Photo-electro synergistic catalysis: Can Pd be active for methanol electrooxidation in acidic medium?

Abstract

Development of alternative Pt-free electrocatalyst for methanol oxidation reaction (MOR) in acidic medium remains a big challenge. As is reported, Pd is a good electrocatalyst for MOR in alkaline medium, but it is commonly recognized as inactive in acidic medium. Herein, we report an active Pd nanoparticles electrocatalyst for MOR in acidic medium although its catalytic activity is low. The photoexcitation of the plasmonic Pd nanoparticles leads to an MOR activity enhancement by a factor of 2 under visible light. Interestingly, the photogenerated electron-hole separation on nanosized TiO2 and the surface plasmon resonance effect of Pd nanoparticles on Pd/TiO2 heterostructure synergistically promote the photo-electrocatalytic activity of MOR under simulated solar light. The 17.9-fold activity enhancement of MOR in the presence of UV light indicates that the photogenerated electron-hole separation on TiO2 plays a crucial role in the photo-electro-synergistic methanol oxidation reaction. This remarkable light-driven activity enhancement of methanol oxidation reaction on Pd/TiO2 heterostructure suggests that the combination of plasmonic Pd nanoparticles and photogenerated electron-hole separation on TiO2 could provide a new strategy for the design and construction of energy conversion system.