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Ta3N5 is a promising material for photocatalytic hydrogen production from water because of its suitable band structure for both solar energy collection and overall water splitting, while its application is restricted by severe charge recombination as well as non‐equilibrium redox capabilities. Herein, atomic‐scale N‐doped NaTaO3@Ta3N5 (NNaTaO3@Ta3N5) core‐shell cubes prepared by nitridation of cubic NaTaO3 are reported. The core‐shell heterojunction cubes present efficient and stoichiometric evolution of H2 and O2 from photocatalytic overall water splitting, with a quantum efficiency of 2.18% at 550 nm without any cocatalyst. The success relies on the Ta3N5 shell having a thickness of only ≈5 nm which enables increased lifetimes of the photogenerated charges. Moreover, the core‐shell heterojunction shows a type‐I band alignment that can steer smooth charge flow from NNaTaO3 to Ta3N5, particularly with the assistance of the shared communal Ta atoms at the interface. This efficiency can be further improved to 6.28% by in situ deposition of a Rh@Cr2O3 core‐shell cocatalyst, which is among the highest reported values over Ta3N5‐based photocatalyst. This study offers a promising pathway for the construction of well‐defined heterojunctions with manipulated charge transfer behavior for photocatalytic overall water splitting. [ABSTRACT FROM AUTHOR]

Z-scheme photocatalysis provides a promising solution to photocatalytic solar water splitting, yet restricted by inferior interfacial charge transfer. Here, we demonstrate a Z-scheme composite photocatalyst made of Fe 2 O 3 , a carbon layer, and g-C 3 N 4 that can achieve efficient hydrogen generation from solar water decomposition. The success relies on in-situ preparation of core-shell Fe 2 O 3 @C structure at the surface of g-C 3 N 4. Carbon as an intermediate layer thus acts as a bridge that significantly accelerates the migration of photogenerated electrons from Fe 2 O 3 conduction band to g-C 3 N 4 valence band. As a result, the highest rate of H 2 generation reaches 5.26 mmol h−1g−1. This activity is approximately 33-time greater than that achieved over pristine g-C 3 N 4 and about 4-time larger than that obtained over a Fe 2 O 3 /g-C 3 N 4 heterojunction without internal carbon layer. This work explicates the potential insight of the composite and paves a promising way to engineer the charge transfer behavior. [Display omitted] • A heterojunction made of Fe 2 O 3 , g-C 3 N 4 , and a carbon interlayer is obtained. • Photocatalytic water splitting proceeds via a Z-scheme mechanism over the catalyst. • The intermediate carbon layer acts as a channel for efficient electron transfer. • The photocatalytic activity for H 2 production is significantly improved. [ABSTRACT FROM AUTHOR]

Distinguishing the contributions from localized surface plasmon resonance (LSPR)induced photothermal effect is a significant challenge in the study of solar hydrogen production. Herein, a well‐defined one‐dimensional Cu/TiO2 heterostructure with Cu size of 3–6 nm is designed to address such issue. Cu nanoparticles present notable LSPR absorption from visible to near‐infrared light, while no hydrogen is produced in the presence of simulated light with λ ≥ 700 nm. Interestingly, a remarkable improvement of hydrogen evolution under full‐spectrum light was observed which is almost twice of that under only ultraviolet–visible light irradiation, implying the critical yet auxiliary role of LSPR‐induced photothermal effect in promoting photocatalytic performance. Significantly, a notable reduction of the apparent activation energy and strengthened charge separation efficiency are observed due to the increased local temperature of catalyst surface caused by the plasmon‐induced photothermal effect. The kinetic and thermodynamic changes should be responsible for the enhanced hydrogen production. [ABSTRACT FROM AUTHOR]

