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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]

Introducing defect engineering into ZnO/ZnS heterojunction photocatalysts is an effective method to simultaneously improve their visible light performance and photocatalytic efficiency. Herein, a defect‐enriched ZnO/ZnS heterostructure photocatalyst was synthesized through a hydrozincite [Zn5(OH)6(CO3)2] intermediate‐deriving reaction. The mechanism analysis showed that there were interstitial Zn and Zn vacancies in the hydrozincite‐derived ZnO, while S vacancies and interstitial S and Zn vacancies were formed in ZnS components after calcination. These specific defect states endowed visible light response ability to both ZnO and ZnS components in the ZnO/ZnS photocatalysts. Under visible light irradiation, the photocatalytic hydrogen evolution rate of ZnO/ZnS reached 11.68 mmol h−1 g−1, and under simulated sunlight irradiation, the best photocatalytic hydrogen evolution rate could reach 27.94 mmol h−1 g−1, which was much higher than most previous reports. The analysis of energy band structure and photodeposition showed that the photocatalytic reduction sites were mainly on ZnS, and the photocatalytic reaction mainly followed the typical Z‐type mechanism. This work presents a simple and low‐cost method for the preparation of defects‐enriched ZnO/ZnS‐based photocatalytic materials with high photocatalytic activity and stability. [ABSTRACT FROM AUTHOR]

TiO2 has garnered a flourish of interest in the field of energy storage and energy conversion. Herein, a new generation of 3D Ni foam supported in situ grown 1D TiO2 nanoarray (Ni/TiO2) is successfully prepared, through an easy solution‐phase hydrothermal process, and then CdS nanorods branched Ni/TiO2 nanoarrays are fabricated (Ni/TiO2@CdS). Their formation parameters and growth mechanism are carefully studied. Both Ni/TiO2 and Ni/TiO2@CdS monolithic catalysts exhibit advantaged photocatalytic (PC) and photoelectrocatalytic (PEC) water splitting properties compared with that of most previously reported TiO2‐based film photocatalysts. Mechanism investigation reveals that both type II and Z‐scheme charge transport mechanisms coexist in Ni/TiO2@CdS sample, and an additional Z‐scheme charge transfer effect accelerates the photogenerated charge separation and transport efficiency. This study may open a new avenue for the utilization of TiO2‐based film catalysts in a broader field of energy and environmental catalysis areas. [ABSTRACT FROM AUTHOR]

The rational design and construction of cost‐effective nickel‐based phosphide or sulfide (photo)electrocatalysts for hydrogen production from water splitting has sparked a huge investigation surge in recent years. Whereas, nickel phosphides (NixPy) possess more than ten stoichiometric compositions with different crystalline. Constructing NixPy with well crystalline and revealing their intrinsic catalytic mechanism at atomic/molecular levels remains a great challenge. Herein, an easy‐to‐follow phase‐controllable phosphating strategy is first proposed to prepare well crystalline NixPy (Ni3P and Ni12P5) modified CdS@Ni3S2 heterojunction electrocatalysts. It is found that Ni3P modified CdS@Ni3S2 (CdS@Ni3S2/Ni3P) exhibits remarkable stability and bifunctional electrocatalytic activities in both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Density functional theory results suggest that P–Ni sites and P sites in CdS@Ni3S2/Ni3P, respectively, serve as OER and HER active sites during electrocatalytic water splitting processes. Moreover, benefiting from the advantageous photocatalyst@electrocatalyst core@shell structure, CdS@Ni3S2/Ni3P delivers an advantaged photoassisted electrocatalytic water splitting property. The champion electrical to hydrogen and solar to hydrogen energy conversion efficiencies of CdS@Ni3S2/Ni3P, respectively, reach 93.35% and 4.65%. This work will provide a general guidance for synergistically using solar energy and electric energy for large‐scale H2 production from water splitting. [ABSTRACT FROM AUTHOR]

The incorporation of oxygenic groups could remarkably enhance the light absorption and charge separation of graphitic carbon nitride (g‐C3N4). The intrinsic role of oxygenic species on photocatalytic activity in g‐C3N4 has been intensively studied, but it is still not fully explored. Herein, the essential relationships between oxygenic functionalities and the catalytic performance are revealed. Results demonstrate that C−O−C functionality as an electron trap could help to increase the resistance of conduction transfer (Rct) by limiting electrons transfer in CNx. In contrast, N−C−O functionality between different tri‐s‐triazine unites could promote the electrons transfer, leading to a reduced Rct in CNx. The best H2 production rate (3.70 mmol h−1 g−1, 12.76‐fold higher than that of CN) is obtained over CN3, because of the highest N−C−O ratio (rN−C−O). The apparent quantum efficiency (AQE) of CN3 at 405 nm, 420 nm, 450 nm, 500 nm and 550 nm is 33.90 %, 20.88 %, 8.25 %, 3.66 % and 1.01 %, respectively. [ABSTRACT FROM AUTHOR]

To improve the photocorrosion of CdS nanorod arrays (CdS NRAs), we have designed a simple and facile treatment method of in-situ hydrogenation to fabricate CdS@SnS/SnO 2 heterostructure on fluorine-doped tin oxide glass, which is a highly photostable hydrogenated CdS-based film photocatalyst (CdS NRAs-H 2 ). Over a 25-h long time irradiation, the total photocatalytic hydrogen production of hydrogenated CdS NRAs is almost 2.0 times higher than that of un-hydrogenated CdS NRAs. Moreover, the average hydrogen production rate of CdS NRAs-H 2 can steadily maintain at 23.75 μmol cm −2 h −1 with 102% of retention rate after 5 reaction cycles, while they are only 6.13 μmol cm −2 h −1 with 30% of retention rate for un-hydrogenated common CdS NRAs. The photocatalytic mechanism on enhanced activity and stability for hydrogenated CdS NRAs photocatalyst is also investigated and discussed in detail. [ABSTRACT FROM AUTHOR]

