Insight into the Role of the Amino-Organosilane Modifier in Improving the Catalytic Activity of ZnO-Supported Gold Species in Base-Free Oxidation of Benzyl Alcohol

Understanding the factors that affect the reactivity of gold nanoparticles (Au NPs) in the catalytic oxidation of organic compounds remains an important issue. Of particular significance is tuning the effect of metal-support interaction toward improving the catalytic performance of Au NPs. The main goal of this study is to provide new insight into the role of the amino-organosilane (APMS) modifier, used for anchoring of gold species on ZnO support, in controlling the reactivity of Au NPs in H2O2 activation and the subsequent catalytic oxidation of benzyl alcohol. This study reveals that APMS modifier weakens the electronic interaction between ZnO and Au NPs, leading to a lower catalase-like activity toward H2O2 in comparison to that observed for modifier-free gold catalyst of similar size of nanoparticles. As a result, a slower rate of oxygen evolution resulted in higher activity in the oxidation of benzyl alcohol and enabled more efficient utilization of H2O2 under base-free conditions. No radical species were formed during the oxidation reaction, and molecular oxygen formed in situ in the reaction medium was the primary oxidant responsible for the catalytic conversion of benzyl alcohol.