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.

Nanoporous Metals: From Plasmonic Properties to Applications in Enhanced Spectroscopy and Photocatalysis

“…(b) Comparison of the photoelectrochemical current density generated by external heat only (red) and by both plasmonic and external heats (green). Reproduced with permission under a Creative Commons Attribution 4.0 License (CC BY) from ref . Copyright 2019 IOP Science.…”

Small-angle X-ray scattering of nanoporous materials

“…We have plotted eqn (17) in Fig. 3b to demonstrate how the intensity changes with parameters d (represented by the black curve) and x (represented by the colored curve).…”

“…These NP materials have been widely investigated for various applications including gas storage (e.g. H 2 storage and CO 2 capture), 30,35,44,45,50 biotechnology, 51 radiation resistance, 52 plasmonics, 16,[53][54][55][56][57] (photo)catalysis, 17,18,35,38,55,[58][59][60][61][62][63][64][65][66] sensing, 67,68 actuation, 8,[68][69][70][71] and energy storage and conversion. 6,9,11,12,19,21,43,47,60,[72][73][74][75] In all of these applications, the characteristic size, specific interfacial area, and curvature are critical and necessitate proper quantification.…”

Dealloyed Air- and Water-Sensitive Nanoporous Metals and Metalloids for Emerging Energy Applications

“…Bulk nanoporous metals (such as Au, Pt, Pd, Ag, Cu, Sn, Ni, Al, and Mg) and metalloids (such as Sb, B, Ge, and Si) are attractive for various applications including heterogeneous catalysis, − electrocatalysis, − electrochemical energy conversion and storage, − electrochemical actuators, − sensors, − surface-enhanced Raman scattering (SERS), − and plasmonics. − These bulk nanoporous metals and metalloids are typically fabricated through a selective leaching process known as dealloying, during which sacrificial atoms from a parent alloy, usually the most (electro)­chemically active alloy component, spontaneously dissolve in an acidic or alkaline corroding medium, − while atoms of the undissolved component coalesce through interfacial diffusion to form an isostructural porous network of interconnected ligaments and pores with average diameter in the nanometer range. Often, when the reduction–oxidation (redox) reaction involved in the process is not spontaneous, an external electrical voltage or current can be used to drive dissolution of the sacrificial component.…”