Summary

Metal aggregation, caused by high current density or long-cycling catalysis, severely affects the stability of ruthenium (Ru)-based catalysts toward hydrogen evolution reaction (HER). Herein, we constructed an anti-growth strategy of phosphorus (P)-induced Ru clusters (1.3 nm) integrated with adjacent Ru single atoms on nitrogen (N)-doped carbon fibers (Ru_SA/NP-PNCFs) for ultra-stable HER. The Ru_SA/NP-PNCFs exhibit outstanding activity (8 and 132 mV at 10 and 1,000 mA cm⁻²) and record durability (100,000 cycles and 1,000 h at 600 mA cm⁻²). Thanks to the optimized binding energy and orbital interaction between Ru and P/N, the size variation is only 0.8 nm, and single atoms are also well preserved. Both experiments and theoretical simulations indicate that the heteroatom P can not only boost the capacity of H₂O dissociation but also suppress the aggregation of Ru clusters and single atoms during HER. This work provides an effective strategy for designing stable metal cluster-single-atom systems for advanced electrocatalysts.