Impacts of Organic Stabilizers on Catalysis of Au Nanoparticles from Colloidal Preparation

Abstract

Metal nanoparticles (NPs) from colloidal synthesis are advantageous in fundamental catalysis research because of their precisely controlled size and morphology but unfortunately are usually contaminated with residues from the organic stabilizer essentially required in the synthesis. These residues could modify the surface property and disturb the catalysis intrinsic to “clean” NPs. Herein, polyvinylpyrrolidone (PVP)-stabilized Au NPs (4.7 ± 1.0 nm) from colloidal synthesis were immobilized on SiO2 support and subjected to ultraviolet-ozone (UVO) treatment to remove the residues. Hydrogenation reactions of p-chloronitrobenzene (p-CNB) and cinnamaldehyde (CAL) were conducted to probe consequences of the stabilizer removal on the catalytic properties of Au NPs. Measurements by FTIR and XPS revealed a controlled removal and degradation of PVP according to the UVO-treatment duration. Careful HRTEM analysis disclosed that both the size and morphology of Au NPs remained unchanged after the UVO-treatment. Residua...