Novel Hierarchical Porous Carbon for Fabrications of Ru/NHPC Catalysts with the High Hydrogen Evolution Reaction Performance (Supporting Information)

To enhance the performance of Ru in hydrogen evolution reaction (HER), the design and fabrication of catalytic supports become one of the critical research topics. Carbon supports possessing the excellent conductivity and remarkable cost advantage have become one of the primary choices in fabrications of composite catalysts. In our present studies, the NHPC (N-doped hierarchical porous carbon) supports are fabricated by the carbonizations of soluble starch, ammonium citrate and sodium bicarbonate, and the Ru/NHPC catalysts are successfully prepared by the reactions of RuCl₃·3H₂O with NaBH₄ and NHPC in the ultrasonic treatment. As a result, it is found that Ru goodly dispersed on the surfaces of NHPC in nano sizes, and the Ru/NHPC catalysts manifest the fabulous HER performance. For instance, the overpotential of 11.2 %Ru/NHPC (the loading of RuCl₃·3H₂O is 0.05 g) is 33 mV at a current density of 10 mA cm⁻², which is remarkably lower than 48 mV of glassy carbon electrode (20 %Pt/C) in alkaline medium (1 M (mol L⁻¹) KOH). The Tafel slope of 11.2 %Ru/NHPC is 36 mV dec⁻¹ at 10 mA cm⁻² in the same conditions. Although the 11.2 %Ru/NHPC is in the acidic medium (0.5 M H₂SO₄), it also displays the routine HER performance. In short, this present study provides a useful approach to facilitate the application of Ru as a hydrogen evolution catalyst.