The insights into the active sites of catalysts have been providing ideas for efficiently designing highly active and selective catalysts in electrochemical reactions. Therefore, it is of great significance for developing a powerful in situ characterization strategy, which can provide strong evidence and persuasive power in the electrochemical process. Scanning electrochemical microscopy (SECM) has gained increasing attention as a powerful analytical tool for characterizing catalytic activity under in situ conditions. In this review, we summarized the application methods of SECM in electrochemical reactions such as the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), oxygen reduction reaction (ORR), carbon dioxide reduction reaction (CO₂RR), and nitrate reduction reaction (NitRR). We also briefly introduced the common operation modes of SECM. The recent progress of SECM in probing the active sites, reaction kinetics and charge transfer of electrocatalysts is reviewed. Finally, we discuss the challenges and prospects of SECM in characterizing the activity of electrocatalysts. This review provides a reference for readers on SECM experimental methods and theoretical analysis.

The presence of dual N, O- coordinated to the Mn single-atom catalyst with Mn–N₂O₂ sites embedded in the 2D carbon nanosheets significantly improve catalytic activity for reduction of CO₂.

The anion regulated channel of LDHs blocked by carbonate was opened by controlling the suberate intercalation, thus discussing the effect of different anions of PMo_12−XV_X, X = 0, 1, 2, 3, 8) intercalation on the photocatalytic nitrogen fixation performance of ZnAl-LDH.