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.

Charge storage in pseudocapacitive materials occurs through electron transfer (i.e. faradaic current) involving oxidation and reduction reactions. This process is usually extremely fast because the reactions take place near the surface of the material, meaning the species involved diffuse over short distances. Ionic species such as H+, OH-, Li+, and Na+ commonly used to store charge in pseudocapacitive materials are usually “foreign” elements in the materials. In this talk, I will demonstrate a pseudocapacitive charge storage approach where the ionic species is part of the material. Here we use Ag+ as the working ion in a non-aqueous electrode and silver (I) oxide grown on a three-dimensional nanoporous gold scaffold as the storage medium. Pseudocapacitive charge storage occurs through electrochemical oxidation/reduction of silver (I) oxide to silver (III) oxide at scan rates as high as 1000 mV/s. These high rates are justified by (i) the intrinsic nature of the working ion (Ag+), which is better accommodated by the host silver oxide material as opposed to foreign ions, and (ii) the excellent electronic conductivity provided by the 3D metallic scaffold current collector.