Key Words:-

Abstract:The sluggish methanol oxidation kinetics has seriously hindered the development of direct methanol fuel cells. Photo-electro-catalysis is expected to accelerate reaction rates, yet suffers from lack of efficient photoelectrocatalysts and more importantly, less understanding on photo-electro-catalysis mechanism. Herein, a unique Cu-Nb 2 O 5 nanorod array with excellent light adsorption and charge transfer ability, on which supports Pt nanoparticles, is constructed for photo-electrocatalytic methanol oxidation reaction (MOR). Systematical investigation discovers a potential -dependent photo-electro-catalysis coupling mechanism, i.e., at lower potential bias where the Fermi level of semiconductor (E f,s ) is beyond the Fermi level of Pt (E f,Pt ), electrons transferring from Pt to semiconductor is switched off, so semiconductor Cu-Nb 2 O 5 alone takes a dominant role for both methanol and water activation; at higher potential bias where E f,s is below E f, Pt , electrons flowing from Pt to semiconductor is switched on, so methanol dehydrogenation on Pt surface is allowed energetically. Further investigation on the MOR processes prompts us to propose a MOR pathway that methanol dehydrogenates on Pt surface, with the aid of *OH from the photo -activated water on Cu-Nb 2 O 5 to proceed via formaldehyde, formic acid to carbon dioxide, resulting to a low apparent activation energy and fast kinetics of MOR as compared to its counterpart Pt/Nb 2 O 5 . This work not only provides an efficient photoelectrocatalyst for methanol oxidation, but also sheds lights on the underlying photo-electro-catalysis coupling mechanism over semiconductor -metal catalysts.

Volume:493

Issue:-

Translation or Not:no