Metal–Support Synchronous Dynamics of an Atomically Dispersed Ruthenium Electrocatalyst for Boosting Hydrogen Production

Atomically dispersed electrocatalysts are a promising materials library for efficient water electrolysis, yet their structural dynamics in the cathode are easily overlooked, especially for their carbon supports constructed by robust C–C/N covalent bonds, hindering mechanistic understanding. Here, the dynamic reconstruction of both the metal and carbon support in a ruthenium monoatom-cluster electrocatalyst is studied during the alkaline hydrogen evolution reaction. Operando/nonoperando characterizations and dynamic/static computational simulations reveal that under reduction bias, Ru single atoms detach from the support and migrate to adjacent clusters, expending nanoparticle sizes. Meanwhile, support hydrogenation and diffusion convert pyridinic N to graphitic N. These changes significantly increase electrical conductivity and Ru electron density, accelerating both Volmer and Heyrovsky steps, which leads to an overpotential decrease from 113 to 19 mV at 10 mA cm–2 and achieves a TOF value (100 mV) of 49.8 s–1. This work provides insights into the structural stability and activity origin of carbon-supported single-atom/cluster catalysts in cathodic electrocatalysis.