Tailoring of Zinc Oxide-based microstructures to efficiently promote piezocatalytic water oxidation and oxygen production

Two zinc oxide (ZnO) nanomaterials, exhibiting distinct morphologies, were synthesized in wurtzite phase through chemical precipitation. The elongated shape rod-like ZnO (R-ZnO) exhibited more pronounced piezoelectric characteristics compared to the more compact flower-like ZnO (F-ZnO). Detailed characterization including piezoforce microscopy, finite element simulation, revealed that the remarkable piezoelectric properties of R-ZnO are due to its strongly anisotropic structure, enabling significant mechanical deformation under ultrasound in aqueous suspension. The piezocatalytical degradation of these materials was assessed using methylene blue as a test organic dye across various ultrasound frequencies, with R-ZnO consistently outperforming F-ZnO. This highlighted the impact of structural deformability on piezocatalytic efficiency. Additionally, the capability of R-ZnO to facilitate oxygen evolution from water through ultrasound-induced stress was explored in an oxygen-free environment. Our findings demonstrate that R-ZnO can effectively catalyze water oxidation and produce oxygen directly, showcasing its potential as a standalone catalyst for environmental remediation and sustainable chemical processes.