Developing high‐efficiency yet low‐cost photocatalyst for solar hydrogen production by avoiding the use of noble metals has received adequate interest but remains a great challenge to date. This work reports a seed‐mediated hydrothermal approach for the synthesis of NiS2 quantum dots (QDs) anchored two‐dimensional graphitic carbon nitride (g‐C3N4) nanosheets. This hybrid shows superior performance toward photocatalytic H2 evolution from water. The highest H2 evolution rate reaches 4.841 μmol h−1, with an apparent quantum efficiency of 2 % at 425 nm, which is even much higher than that of Pt‐modified g‐C3N4 photocatalyst (2.865 μmol h−1). Moreover, the composite presents good stability without notable activity decay after several cycled tests. It is found that NiS2 QDs are essential for this improvement. These small nanoclusters not only benefit rapid and vectorial diffusion of photogenerated electrons from g‐C3N4 to NiS2, but also promote H2 evolution by decreasing the thermodynamic overpotential for proton reduction. This work thus marks an important step toward designing good‐performance and low‐cost photocatalytic materials for solar H2 conversion. Quantum on the dot: NiS2 quantum dot successfully anchored on the surface of g‐C3N4 promotes both vectorial charge diffusion and rapid proton reduction during photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

The feasibility of solar hydrogen production from water has long relied on the activity and stability of a given photocatalyst. In this study, using Cd x Zn 1-x S as a model photocatalyst, we demonstrated that the activity and stability of chalcogenide photocatalyst could be readily adjusted by changing the reaction conditions, including sacrificial reagents, reaction temperature. Our results showed that the combined use of proper sacrificial reagents play a key role against photocorrosion. Under optimized reaction conditions, the photocatalyst remained stable for more than 500 h. Under irradiation from a simulated sun light (light intensity: 789.92 W/m 2 ), the average rate of hydrogen evolution reached 1.43 mmol/h with an energy conversion efficiency from solar to hydrogen of 6.22%. [ABSTRACT FROM AUTHOR]

Most photocatalytic reactions are conducted near room temperature. In this work, we explored photothermal hydrogen production in a carefully designed photo reactor with external heating. Light sources of different wavelength bands were investigated. Formic acid was used as sacrificial regent to study the photothermal hydrogen production activity. Interestingly, the photothermal reaction is not the simple sum of the photo and thermal effects but their synergetic coupling and at 90°C it is 8.1 and 4.2 times of that under photo or thermal conditions alone. With thermal excitation, the bound electrons in Pt can be excited which can easily overcome the energy barrier between Pt and lowest unoccupied molecular orbital of the adsorbed reactants. Activation of the substrate itself by light is also found to be crucial to trigger such photothermal reaction. It is therefore different from traditional plasma resonance induced photothermal reaction where long wavelength IR light is more preferred. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2916-2925, 2017 [ABSTRACT FROM AUTHOR]

Abstract: A series of CdS and CdS/CNTs photocatalysts were successfully prepared by hydrothermal method and they were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–visible optical absorption spectra (UV–Vis), etc. By studying their photocatalytic properties, it is found that, for CdS, photocatalysts prepared in appropriate alkaline environment presented higher hydrogen production activity, reaching 794.6 μmol h−1 g−1; the photocatalytic activity of CdS was obviously enhanced by combining it with CNTs via a special two-step hydrothermal method, and the corresponding hydrogen production rate reached 1.771 mmol h−1 g−1; the photocatalytic activity was further improved by loading co-catalyst NiS, achieving 12.13 mmol h−1 g−1. [Copyright &y& Elsevier]

The article discuses a research on determination of photo catalytic Hydrogen gas production activity using a multichannel system. It says that photo catalytic hydrogen is produced from water under visible range of light over a semiconductor. It mentions that newly designed catalysts are not exactly evaluated and tested due to lack of rapid screening technologies for photo catalytic activity analysis.

