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It is important to design high performance photoelectrode materials in the process of photoelectrochemical (PEC) water splitting. Herein, ZnIn2S4 nanomaterial with highly exposed active (110) facets were prepared by a simple hydrothermal method. Meanwhile, piezoelectric polarization was used to induce the generation of built‐in electric field, which can suppress the compounding of photogenerated charge carriers caused by structural defects at the semiconductor surface. By controlling the crystal facet structure, ZnIn2S4 with a highly exposed active (110) facet shows a better photoelectrochemical water splitting performance under ultrasound, and its photocurrent density increases with the increase of ultrasound frequency, reaching a maximum value of 0.36 mA/cm2 at 1.23 VRHE, which is 2.8 times higher than that without ultrasound. It can be concluded that the (110) facet of ZnIn2S4 can induce a larger internal piezoelectric potential which allows rapid electron transer at the ZnIn2S4 surface, under ultrasonic conditions. And the highly exposed (110) facet also provides more reactive sites, leading to further enhanced catalytic activity. Such nanomaterial with highly exposed active facets will provide inspiration for the construction of photoelectrode systems with high photoelectrochemical water splitting efficiency. [ABSTRACT FROM AUTHOR]

Rational defect regulation is an effective way to enhance the performance of photoelectrocatalytic (PEC) water splitting. In this paper, we firstly constructed internal and surface defects to modulate the crystal structure of CdS, and investigated the synergistic impact of 0D (0‐dimensional) internal and surface defects regulation coupled with pyroelectric effects for optimizing the photoelectrocatalytic properties of CdS. It was found that the synergistic impact had a significant enhancement effect on the carrier separation and transfer, and the current density reached 3.93 mA/cm2 at 1.23 V vs. RHE increased by 16.38 times, meanwhile, the stability of the photoelectrodes was greatly promoted. The advantages and intrinsic relationships are also described: the formation of 0D dual‐type of defects alters the atomic arrangement in the crystal, optimizes the energy band structure, reduces carrier recombination, and increases carrier density. What's more, the introduction of defects induces electron redistribution and changes the state of dipoles inside the crystal, thus increasing built‐in electric field and generating more thermally generated carriers to optimize the pyroelectric effect. This work demonstrates the feasibility of defect modulation for optimizing pyroelectric performance and photocatalytic performance and bringing new light to PEC water splitting. [ABSTRACT FROM AUTHOR]

The low utilization of light and the severe recombination of charge carriers have always restricted the development of photoelectric catalysis. In this work, the photoelectric catalytic performance is tuned by doping Sr in BaTiO3 pyroelectric material and simultaneously introducing oxygen vacancies to form double‐type defects, combined with pyroelectric polarization. Under the light and 20–50 °C cold‐heat cycle, the current density of Ba0.7Sr0.3TiO3‐X reaches the maximum of 0.92 mA ⋅ cm−2, which is higher than the current density of Ba0.7Sr0.3TiO3‐X under only light (0.69 mA ⋅ cm−2). Under light alone, the current density of Ba0.7Sr0.3TiO3‐X is higher than that of BaTiO3 (0.19 mA ⋅ cm−2) and Ba0.7Sr0.3TiO3 (0.44 mA ⋅ cm−2). This is because the incorporation of Sr can introduce the Fermi level, improve the utilization rate of solar energy, and improve the pyroelectric polarization effect with volume shrinkage, and promote the separation and transfer of carriers. Oxygen vacancies can be used as reactive centers for excited electrons to suppress the recombination of excited electron‐hole pairs. Furthermore, the generation of photogenerated and pyrogenerated carriers increases the overall carrier concentration. This provides ideas for the modification of traditional photoelectrodes for photoelectric catalysis water splitting. [ABSTRACT FROM AUTHOR]

The enhanced separation and injection efficiencies of photogenerated carriers is essential to improve the photoelectrochemical (PEC) performance of WO3 photoanode. In this work, we firstly synthesized WO3/NiCo2O4 heterojunction through simple hydrothermal‐annealing method as well as investigate the effect and mechanism of NiCo2O4 on WO3 for PEC performances. The measurements demonstrate that the nano‐needle NiCo2O4 grown on the surface of WO3 induces the bimetallic Ni/Co redox reaction sites extensively exposed to the electrolyte, which is beneficial to enhance the PEC performances of WO3 photoanode, such as photocurrent density improved by four times (0.84 mA/cm2 at 1.23 V vs. RHE) as well as more negative initial potential (∼280 mV) in contrast to bare WO3. Further investigation shows the remarkable enhancement of PEC performances is attributed to improved surface reaction kinetics, the enhanced injection efficiency and separation efficiency of photogenerated carriers due to the co‐catalyst effect of NiCo2O4 and the formation of WO3/NiCo2O4 heterojunction. This work provides reference for application of heterojunction with co‐catalyst function, which is beneficial to the development and application of similar structures. [ABSTRACT FROM AUTHOR]