Synthesis of atomically dispersed catalysts via hydrogen embrittlement-like assisted thermal activation for acidic oxygen reduction

Atomically dispersed catalysts based on 3 d metals have been extensively explored in the catalytic field, but stabilizing 4 d and 5 d metals like Ru, Pd, and Pt as single atoms remains a challenge due to their high cohesive energies. Herein, we develop a hydrogen-embrittlement-inspired strategy that leverages H 2 permeation to weaken metal-metal cohesion in 4 d /5 d metal clusters during high-temperature synthesis. Hydrogen diffuses into the clusters, driving their dissociation into individual atoms, which are subsequently stabilized by nitrogen dopants in carbon supports, resulting in the formation of stable M-N 4 single-atom sites. Taking Ru as a model system, ex-situ microscopy and spectroscopy offer definitive evidence that hydrogen permeation disrupts Ru-Ru bonding interactions, facilitating the conversion of Ru clusters into isolated RuN 4 sites during the H 2 -assisted thermal activation process. Consequently, the prepared NC-Ru-950 catalyst achieves satisfactory activity and stability for acidic oxygen reduction and proton exchange membrane fuel cells. This work introduces a robust and universal strategy for stabilizing 4 d and 5 d transition metals as single-atom catalysts, offering a promising route to develop high-performance electrocatalysts.