Novel method for preparation of the hybrid metal (I)-metal (II) oxide nanoparticles

摘要

Metal-based core-shell nanoparticles (NPs) as a research topic has attracted attention owing to their unique catalytic, biomedical, magnetic and electric properties compared to their bulk counter parts. Surface functionalisation of free-standing metal NPs by coupling with another metal oxide provides means to prepare a hybrid nanomaterial with target properties. A novel bottom-up strategy has been developed to synthesise metal (I)-metal (II) oxide hybrid NPs, which involves electrochemical formation of metal (I) nanoparticles spatially stabilised by organic shell molecules and coupling with a metal (II) oxide formed via oxide-precursor reduction by organic shell. This paper describes application of a novel strategy to synthesise Ag-MnO2 nanocomposites with improved catalytic properties. Kinetic study indicates relatively fast three-step reduction of a permanganate ion (MnO2 precursor) by an oleic acid (shell material) catalysed by a silver core. Surface analytical (SEM, TEM and EDX), spectroscopic (UV-VIS, FT-IR and XRD) and thermal stability (TGA and DTA) studies of Ag-MnO2 nanocomposites reveal strong chemical bonding of the components in a bi-composite. The catalytic properties of supported Ag-MnO2 nanocomposites were tested for oxidation of carbon monoxide. The improvement of a CO conversion rate compared to a single AgNP nanocatalyst was demonstrated.