Boosting the hydrogen evolution reaction activity of Ru in alkaline and neutral media by accelerating water dissociation

Abstract

Electrochemical water splitting via a cathodic hydrogen evolution reaction (HER) is an advanced technology for clean H₂ generation. Ru nanoparticle is a promising candidate for the state-of-the-art Pt catalyst; however, they still lack the competitiveness of Pt in alkaline and neutral media. Herein, a ternary HER electrocatalyst involving nano Ru and Cr₂O₃ as well as N-doped graphene (NG) that can work in alkaline and neutral media is proposed. Cr₂O₃ and NG feature strong binding energies for hydroxyl and hydrogen, respectively, which can accelerate the dissociation of water, whereas Ru has weak hydrogen binding energy to stimulate hydrogen coupling. The HER activity of Ru is greatly enhanced by the promoted water-dissociation effect of NG and Cr₂O₃. To achieve a current density of 10 mA cm⁻², the as-obtained Ru–Cr₂O₃/NG only needs a very low overpotential of 47 mV, which outperforms the activity of Pt/C in alkaline media. The strategy proposed here, multi-site acceleration of water dissociation, provides new guidance on the design of a highly efficient, inexpensive, and biocompatible HER catalyst in nonacidic condition.