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Charge recombination severely restricts the photocatalytic efficiencies of materials. Loading cocatalysts on the surface of host photocatalysts is a promising strategy for charge separation, which, however, suffers from the large Schottky barrier at the cocatalyst/host interface. Herein, a series of Pt/PbTiO3 compounds were constructed as a proof-of-concept utilizing the piezoelectric field of PbTiO3 under acoustic vibrations to modulate the height of the interfacial Schottky barrier. These hybrid systems achieved highly efficient piezo-photocatalytic H2 evolution under simultaneous ultrasonication and light illumination. The manipulation of the height of the Schottky barrier by the piezoelectric effect was validated by the I–V characteristics collected from conductive AFM. It is proposed that the acoustic-wave-induced piezoelectric field increased the electron flow from PbTiO3 to Pt over the modulated Schottky barrier, which promoted the spatial separation of photo-generated charge carriers and consequently enhanced the H2 evolution. These findings will extend the fundamental understanding of the synergistic piezo-photocatalysis mechanism and provide a new opportunity toward the rational design of novel materials systems for clean energy conversion. [ABSTRACT FROM AUTHOR]

A series of well-defined 1D/2D Zn 1- x Cd x S/D-ZnS(en) 0.5 hybrids are fabricated via an one-pot synthesis method. The resulting composites exhibit enhanced visible-light-driven photoactivities for H 2 production from water in the presence of sacrificial reagents. The optimized Zn 0.41 Cd 0.59 S/D-ZnS(en) 0.5 hybrid shows the extremely high H 2 evolution rate of 463.6 μmol H −1 per 30 mg under visible light irradiation (λ > 420 nm), without any cocatalysts. The highest H 2 production rate presents 826-fold and 24-fold enhancement compared to pristine D-ZnS(en) 0.5 and CdS, respectively. The corresponding apparent quantum yield (AQY) at 440 nm reaches up to 49.95%. The dramatically improved photocatalytic performance could be attributed to the effective interfacial and interior carriers separation. The former is based on the perfect Zn 0.41 Cd 0.59 S/D-ZnS(en) 0.5 heterojunctions with well-matched lattice and band structure, which is obtained by collaborative optimization of composition regulation and defect mediation. While the latter is achieved by low dimension control on the basis of the unique electronic behavior in low-dimensional materials. Besides, the stability of Zn 0.41 Cd 0.59 S/D-ZnS(en) 0.5 heterostructure is also investigated. Several possible causes of slight deactivation are proposed, which mainly includes the weakened interfacial contact, partial ethylenediamine (en) ligands dissociation or substitution by H 2 O, OH − and S 2− , repair of S vacancies and partial oxidation of Cd-S bonds. It may provide theoretic guidance for further designing high-stability photocatalysts. In addition, the optimized hybrid can be used at ambient pressure and under natural sunlight illumination, and the synthesis method is facile, economic and short-period. Thus our proposed system is highly attractive for large scale energy applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • CdS-based core–shell structure was synthesized via one-step cation exchange reaction. • Rationally designed orthogonal field could efficient promotes the carriers separation. • Z-scheme charge transfer can selectively draw internal holes out of the material. • The photo-corrosion is effectively suppressed in this photocatalytic system. Sluggish photogenerated carrier separation and serious photo-corrosion restrict the application of CdS-based materials in the field of photocatalysis. Herein, rationally designed orthogonal field which consists of axial polarized internal electric field (PIEF) and radial internal electric field (IEF) is realized in CdS-based core–shell heterojunction. The axial PIEF could drive efficient separation of electron-hole pairs and the radial IEF could alleviate the accumulation of carriers in the end of nanorods. Furthermore, the radial IEF provides a selective bulk holes transmission channel and consumes in the Z-scheme, which can effectively alleviate the aggregation of holes in bulk phase and interface. Impressively, two IEFs in CdS@Mo-doped CdS core–shell structures synergistically enhance the separation efficiency of carriers and inhibit the photo-corrosion of materials, and the exceptional hydrogen evolution rate of 11.23 mmol·g−1·h−1 is obtained which is approximately 11 times than that of pure CdS. This work discloses a new route for enhance CdS-based photocatalytic activity by in-situ construction of orthogonal field. [ABSTRACT FROM AUTHOR]

Non-noble metal Cd nanoparticles, as an efficient cocatalyst, are successfully constructed onto the surface of hexagonal CdS nanorods (CdS NRs) for the photocatalytic hydrogen evolution reaction by a facile in situ chemical reduction approach based on a thermal treatment process. The in situ introduction of Cd can significantly improve the photocatalytic H 2 production performance of CdS NRs in sodium sulfide and sodium sulfite aqueous solutions under visible light irradiation. The superior electrical conductivity of metallic Cd and the intimate interfacial contact between Cd and CdS NRs are suggested to account for the enhanced light absorption intensity, more efficient charge separation, and faster interfacial charge migration, resulting in the dramatically promoted photocatalytic H 2 production activity. This work provides a new route for the in situ deposition of Cd nanoparticles onto CdS and other Cd-containing semiconductor photocatalysts with desired morphologies. [ABSTRACT FROM AUTHOR]