Abstract: Reduction is considered to be an effective method to improve the photocatalytic activity of TiO2; however, the underlying relationship between structure and photocatalytic performance has not been adequately unveiled to date. To obtain insights into the effect of structure on photocatalytic activity, two types of reduced TiO2 were prepared from CO (CO‐TiO2) and H2 (H‐TiO2). For H‐TiO2, Ti−H bonds and oxygen vacancies are formed on the surface of H‐TiO2, which results in a more disordered surface lattice. However, for CO‐TiO2, more Ti−OH bonds are formed on the surface and more bulk oxygen vacancies are introduced; the disorder layer of CO‐TiO2 is relatively thin, owing to most surface vacancies being filled by Ti−OH bonds. Under simulated solar irradiation, the photocatalytic H2 evolution rate of CO‐TiO2 reaches 7.17 mmol g−1 h−1, which is 4.14 and 1.50 times those of TiO2 and H‐TiO2, respectively. The photocatalytic degradation rate constant of methyl orange on CO‐TiO2 is 2.45 and 6.39 times those on H‐TiO2 and TiO2. The superior photocatalytic activity of CO‐TiO2 is attributed to the effective separation and transfer of photogenerated electron–hole pairs, due to the synergistic effects of oxygen vacancies and surface Ti−OH bonds. This study reveals the relationship between the photocatalytic properties and structure, and provides a new method to prepare highly active TiO2 for H2 production and environmental treatment. [ABSTRACT FROM AUTHOR]

Homogeneous p-type cobalt (II) oxide (CoO) nanoparticles were successfully deposited on n-type three-dimensional branched TiO nanorod arrays (3D-TiO) through photochemical deposition and thermal decomposition to form a novel CoO/3D-TiO p-n heterojunction nanocomposite. Due to the narrow band gap of CoO nanoparticles (~2.4 eV), the as-synthesized CoO/3D-TiO exhibited an excellent visible light absorption. The amounts of deposited CoO nanoparticles obviously influence the hydrogen production rate in the photoelectrochemical (PEC) water splitting. The as-synthesized CoO/3D-TiO-5 obtains the highest PEC hydrogen production rate of 0.54 mL h cm after five-time CoO deposition cycles (at a potential of 0.0 V vs Ag/AgCl). The photocurrent density of CoO/3D-TiO-5 is 1.68 mA cm, which is ca. 2.5 times greater than that of pure 3D-TiO. The results showed that the formation of internal electrical-field between the CoO/3D-TiO heterojunction, which has a direction from n-type TiO to p-type CoO, facilitated the charge separation and transfer and resulted in a high efficiency and stable PEC activity. [ABSTRACT FROM AUTHOR]

Graphical abstract 2H- and 1T- mixed phase few-layer MoS 2 is prepared by a simple hydrothermal synthesis method for the first time. The designed MoS 2 @TiO 2 catalyst exhibits two times activity of Pt@TiO 2 for photocatalytic H 2 evolution, where the mixed phase MoS 2 as a co-catalyst shows the characteristic of 1 T-MoS 2 like Pt, rather than a semiconductor. Highlights • 1T-phase MoS 2 can be obtained by a facile hydrothermal method for the first time. • The MoS 2 @TiO 2 exhibits two times activity of Pt@TiO 2 for photocatalytic H 2 evolution. • The photo-generated electrons transfer path of MoS 2 @TiO 2 is clearly proven by KPFM. • The mixed phase MoS 2 apparently shows the characteristic of 1 T-MoS 2 like Pt. • MoS 2 here is as a superior to Pt co-catalyst rather than as a semiconductor. Abstract Recently, MoS 2 as an efficient co-catalyst has attracted much attention for photocatalytic water splitting. MoS 2 has two polymorphs: semiconducting phase (2H) and metallic phase (1T). The 2H- and 1T- MoS 2 show different reaction mechanism in photocatalytic H 2 evolution. However, so far, very few experiments have clearly evidenced the electron transfer process between TiO 2 and mixed phase MoS 2. This study for the first time has reported a simple hydrothermal synthesis method to prepare mixed phase few-layer MoS 2 nanosheets coated on TiO 2 nanorod arrays (MoS 2 @TiO 2) with a conductive fluorine-doped tin oxide (FTO) as a substrate. The structure of mixed phase MoS 2 was characterized carefully. The designed MoS 2 @TiO 2 exhibits two times higher activity than Pt@TiO 2 for photocatalytic H 2 evolution. The reliable conclusion that the photo-generated electrons from TiO 2 to MoS 2 nanosheets has clearly been evidenced by photoelectrochemical analyses and in-situ KPFM experiments, and the mixed phase MoS 2 here is a co-catalyst such like Pt rather than as a semiconductor. This study not only presents a series of solid experimental evidences to verify the electrons transfer process and photocatalytic mechanism, but also provides a new method in substituting MoS 2 for noble metal Pt as co-catalyst in high-efficiency photocatalytic water splitting into hydrogen. [ABSTRACT FROM AUTHOR]

The magnesium-lanthanum-hydrogen systems possess the goodish stability and high hydrogen storage capacity, which make them perspective as commercial Mg-based hydrogen storage materials. The exploration of these intriguing properties evolving from small atomic and molecule cluster to bulk phase are, to our knowledge, the longstanding challenge. Here, we perform a theoretical study on the structural and electronic properties of Mg 3 LaH n (9 ≤ n ≤ 20) clusters by using the Crystal Structure AnaLYsis by Particle Swarm Optimization method combined with density functional theory calculations. It is found that Mg 3 LaH 15 is the most stable cluster in the series, with hydrogen storage capacity of 6.6 wt% and adsorption energy of 2.76 eV. The present results offer new insights for the design and synthesis of novel hydrogen storage materials in the future. [Display omitted] • Structural and electronic properties of Mg 3 LaH n (n = 9–20) clusters are studied. • The Mg 3 LaH 15 is the most stable cluster with the HOMO-LUMO gap of 5.19 eV. • The Mg 3 LaH 15 can serve as prospective material for hydrogen storage. [ABSTRACT FROM AUTHOR]

Abstract: A thermodynamic analysis of the oxidative steam reforming of glycerol (OSRG) for hydrogen production has been carried out with Aspen plus TM. The reaction was investigated at ambient pressure within the carbon-to-oxygen (C/O) ratio of 0.5–3.0, steam-to-carbon (S/C) ratio of 0.5–8.0 and temperature of 400–850 °C. Higher C/O and S/C ratios favor the production of hydrogen from glycerol. The highest hydrogen selectivity is obtained at 600–700 °C. To predict the potential technical obstacles in the glycerol reforming process, the OSRG process was compared with oxidative steam reforming of ethanol (OSRE) in terms of hydrogen production, autothermal condition and carbon deposition. The selectivity to hydrogen via OSRG is lower than that via OSRE under identical conditions. To achieve autothermal reforming, higher S/C and C/O ratios are required for reforming of glycerol than for ethanol due to the higher oxygen content in a glycerol molecule. From the viewpoint of thermodynamics, the glycerol reforming is more resistant to the carbon deposition. On the basis of the thermodynamic analysis and the preliminary experimental study, suggestions were proposed to guide the development of the glycerol reforming technique. [Copyright &y& Elsevier]

