Insight into active sites of nitrogen-doped carbon catalyst by stochastic collision electrochemistry.

Identifying the active sites of electrocatalysts is important for catalyst design. However, determining the specific active sites of catalysts is still a challenge. Herein, we demonstrate that stochastic collision electrochemistry could be used as a simple but efficient method for identifying the active sites of electrocatalysts, which can overcome the problems caused by the considerable difference between the giant geometric area and the limited exposure of active sites when using traditional cyclic voltammetry. To validate the method, the oxygen reduction reaction and ascorbic acid electrooxidation with the as-synthesized nitrogen-doped carbon catalysts were selected as model reactions. The results show that the pyridinic N dominates the reactivity of the oxygen reduction reaction while the CO functional group is the active site for ascorbic acid oxidation, which could not be identified by cyclic voltammetry with the ensemble drop-casting method. This manuscript demonstrates a new method for identifying the active sites of electrocatalysts, essentially enriching the methodology for identifying active sites.