Covalent organic framework assisted low‐content ultrafine Ru on porous N‐doped carbon for efficient hydrogen evolution reaction

Pt‐based materials are the benchmarked catalysts in the cathodic hydrogen evolution reaction (HER) of water splitting; the prohibitive cost and scarcity of Pt immensely impede the commercialization of hydrogen energy. Ru has aroused significant concern because of its Pt‐like activity and much lower price. However, it’s still a top priority to minimize the Ru loading and pursue the most superior cost performance. Herein, N‐rich covalent organic framework (COF) was employed to assist the preparation of ultrafine Ru, including nanoclusters and single atoms loaded onto porous N‐doped carbon by a simple impregnation‐pyrolysis process with a low Ru content of 6.60 wt%, exhibiting superior HER activity with mass activity of 21.86 and 11.52 A·mg −1 Ru (@100 mV) in alkaline and acidic conditions, separately 14.7 and 2.12 times higher than that of commercial Pt/C. Both alkaline and acidic HERs proceed via the Volmer–Tafel route with the Tafel step as the rate‐determining step (RDS), and the alkaline HER contains the water dissociation on Ru single atoms and H desorption on Ru nanoclusters accompanied by H transfer between the two. The simple synthesis, low‐content Ru and exceptional activity render our catalyst greatly promising as an alternative to commercial Pt/C in the advancement of hydrogen economy.