Abstract: LaMnO3, LaFeO3, LaCoO3 and LaNiO3 perovskite oxides were prepared using combustion method for autothermal reforming of ethanol (ATRE). Fresh, reduced and used catalysts were characterized by XRD, TEM, ethanol-TPD, and H2-TPR. The perovskite-type oxides exhibit moderate activities in the ATRE reaction. Well dispersed Ni particles on lanthanum oxide species were obtained by reducing the LaNiO3 sample. It favors the dehydrogenation, decomposition of ethanol/acetaldehyde, methane reforming and water gas shift reactions, thus leads to good activity and H2 selectivity in ATRE reaction. Typically, 3.2 H2 molecules per ethanol molecule were produced at EtOH:H2O:O2 =1:2:0.98 and GHSV=4×105 h−1. A comparison between LaNiO3 derived and impregnated Ni/La2O3 shows that the LaNiO3 derived sample favored the dispersion of Ni, which increased the activity and the resistance to coke deposition. [Copyright &y& Elsevier]

Abstract: La2O3-supported Ir catalyst was prepared by wetness impregnation method for the oxidative steam reforming of ethanol (OSRE). Fresh, reduced, and used catalysts were characterized by N2 adsorption, H2 chemisorption, XRD, FT-IR, TEM, and XPS. La2O3 would transform into hexagonal La2O2CO3 during OSRE, which suppress coking effectively. Reduced Ir metal can interplay with La2O2CO3 to form Ir-doped La2O2CO3. It dynamically forms and decomposes to release active Ir nanoparticles, thereby preventing the catalyst from sintering and affording high dispersion of Ir/La2O3 catalysts at elevated temperatures. By introducing ultrasonic-assisted impregnation method during the preparation of a catalyst, the surface Ir concentration was significantly improved, while the in situ dispersion effect inhibited Ir from sintering. The Ir/La2O3 catalyst prepared by the ultrasonic-assisted impregnation method is highly active and stable for the OSRE reaction, in which the Ir crystallite size was maintained at 3.2nm after 100h on stream at 650°C and metal loading was high up to 9wt%. [Copyright &y& Elsevier]

The substitution of noble metal platinum catalyst is one of the important research contents for sustainable development and is also the key to the practical application of photoelectrochemical (PEC) hydrogen production. In this work, we loaded the 1T-2H mixed phase MoS 2 on the hydrogenated anatase/rutile heterophase TiO 2 (A-H-RTNA) by hydrothermal method to prepare a new MoS 2 /A-H-RTNA electrode material. The prepared material exhibited higher carrier density, lower PL intensity and higher conductivity than Pt/A-H-RTNA because 1T-MoS 2 has more active sites and lower charge transfer resistance than Pt. With the bias voltage of −0.4 V, the optimized 16MoS 2 /A-H-RTNA as photocathode shows the largest PEC hydrogen production rate of 1840 mmol m−2 h−1, which is 2.9 and 2.2 times higher than those of A-H-RTNA (625 mmol m−2 h−1) and Pt/A-H-RTNA (848 mmol m−2 h−1), respectively. We innovatively used the prepared 16MoS 2 /A-H-RTNA film as counter electrode instead of Pt electrode to construct a PEC system without any noble-metal. The result demonstrates that the noble-metal-free MoS 2 loaded on TiO 2 electrode as counter electrode has 75% PEC activity of noble metal Pt electrode. This study develops a PEC method for hydrogen evolution, which no longer depends on precious metal platinum as cathode. A new MoS 2 /A-H-RTNA electrode with 2 times higher hydrogen production rate than Pt/A-H-RTNA was prepared by loading MoS 2 on the hydrogenated TiO 2 heterostructure film. The prepared MoS 2 /A-H-RTNA film was used as photocathode instead of Pt electrode to construct an innovative and efficient PEC system without any noble-metal. Image 1 • MoS 2 is loaded on hydrogenated anatase/rutile TiO 2 heterophase structure (A-H-RTNA). • MoS 2 /A-H-RTNA has low charge transfer resistance for photoelectrochemical (PEC) reaction. • MoS 2 /A-H-RTNA as photocathode has 2 times higher PEC hydrogen production rate than Pt/A-H-RTNA. • MoS 2 /A-H-RTNA film can be used as photocathode instead of Pt electrode. • An innovative and efficient PEC system without any noble metal is constructed. [ABSTRACT FROM AUTHOR]

A facile method of loading CoS x nanosheet onto CdS nanorod has been designed, and the prepared CdS-CoS x composite catalyst exhibited significantly improved performance for photocatalytic hydrogen evolution compared with CdS catalyst. This composite catalyst was also used as a photoanode for photoelectrochemical (PEC) hydrogen production. The hydrogen production rate reached 168.6 μmol cm−2 h−1 (37.77 L m−2 h−1) under the simulated solar light, which is 2.7 times that of CdS and the same as that of CdS–Pt. In addition, in the Na 2 S–Na 2 SO 3 system for PEC hydrogen production, an abnormal relationship between photocurrent and the hydrogen production yield was found. By designing a series of experiments, the photocatalytic and photoelectrochemical characteristics for hydrogen production were reasonably revealed for the first time. In this work, the prepared structured catalyst is easy to be recycled, and CoS x can replace precious metal Pt, showing a promising application. Image 1 • CoS x as co-catalyst is loaded on CdS nanorod by a facile method. • CdS-CoS x has good activity and stability for photoelectrochemical (PEC) reaction. • PEC activity of CdS-CoS x as photoanode for H 2 production is the same as that of CdS–Pt. • An abnormal relationship between photocurrent and hydrogen production is found. • The reaction network in Na 2 S–Na 2 SO 3 system for PEC H 2 production is proposed. [ABSTRACT FROM AUTHOR]

