Résumé
While supported metal nanoparticles cannot achieve full electrochemical utilisation of metal atoms, catalysts featuring single metal atom sites may offer this possibility, along with advantages in selectivity. However, the passage from nanometric to atomic dimension is not without consequences. It first raises the question of efficient and robust synthesis methods, and underlines the need of cutting-edge characterization techniques that can target single metal atoms. These analytical tools are also pivotal to gain insights into the structure of the active sites, and establish atomic structure-catalytic activity-selectivity-stability relationships. Herein, we illustrate these topics for electrocatalysis, with a particular focus on metal-nitrogen-carbon single metal atom catalysts, for which a fantastic leap forward has been achieved in the last 15 years, triggered by the growing interest in sustainable energy storage and conversion systems.