contents onto solvothermally treated g-C3N4 (SCN) and a successive hydrogen reduction. The physicochemical interactions between Pt species and O-containing functional groups over SCN were tracked, and we investigated how the interactions influenced the photocatalytic properties and performance of Pt/SCN. During the reduction process, Pt(OH)22+ ions in liquid phase specifically interacted with neighboring C = O groups over SCN, resulting in highly dispersed PtO species via chemical bonding to SCN. Due to the limited number of the neighboring C = O groups over SCN, the chemically bonded PtO species were saturated at a certain amount, and 1Pt/SCN (1 wt% of Pt) showed the highest Pt dispersion in this study. In the reduction process, excess Pt was readily reduced to Pt metallic phase and then agglomerated in Pt clusters at high Pt loadings. Therefore, the highly active and stable Pt2+ sites were uniformly dispersed and immobilized over 1Pt/SCN by specific interactions with the O-containing functional groups, showing an outstanding HER activity per gram Pt (120.6 mmol∙gPt−1∙h−1). However, data for the optical and electrochemical properties demonstrated that 3Pt/SCN (3 wt% of Pt) had the best charge separation efficiency because of the optimal distribution of the Pt species over SCN. Correspondingly, the optimized 3Pt/SCN exhibited the highest HER rate of 1255.52 μmol∙gcat−1∙h−1, which was about 50 times higher than SCN photocatalyst (25.2 μmol∙gcat−1∙h−1).

Advanced Catalyst for CO2 Photo-Reduction: From Controllable Product Selectivity by Architecture Engineering to Improving Charge Transfer Using Stabilized Au Clusters.

Despite enormous progress and improvement in photocatalytic CO2 reduction reaction (CO2 RR), the development of photocatalysts that suppress H2 evolution reaction (HER), during CO2 RR, remains still a challenge. Here, new insight is presented for controllable CO2 RR selectivity by tuning the architecture of the photocatalyst. Au/carbon nitride with planar structure (p Au/CN) showed high activity for HER with 87% selectivity. In contrast, the same composition with a yolk@shell structure (Y@S Au@CN) exhibited high selectivity of carbon products by suppressing the HER to 26% under visible light irradiation. Further improvement for CO2 RR activitywasachieved by a surface decoration of the yolk@shell structure with Au25 (PET)18 clusters as favorable electron acceptors, resulting in longer charge separation in Au@CN/Auc Y@S structure. Finally, by covering the structure with graphene layers, the designed catalyst maintained high photostability during light illumination and showed high photocatalytic efficiency. The optimized Au@CN/Auc /G Y@S structure displays high photocatalytic CO2 RR selectivity of 88%, where the CO and CH4 generations during 8h are 494 and 198µmol/gcat., respectively. This approach combining architecture engineering and composition modification provides a new strategy with improved activity and controllable selectivity toward targeting applications in energy conversion catalysis.

Rapid Synthesis of C60-MoC Nanocomposites by Molten Salt Electrolysis for Hydrogen Evolution

Molybdenum carbide is a promising alternative of Pt/C in H2 evolution reaction (HER). However, its synthesis is time-consuming and energy-intensive. In this work, we propose a rapid one-pot strategy to fabricate C60-MoC nanocomposites in Li2CO3-K2CO3 molten salt using CO2 and ammonium molybdate as carbon and Mo sources, respectively. The as-obtained C60-MoC-600 sample at 600 °C shows high HER activity in both acid and alkaline electrolytes. Especially in 1 M KOH, the η 10 (overpotential at 10 mA cm−2) of C60-MoC-600 is 142 mV. Under an industrial current density of 220 mA cm−2, its activity with an overpotential of 250 mV is close to that of commercial Pt/C and exhibits excellent constant current stability during 10 h. This strategy not only implements the simple synthesis of MoC-based catalysts but also paves a highly efficient way for the rapid abatement and high-value-added utilization of CO2.

