Micropore anchoring strategy for Ru nanoclusters toward hydrogen evolution reaction

Hitherto, much of the effort in catalysts has focused on enhancement of intrinsic activity. However, the increase in the number of active sites is equally crucial, especially for noble metal-based catalysts, as it is directly related to the atomic utilization efficiency and economy. Herein, by pyrolyzing ZIF-8 in a H 2 /Ar atmosphere and taking advantage of its reducing property to promote the reduction and volatilization of Zn, the nitrogen-doped carbon (NC-H 2 /Ar) with rich microporous and mesoporous structures is prepared. By means of the anchoring effect of micropores, Ru nanoclusters are formed and homogeneously dispersed on NC-H 2 /Ar (RuNC-H 2 /Ar). Thanks to the efficient mass transport channel provided by a large number of mesopores and the high Ru dispersion, the quantity of effective active sites of RuNC-H 2 /Ar is 2.92 times that of RuNC-Ar which is based on the support obtained by pyrolysis under Ar atmosphere. Therefore, compared with a larger overpotential of 22 mV for RuNC-Ar to achieve 10 mA cm −2 for hydrogen evolution reaction (HER), RuNC-H 2 /Ar only needs 14 mV to achieve the same current density, and its mass activity reaches 43.43 A g −1 @ 50 mV, which is 1.47 and 28.02 times that of RuNC-Ar and commercial Pt/C. In addition, in alkaline seawater, the RuNC-H 2 /Ar still maintains a high activity as 16 mV @ 10 mA cm −2 . Furthermore, this strategy for regulating the pore structure of the support based on H 2 atmosphere can also be extended to other zinc-based zeolitic imidazolate frameworks (Zn-ZIFs). This study provides a regulatory strategy that is both operational and universal for optimizing the pore structure of catalysts and increasing the quantity of effective active sites.