Abstract: A series of Mn2+ doped CdS photocatalysts were prepared by a co-precipitation method and characterized by XRD, DRS, TEM, and XPS techniques. While the band gap, crystal phase and the morphology of CdS nanocrystal were not found to be affected noticeably by Mn2+ doping, there was an optimal Mn2+ doping content of wt 0.5% where the hydrogen production was more than doubled compared to pure CdS. Calculations of density functional theory (DFT) with plane waves and pseudopotentials were used to characterize the doping effect of Mn in cubic CdS. It is assumed that Mn2+ serving as shallow trapping sites can separate e−/h+ pairs at surface of nanosized CdS, so as to greatly reduce their surface recombination and which in turn leads to improved hydrogen yield. [Copyright &y& Elsevier]

Abstract: Hydrogen production under visible light by photocatalytic reforming of glucose over an oxide solid solution photocatalyst BixY1−xVO4 (BYV) was demonstrated for the first time. It was found that a certain amount of Y doping would promote the transition of BiVO4 from monoclinic to tetragonal phase and finally lead to the formation of tetragonal BYV solid solution. BYV with a B/Y ratio of 1:1 showed the highest activity for hydrogen production. The amount of photoproduced hydrogen lowered after several hours of reaction. However, when the gas product was replaced with N2 atmosphere, hydrogen production recovered. It is supposed that the generated CO2 might participate in the redox reaction and in some way inhibit the hydrogen production. Therefore, for photocatalytic reforming of glucose, removal of gas product in time is indispensable. [ABSTRACT FROM AUTHOR]

Abstract: Decahedral Cu2WS4 was synthesized by a facile hydrothermal method and employed as photocatalyst for photocatalytic hydrogen production for the first time. The hydrothermal method avoids the traditional use of H2S for the preparation of such chalcogenide, which guarantees an environmental-friendly process. The properties of the Cu2WS4 samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–Vis reflectance spectra, etc. The results showed that the decahedral Cu2WS4 possessed a band gap of ca. 2.1ev. The photocatalyst was demonstrated to be very active under visible light for hydrogen production. Especially, Cu2WS4 synthesized at 200 °C for 72 h showed the highest activity with the apparent quantum yield of 11% at 425 nm. The correlation between the preparation parameters and the photocatalytic properties were investigated. It was expected this first report of W-based chalcogenide photocatalyst would add to the photocatalyst group and lead to the finding of new photocatalyst with much higher activity. [ABSTRACT FROM AUTHOR]

Abstract: A novel catalyst-fixed way is present. And two series of novel CdS-incorporated special glass composite photocatalysts working under visible light were successfully prepared in this way by a two-step thermal sulfidation procedure for the use of catalyst-fixed system. One was by a high temperature way, and the other was by a low temperature way. The composite photocatalysts with different content of CdS prepared by the methods were found to show a good activity for the decomposition of water under visible light. The highest rate of H2 revolution is 1549μmol/(hgCdS) with wt1%-Pt loaded. The composites prepared by high and low temperature were characterized by X-ray diffraction (XRD), diffuse reflectance UV–vis spectra and scanning electron microscopy (SEM). The as-prepared photocatalysts exhibited different photochemical and photophysical properties for the combined way between glass-base and CdS. The photochemical and photophysical properties were very important in the catalyst-fixed system used for large-scale hydrogen production. [Copyright &y& Elsevier]

We report a photocatalytic system that utilizes Cd 0.5 Zn 0.5 S nanotwins decorated with various Ni-based co-catalysts for solar-driven hydrogen production through lignocellulose reformation. In this noble-metal-free system, Ni(OH) 2 emerges as the most effective Ni form in enhancing the photocatalytic evolution of H 2. By optimizing the composition with 3 wt% Ni(OH) 2 loading, we achieved the highest activity, with the hydrogen production rates of 7.00 mmol g−1 h−1 and 1.97 mmol g−1 h−1 from α-cellulose and waste straw photoreforming, respectively. This optimized composition exhibited the highest quantum efficiency of 7.68%. In principle, the lower potential of Ni2+/Ni compared to the conduction band of Cd 0.5 Zn 0.5 S facilitates the transfer of electrons from the conduction band of Cd 0.5 Zn 0.5 S to Ni(OH) 2. Specifically, during the photocatalytic reaction, a fraction of surface Ni(OH) 2 is reduced to Ni. The in-situ formed Ni clusters, along with the Ni(OH) 2 , enhance the separation photogenerated electrons and facilitate their transfer to H+, leading to significantly improved photocatalytic activity. This work not only provides an effective strategy for developing more efficient photocatalysts, but also offers a direct means of harnessing clean energy from abundant waste biomass on Earth. • Ni(OH) 2 /Ni atoms or clusters can serve as co-catalysts enhance the hydrogen production activity of Cd 0.5 Zn 0.5 S. • The cellulose/lignocellulose photoreforming system exhibits exceptional H 2 production efficiency. • The photothermal effect of the Ni(OH) 2 /Cd 0.5 Zn 0.5 S photocatalyst enhances the reaction activity. [ABSTRACT FROM AUTHOR]