Directly growth of highly uniform MnS–MoS2 on carbon cloth for advanced H2 evolution electrocatalyst in different pH electrolytes

The activation energy barrier of the H–O bond of water molecules is high, and thus the rate of H2 evolution reaction (HER) via water splitting is very slow. Hence, chemists are committed to finding high-performance, cheap and stable catalysts for realizing efficient H2 production. The molybdenum disulfide (MoS2)-based bimetallic sulfide electrocatalysts are favored by researchers because of their particular structures and properties. Herein, the Waugh type polyoxometalate (POM) is used as raw materials. A series of MnS–MoS2 electrocatalysts are in-situ coupled on carbon cloth (CC) substrate by a hydrothermal sulfidation method. The catalyst MnS-MoS2-CC possesses high catalytic activity for HER in a alkaline electrolyte, showing a low overpotential of 54 mV at a current density of 10 mA cm−2, which is very close to 35 mV of the 20% Pt/C electrode. Meanwhile, under a current density of over 50 mA cm−2, the overpotential of MnS-MoS2-CC is less than that of the 20% Pt/C electrode. Moreover, the electrocatalysts show overpotentials of 141 mV and 201 mV at a current density of 10 mA cm−2 in 0.5 M H2SO4 and 1.0 M phosphate buffer solution (PBS), respectively. Besides the high catalytic activity, the MnS-MoS2-CC electrode shows long-term durability in a wide pH range, which is confirmed by several methods including the tests of linear sweep voltammetry (LSV) curve, current density vs. time (I-t) curve, and scanning electron microscopy (SEM). This work provides a feasible route for the preparation of HER electrocatalysts applied in broad pH conditions, especially for alkaline solutions.

Self-assembly of Ag photosensitized SrTiO3 3D binary architectures for highly efficient visible light-driven dyeing wastewater splitting

Semiconductor/metal hybrid nanostructures-based finely tuning the charge transfer as a promising approach has been identified for photocatalytic activity recently towards renewable hydrogen (H 2 ) evolution reaction (HER) and environmental remediation. Engineering surface-active facets of the metal cocatalyst on the surface of 3-dimensional (3D) structured photocatalysts not only efficiently promotes charge separation and transfer but also serves as reaction active sites for the further development of advanced photocatalysts. Herein, taking 3D SrTiO 3 (STO) as a model, we introduce a plasmonic photocatalyst involving the adjusted loading of well-defined Ag active components as a cocatalyst deposited on the surface of 3D STO nanocubes to form the binary Ag/STO nanostructures for photocatalytic behavior driven by light at wavelengths of 365 nm and 420 nm. After the incorporation of the functional cocatalyst, the photocurrent response of STO was substantially increased, while its photoluminescence emission significantly declined, which could be due to the Schottky channel and enrichment of surface reactants: (i) the enhancement of the interfacial separation and inhibition of the recombination process of the photogenerated electron-hole pairs; and (ii) the Ag arrangement on the 3D structure could not only promote the enhanced light absorption but also provide a large surface area with highly active sites for the photocatalytic reaction. The as-synthesized hybrid photocatalyst with a loading content of 1 wt% Ag displays a high photocatalytic H 2 evolution and RhB degradation reaching 30 μmol g −1 h −1 (H 2 gas) and a rate constant (k) of 0.027 min −1 (RhB dye), which was 2.5, and 3.4 times higher than that of the pristine STO specimen (12.5 μmol g −1 h −1 and k = 0.008 min −1 , respectively, at 385 nm). Under a wavelength of 420 nm, the binary Ag/STO structures exhibited excellent performance for the H 2 production (17.5 μmol g −1 h −1 ) and RhB degradation (k = 0.0134 min −1 ) in comparison with the pristine STO specimen. They also demonstrated remarkable stability for H 2 evolution and dye degradation performance in continuous cycles. Based on the experimental outcomes, an energy band outline and a plausible mechanism have been proposed to describe the charge transfer and separation process for enhanced HER activity and RhB degradation. • 3D SrTiO 3 with well-defined SrTiO 3 nanocubes was fabricated via facile hydrothermal method. • AgNPs decorated 3D SrTiO 3 nanocubes were easily prepared by a one-step process. • The as-synthesized hybrid photocatalyst exhibits an outstanding photocatalytic dyeing wastewater splitting. • The properties of photocatalyst before and after the photocatalytic performance were further assessed.

