Frequently Encountered Factors Which Obstruct the Evaluation of the Intrinsic Kinetics of Electrocatalytic Reactions

Obtaining reproducible experimental data free of artefacts is of paramount importance in evaluating the intrinsic kinetics of electrocatalytic reactions, for discovering the activity trends, unveiling the intrinsic effect from the electrolyte such as solution pH and composition ions. In this paper, we will take HER at Au(111) electrode under hanging meniscus rotating disk electrode (HMRDE) configuration as a model reaction, the impact of the quality of single crystal electrode (the height of hanging meniscus of the HMRDE), possible participation of edge sites between the sphere and (111) plane, the purity of the reagent used for preparing the supporting electrolyte, on the j-E and j-t curves for HER will be exemplified. In addition to the introduction of defects, either with Au(111) of poor quality or slight involvement of the edge sites of Au(111) bead, deposition of elements such as Fe and Ni onto Au(111) from the ultrapure alkali reagent as received (without further purification) can also lead to more than 10 times of enhancement of HER current. Our results indicate that great care should be made in order to avoid such artefacts on the derivation of the pH dependent activity trend for HER as well as for the quantification of its intrinsic kinetic parameters. Implication of present findings to the kinetic analysis of other electrocatalytic reactions will be briefly discussed.