Tracking the Electrocatalytic Activity of a Single Palladium Nanoparticle for the Hydrogen Evolution Reaction

The nanoparticle‐based electrocatalysts’ performance is directly related to their working conditions. In general, a number of nanoparticles are uncontrollably fixed on a millimetre‐sized electrode for electrochemical measurements. However, it is hard to reveal the maximum electrocatalytic activity owing to the aggregation and detachment of nanoparticles on the electrode surface. To solve this problem, here, we take the hydrogen evolution reaction (HER) catalyzed by palladium nanoparticles (Pd NPs) as a model system to track the electrocatalytic activity of single Pd NPs by stochastic collision electrochemistry and ensemble electrochemistry, respectively. Compared with the nanoparticle fixed working condition, Pd NPs in the nanoparticle diffused working condition results in a 2–5 orders magnitude enhancement of electrocatalytic activity for HER at various bias potential. Stochastic collision electrochemistry with high temporal resolution gives further insights into the accurate study of NPs’ electrocatalytic performance, enabling to dramatically enhance electrocatalytic efficiency. Stochastic collision model: A carbon ultramicroelectrode (C‐UME) is used to obtain a 2–5 orders magnitude enhancement of maximum turnover frequency (kcat) by stochastic collision electrochemistry compared with the ensemble electrochemistry. The electrocatalytic activity of nanoparticle‐based electrocatalysts is directly related to their working conditions, and the electrocatalytic heterogeneity among palladium nanoparticles (Pd NPs) could be displayed by stochastic collision electrochemistry.