Unique Mo2C–CdS–Co@C heterojunction integrated with redox cocatalysts and multiple active sites for efficient photocatalytic H2 generation

Photocatalytic water-splitting has encouraged great interest to obtain renewable H2 fuel via the transformation of solar energy. Although significant progress has been achieved, realizing efficient H2 evolution reaction (HER) with non-noble-metal photocatalysts is still challenging. Herein, we report a facile synthesis of Mo2C–CdS–[email protected] heterojunction by anchoring CdS and Mo2C nanoparticles onto [email protected] micro-flowers. The [email protected] micro-flowers were composed of graphitic carbon nanoflakes partially embedded with Co, CoOx, Co9S8 nanocrystals and obtained through the carbonization of metanilic-anion intercalated Co(OH)2 precursor. Due to excellent visible-light harvesting capacity, efficient charge transmission and isolation caused by the existence of superior electron mediator (graphitic carbon) together with oxidation (CoOx) and reduction (Co, Co9S8, Mo2C) cocatalysts, as well as the plentiful H2-evolving active sites originating from the metal (Co), metal sulfide (Co9S8), and metal carbide (Mo2C), the Mo2C–CdS–[email protected] hybrid micro-flowers delivered an exceptional HER (λ > 400 nm) activity of 760.58 μmol h−1 (10 mg), approximately 32 and 15 folds that of pristine CdS and platinum (3 wt%)-decorated CdS, respectively. Moreover, both the cycling and long-term photocatalytic tests confirm that the Mo2C–CdS–[email protected] possesses an outstanding durability for H2 production. The study results might inspire the rational integration of cocatalysts to simultaneously optimize the charge trapping and H2-evolving kinetics for strengthening the photocatalytic HER activity efficiently.

Modification of carbon nitride with noble-metal-free cobalt phosphide for effective photocatalytic hydrogen evolution

In this paper, CoP/g-C3N4 composite photocatalysts were prepared, in which CoP was used as a noble-metal-free cocatalyst. Using dye Eosin Y (EY) as the sensitizer and triethanolamine (TMA) as the electron donor, the performance of the photocatalytic H2 evolution reaction (HER) under visible light (λ ≥ 420 nm) was investigated. When the loading of CoP is 5 wt%, the CoP(5 wt%)/g-C3N4 composite shows the best photocatalytic HER performance, even better than that of Pt(5 wt%)/g-C3N4. The apparent quantum yield (AQY) achieves 56.3% under 420 nm light irradiation, one of the best values reported for noble-metal-free cocatalysts in the dye-sensitized HER system, and the catalyst also exhibits good stability under 36 h of irradiation. The high activity and stability of CoP(5 wt%)/g-C3N4 are the results of efficient electron transfer among photoexcited EY, g-C3N4 and CoP, and the excellent HER activity of CoP.

One-step preparation of cobalt phosphate at room temperature for effective photocatalytic H2 evolution

Cobalt phosphate materials were prepared in the present work in one step at room temperature using different raw materials and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and N2 gas adsorption. Cobalt phosphates exhibit 3D flower-like structures, and the assembly of nanosheets (petals of the "flowers") of cobalt phosphate prepared with sodium phosphate and cobalt acetate as raw materials (denoted as Co-P(A)) is more incompact than that of cobalt phosphate prepared with diammonium hydrogen phosphate and cobalt nitrate as raw materials (denoted as Co-P(B)) due to the former's mildly basic environment. The cobalt phosphates show relatively high photocatalytic activity for H2 evolution reaction (HER) in the presence of Eosin Y as a sensitizer in an aqueous triethanolamine solution. The activity of Co-P(A) (0.40 mmol h-1 g-1) exceeds that of Co-P(B) (0.19 mmol h-1 g-1), which can be attributed to a more dispersive nanosheet and larger BET-specific surface area of Co-P(A). The mechanisms of photocatalytic HER and the formation of flower-like Co3(PO4)2 were discussed. The present system comprising of only abundant elements contributes toward the development of cost-efficient solar HER to achieve sustainable development.

Non-metal fluorine doping in Ruddlesden–Popper perovskite oxide enables high-efficiency photocatalytic water splitting for hydrogen production

