Biphasic Ag block assisting electron and energy transfer to facilitate photothermal catalytic oxidation of HCHO over manganese oxide

Abstract

Small-size particles are not necessarily more active than large blocks in terms of solar light-driven photothermal catalysis. In this work, Ag block exhibits higher activity than small-size Ag nanoparticles in facilitating photothermal removal of HCHO over manganese oxide (MO). In contrary to oxide state of Ag nanoparticle, metallic core and oxide-state shell assemble into biphasic Ag block (Ag@AgOx), because the shell prevents further oxidation of inner metallic Ag. Owing to LSPR effect of metallic core, the activation and mobility of lattice oxygen within MO are enhanced, so the efficiency in utilizing solar energy and catalytic activity are improved. Among them, the catalyst of 5% Ag@MO with Ag/Mn molar ratio of 0.05 exhibits an optimized and considerable activity in catalytically cleaning HCHO under irradiation of solar light even with light intensity of 25 mW/cm2, which makes it possible to work under exposure of nature solar light. Meanwhile, the catalyst exhibits a remarkable stability as well as tolerance to humidity.