Preparation of Pd@CuBi2O4 photocatalysts and their performance for selective oxidation of benzyl alcohol under visible light illumination

Abstract

A replacement of the traditional thermal synthesis of fine chemicals with selective photocatalysis can promote a more environmentally friendly process. A novel Pd@CuBi2O4 with robust stability has been synthesized by a simple hydrothermal method combined with NaBH4 reduction method. This study reported the selective oxidation of benzyl alcohol to benzaldehyde via photocatalysts (CuBi2O4, x wt% Pd@CuBi2O4 composite, x = 1, 2, 3, 4, 5) under visible light illumination. The 3 wt% Pd@CuBi2O4 catalyst exhibited an excellent photocatalytic activity and a good selectivity for the oxidation of benzyl alcohol to benzaldehyde. Compared with bare CuB2O4, the photocatalytic activity was increased by 4 times under visible light illumination. Multiple characterization methods, including XRD, XPS, SEM, TEM, UV–vis DRS, PL, BET, and EIS, were used to investigate the origin of the excellent photocatalytic activity. Next, the capturing experiments were conducted to offer a logical mechanism for the reaction. •O2−, e− and h+ are the main active species in the reaction. In addition, 3 wt% Pd@CuBi2O4 remained stable during the photocatalytic transformation process and can be reused five times, indicating its practical application potential.