Perovskite oxides have been extensively investigated as catalysts for solar water splitting to generate hydrogen (H2) due to the easily tuned band gap, distinct optical/chemical properties and superior structural/compositional flexibility. Cation doping is widely used to boost the photocatalytic activity of perovskite oxides while the anion doping into the oxygen (O)-site of perovskite oxides is less investigated. Herein, we present a non-metal fluorine (F−) doping strategy to improve the photocatalytic activity of Ruddlesden–Popper Sr2TiO4 perovskites for H2 evolution reaction (HER). By optimizing the F− doping amount in Sr2TiO4−xFx, the highest H2 generation rate of 282 μmol/h/g is achieved by Sr2TiO3.97F0.03 under full-range sunlight illumination (λ ≥ 250 nm), which is 44% larger than that of Sr2TiO4 (195 μmol/h/g). Such enhancement in the photocatalytic HER activity of Sr2TiO3.97F0.03 can be assigned to the increased surface oxygen vacancy amount, suppressed charge carrier recombination, more negative conduction band position as well as well-balanced band gap energy, particle size, and specific surface area induced by the F− doping. Our current study presents a facile and effective strategy for the future design of highly efficient catalysts for solar water splitting.

Dual-Modified Cu2S with MoS2 and Reduced Graphene Oxides as Efficient Photocatalysts for H2 Evolution Reaction

Noble metal-free cocatalysts have drawn great interest in accelerating the catalytic reactions of metal chalcogenide semiconductor photocatalyst. In particular, great efforts have been made on modifying a semiconductor with dual cocatalysts, which show synergistic effect of a fast transfer of exciton and energy simultaneously. Herein, we report the dual-modified Cu2S with MoS2 and reduced graphene oxides (Cu2S-MoS2/rGO). The in situ growth of Cu2S nanoparticles in the presence of MoS2/rGO resulted in high density of nanoscale interfacial contacts among Cu2S nanoparticles, MoS2, and rGO, which is beneficial for reducing the photogenerated electrons’ and holes’ recombination. The Cu2S-MoS2/rGO system also demonstrated stable photocatalytic activity for H2 evolution reaction for the long term.

Comparative studies of photoactivated H2 evolution for nano-needle WO3 films with crystalline 2H-WS2 and amorphous a-MoSx co-catalysts

(Photo)electrocatalytic properties of nanostructured WO3 films used for H2 evolution reaction (HER) were modified by forming hybrid structures containing a crystalline 2H-WS2 and an amorphous a-MoS c phases. For this, respectively, thermochemical treatment of metal oxide films in H2S gas and reaction pulsed laser deposition of molybdenum in H2S were applied. The functional characteristics of the hybrid structures were studied in a three-electrode electrochemical cell in an acid solution under intermittent illumination with a Xe lamp. a-MoSx film deposition caused a more significant improvement in the HER activity of MoSx/WO3 structure compared to that of WS2/WO3 structure. However, WS2/WO3 structures were superior to MoSx/WO3 structures in the efficiency of the photoactivated HER. The factors that could influence the (photo)electrocatalytic behaviour of the created structures were analysed.

Se and O co-insertion induce the transition of MoS2 from 2H to 1T phase for designing high-active electrocatalyst of hydrogen evolution reaction

MoS2 is identified as a potential electrocatalyst for H2 evolution reaction (HER) due to its low cost and robust durability. However, the limited active site and low electrical conductivity severely hinder the practical application of MoS2. To address these issues, we herein propose a Se-insertion engineering strategy to fabricate Se- and O-co-inserted MoS2 (Se-MoS2) microspheres composed of intertwined nanosheets. Se and O co-insertion create abundant S defects on the basal plane of MoS2 and thus increase the number of active sites. Additionally, Se and O co-insertion are apt to induce the transition of MoS2 from 2H to 1T phase (~60% 1T MoS2), thereby exhibiting more excellent electric conductivity (~2 orders larger than that of MoS2). Furthermore, optimized Se-MoS2 not only shows electrocatalytic HER activity (an overpotential of 108 mV at 10 mA cm−2 and a Tafel slope of 47 mV dec–1), also inherits the outstanding electrocatalytic durability of pristine MoS2. Density function theory (DFT) calculations reveal that the excellent HER performance of optimized Se-MoS2 can be explained with Volmer-Heyrovsky mechanism, which is intrinsically attributed to the emergence of new band structures near the Fermi energy level of MoS2, increasing the electrical conductivity and reducing the Gibbs free energy of hydrogen adsorption.

