Proton coupled electron transfer tunneling reactions in WO3 and MoO3 nanostructured films

Abstract

WO3 and MoO3 are famous hydrogenphilics, hydrogen loving materials, capable of performing various functions concerning atomic hydrogen. They are active catalysts in photochemical reactions connected with detachment of hydrogen atoms, being, at the same time, capable of accomodating great quantities of the detached hydrogen atoms, and transporting them to other functional materials via employment of various heterostructures. It was shown that tunneling proton-coupled electron transfer is the mechanism of the photochemical hydrogen abstraction reaction on the surface of highly disordered nanostructured WO3 and MoO3 thin films. Specially selected hydrogen donor molecules were adsorbed on the oxide surface bonding via donor-acceptor and hydrogen bonds which yield a decrease in the energy barrier for the hydrogen transfer from the adsorbed hydrogen donor molecule to the oxide surface. The very rough and heterogeneous film surface yields space fluctuations of the energy barrier parameters whereas intermolecular vibrations yield time fluctuations; the fluctuative barrier preparation being responsible for the tunneling photo-stimulated proton-coupled electron transfer.