In photocatalytic field, it is a significant challenge to synthesize cocatalyst with high performance, noble-metal free and facile methods to recycle. Herein, carbon layer coated Fe 3 C (Fe 3 C@C) nanoparticles were prepared by one-step method and for the first time utilized as highly efficient cocatalysts for improving visible-light-driven hydrogen evolution activity of g-C 3 N 4. The photocatalytic hydrogen evolution rate of optimal Fe 3 C@C/g-C 3 N 4 was about 27.2 times of bare g-C 3 N 4 samples. Furthermore, the Fe 3 C@C/g-C 3 N 4 composite catalyst showed excellent stability and reusability. The apparent quantum yield (AQY) of the optimized FeC@C/g- C 3 N 4 reaches 0.501% and 0.124% at 400 nm and 420 nm, respectively. The AQY of the FeC@C/g- C 3 N 4 is 26.2 times higher than that of g-C 3 N 4 at 400 nm Fe 3 C@C has an extraordinary cocatalytic effect for g-C 3 N 4 photocatalytic hydrogen evolution mainly due to three aspects: Firstly, the Fe 3 C acts as a trap to lure electrons because of its lower Fermi energy level and higher conductivity, which can increase the hydrogen production activity by trapping the photogenerated electrons produced by g-C 3 N 4 ; Secondly, the coated carbon layer can provide chemical protection for Fe 3 C nanoparticles and promote the transfer of photogenic electrons, thus further improving the efficiency and stability of photocatalytic hydrogen production; Thirdly, the strong magnetic property of Fe 3 C@C nanoparticles gives Fe 3 C@C/g-C 3 N 4 photocatalysts the advantages of low cost and high recovery efficiency. It is believed that this work provides a new strategy and possibility for the application of photocatalytic hydrogen production. • Carbon layer coated Fe 3 C (Fe 3 C@C) nanoparticles are prepared by one-step method. • The Fe 3 C@C as cocatalyst for boosting photocatalytic performance of g-C 3 N 4. • Fe 3 C@C/g-C 3 N 4 photocatalyst possesses strong magnetism and is easy to be recycled. • The Fe 3 C can efficiently trap the photogenerated electrons generated by g-C 3 N 4. • The carbon layer can provide chemical protection for Fe 3 C nanoparticles. [ABSTRACT FROM AUTHOR]

Rationally designing and constructing high-efficiency composite photocatalysts with advantaged structure play significant roles in efficient photoelectrochemical or photocatalytic solar energy conversion systems. In this work, contrasted to the typical CdS nanoparticles modified TiO 2 nanomaterials, a novel rods-on-rods CdS branched TiO 2 nanoarrays have been firstly synthesized by a simple in-situ growth strategy. The controllable surface-to-volume ratios of CdS nanorods, combining with their original intimate connection with TiO 2 nanorods, not only enhance both the solar light scattering and absorption performance, but also effectively promote the separation and transportation of photogenerated charges. In addition, this structure ensures adequate exposure of CdS to the electrolyte, thus increasing the photooxidation reactive sites. In a typical photoelectrochemical water splitting system, the maximum photon-to-current conversion efficiency reaches 34% under 450 nm wavelength light irradiation, and the best applied bias photo to current conversion efficiency of the samples runs up to 1.5% under solar light irradiation. Interestingly, by using a 'cocatalysts-separated-loading' strategy, the novel CdS branched TiO 2 nanoarrays films can be further employed as self-bias photocatalytic films, which also obtain an enhanced photocatalytic hydrogen production activity and stability. • Rods-on-rods CdS directly branched TiO 2 nanoarrays were originally synthesized. • CdS nanobranches enhance the solar light scattering and absorption properties. • In-situ growth and intimate connection enhance charges separation and transport. • CdS branches provide adequate active sites for photooxidation reaction. • A 'cocatalysts-separated-loading' strategy was proposed to improve H 2 production. [ABSTRACT FROM AUTHOR]

• Cu/Ni alloy foam supported CdS@Ni 3 S 2 /Cu 2 S nanorod arrays were fabricated for the first time. • Both electrocatalysis (EC) and photo-assisted electrocatalysis (PA-EC) water splitting properties were investigated. • Highest electrical-to-hydrogen (η ETH) and solar-to-hydrogen (η STH) efficiency reaches to be 97% and 8.9%, respectively. • CdS@Ni 3 S 2 /Cu 2 S possesses considerable durability of more than 50 h under both light and dark conditions. • The underling PA-EC water splitting mechanism of CdS@Ni 3 S 2 /Cu 2 S was investigated. Photo-assisted electrocatalysis (PA-EC) water splitting technology, which combines photocatalysis and electrocatalysis, has gradually become a research hotspot in the production of green hydrogen energy. Herein, for the first time, novel Cu/Ni alloy foam self-supporting CdS@Ni 3 S 2 /Cu 2 S core–shell nanorod arrays are prepared by a simple one-pot hydrothermal process. The CdS@Ni 3 S 2 /Cu 2 S exhibits both excellent electrocatalytic and photo-assisted electrocatalytic water splitting performance. During the long-time PA-EC water splitting test, the average H 2 production rate reaches 568.1 μmol cm-2h−1, which is about 1.8 times higher than that of 284.1 μmol cm-2h−1 under dark condition. In addition, the electrical-to-hydrogen (η ETH) and solar-to-hydrogen (η STH) conversion efficiency reaches to be 97% and 8.9%, respectively. Mechanism investigation results show that during EC water splitting process, CdS nanorods mainly play as support material for the electroactive Ni 3 S 2 and Cu 2 S. While, in the PA-EC process, CdS, Cu 2 S and Ni 3 S 2 were photoexcited by light irradiation, and just as the presence of additional photogenerated electrons and holes, CdS@Ni 3 S 2 /Cu 2 S exhibits boosted photo-assisted water splitting properties. This work provides a new strategy for the construction of bifunctional photocatalysts combined with electrocatalysts in photo-assisted electrocatalysis overall water splitting. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A feasible technology that coupled the SESR of glycerol with CH 4 reforming of carbonates was proposed. • The carbonates was directly converted to syngas by reacting with CH 4. • Hydrogen purity of 98.53% was achieved from SESR of glycerol over 10Ni-CA2.8 catalyst. • CH 4 conversion was high up to 95.3% during the CH 4 reforming of carbonates. Abstract The sorption enhanced steam reforming (SESR) produces high-purity hydrogen and capture CO 2 in the form of carbonates, allowing for controllable CO 2 storage or utilization. However, the decarbonation of carbonates at temperatures high up to 800–900 °C makes the SESR process and the subsequent CO 2 utilization energy-intensive. Herein, we report the feasibility coupling the SESR of glycerol with CH 4 reforming of carbonates, which combines the decarbonation with CO 2 utilization to simplify the technology and avoid the energy-consuming temperature swing. A high-efficiency bi-functional Ni-CaO-Ca 12 Al 14 O 33 catalyst was proposed to this process. The catalyst was derived from a Ni-Ca-Al hydrotalcite-like (HTl) material to achieve homogeneous mixing of Ni, CaO and Ca 12 Al 14 O 33 which were active metal, sorbent and a spacer to prevent CaO sintering. Thanks to the high activity and stability of Ni-CaO-Ca 12 Al 14 O 33 catalysts, 98.53% hydrogen-enriched gas could be obtained in SESR of glycerol, and the high CH 4 conversion (95.3%) and H 2 /CO molar ratio (<2) suitable for further Fisher-Tropsch synthesis were achieved during the CH 4 reforming reaction. Meanwhile, Ca 12 Al 14 O 33 as a spacer had provided a stability for ten cycles. Our results highlight the significance of process intensification and high-efficiency bi-functional catalysts for the hydrogen production with low carbon emissions. [ABSTRACT FROM AUTHOR]

