Silica Nanospheres Coated by Ultrasmall Ag-0 Nanoparticles for Oxidative Catalytic Application

The present work introduces optimal modification of core-shell composite nanomaterial, where small (2-8 nm) Ag-0 nanoparticles are deposited onto large (about 140 nm) silica spheres for application in oxidative catalysis. The size of Ag-0 and density of its deposition onto silica spheres was modified by the post treatment of initially deposited Ag-0 (about 30 nm) by hydrogen peroxide in specific conditions. The comparison of catalytic effect of the post-treated and initial SN-Ag-0 in electrochemical phosphonation of benzo(thia) oxazoles by diethyl phosphite in oxidative conditions revealed the difference between the composite nanoparticles. In particular, the post-treated SNs-Ag-0 nanoparticles exhibit efficient catalytic effect in oxidative conditions resulting in facile and green method for synthesis of phosphonated benzooxa(thia)zoles, while no catalytic effect is observed under the use of larger Ag-0 nanoparticles deposited onto silica spheres. The use of Ag-0-based nanomaterial in oxidative catalysis had been never demonstrated before.