Enhanced piezocatalytic and piezo-photocatalytic dye degradation via S-scheme mechanism with photodeposited nickel oxide nanoparticles on PbBiO 2 Br nanosheets.

The fabrication of an S-scheme heterojunction demonstrates as an efficient strategy for achieving efficient charge separation and enhancing catalytic activity of piezocatalysts. In this study, a new S-scheme heterojunction was fabricated on the PbBiO ₂ Br surface through the photo-deposition of NiO nanoparticles. It was then employed in the piezoelectric catalytic degradation of Rhodamine B (RhB). The results demonstrate that the NiO/PbBiO ₂ Br composite exhibits efficient performance in piezocatalytic RhB degradation. The optimal sample is the NiO/PbBiO ₂ Br synthesized after 2 h of irradiation, achieving a RhB degradation rate of 3.11 h ^-1 , which is 12.4 times higher than that of pure PbBiO ₂ Br. Simultaneous exposure to visible light and ultrasound further increases in the RhB degradation rate, reaching 4.60 h ^-1 , highlighting the synergistic effect of light and piezoelectricity in the NiO/PbBiO ₂ Br composite. A comprehensive exploration of the charge migration mechanism at the NiO/PbBiO ₂ Br heterojunction was undertaken through electrochemical analyses, theoretical calculations, and in-situ X-ray photoelectron spectroscopy analysis. The outcomes reveal that p-type semiconductor NiO and n-type semiconductor PbBiO ₂ Br possess matching band structures, establishing an S-scheme heterojunction structure at their interface. Under the combined effects of band bending, interface electric fields, and Coulomb attraction, electrons and holes migrate and accumulate on the conduction band of PbBiO ₂ Br and valence band of NiO, respectively, thereby achieving effective spatial separation of charge carriers. The catalyst's synergistic photo-piezoelectric catalysis effect can be ascribed to its role in promoting the generation and separation of charge carriers under both light irradiation and the piezoelectric field. The results of this investigation offer valuable insights into the development and production of catalytic materials that exhibit outstanding performance through the synergy of piezocatalysis and photocatalysis.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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