Modern applications of scanning electrochemical microscopy in the analysis of electrocatalytic surface reactions

Development of reaction-tailored electrocatalysts is becoming increasingly important as energy and environment are among key issues governing our sustainable future. Electrocatalysts are inherently optimized for application towards reactions of interest in renewable energy, such as those involved in water splitting and artificial photosynthesis, owing to its energy efficiency, simple fabrication, and ease of operation. In this view, it is important to secure logical design principles for the synthesis of electrocatalysts for various reactions of interest, and also understand their catalytic mechanisms in the respective reactions for improvements in further iterations. In this review, we introduce several key methods of scanning electrochemical microscopy (SECM) in its applications towards electrocatalysis. A brief history and a handful of seminal works in the SECM field is introduced in advancing the synthetic designs of electrocatalysts and elucidation of the operating mechanism. New developments in nano-sizing of the electrodes in attempts for improved spatial resolution of SECM is also introduced, and the application of nanoelectrodes towards the investigation of formerly inaccessible single catalytic entities is shared.