Scanning Electrochemical Microscopy

Abstract Scanning electrochemical microscopy (SECM) enables the high‐resolution imaging and measurement of electrochemical, chemical, and biological reactions at various interfaces. The power of SECM originates from the versatility based on the highly accurate and precise positioning of a micrometer‐ or nanometer‐sized ultramicroelectrode tip near the surface of substrates including nanomaterials and biological cells. The current response of the SECM tip (and that of the substrate when needed) is monitored to quantitatively probe the dynamics of a targeted reaction in situ and in real‐time. This article is concerned about the fundamental principle and recent progress of SECM for both imaging and nonimaging applications. Major progress was made through the development of specific instrumentation and protocols to transition nanoscale SECM into a reliable and powerful scientific tool. Nanoscale SECM can image and characterize single molecules and single nanostructures, quantitatively address the kinetics of otherwise unmeasurably fast reactions, and dynamically resolve a complicated reaction into multiple steps. Further technological advancement will find the wide and routine applications of nanoscale SECM. By contrast, microscale SECM is broadly used as an established method in various research areas including biology, corrosion, energy, and materials science to gain deeper insights into the mechanisms of important processes such as electrocatalysis and cellular activity and signaling. The ever‐lasting development of SECM during the last three decades manifested that the fundamental concept of SECM far exceeded and preceded our research needs and technological capabilities, which have not matched yet to fully realize the high potentials of this already remarkable methodology.