16. Amorphous Ruthenium-Sulfide with Isolated Catalytic Sites for Pt-Like Electrocatalytic Hydrogen Production Over Whole pH Range

Li, P., Duan, X., Wang, S., Zheng, L., Li, Y., Duan, H.*, Kuang, Y.*, Sun, X.*
Small 2019, 15, e1904043.
DOI: 10.1002/smll.201904043

Abstract
Electrocatalytic hydrogen evolution reaction (HER) is an efficient way to generate hydrogen fuel for the storage of renewable energy. Currently, the widely used Pt-based catalysts suffer from high costs and limited electrochemical stability; therefore, developing an efficient alternative catalyst is very urgent. Herein, one pot hydrothermal synthesis is reported of amorphous ruthenium-sulfide (RuS_x) nanoparticles (NPs) supported on sulfur-doped graphene oxide (GO). The as-obtained composite serves as a Pt-like HER electrocatalyst. Achieving a current density of −10 mA cm⁻² only requires a small overpotential (−31, −46, and −58 mV in acidic, neutral, and alkaline electrolyte, respectively) with high durability. The isolated Ru active site inducing Volmer–Heyrovsky mechanism in the RuS_x NPs is demonstrated by the Tafel analysis and X-ray absorption spectroscopy characterization. Theoretical simulation indicates the isolated Ru site exhibits Pt-like Gibbs free energy of hydrogen adsorption (−0.21 eV) therefore generating high intrinsic HER activity. Moreover, the strong bonding between the RuS_x and S–GO, as well as pH tolerance of RuS_x are believed to contribute to the high stability. This work shows a new insight for amorphous materials and provides alternative opportunities in designing advanced electrocatalysts with low-cost for HER in the hydrogen economy.