In this perspective, we discuss the challenges, advances and opportunities in electroanalytical chemistry at nanoelectrodes, including nanoelectrode fabrication, real-time characterizations, and high-performance electrochemical instrumentation.

Micro/nano-machining (MNM) is becoming the cutting-edge of high-tech manufacturing because of the ever increasing industrial demands for super smooth surfaces and functional three-dimensional micro/nano-structures in miniaturized and integrate devices, and electrochemistry plays an irreplaceable role in MNM.

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.