Construction\nof a Bi<sub>2</sub>S<sub>3</sub>/Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub> Composite Catalyst with\nS Vacancies for Efficient Piezo-Photocatalytic Hydrogen Production

Photocatalytic hydrogen production with low environmental\nand economic\ncosts is expected to be a powerful means to alleviate energy and environmental\nproblems. However, how to inhibit the rapid recombination of photogenerated\ncarriers is a challenge that photocatalytic hydrogen production has\nto face. In this study, the coupling of the piezoelectric effect and\nvacancy engineering into the photocatalytic reaction process synergistically\npromoted carrier separation, thereby promoting the improvement of\nhydrogen production performance. Specifically, the novel dual piezoelectric\nBi<sub>2</sub>S<sub>3</sub>/Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub> (BS-12/BNT) piezo-photocatalyst rich in S vacancies was synthesized\nby an impregnation method. The hydrogen generation rate of 5% BS-12/BNT\nunder the combined impact of light and ultrasound was up to 1019.39\nμmol/g/h, which is 9.5 times higher than that of pure BNT. Various\ncharacterization analyses have confirmed that the piezoelectric-photocatalytic\nactivity of BS/BNT composite materials is significantly improved,\nmainly due to the introduction of S vacancies and piezoelectric fields,\nwhich enhance the absorption of sunlight, reduce interface resistance,\nand so raise the photogenerated carriers’ separation efficiency.\nIn addition, the stability of BS/BNT is significantly better than\nthat of the previously synthesized catalysts. Finally, according to\nthe results of XPS, UV–vis, and ESR, the active groups and\npossible electron transfer paths generated during the piezoelectric-photocatalytic\nhydrogen production process were studied. This work presents a new\napproach to promote hydrogen production performance through the synergistic\neffect of the piezoelectric effect and S vacancies.