Visible Light Plasmonic Heating-Enhanced Electrochemical Current in Nanoporous Gold Cathodes

Abstract

Taking advantage of the localized surface resonance effect to boost the performance of electrochemical cells has rarely been demonstrated using nanoporous metal films as photoactive electrodes. Rather, studies on plasmon-enhanced electrochemical processes use plasmonic metal nanoparticles loaded onto semiconductor or conductor substrates. Here we present experimental evidence for the use of visible light to significantly enhance the kinetics of a redox reaction involving the oxidation of aluminum at the anode, and the reduction of hydrogen ions to hydrogen gas at the cathode. This reduction reaction is allowed to take place on a nanoporous Au film used as plasmonic photocathode. A 20-fold increase in the electrochemical current density was recorded upon exposure of the nanoporous Au cathode to visible light. We demonstrate that this significant current enhancement is associated with local heat generated in Au during localized surface plasmon resonance. These results could be exploited to develop high-performance heterogeneous photocatalysts based on plasmonic heating, for the conversion of renewable energy resources into fuels and value-added chemicals.