Mechanistic insights into homogeneous electrocatalytic reaction for energy storage using finite element simulation

Abstract

• Electrocatalytic reactions for energy storage is studied by finite element modelling. • Reaction rate constant of HMF and L-cysteine is determined by SWV. • Increase of potential frequency and increment weakens the split current peaks in SWV. • Potential amplitude increase results in conspicuous current protuberance in SWV. The application of homogeneous electrocatalytic reactions in energy storage and conversion has driven surging interests of researchers in exploring the reaction mechanisms of molecular catalysts. In this paper, homogeneous electrocatalytic reaction between hydroxymethylferrocene (HMF) and L-cysteine is intensively investigated by cyclic voltammetry and square wave voltammetry for which, the second-order rate constant ( k ec ) of the chemical reaction between HMF + and L-cysteine is determined via a 1D homogeneous electrocatalytic reaction model based on finite element simulation. The corresponding k ec (1.1 (mol·m −3 ) −1 ·s −1 ) is further verified by linear sweep voltammograms under the same model. Square wave voltammetry parameters including potential frequency ( f ), increment ( E step ) and amplitude ( E SW ) have been comprehensively investigated in terms of the voltammetric waveform transition of homogeneous electrocatalytic reaction. Specifically, the effect of potential frequency and increment is in accordance with the potential scan rate in cyclic voltammetry and the increase of pulsed potential amplitude results in a conspicuous split oxidative peaks phenomenon. Moreover, the proposed methodology of k ec prediction is examined by hydroxyethylferrocene (HEF) and L-cysteine. The present work facilitates the understanding of homogeneous electrocatalytic reaction for energy storage purpose, especially in terms of electrochemical kinetics extraction and flow battery design.