An efficient MoO 2 /CdS photocatalyst has been successfully constructed by a relatively facile way to construct a specific combination mode through chemical bond, which results in strong interaction between MoO 2 nanoparticles and CdS nanorods. X-ray photoelectron spectroscopy further confirms the formation of Mo–S bonding, which acts as a connection bridge and develops an intimate contact between CdS-NRs and MoO 2 nanoparticles. Benefitting from the synergic effect of the enhancement on the light absorption, carriers' efficient separation and lower the overpotential of hydrogen evolution, the obtained MoO 2 /CdS composite has shown an excellent enhancement in photocatalytic H 2 generation and the optimal H 2 evolution rate reaches as high as 30 times than that of pure CdS nanorods. We have experimentally shed light on the mechanism of this excellent enhancement performance in detail. Moreover, our work can broaden the construction and the application of developing other efficient photocatalytic material containing transition metal oxide. • MoO 2 /CdS photocatalyst with chemical bonding Mo–S has been synthesized through a mild method. • The MoO 2 /CdS composites show largely enhanced photocatalytic performance for water splitting. • This strategy can obliterate the passivation layer, leading to more active sites exposed on MoO 2. • A possible mechanism of this enhancement for H 2 evolution is given. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Inexpensive NiCd bimetallic nanoparticles are assembled on the surface of CdS nanorods. • An ingenious two-step in-situ deposition reduction method is proposed. • The morphology of CdS substrate could be controlled elaborately in this system. • A perfect interface is built between NiCd bimetallic nanoparticles and CdS NRs. Abstract In order to obtain the high H 2 evolution activity, an inexpensive and efficient photocatalyst CdS nanorods decorated with NiCd bimetallic nanoparticles has been designed and successfully prepared via an ingenious in situ deposition method. The experiment results indicate that NiCd bimetallic cocatalysts can efficiently inhibit the recombination of the photoinduced electron-hole pairs and promote the interfacial charge transfer, resulting in a significant improvement in photocatalytic H 2 production performance. The NiCd/CdS NRs sample exhibits an excellent photocatalytic H 2 evolution activity under visible light irradiation (λ > 410 nm), and the corresponding H 2 evolution rate is 11.57 mmol·h−1·g−1, which is about 64.8, 17.2 and 2.3 times as that of pristine CdS NRs, Cd/CdS and Ni/CdS, respectively. This work is expected to provide a new inspiration for rationally designing highly efficient and practical hybrid photocatalyst systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Free layer-dependent O-doped MoS 2 with considerable piezoelectricity was synthesized. • Out-of-plane polarization of MoS 2 was constructed to realize the enhanced piezoelectricity. • O-doped MoS 2 shows high piezocatalytic H 2 production performance from pure water. The piezoelectricity of MoS 2 only exists in monolayer and odd-number layers, owing to the inversion symmetry of the even number layers, which limits the efficient utilization and mass synthesis of MoS 2. Herein, the structure of MoS 2 is adjusted by oxygen doping, which could break the layer-dependent piezoelectricity and induce out-of-plane polarization. This endows O-doped MoS 2 the free layer-dependent and enhanced piezoelectricity. Benefiting from the optimized piezoelectricity, higher concentration of carriers, higher Hall mobility and lower resistivity, the O-doped MoS 2 exhibits an improved activity of piezocatalytic H 2 production from pure water, and the corresponding H 2 evolution rate reaches up 47.75 μmol·h−1·g−1. Under the same conditions, the hydrogen production rate of MoS 2 is only 20.19 μmol·h−1·g−1. This work not only provides a new strategy for modulating piezoelectricity of transition mental dichalcogenides, whose bulk materials are non-piezoelectric, but also breaks new ground for developing high-efficiency piezocatalysts. [ABSTRACT FROM AUTHOR]

• As a charge transfer mode switcher, MoS 2 can transform the conventional type-II charge transfer mode to Z-scheme. • As electron-hole mediator, MoS 2 can quench the energy of the electrons from WO 3 and the holes from CdS in shorten length. • As a cocatalyst, the CB of MoS 2 can provide active sites for photocatalytic evolution H 2 driven by the electrons from CdS. • WO 3 @MoS 2 /CdS shows improved performance compared with WO 3 /CdS or MoS 2 /CdS owing to the multifunctional roles of MoS 2. A novel ternary Z-scheme system of WO 3 @MoS 2 /CdS is successfully constructed using a three-step wet-chemical route, where MoS 2 locates between the rod-shaped WO 3 and CdS nanoparticles and simultaneously plays multiple roles of the charge transfer mode switcher, electron-hole mediator and cocatalyst. As a charge transfer mode switcher, MoS 2 can transform the conventional type-Ⅱ charge transfer mode to Z-scheme. In such a Z-scheme system, as an electron-hole mediator, MoS 2 is applied to quench the energy of the electrons from WO 3 and the holes from CdS in shorten length, and thus the more left electrons from CdS can transfer to MoS 2 , which can be further applied to photocatalytic evolution H 2 owing to the cocatalyst role of MoS 2. Benefitting from the multifunctional roles of MoS 2 , such a Z-scheme system of WO 3 @MoS 2 /CdS shows an enhanced photocatalytic performance. [ABSTRACT FROM AUTHOR]