Frequently Encountered Factors Which Obstruct Evaluation of Intrinsic Kinetics of Hydrogen Electrocatalytic Reaction

Obtaining reproducible experimental data free from artifacts is of paramount importance in evaluating the intrinsic kinetics of electrocatalytic reactions, discovering the activity trends, and unveiling the intrinsic effects from the electrolyte such as solution pH and composition ions. In this work, we will take hydrogen evolution reaction (HER) at Au(111) electrode under hanging meniscus rotating disk electrode (HMRDE) configuration as a model reaction. The impacts 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, and the purity of the reagents used for preparing the supporting electrolyte on the j\text-E and j\text-t curves for HER will be exemplified. In addition to the introduction of defects, whether it is 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 artifacts 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 for the kinetic analysis of other electrocatalytic reactions will be briefly discussed.