Resumo

GUTIERREZ-PORTOCARRERO, Salvador  e  ALPUCHE-AVILES, Mario A.. Why Measure Particle-by-Particle Electrochemistry? A Tutorial and Perspective. J. Mex. Chem. Soc [online]. 2023, vol.67, n.4, pp.566-580.  Epub 26-Abr-2024. ISSN 1870-249X.  https://doi.org/10.29356/jmcs.v67i4.2014.

Single-particle electrochemistry has become an important area of research with the potential to determine the rules of electrochemical reactivity at the nanoscale. These techniques involve addressing one entity at the time, as opposed to the conventional electrochemical experiment where a large number of molecules interact with an electrode surface. These experiments have been made feasible through the utilization of ultramicroelectrode (UMEs), i.e., electrodes with at least one dimension, e.g., diameter of 30 μm or less. This paper provides a theoretical and practical introduction to single entity electrochemistry (SEE), with emphasis on collision experiments between suspended NPs and UMEs to introduce concepts and techniques that are used in several SEE experimental modes. We discuss the intrinsically small currents, below 1 nA, that result from the electroactive area of single entities in the nanometer scale. Individual nanoparticles can be detected using the difference in electrochemical reactivity between a substrate and a nanoparticle (NP). These experiments show steady-state behavior of single NPs that result in discrete current changes or steps. Likewise, the NP can have transient interactions with the substrate electrode that result in current blips. We review the effect of diffusion, the main mass transport process that limits NP/electrode interactions. Also, we pointed out the implications of aggregation and tunneling in the experiments. Finally, we provid a perspective on the possible applications of single-element electrochemistry of electrocatalyst.

Palavras-chave : Single-entity electrochemistry; nano-impact; nanoelectrochemistry; electroactivity; electrocatalysis.