Cooperative defect-enriched SiO2 for oxygen activation and organic dehydrogenation

Abstract

Tailoring oxide functionalities via defect engineering is an effective approach in many advanced materials. Here we report that introducing defect sites in SiO2 via sequential hydrogenation and UV light pre-treatment steps can invoke synergism for oxygen activation and organic dehydrogenation under ambient conditions in the absence of light. The hydrogenation step is proposed to break SiOSi bonds to give an E′δ center – silanol pair. UV light pre-treatment then serves to dehydroxylate the silanol group to give a non-bridging oxygen hole centers (NBOHC). The two defect sites work in harmony to activate oxygen and in turn oxidize formic acid. First-principles calculations indicated that UV light pre-treatment lowered the energy barrier for oxygen activation and formic acid decomposition on the defect sites. Re-illuminating the used SiO2 led to partial recovery of the defect sites and hence oxidation performance. The study demonstrates the capacity for generating synergistic defects in simple metal oxides as an effective way to enhance performance for oxidation processes.