Flower-like Au/Ni–Al hydrotalcite with hierarchical pore structure as a multifunctional catalyst for catalytic oxidation of alcohol

Abstract

Flower-like hierarchical Au/NiAl-LDH catalysts were synthesized for selective oxidation of alcohols. The abundant hydrogen vacancies at the edge of the flowers as nucleation centers contributed to the uniform dispersion of Au NPs. The confinement effect of the hierarchical pores promoted 60% higher activity than the common Au/NiAl-LDH nanoparticle catalyst in the oxidation of benzyl alcohol by heightening the effective collisions between substrates and active sites. The evolution process of the hierarchical pores in the support was further proposed. Moreover, the reaction mechanism of the cooperation among Brønsted base sites, Ni^III coordinatively unsaturated metal sites and isolated gold cations was concretely proved. In the oxidation of other typical alcoholic substrates, the flower-like catalyst showed higher activity than the common nanoparticle one except for linear alcohols, which could be attributed to the shape selectivity of straight macropores.