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

Atomically dispersed catalysts based on 3d metals have been extensively explored in the catalytic field, but stabilizing 4d and 5d 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 H₂ permeation to weaken metal-metal cohesion in 4d/5d 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-N₄ 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 RuN₄ sites during the H₂-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 4d and 5d transition metals as single-atom catalysts, offering a promising route to develop high-performance electrocatalysts.