Shape-controlled synthesis of semiconductor nanocrystals enables fine manipulation over their physicochemical properties. In this paper, unique Cd 0.9 Zn 0.1 S tetrapod nanostructures consisting of two different polymorphisms, i.e. , wurtzite and zinc blende, were successfully synthesized via a simple ethylenediamine-assisted solvothermal route. It is found that the temperature determines the formation of the zinc blende-structured seeds, while the ethylenediamine facilitates the subsequent preferential growth of the wurtzite phase arms. Furthermore, the tetrapods, characterized by a type-II staggered band alignment, have shown enhanced photocatalytic performance for H 2 generation from an aqueous solution containing electron donors under visible light irradiation, in comparison to the nanocrystals with distinct morphologies. Our results indicate that coupling different polymorphisms in a nanocrystal may be advantageous for photocatalytic proton reduction over single-crystal photocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: Na2Ti2O4(OH)2 nanotubes were obtained by hydrothermal reaction of TiO2 with concentrated NaOH solution. CdS nanoparticles were then decorated on Na2Ti2O4(OH)2 nanotubes through partial ion-exchange method. The composite photocatalysts were characterized by X-ray diffraction (XRD), ultraviolet–visible spectra (UV–vis), transmission electron microscope (TEM), etc. The results showed that CdS nanoparticles of 5–6nm were anchored on the surface of the Na2Ti2O4(OH)2 nanotubes. Under irradiation of visible light (λ ≥430nm), the prepared CdS/Na2Ti2O4(OH)2 showed high photoactivity for hydrogen production. [Copyright &y& Elsevier]

Abstract: Ni2+ doped Cd1−x Zn x S microsphere photocatalysts were prepared by a new hydrothermal method. Experimental results showed that the doped Ni2+ can not only affect the crystal structure and morphology of Cd1−x Zn x S photocatalysts, but also greatly improve its photocatalytic activity. It was found that 0.1wt% Ni2+ doped Cd0.1Zn0.9S photocatalyst showed the highest activity with the apparent quantum yield of 15.9% at 420nm. The reason for the positive effects of Ni2+ was discussed. [Copyright &y& Elsevier]

Abstract Solar-driven photocatalytic water splitting for hydrogen production has emerged as one of the foremost scientific issues. However, the efficient, low-cost, and large-scale operable system is still missing. Photocatalytic water splitting has multiple processes that involve light absorption, charge excitation and transfer, mass transfer, and chemical reaction, making it extremely complicated and challenging. Herein, we review the whole-process photocatalytic water splitting from two kinds of "flow": energy flow and mass flow. The energy flow represents transmission and conversion of solar energy through the concentrator, reactor, reaction solution, and photocatalyst. The mass flow refers to transfer of reactants and products in the gas-liquid-solid multiphase environment. For the first time, we clearly describe the energy flow and mass flow in photocatalytic water splitting from multiple spatiotemporal scales, and point out that the low efficiencies of photocatalytic water splitting are attributed to obstacles in energy flow and mass flow, as well as non-coupling and mismatching of energy flow and mass flow. The mechanistic insights learned from this perspective indicate that, in addition to the material optimization, the scientific and engineered design of sunlight collection, interfacial reaction, and mass transfer is of great significance. Graphical abstract Image 1032150 Highlights • Energy flow and mass flow in photocatalytic water splitting are presented. • Obstacles of photocatalytic water splitting are disclosed. • Energy losses in the whole process of photocatalytic water splitting are examined. • Integration of science and engineering is crucial to photocatalytic water splitting. [ABSTRACT FROM AUTHOR]