A Synergistic Combination of P‐doped Zn0.5Cd0.5S and CoP for Dual‐Stage Electron Trapping and Its Application in Seawater Splitting

Over the years, researchers have placed increasing focus on extending the application of photocatalytic hydrogen (H2) evolution to seawater. Herein, a photocatalytic system with a unique combination of P‐doped Zn0.5Cd0.5S (pZCS) and noble‐metal‐free CoP is first fabricated to evaluate the synergy between them. The resultant sample achieves a significantly boosted photocatalytic H2 evolution reaction (HER) with a rate of 5488.8 μmol g−1 h−1, which is an almost 50‐fold enhancement from its pristine ZCS counterpart. Impressively, the CoP–pZCS composite also demonstrates overall water splitting where no sacrificial reagent is used, with an H2 evolution rate of 154.6 μmol g−1 h−1. The sample is then tested for its HER activity in seawater, and 3956.0 μmol g−1 h−1 of H2 is acquired. The main factor that contributes to its high performance in seawater despite various distractions coming from the abundance of ions present is the synergistic relation between pZCS and CoP. The midgap state procured through the introduction of the P dopant has excellent electron–hole separating ability, and CoP further serves as an electron sink where the photogenerated electrons can rapidly assemble. Ultimately, the charge carrier recombination within the resultant composite is greatly hindered, thus a spectacular photocatalytic HER in seawater is enabled.

Schottky Junctions with Bi Cocatalyst for Taming Aqueous Phase N2 Reduction toward Enhanced Solar Ammonia Production

Solar‐powered N2 reduction in aqueous solution is becoming a research hotspot for ammonia production. Schottky junctions at the metal/semiconductor interface have been effective to build up a one‐way channel for the delivery of photogenerated electrons toward photoredox reactions. However, their applications for enhancing the aqueous phase reduction of N2 to ammonia have been bottlenecked by the difficulty of N2 activation and the competing H2 evolution reaction (HER) at the metal surface. Herein, the application of Bi with low HER activity as a robust cocatalyst for constructing Schottky‐junction photocatalysts toward N2 reduction to ammonia is reported. The introduction of Bi not only boosts the interfacial electron transfer from excited photocatalysts due to the built‐in Schottky‐junction effect at the Bi/semiconductor interface but also synchronously facilitates the on‐site N2 adsorption and activation toward solar ammonia production. The unidirectional charge transfer to the active site of Bi significantly promotes the photocatalytic N2‐to‐ammonia conversion efficiency by 65 times for BiOBr. In addition, utilizing Bi to enhance the photocatalytic ammonia production can be extended to other semiconductor systems. This work is expected to unlock the promise of engineering Schottky junctions toward high‐efficiency solar N2‐to‐ammonia conversion in aqueous phase.

Vanadium Oxide Clusters Decorated Metallic Cobalt Catalyst for Active Alkaline Hydrogen Evolution

Summary Promoting active and stable H2 evolution reaction (HER) on metallic Fe triad materials is important yet challenging. Here, we report a metallic Co catalyst modulated by vanadium oxide (VOx) clusters (denoted as Co(VOx)) for active alkaline HER activity. Systematic X-ray absorption spectroscopy (XAS) and X-ray crystallography studies verify that VOx clusters endow Co with a highly disordered lattice and downsized particle size. The best Co(VOx) electrode is achieved with an optimal doping level of 3%, which delivers −100 mA cm−2 at an overpotential merely of 178 mV, in contrast to 344 mV and continuous activity decay on pure Co. The lower or higher doping level is unable either to regulate the atomic structure and reduce the H binding or to provide fewer active sites. Density functional theory (DFT) calculations reveal that VOx enables efficient electron transfer from Co to VOx, thus decreasing the H-adsorption on V-Co(001) for enhanced HER.

Unique ternary Cd0.85Zn0.15S@WO3/WS2 core-shell nanorods for highly-efficient photocatalytic H2 evolution under visible-light irradiation

Development of noble-metal-free photocatalysts for efficient solar-powered water-splitting is of great interest yet still challenging to date. In this work, unique ternary Cd0.85Zn0.15S@WO3/WS2 (CZ0.15S@WO3/WS2) core-shell nanorods consisting of amorphous WO3 and few-layered WS2 nanosheets were synthesized through a two-step solvothermal method for the first time. The composition of WO3/WS2 shell is found to vary with the change of W content, which has a significant impact on the photocatalytic property of CZ0.15S@WO3/WS2 toward H2 evolution reaction (HER). Under visible-light irradiation (λ > 420 nm), the optimized CZ0.15S@WO3/WS2 composite (n (WO3): n (WS2) = 3:1) demonstrates a superior HER activity of 76.33 mmol h−1 g−1 (corresponding to an AQY of 23.9% at 420 nm), which can be further remarkably increased to 157.29 mmol h−1 g−1 when the reaction is driven by full Xe-lamp spectrum. The HER capability of CZ0.15S@WO3/WS2 is much better than that of Pt-decorated CZ0.15S and most CdS-based photocatalysts ever reported, due to the notably enhanced charge transfer and separation via the synergistic cooperation of Z-scheme and type-I charge transfer processes. The findings displayed here could inspire new strategies to optimize the charge separation of multi-component photocatalysts for highly-effective solar conversion and utilization.