Photocatalytic water splitting into hydrogen is a very attractive and desirable technology to realize sustainable and renewable green energy conversion. Up to now, many research results have confirmed that cocatalyst such as Pt is essential for a high efficiency photocatalytic H 2 evolution system. In a traditional view, the cocatalyst should be closely combined with the photocatalyst to achieve a high H 2 or O 2 photo-productive rate. In this work, an unusual point has been put forward that the suitable loading position of cocatalyst Pt for film-type TiO 2 catalyst is on the bare Fluorine-doped tin oxide (FTO) substrate instead of on the surface of TiO 2 in the electrolyte solutions. Especially, in acidic electrolyte, the hydrogen production rate of this new designed catalyst with Pt loaded on FTO (TiO 2 -Pt/FTO) reaches 2.4 times that of the common catalyst with Pt loaded on TiO 2 (Pt/TiO 2 -FTO). According to the experiment results, it is supposed that this loading way of cocatalyst on the substrate can construct a self-bias photocatalytic electrochemical cell system, drive electrolyte ions' movement directionally, and obtain high photocatalytic H 2 production efficiency. The universality of this innovation has been verified by CdS and CdS@TiO 2 film-type catalysts. This study provides a new guide in exploring high-efficiency film-type photocatalytic system for water splitting into hydrogen in the electrolyte solution. [ABSTRACT FROM AUTHOR]

CuO 1− x cluster-modified TiO 2 (CuO 1− x /TiO 2 ) photocatalysts were prepared by an in-situ photoreduction deposition of Cu on TiO 2 powder support using copper acetate as a Cu source. The prepared samples without any Pt co-catalyst present an especially high photocatalytic H 2 -evolution activity under solar light irradiation with 5% glycerol as sacrificial agent. The optimal CuO 1− x /TiO 2 catalyst with only 1 wt% CuO 1− x exhibits a high activity of 1725 μmol h −1 g −1 for H 2 evolution, which reaches 120 times that of TiO 2 . The high photocatalytic activity of H 2 production is attributed to the highly dispersed CuO 1− x nano clusters on the surface of the TiO 2 . In addition, Pt/CuO 1− x /TiO 2 was also prepared by loading Pt on CuO 1− x /TiO 2 sample, and its photocatalytic hydrogen evolution activity is enhanced 1.8 times compared with that of Pt/TiO 2 for overall water splitting reaction under solar light, demonstrating that a small amount CuO 1− x wondrously improves the photocatalytic activity of Pt/TiO 2 for overall water splitting reaction. This paper reports an economic and simple approach to prepare a photocatalyst with high hydrogen-production activity. [ABSTRACT FROM AUTHOR]

Catalytic conversion efficiency from aqueous formaldehyde (HCHO) into hydrogen (H 2) on non-noble metal catalysts is much lower than that on noble metal catalysts. Modulating the electronic properties of non-noble metal-based catalysts has been demonstrated an effective approach to improve their catalytic performance. In this work, assisted by light irradiation, photoinduced electron-rich surface structure was designed for the thermal catalytic conversion of HCHO to H 2. In detail, a heterostructure of CuNi@C composited with TiO 2 was obtained, in which TiO 2 can be photoexcited under light irradiation to provide photoinduced electrons onto the surface of CuNi@C. On the photoinduced electron-rich surface of the CuNi@C/TiO 2 heterostructure, the H 2 evolution rate reached 254.65 mmol h−1 g−1, which was 1.88 times higher than that on CuNi@C. It is worth noting that the catalytic HCHO conversion efficiency outperforms the current reported non-noble metal catalysts for this reaction. Combining with density functional theory (DFT) calculations and experimental studies, it is concluded that the electron-rich CuNi@C dramatically reduced the activation energies of the dissociation of HCHO and H 2 O and accelerated the overall reaction rate. • CuNi@C alloy is composited with TiO 2 to form a CuNi@C/TiO 2 heterostructure. • The CuNi@C/TiO 2 exhibits high efficiency HCHO reforming H 2 evolution. • Photoexcited TiO 2 enhances the electron density on the surface of CuNi@C. • The electron-rich CuNi@C dramatically reduced the activation energy of HCHO to H 2. [ABSTRACT FROM AUTHOR]

The concentration of CO in the high-purity hydrogen from sorption-enhanced steam reforming (SESR) processes is usually too high to be directly used in fuel cells. Herein, we report a production of fuel-cell grade H 2 with <30 ppm CO through SESR of glycerol (SESRG), a by-product of biodiesel manufacture. High purity H 2 can be produced by employing a catalyst-sorbent hybrid material composed of Ni as catalyst, CaO as CO 2 sorbent and Ca 12 Al 14 O 33 as spacer. By introducing copper as promoter, the performance of the bi-functional catalyst could be modified to produce a 97.15 vol% purity of H 2 with 28 ppm CO. With an optimized Ni/Cu ratio, the 7.5Ni–7.5Cu catalyst shows the excellent stability for producing about 97% H 2 with <30 ppm CO for ten cycles. The characterizations and model reaction tests indicate that copper can affect CO, CO 2 hydrogenation and water gas shift reaction to adjust the performance of SESRG reaction. The results presented here show the promise of tuning the catalyst composition for achieving high quality H 2 through SESR processes. [ABSTRACT FROM AUTHOR]

High-purity hydrogen is usually produced through increasing inventory of CO 2 sorbents in the sorption-enhanced steam reforming (SESR) processes. Herein, we report an effective approach to the high-purity hydrogen from SESR of glycerol by modifying a bi-functional Co-CaO catalyst to suppress the methanation side-reaction, which significantly consumes hydrogen. Bimetallic Co-based catalysts containing Ni, Cu and Zn were prepared from hydrotalcite-like materials as precursors. Over the 10Co-5Cu catalyst, the highest hydrogen purity up to 99.27% could be reached. Through temperature programmed desorption, oxidation, hydrogenation and CO disproportionation reactions, it was revealed that copper suppressed the formation of active coke species and CO methanation, thus alleviated the hydrogen consumption to allow for the production of high-purity hydrogen through SESR of glycerol. [ABSTRACT FROM AUTHOR]

