Emerging Techniques and Scenarios of Scanning Electrochemical Microscopy for the Characterization of Electrocatalytic Reactions

To fulfill the evergrowing energy consumption demands and the pursuit of sustainable and renewable energy, electrocatalytic reactions such as water electrocatalysis, O2 reduction, N2 reduction (NRR), CO2 reduction (CO2RR), etc., have drawn a lot of attention. Scanning electrochemical microscopy (SECM) is a powerful technique for in-situ surface characterization, providing critical information about the local reactivity of electrocatalysts and unveiling key information about the reaction mechanisms, which are essential for the rational design of novel electrocatalysts. There has been a growing trend of SECM-based study in electrocatalytic reactions, with a major focus on water splitting and O2 reduction reactions, and relying mostly on conventional SECM techniques. Recently, novel operation modes of SECM have emerged, adding new features to the functionality of SECM and successfully expanding the scope of SECM to other electrocatalytic reactions, i.e., NRR, NO3- reduction (NO3RR), CO2RR and so on, as well as more complicated electrolysis systems, i.e. gas diffusion electrodes. In this perspective, we summarized recent progresses in the development of novel SECM techniques and recent SECM-based researches in NRR, NO3RR, CO2RR, and so on, where quantitative information on the reaction mechanism and catalyst reactivity were uncovered through SECM. The development of novel SECM techniques and the application of these techniques can provide new insights into the reaction mechanisms of diverse electrocatalytic reactions as well as the in-situ characterization of electrocatalysts, facilitating the pursuit of sustainable and renewable energy.