Interface engineering in CeO2 (1 1 1) facets decorated with CdSe quantum dots for photocatalytic hydrogen evolution

The interfaces of heterostructures have been widely studied in the field of photocatalytic H2 evolution reaction (HER). In the present study, the CdSe QDs/CeO2(111) heterostructures were synthesized by wet chemistry method. The CdSe QDs/CeO2(111)-0.075 showed higher photocatalytic H2 evolution with 283.32 µmol g-1h−1, because of the enhanced light absorbance intensity and edge, lower recombination, higher separation and transfer, as well as longer lifetime of the photogenerated carrier. Density functional theory (DFT) calculations further confirmed that the enhanced HER activity of CdSe QDs/CeO2(111) heterostructures is resulted from a stronger water adsorption, a lower energy barrier of water dissociation and a more optimal free energy of hydrogen adsorption than CdSe and CeO2. The strategy of construction heterostructures provides a promising pathway for enhancing the performance of photocatalytic H2 evolution as well as other catalytic reactions.

Modified Graphitic Carbon Nitride Nanosheets for Efficient Photocatalytic Hydrogen Evolution.

Considerable research efforts have been devoted to develop noble-metal-free cocatalysts coupled with semiconductors for highly efficient photocatalytic H2 evolution as part of the challenge toward solar-to-fuel conversion. Herein, a new cocatalyst with excellent activity in the electrocatalytic H2 evolution reaction (HER) that is based on Co sheathed in N-doped graphitic carbon nanosheets (Co@NC) was fabricated by a surfactant-assisted pyrolysis approach and then coupled with g-C3 N4 nanosheets to construct a 2 D-2 D g-C3 N4 /Co@NC composite photocatalyst by a simple grinding method. As a result of advantages in effective electrocatalytic HER activity, suitable electronic band structure, and rapid interfacial charge transfer brought about by the 2 D-2 D spatial configuration, the g-C3 N4 /Co@NC photocatalyst that contained 4 wt % Co@NC presented a high photocatalytic H2 generation rate of 15.67 μmol h-1 under visible-light irradiation (λ≥400 nm), which was 104.5 times higher than that of pristine g-C3 N4 . The optimum g-C3 N4 /Co@NC photocatalyst showed a high apparent quantum efficiency of 10.82 % at λ=400 nm.

Dye-sensitized black phosphorus nanosheets decorated with Pt cocatalyst for highly efficient photocatalytic hydrogen evolution under visible light

Although black phosphorous (BP) and its derived materials have shown great potential for application in photocatalytic H2 evolution reaction (HER), their HER activity and stability still remains unsatisfied mainly due to the insufficient charge separation, the lack of surface active sites, and the defect-riched nature of BP. Herein, we report that BP nanosheets decorated with in situ grown Pt (BP NSs/Pt) could act as a highly efficient catalyst for photocatalytic H2 evolution in an Erythrosin B (ErB)-sensitized system under visible light irradiation (≥450 nm) in the presence of triethanolamine (TEOA) as sacrificial electron donor. It is found that BP NSs can provide large surface area for the confined growth of Pt nanoparticles with a high dispersion and a reduced size but also stabilize the loaded Pt nanoparticles by covalent bonds at the BP NSs/Pt interfaces. Moreover, BP NSs offer a fast electron transfer pathway to facilitate the photocatalytic HER over in situ grown Pt catalyst. As a result, BP NSs/Pt catalyst exhibits ∼6 times higher H2 evolution activity than free Pt nanoparticles and an apparent quantum yield (AQY) of 0.57% at 500 nm irradiation in ErB-TEOA system. This work indicates the potential of BP NSs as an effective 2D matrix to construct numerous high performance photocatalysts and photocatalytic systems.