Probing the reactive intermediate species generated during electrocatalysis by scanning electrochemical microscopy

Reactive intermediate species (RIS) play a major role in many chemical and biological reactions. Due to the high reactivity their presence are usually confined at the place of their formation. Whereas electrochemical tools can electrogenerate them through various mechanistic paths, the local electrochemical probes, such as a micro/nanoelectrode tip of the scanning electrochemical microscopy (SECM), are by essence well adapted to catch their formation and reactivity at the location of their production. This review presents the recent local electrochemical probe strategies employed to probe RIS down to the nanometer scale, either immobilized on the surface of an electrode or within a reaction layer, in solution. It is illustrated by examples borrowed from the field of electrocatalysis, with emphasis on the contributions of numerical simulation to derive quantitative information.