Laser-induced periodic surface structured electrodes with a 45 % energy saving in electrochemical fuel generation through field localization

TL;DR

This paper introduces laser-induced surface structures on electrodes that significantly reduce energy consumption in electrochemical fuel generation by enhancing local electric fields and catalyst performance.

Contribution

It presents a novel laser patterning technique to create electrodes with improved field localization, leading to 45% energy savings in hydrogen production.

Findings

Achieved 45% energy saving at 10 mA/cm2 hydrogen generation rate.

Decreased HER and OER overpotentials by 40% and 25%.

Operated effectively across various electrolytes including seawater.

Abstract

Electrochemical oxidation-reduction of radicals is a green and environmentally friendly approach to generating fuels. These reactions, however, suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst. A large electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites, but this comes at the cost of electricity. Here, we report about a 45 percent saving in energy to achieve an electrochemical hydrogen generation rate of 10 mA per cm2 through localized electric field-induced enhancement in the reagent concentration (LEFIRC) at laser-induced periodic surface structured (LIPSS) electrodes. The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization. When the LIPSS patterned electrodes are used as substrates to support Pt-C and RuO2 electrocatalysts, the overpotentials for HER and OER are decreased by 40 and 25 percent, respectively. Moreover, the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes including alkaline, acidic, neutral, and seawater. Importantly, when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell, it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm2. This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.