Well-dispersed pyrite-type RuS2 nanocrystals anchored on porous nitrogen and sulfur co-doped hollow carbon spheres for enhanced alkaline hydrogen evolution

Abstract

The hydrogen evolution reaction (HER) activity in alkaline condition is generally suppressed due to sluggish water dissociation–related Volmer process. Consequently, developing new highly-active and cost-efficient electrocatalysts for the alkaline hydrogen production is greatly desirable for achieving sustainable water splitting in industrial plants. Pyrite-type RuS2 is a potential excellent electrocatalyst for alkaline HER but the related research is still in its infancy. Herein, well-dispersed crystalline RuS2 nanoparticles (c-RuS2 NPs) with ultrasmall particle size anchored on porous nitrogen and sulfur co-doped hollow carbon spheres (NSC) are synthesized for alkaline HER electrocatalysis. The conductive and porous hollow carbon spheres with nitrogen and sulfur doping is used as the effective support to provide abundant anchoring sites and modify the electronic structure of RuS2, beneficial to increasing the active sites and improving the intrinsic activity. Furthermore, the crystallinity modulation of ruthenium sulfide also has a significant impact on HER activity. In 1.0 M KOH solution, the proposed c-RuS2 NPs/NSC catalyst exhibits admirable activity for HER electrocatalysis with a low overpotential of 11 mV at a current density of 10 mA cm−2 and a small Tafel slope of 35.4 mV dec−1. With low Ru loading, superior hydrogen evolution in alkaline media is achieved for c-RuS2 NPs/NSC compared to the commercial Pt/C and the reported ruthenium-sulfide-based electrocatalysts.