Photocatalytic activity of CuBi2O4/WO3 p-n heterojunction photocatalysts in benzyl alcohol oxidation to benzaldehyde

Abstract

CuBi2O4/WO3 (CBO/WO3) p-n heterojunction composite was synthesized by mechanical stirring and sonication for the selective oxidation of benzyl alcohol to benzaldehyde under visible light. Multiple characterization methods, including XRD, XPS, SEM, TEM, UV–vis DRS, BET, EIS and ESR, were used to investigate the origin of the excellent photocatalytic activity. The results of XRD, XPS, SEM, and TEM revealed that CBO/WO3 catalyst was successfully synthesized. Benzaldehyde selectivity of over 99 % and benzyl alcohol conversion of 54.8 % were obtained under an optimized condition using 50 mg of 40-CBO/WO3 (40 stood for the mass percentage of CBO in CBO and WO3.). DFT results showed that ∆Eads values of benzyl alcohol were − 0.51, − 0.66 and − 0.88 eV on CBO, WO3 and CBO/WO3. The oxidation of benzyl alcohol occurred more easily on the surface of CBO/WO3. Meanwhile, the stability of 40-CBO/WO3 was investigated. After 5 repeated experiments, a high conversion was still maintained, indicating its potential in practical application. A possible mechanism of benzyl alcohol to benzaldehyde was proposed through the capturing experiment of active species. This work successfully designed an efficient p-n heterojunction composite catalyst for selective oxidation of benzyl alcohol. Replacing traditional thermal synthesis with selective photocatalysis can promote more environmentally friendly processes.