In recent years, tremendous efforts have been devoted to develop new photocatalyst with wide spectrum response for H 2 generation from water or aqueous solution. In this work, CdS nanoparticles (NPs) have been immobilized on hydrogenated three-dimensional (3D) branched TiO 2 nanorod arrays, resulting in a highly efficient photocatalyst, i.e, CdS/H-3D-TiO 2 . In addition, electrochemical reduction of H + ion is identified as a limiting step in the photocatalytic generation of H 2 at this catalyst, while here a Pt wired photocatalysis system (CdS/H-3D-TiO 2 /Pt-wire) is designed to overcome this barrier. Without the application of potential bias, visible light photocatalytic hydrogen production rate of CdS/H-3D-TiO 2 /Pt-wire is 18.42 μmol cm −2 h −1 , which is 11.2 times that of CdS/H-3D-TiO 2 without Pt (1.64 μmol cm −2 h −1 ). The Pt wire acts as an electron super highway between the FTO substrate and H + ions to evacuate the generated electrons to H + ions and catalyze the reduction reaction and consequently generate H 2 gas. This work successfully offers a novel direction for dramatic improvement in H 2 generation efficiency in photocatalysis field. [ABSTRACT FROM AUTHOR]

Two kinds of branched hydrogenated TiO 2 nanorod arrays, i.e., hydrogenated TiO 2 nanorod supported hydrogenated TiO 2 branch arrays (H-BTNRs) and hydrogenated TiO 2 nanorod supported unhydrogenated TiO 2 branch arrays (B/H-TNRs), have been successfully designed and prepared by a facile approach. Under simulated solar light, the prepared B/H-TNRs have the highest hydrogen evolution rate of 6.65 μmol cm −2 h −1 , which is 4.7 and 2.4 times those of hydrogenated TiO 2 nanorod arrays (H-TNRs) and H-BTNRs, respectively. This study indicates that the heterostructure design of the unhydrogenated TiO 2 branch and hydrogenated TiO 2 nanorod promotes the separation of charge carries on the interface and enhances photocatalytic hydrogen evolution. [ABSTRACT FROM AUTHOR]

Currently, photovoltaic-electrocatalytic (PV-EC) water splitting possesses the paramount solar-to-hydrogen energy conversion efficiency (STH) among various solar energy conversion and storage systems. However, three principal factors including noble metal-based electrodes, expensive photovoltaic cell, and concentrated solar light systems largely limited the large-scale practicable implementation of this strategy. In this work, CoNi layered-double-hydroxide (LDH) nanosheets arrays, CoFe 2 O 4 nanoparticles and CoNi LDH/CoFe 2 O 4 composite electrodes are controllably synthesized on Ni foam, Fe foam and NiFe alloy foam, respectively, via a facile hydrothermal process. Experiments and density-functional theory calculation results demonstrate that CoFe 2 O 4 and CoFe 2 O 4 /CoNi LDH electrodes are suitable to be used as highly efficient, stable, and freestanding water-splitting electro anode and cathode, respectively. Significantly, combining with a commercial silicon-based solar cell, the assembled PV-EC water splitting device receives 12.7% STH under natural sunlight irradiation. This work provides a typical demonstration and valuable guidelines for practical large-scale solar-to-hydrogen generation using an inexpensive PV-EC technology. [Display omitted] • CoFe 2 O 4 and CoNi LDH/CoFe 2 O 4 composite electrodes are controllably prepared. • An efficient and stable two-electrode system for water-splitting is developed. • Natural light driven photovoltaic-electrolysis reaches 12.7% efficiency. • The active sites and electrolysis water splitting mechanism are determined. [ABSTRACT FROM AUTHOR]

Sorption enhanced steam reforming of glycerol (SESRG) enables the production of high-purity hydrogen from the by-product of biodiesel manufacture. To this end, highly stable catalysts and CO 2 sorbents are desired to overcome the performance degradation at high temperatures. Herein, a bi-functional catalyst, Co–CaO–Ca 12 Al 14 O 33 , is proposed to couple CO 2 sorption and catalytic reforming of glycerol on nanoscale. The catalyst was derived from a Co–Ca–Al hydrotalcite-like (HTl) material to achieve homogeneous mixing of Co, CaO and Ca 12 Al 14 O 33 as a spacer to prevent CaO sintering. At Ca/Al of 2.8, the highest catalytic activity and sorption capability were reached. Over the optimized catalyst, high-purity H 2 of 96.4% was produced at 525 °C through SESRG during the pre-breakthrough stage. High stability of the bi-functional catalyst was demonstrated by a cyclic SESRG-calcination operation up to 50 times. The role of Ca 12 Al 14 O 33 as spacer of CaO was proved by XRD and TEM-EDS analysis. In addition, it was found that Ca 3 Co 2 O 6 , which is formed during the calcination stage and is reduced during the SESRG to release Co catalysts, may act as a dynamic reservoir of Co catalysts to prevent Co from sintering, leading to an excellent SESRG activity and stability. [ABSTRACT FROM AUTHOR]

The hierarchical Ag NPs with a bimodal size distribution were auto-decorated on the surface of rice-like N-TiO 2 (named h-Ag/N-TiO 2 ) by semiconductor-metal double excitation process under solar light irradiation. The photoinduced growth process of self-assembled h-Ag/N-TiO 2 and its photocatalytic mechanism of photo-splitting ethanol into hydrogen have been discussed in detail. The synthesized h-Ag/N-TiO 2 as a plasmonic photocatalyst for photo-splitting ethanol exhibited a higher hydrogen production rate (4.7 mmol h −1 g −1 ) than Ag NPs universally loaded N-TiO 2 (3.4 mmol h −1 g −1 ) and pure N-TiO 2 (2.1 mmol h −1 g −1 ). This work presents a reversed photo-induced synthesis strategy to design a stable Ag-TiO 2 plasmonic photocatalyst with high photocatalytic efficiency under solar light. A better understanding of this solar light induced self-assembled process for Ag-TiO 2 is crucial in developing metal-semiconductor system for solar energy materials. [ABSTRACT FROM AUTHOR]

