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Charge transfer in a semiconductor is crucial for photocatalytic pure water splitting. Herein, we construct a series of P-doped- g -C 3 N 4 /Fe 2 P/red-P (PCN/Fe 2 P/RP) ternary composite by in-situ phosphorization of a Fe 2 O 3 @C/ g -C 3 N 4 heterojunction. The as-prepared composite show substantially improved photocatalytic activity toward pure water splitting under visible light irradiation without adding any noble metal. The optimized composite containing 15 wt% Fe 2 P presents the best activity, with the H 2 production rate of 429 µmol g−1 h−1, which is 107 and 39 times higher than that of pristine g-C 3 N 4 and P doped g -C 3 N 4 (PCN), respectively. This noble-metal-free photocatalyst presents a solar-to-hydrogen conversion efficiency of about 0.2% for pure water splitting. It is found that water splitting proceeds via a two-electron pathway with simultaneous production of H 2 and H 2 O 2. The improvement relies on the formation of intermediate Fe 2 P for rapid Z-scheme electron transfer from the midgap state of PCN to the valence band of RP. This work provides a versatile method for fabricating noble-metal-free photocatalyst with controlled charge transfer behavior for efficient photocatalytic pure water splitting. [Display omitted] • Efficient P-doped- g -C 3 N 4 /Fe 2 P/red-P photocatalyst is successfully prepared. • Photocatalytic pure water splitting is achieved by two-election Z-scheme mechanism. • Fe 2 P acts as an intermediate layer for rapid Z-scheme electron transfer. • Solar-to-hydrogen conversion efficiency of the composite is about 0.2%. [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]

Graphical abstract Highlights • Ultrathin TiO 2 shell was coated on chalcogenide nanorod as a protecting layer. • The synthesis relies on kinetic control for layer-by-layer deposition of TiO 2. • The heterostructure enables superior activity and stability of solar H 2 evolution. • Charge transfer is controlled by type-II band alignment and tunneling effect. Abstract It has been a subject of intensive research on avoiding photocorrosion of sulfide photocatalysts while retaining their activity for visible-light-driven photocatalysis. Herein, using Cd 0.9 Zn 0.1 S (CZS) nanorod as an example, we report an effective strategy based upon conformal coating of an ultrathin pinhole-free TiO 2 shell, with controllable thickness from 2 to 7 nm, on the nanorod as protecting layer. The synthesis relies on the use of a syringe pump for kinetic control, by which, TiO 2 can grow on the surface of CZS in a layer-by-layer mode. The core–shell heterostructures were found with excellent photocatalytic performance toward solar hydrogen production from a Na 2 S-Na 2 SO 3 aqueous solution. The reaction can stably proceed for 200 h without notable decay of the hydrogen evolution rate. A volcano-type relationship between the mass activity and the shell thickness was gained either in the presence of a cocatalyst or not. The heterostructure with a shell thickness of 2 nm presented the highest H 2 -evolution activity with a quantum efficiency of 19%. However, the one with a shell thickness of 7 nm, instead, was found to be more active, with a quantum efficiency reaching 44%, when 1 wt% NiS x cocatalyst was introduced. It is believed that photogenerated electrons transfer from CZS to TiO 2 , while the holes vanish via quantum-tunneling-induced recombination with the electrons. This work suggests that sulfide photocatalysts with desirable efficiency and corrosion resistance could be achieved by introducing conformal atomic TiO 2 layers. [ABSTRACT FROM AUTHOR]

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]

Comprehensive Summary: Heterojunction design in a two‐dimensional (2D) fashion has been deemed beneficial for improving the photocatalytic activity of g‐C3N4 because of the promoted interfacial charge transfer, yet still facing challenges. Herein, we construct a novel 2D/2D Cu3P nanosheet/P‐doped g‐C3N4 (PCN) nanosheet heterojunction photocatalyst (PCN/Cu3P) through a simple in‐situ phosphorization treatment of 2D/2D CuS/g‐C3N4 composite for photocatalytic H2 evolution. We demonstrate that the 2D lamellar structure of both CuS and g‐C3N4 could be well reserved in the phosphorization process, while CuS and g‐C3N4 in‐situ transformed into Cu3P and PCN, respectively, leading to the formation of PCN/Cu3P tight 2D/2D heterojunction. Owing to the large contact area provided by intimate face‐to‐face 2D/2D structure, the PCN/Cu3P photocatalyst exhibits significantly enhanced charge separation efficiency, thus achieving a boosted visible‐light‐driven photocatalytic behavior. The highest rate for H2 evolution reaches 5.12 μmol·h–1, nearly 24 times and 368 times higher than that of pristine PCN and g‐C3N4, respectively. This work represents an excellent example in elaborately constructing g‐C3N4‐based 2D/2D heterostructure and could be extended to other photocatalyst/co‐catalyst system. [ABSTRACT FROM AUTHOR]

