Aerobic Oxidation of Alcohols on Au Nanocatalyst: Insight to the Roles of the Ni–Al Layered Double Hydroxides Support

Abstract

AbstractAu nanoparticles (NPs) supported on Ni–Al layered double hydroxides (LDHs) were shown to be efficient heterogeneous catalysts for the highly selective oxidation of alcohols to the corresponding aldehydes or ketones under base‐free or even solvent‐free conditions with O2 as the sole oxidant. The Au NPs can be uniformly distributed on Ni–Al LDHs support, which is beneficial to the catalytic activity. In addition, the weak Brønsted basic property of the support enables the aerobic oxidation of alcohols under base‐free conditions. More importantly, unlike Al2O3, which is inert, Ni–Al–LDHs are redox‐actively involved in prompting the electron transfer to O2 via the Au nanocatalyst because of the presence of NiII. Both of the basic and the redox properties of Ni–Al–LDHs can be tuned by adjusting the ratio of Ni:Al to achieve the best synergistic effects between Au NPs and the supports. The activity of the obtained Au catalysts was found to be structurally associated with the arrangements of NiO6 and AlO6 octahedra in the surface hydroxide layers which were different from the bulk Ni:Al ratio.