Oxygen vacancy regulated selective hydrogenation of α,β-unsaturated aldehydes over LDH surface group coordinated transition metal photocatalysts

Abstract

Selective hydrogenation of α,β-unsaturated aldehydes under mild conditions is a great challenge in the synthesis of the corresponding alcohols. Herein, we report that a series of oxygen vacancy enriched MgAl-LDH coordinated transition metal hydroxide M(OH)_x (M = Ru, Pt, Pd, Ag, Rh, Fe, Co, Ni and Cu) photocatalysts were successfully prepared taking advantage of the “memory effect” of MgAl-LDH. A high yield of α,β-unsaturated alcohols was achieved under visible light irradiation. DFT simulations and DRIFTS results show that oxygen vacancies facilitate the adsorption of –CO groups and hinder the adsorption of –CC groups in cinnamaldehyde, which ensures the high selectivity to cinnamyl alcohol. The highly dispersed and electron-rich transition metal hydroxides facilitated the activation of isopropanol to provide active H species under light irradiation and then enhanced the photocatalytic performance. This study demonstrated oxygen vacancy enriched MgAl-LDH supported transition metal hydroxide M(OH)_x photocatalysts for efficient selective hydrogenation under visible light irradiation.