Physico-chemical and catalytic properties of polymer-protected and hydrogel-immobilized gold, silver and palladium nanoparticles

Abstract

Gold (AuNPs), silver (AgNPs) and palladium (PdNPs) nanoparticles stabilized by various hydrophilic polymers are considered. Embedding of polymer-protected AuNPs, AgNPs and PdNPs within hydrogel matrix restricts the diffusion of nanoparticles both inside of and outside of gel matrix. Catalytic properties of metal nanoparticles supported onto either metal oxides or immobilized within hydrogel matrix have been studied in model reaction – decomposition of hydrogen peroxide. The influence of catalyst amount (mcat), concentration of substrate (H2O2) and temperature (T) was studied in order to find the optimal conditions of H2O2 decomposition. Examples of hydrogel-based catalytic system acting by “on-off” mechanism are demonstrated. The catalytic activity of gel-immobilized metal nanoparticles is proved to be much lower than deposited on the metal oxides due to lesser accessibility of active centers in hydrogel matrix to substrate molecules.