MXenes, 2D transition metal carbides/nitrides, have been demonstrated as promising platform for fabricating novel composites with interesting photo-/electrochemical properties. It is desirable to gain insights into the reactivity of MXenes, enabling the controllable transformation of MXenes. Here, a one-pot hydrothermal synthesis method of MXene-based photocatalyst is validated by harnessing the reducibility of Nb 2 CT x MXene. The origin of reducibility of Nb 2 CT x during the hydrothermal oxidation process was demonstrated as the active hydrogen produced from the water splitting in the presence of Nb 2 CT x , which reduced Ru3+ in situ to Ru nanoparticles on Nb 2 O 5 nanowires derived from Nb 2 CT x. Compared with the traditional photo-deposition method, the chemical valance of the noble metal Ru/Pt obtained by the one-pot synthesis method was closer to the metal state, which reduced the charge transfer resistance by 82.5%. It led to the photocatalytic hydrogen production of 10.11 mmol·h−1·g−1 with 41.25% apparent quantum yield at 313 nm. [Display omitted] • Harnessing hydrothermal reactions over Nb 2 C allows for a one-pot synthesis of Ru/Nb 2 O 5 @Nb 2 C. • Hydrogen released from water is the origin of reducibility of MXene. • One-pot synthesis reduces the carrier transfer resistance by 82.5% compared to photo-deposition. • Ru/Nb 2 O 5 @Nb 2 C achieves a quantum efficiency of 41.25% for water splitting. [ABSTRACT FROM AUTHOR]

Abstract: The influence of the electrodeposition potential on the morphology of Cu2O/TiO2 nanotube arrays (Cu2O/TNA) and their visible-light-driven photocatalytic activity for hydrogen evolution have been investigated for the first time in this work. The photocatalytic hydrogen evolution rate of the as-prepared Cu2O/TNA at the deposition potential of −0.8 V was about 42.4 times that of the pure TNA under visible light irradiation. This work demonstrated a feasible and simple electrodeposition method to fabricate an effective and recyclable visible-light-driven photocatalyst for hydrogen evolution. [Copyright &y& Elsevier]

• CdS/ZnS has high photocatalytic activity and excellent stability for H 2 production. • The existence of zinc vacancy is verified by the photoluminescence emissions. • Kelvin probe force microscopy intuitively proves the electron transfer direction. • Zinc vacancy induces CdS/ZnS to form Z-scheme structure. An integrated Z-scheme hybrid structure is constructed with the zinc vacancy mediated CdS/ZnS for hydrogen production with superior stability. The distribution of surface photovoltage (SPV) intuitively proved the efficient transfer of photogenerated electrons from the CdS to the ZnS, forming a Z-scheme photocatalytic system. [Display omitted] Photocatalytic hydrogen evolution reaction (HER) has been considered as a promising technology to provide a better energy supply and address the environmental concerns. CdS/ZnS hybrid composite structure has been proved an ideal system for photocatalytic hydrogen production. It is commonly referred to as a type-I semiconductor heterostructure. After an in-depth research work, it is found that the CdS/ZnS has a type II structure or direct Z-scheme structure due to the defect energy levels of zinc vacancies. In this work, the zinc vacancy mediated CdS/ZnS core/shell hybrid structure on FTO was synthesized. The best hydrogen production rates of CdS/ZnS reached 6.27 µmol cm−2 h−1 and 137 μmol cm−2 h−1 in the photocatalytic and photoelectrochemical (PEC) systems. More importantly, it exhibited excellent stability of 5 cycles in 25 h. The photoluminescence emissions spectra peaking in the visible light region verified the existence of zinc vacancies. Kelvin probe force microscopy (KPFM) proved the efficient transfer of photogenerated electrons from the CdS to the ZnS, thus forming a Z-scheme photocatalytic system. [ABSTRACT FROM AUTHOR]

Abstract: Cu(OH)2/TNAs photocatalyst was prepared by loading Cu(OH)2 nanoparticles on TiO2 nanotube arrays (TNAs) using a chemical bath deposition method. The amount of Cu(OH)2 loaded on the arrays was controlled by the repeated deposition times. The prepared catalyst was used to generate hydrogen under simulated solar light irradiation, and the results demonstrated that the hydrogen yield of Cu(OH)2/TNAs was 20.3 times that of the pure TNAs. Furthermore, the photocatalytic efficiency for hydrogen production decreased only 5.8% after five cycles, indicating that Cu(OH)2/TNAs photocatalyst showed excellent stability and reusability. This work presents an applicable and facile method to fabricate a highly active and stable photocatalyst for hydrogen production. [Copyright &y& Elsevier]

Abstract: The superfluous glycerol derived from biodiesel production can be a low-cost feedstock for hydrogen production via reforming technology. In this work, a La2O3 supported iridium catalyst was employed to catalyze the oxidative steam reforming of glycerol (OSRG) for hydrogen production, in the range of S/C ratio of 1–3, C/O ratio of 0.75–1 and 550–750°C. The catalyst was modified with Na, Mg and Ca to optimize the catalytic performance in OSRG reaction. It was found that Ca is promising in promoting Ir/La2O3 catalyst for OSRG, offering excellent activity, hydrogen selectivity and stability. By combining multiple techniques, i.e. XRD, FTIR, Raman, XPS, H2-TPR, CO2-TPD and HRTEM, the Ca modified Ir/La2O3 catalyst was characterized to understand the role of Ca promoter. Multi-functions of Ca were demonstrated, including inducing structural defects of La2O2CO3, endowing the catalyst strong basicity and tuning the metal–support interaction, which make the catalyst highly resistant to coking and sintering, therefore performing excellent long-term stability for 100h. [Copyright &y& Elsevier]

Abstract: An auto-thermal micro-reformer was fabricated to produce hydrogen from ethanol–water mixture. The reformer employed an Ir/La2O3 catalyst supported on ceramic foam. The effect of ceramic foam materials, including Al2O3, SiC and ZrO2, on the performance of the micro-reformer was investigated. The optimal catalytic activity and hydrogen selectivity were achieved over the ZrO2 loaded catalyst. The strong interaction between the ceramic ZrO2 foam and the catalyst results in the reduction of the Ir particle size, which significantly improves the ethanol reforming activity, hydrogen selectivity and catalyst stability. The resistance to vibration and the stability of the reformer during the repeated start-up and shut-down (RSS) operation were studied. The reformer can be auto-thermally started-up within ∼90s. During a continuous operation, the reformer produces 3.1mol H2 per mol ethanol with a hydrogen flow rate of ∼0.41m3/h, which can feed a H2–O2 fuel cell at the level of ∼765W. These results demonstrate the potential application of the proposed reformer in the portable distributed hydrogen source. [Copyright &y& Elsevier]

