Highly Efficient Photoelectrochemical Hydrogen Generation Using Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub> Sensitized Platelike WO<sub>3</sub> Photoelectrodes

Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub> sensitized platelike WO<sub>3</sub> photoelectrodes on FTO substrates were for the first time prepared via a sequential ionic layer adsorption reaction (SILAR) process. The samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectrometry (UV–vis), and Raman spectra. The results show that the Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub> quantum dots (QDs) are uniformly coated on the entire surface of WO<sub>3</sub> plates, forming a WO<sub>3</sub>/Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub> core/shell structure. The Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub>/WO<sub>3</sub> films show a superior ability to capture visible light. High-efficiency photoelectrochemical (PEC) hydrogen generation is demonstrated using the prepared electrodes as photoanodes in a typical three-electrode electrochemical cell. Compared to the Bi<sub>2</sub>S<sub>3</sub>/WO<sub>3</sub> photoelectrodes, the Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub>/WO<sub>3</sub> photoelectrodes exhibit good photostability and excellent PEC activity, and the photocurrent density is up to 7.0 mA cm<sup>–2</sup> at −0.1 V versus Ag/AgCl under visible light illumination. Investigation of the electron transport properties of the photoelectrodes shows that the introduction of ZnS enhances the photoelectrons’ transport rate in the photoelectrode. The high PEC activity demonstrates the potential of the Zn<sub><i>x</i></sub>Bi<sub>2</sub>S<sub>3+<i>x</i></sub>/WO<sub>3</sub> film as an efficient photoelectrode for hydrogen generation.