Highly Dispersed Quasi‑1 nm Ruthenium Nanoclusters on Hierarchical Nitrogen-Doped Carbon Nanocages Constructed by Surface-Constrained Sintering for Alkaline Hydrogen Evolution

A cost-efficient catalyst for electrochemical water splitting is crucial to green hydrogen production. Ru has a much lower cost and only slightly stronger adsorption to the hydrogen intermediate (*H) than Pt, demonstrating great potential for catalyzing the hydrogen evolution reaction (HER). Herein, Ru nanoclusters of quasi-1 nm size are highly dispersed on hierarchical N-doped carbon nanocages (hNCNC) by surface-constrained sintering, showing strong metal–support interaction due to the anchoring effect of abundant N dopants. The optimized electrocatalyst exhibits impressive HER performance in 1 M KOH, with a low overpotential of 21 mV at 10 mA cm–2 and superior electrocatalytic stability, which is attributed to the quasi-1 nm Ru nanoclusters with large electrochemical active surface area and optimized *H desorption behavior. This study provides an efficient and inexpensive alkaline HER electrocatalyst and also suggests a convenient strategy to develop highly dispersed noble-metal-based electrocatalysts by surface-constrained sintering.