In this paper, a direct solar photocatalytic water splitting system with surface uniform concentrators (SUCs) is designed. Parameters influencing hydrogen production rates and energy conversion, viz. sacrificial agent concentration, catalyst concentration and circulation speed, are analyzed under typical days. It is found that the system with SUCs has better performances with higher sacrificial agent, higher catalyst concentration and lower speed: double and triple concentration of the sacrificial agent will improve the energy conversion efficiency by 4.52% and 19.35%, respectively; double and triple the photocatalyst concentration will improve the energy conversion efficiency by 81.32% and 200.00%, respectively; energy conversion efficiency under valve-half-closed and the valve-closed conditions are improve by 21.82% and 118.18% comparing with the valve-open condition. [ABSTRACT FROM AUTHOR]

• Solvothermal processed melem is crucial for tailoring carbon nitride structure. • Nitrogen defects and few-layer nanosheet are simultaneously formed in carbon nitride. • DCNS-120 has optimal properties by combining nitrogen defect and nanosheet structure. • DCNS-120 shows 33-folds increase compared to BCN for photocatalytic H 2 production. Carbon nitride nanosheets have shown a great promise for photocatalytic water splitting among numerous photocatalysts due to the versatile advantages. The crucial issues of the weak visible-light absorption and the separation of photo-generated carrier remain a matter of serious concern. Herein, we report a facile calcination-solvothermal-calcination method to prepare nitrogen-deficient carbon nitride nanosheets (DCNS) for the first time, which leads to the simultaneous introduction of nitrogen defects and formation of a fragmented few-layer nanosheet structure. The fragmented few-layer nanosheet structure is known to possess a high specific surface area and abundant interfacial reaction sites, contributing to the rapid consumption of photo-generated carrier. The nitrogen defects are responsible for further boosting the photocatalytic performance by regulating the band structure and optical properties as well as improving the separation efficiency of photo-generated carrier. The optimized DCNS-120 delivers a superior H 2 production rate of 5375 μmol·g−1·h−1, considerably higher than that of bulk carbon nitride (164 μmol·g−1·h−1). We anticipate that this work may pave a new pathway to engineering carbon nitride with a matched structure to achieve the desired efficient photocatalytic H 2 production under visible-light irradiation. [ABSTRACT FROM AUTHOR]

• Pd nanocubes integrate on the surface of STO nanocubes at [100] orientation. • Lattice-oriented contact at the interface contributes to fluent charge transfer. • An appropriate Schottky barrier is achieved over smaller Pd nanocubes. • Integration of smaller Pd nanocubes gives better photocatalytic activity. Semiconductor-metal hybrids have been extensively studied for solar-to-hydrogen conversion. Delicate control on surface of cocatalysts and primary photocatalysts and interface therein can remarkably improve the photocatalytic efficiency. Herein, taking size-controlled Pd nanocubes and SrTiO 3 (STO) nanocubes as models, the integration of Pd nanocubes on STO nanocubes (Pd/STO) surface was achieved via an in-situ growth method. The composite photocatalyst presents significant enhancement toward photocatalytic hydrogen production compared to the similar counterpart prepared by simple mechanical self-assembly of Pd and STO, as well as to the pristine STO. The highest hydrogen evolution rate reaches 0.44 mmol h−1 g−1. The success relies on the lattice-oriented growth of Pd nanocubes on STO nanocubes for rapid charge separation from STO to Pd, and accelerated energy and mass exchange on surface of Pd. We believed that the strategy can provide a general guidance to develop more surface and interface-modified metal-semiconductor hybrid systems for hydrogen production. [ABSTRACT FROM AUTHOR]