Cu, Zn-coordinated ZIF-derived bimetal N-doped carbon frameworks for aerobic alcohol oxidation

Abstract

Cu–Zn–N–C catalysts were successfully synthesized through carbonization of Cu–Zn-coordinated ZIF materials and were used to selectively oxidize benzyl alcohol with O₂ at low temperatures, without the need for precious metals. The physicochemical properties were investigated using N₂-physisorption, XRD, Raman techniques, SEM, TEM, and XPS. The results showed that the carbonization temperature has an impact on the microstructure, carbonization degree, and elemental distribution of the catalysts, ultimately affecting their catalytic performance. Zn played a crucial role in the activation of oxygen species, while pyridine N served as a Lewis base for the adjacent C atoms, enhancing the adsorption of benzyl alcohol. The optimal doping levels of Zn, N and C in Zn–N–C-800 accounted for 95% conversion of benzyl alcohol and nearly 100% selectivity to benzaldehyde. Additionally, by substituting Zn atoms with Cu, the low-temperature catalytic performance was further enhanced by 12% due to the improved interactions between Cu and Zn species. Overall, this study provides insights into the effectiveness of Cu–Zn–N–C catalysts in the selective oxidation of benzyl alcohol and suggests avenues for further exploration on improving their catalytic activity.