[Display omitted] • A 2D/2D gC 3 N 4 /MoS 2 van der Waals heterojunction photocatalyst was prepared by a novel one-step method. • The type II band arrangement promotes an increase in photogenerated carrier concentration and separation of photogenerated charge carriers. • The in-situ formed heterojunction interface between gC 3 N 4 and MoS 2 boosts H 2 evolution by 3 times. Two-dimensional (2D) heterostructures have proven their efficiency in separating charges. Herein, a gC 3 N 4 /MoS 2 (CN/MoS 2) photocatalyst, in the form of 2D/2D van der Waals heterojunction with a type-II band alignment, was synthesized using a novel one-step method. The resulting in-situ formed heterojunction interface enhances electron transfer from gC 3 N 4 to MoS 2. The CN/MoS 2 photocatalyst exhibits exceptional activity in generating hydrogen from water under simulated solar light. Its hydrogen production rate was 1285 μmol/h/g, which was approximately 3 times higher compared to gC 3 N 4. This superiority is due to a significant increase in photogenerated carrier density and efficient charge separation facilitated by the type-II heterojunction. This study demonstrates a straightforward one-step approach for synthesizing 2D/2D composite photocatalysts, highlighting the effective synergy between different 2D materials in promoting hydrogen generation. [ABSTRACT FROM AUTHOR]

Artificial photosynthesis, in which solar energy drives CO2 to produce hydrocarbon fuels, is considered an effective way to solve the increasingly serious energy crisis and mitigate the greenhouse effect. Herein, layered porous Ru‐loaded and La‐doped g‐C3N4 nanosheets (Ru‐LGCNs) were prepared by one‐step calcination, followed by in situ photoreduction deposition of Ru. The layered Ru‐LGCN showed excellent photocatalytic CO2 reformation of methane performance under visible light, and the generation rates of CO, CH3CH3, CH3OH and CH3CH(OH)CH3 were 133, 154, 251 and 133 μmol h−1 g−1, respectively. The reason for the enhanced photocatalytic activity of Ru‐LGCN is the synergistic effect of bimetallic Ru and La. It is worth noting that the doped La can provide a good channel for charge transfer between LGCNs and CO2. This change in the charge behavior of the transport path is beneficial to break the C=O bonds on the active site La and generate methyl radicals on Ru, resulting in the generation of C2+ hydrocarbons. [ABSTRACT FROM AUTHOR]

• TiO 2 -graphene-Ta 3 N 5 can be fabricated by ultrasonic-hydrothermal method. • Graphene at the interface contributes to fluent charge transfer. • Improved photocatalytic activity is achieved via a Z-scheme mechanism. • Photocatalytic pure water splitting is experimentally demonstrated. Titanium dioxide (TiO 2)-based photocatalysts are a class of hottest materials in solar water splitting, while limited achievements have been gained to date due to its broad band-gap only responding in UV region and sluggish charge transfer. Here, we reported a ternary TiO 2 -graphene-Ta 3 N 5 hybrid photocatalyst synthesized via an ultrasonic-hydrothermal method. Compared with pristine TiO 2 and Ta 3 N 5 , the prepared TiO 2 -graphene-Ta 3 N 5 present remarkably enhanced photocatalytic pure water splitting behavior with an optimal H 2 -evolution rate of 180 μmol h−1 g−1. In conjunction with systematic characterizations, we demonstrated the boosted photocatalytic performance is ascribed to both improved visible light utilization and charge transfer behavior. Particularly, it is found that water splitting is achieved through a Z-scheme mechanism, in which the two-dimensional lamellar graphene served as a bridge accelerating the electron transfer from TiO 2 to Ta 3 N 5. This work opens avenues to design efficient TiO 2 -based photocatalyst by embedding conducting layer for rapid electron transfer during solar-fuel conversion. Graphiocal Abstract [Display omitted] [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]

• A core-shell p -type GIZON homojunction photocatalyst is prepared. • The homojunction shows an ideal type-I band alignment. • An intermediate band nearby the Fermi level of the shell promotes charge transfer. • Photocatalytic overall water splitting with an AQY of 3.5% is achieved. Direct overall water splitting via photocatalysis provides a potential pathway for solar energy conversion. The essential section is to develop efficient and stable photocatalysts, yet with limited success to date. Here a novel p -type gallium indium zinc oxynitride homojunction photocatalyst with core-shell structure is reported, which exhibits H 2 and O 2 evolution rates of 603 and 274 μmol h−1 g−1 with an apparent quantum efficiency of 3.5% at 430 nm from overall pure water splitting. Precise characterizations and DFT calculations reveal that the excellent photocatalytic performance is ascribed to the facilitated charge transfer contributed by the ideal type-I band alignment between GaInZnON core and GaInON shell, combined with the intermediate level formed nearby the Fermi level of GaInON shell. Our work offers insight into the development of facile synthesis of core-shell structure photocatalysts towards efficient solar-driven overall water splitting. [ABSTRACT FROM AUTHOR]