Abstract: An equilibrium model of steam methane reforming coupled with in-situ membrane separation for hydrogen production was developed. The model employed Sievert’s Law for membrane separation and minimum Gibbs energy model for reactions. The reforming and separation processes were coupled by the mass balance. The model assumed a continuously stirred tank reactor for the fluidized bed hydrodynamics. The model predictions for a typical case were compared with those from the model of Ye et al. which assumed a plug flow for bed hydrodynamics. The model predictions show satisfactory agreement with experimental data in the literatures. The influences of reactor pressure, temperature, steam to carbon ratio, and permeate side hydrogen partial pressure on solid carbon, NHx and NOx formation were studied using the model. [ABSTRACT FROM AUTHOR]

Abstract: A methanol steam micro-reformer was constructed to produce hydrogen (H2) for polymer electrolyte membrane fuel cells (PEMFCs), in which a Cu/Zn/Al/Zr catalyst was supported on metal foams. To optimize the performance of the micro-reformer, the effect of metal foams on the catalytic property was investigated in details, including catalytic activity, carbon monoxide (CO) selectivity and mechanical properties. It was found that the strong interaction between the Ni or FeCrAl metal foams and catalyst resulted in the low activity for water gas shift (WGS) reaction, therefore, increased the CO selectivity significantly. As a general principle, it was proposed that the metal materials poisoning or reducing the reforming activity should be excluded in the design of micro-reformers. [Copyright &y& Elsevier]

[Display omitted] • 98.5% hydrogen is produced from sorption-enhanced steam reforming of iso -octane. • 90% hydrogen yield was achieved for 10 SESRI-decarbonation cycles. • The SESRI reaction lowered the reaction temperature by >200 °C. Liquid hydrocarbon fuels produced from fossil resources are potential portable hydrogen carriers given their sufficient supply and extensively available infrastructures. However, effective approaches to hydrogen production from liquid hydrocarbons fuels are still insufficient, especially in the context of carbon emission control. Here, we report that high-purity hydrogen is produced with minimized CO 2 emissions via the sorption enhanced steam reforming of iso -octane (SESRI), a model compound of gasoline. With a Pd-promoted Ni-CaO-Ca 12 Al 14 O 33 bi-functional catalyst, 98.0% purity of hydrogen with 90% hydrogen yield was obtained for 10 consecutive SESRI-decarbonation cycles. XRD, SEM, and TEM techniques revealed that structural and morphological properties of the bi-functional catalyst were preserved after 10 cycles. Raman spectroscopy, CO 2 -TPO and TGA further demonstrated that coke formation was substantially suppressed in the presence of Pd, which played a key role in maintaining stable SESRI performance in terms of hydrogen production. Our results provide a feasible alternative for production of high-purity hydrogen from liquid fossil fuels, thereby being prospective in meeting the demand of portable hydrogen on short to medium term basis. [ABSTRACT FROM AUTHOR]

CdS@Ni 3 S 2 photoelectrode exhibits both excellent electron-to-hydrogen and photo-to-hydrogen conversion efficiency in an innovative P-EC overall water splitting process. • CdS@Ni 3 S 2 photoelectrode realized photo-assisted electrochemical overall water splitting. • The photo-assisted electrochemical and pure electrochemical water splitting were contrastively investigated. • The intrinsic functions of photocatalyst and electrocatalyst in CdS@Ni 3 S 2 photoelectrode were revealed. • Both of electrical-to-hydrogen (η ETH) and solar-to-hydrogen (η STH) conversion efficiency were investigated. CdS-based photoanodes have attracted tremendous attention for photoelectrochemical (PEC) water splitting. Combining CdS with state-of-the-art transition-metal electrocatalyst is an advantages strategy to increase both the photoactivity and photostability of CdS. It is worth noting that in this study, with considering the original electrocatalytic (EC) water decomposition function of the electrocatalyst, we provide further understanding on how the photocatalyst affect the electrocatalyst. By using an advantageous photo-assisted electrochemical (P-EC) overall water splitting strategy, it is found that CdS@Ni 3 S 2 core–shell nanoarrays is an efficient photoanode for synergistically photo-electrical catalytic hydrogen production. The intrinsic EC, PEC and P-EC properties of CdS photocatalyst and Ni 3 S 2 electrocatalyst in CdS@Ni 3 S 2 photoelectrode are comparably studied. In a six-hour long time period, the average P-EC water splitting H 2 production rate of CdS@Ni 3 S 2 is 178.1 μmol∙cm−2∙h−1, which reaches 123.3% times of its neat electrochemical (EC) water splitting (144.4 μmol∙cm−2∙h−1), corresponding to a 2.22% solar-to-hydrogen (STH) efficiency. This work provides an important research foundation for the development of high-efficiency photo-electrical catalytic system. [ABSTRACT FROM AUTHOR]

• The density functional theory calculations reveal highly active phase structure of MoSe 2. • A volcano-like correlation of MoSe 2 structure and photocatalytic activity is presented. • The mixed phase MoSe 2 is prepared controllably as an excellent cocatalyst for H 2 production. • The photogenerated electron-hole transfer mechanism is confirmed. It is still of great practical significance to exploring low-cost and earth-abundant alternative materials as cocatalyst for photocatalytic hydrogen evolution. The density functional theory (DFT) calculations indicated that both the basal plane and the edge of mixed phase MoSe 2 provide the highly catalytic activity for hydrogen evolution reaction (HER). Based on this, the mixed phase MoSe 2 was designed as an excellent cocatalyst because of superior ability to receive electrons and optimal active sites for HER. Herein, the ternary (1T/2H) MoSe 2 /CdS-CdSe structure was prepared by a simple hydrothermal method. The hydrazine monohydrate as reductant helps to control 1T phase content of MoSe 2 , and the maximum content of 1T phase MoSe 2 reaches 66.5%. The results showed that the H 2 evolution rate of the optimized MoSe 2 /CdS-CdSe reached a value of 24.34 mmol h−1 g−1 and a high quantum efficiency (QE) of 28.5% at 500 nm. A volcano-like correlation has been presented for the first time to illustrate the effect of structures of MoSe 2 on photocatalytic activity for HER, which provides the direction of design of MoSe 2 cocatalyst. [ABSTRACT FROM AUTHOR]