Paired Ru-O-Mo ensemble for efficient and stable alkaline hydrogen evolution reaction

TL;DR

This paper introduces Ru-O-Mo site engineering in Ru/MoO2 catalysts, significantly enhancing water adsorption and achieving record-low overpotentials for alkaline HER, with excellent stability, advancing electrochemical hydrogen production.

Contribution

The study demonstrates a novel Ru-O-Mo interface construction that greatly improves water adsorption and catalytic performance in alkaline HER, surpassing existing catalysts.

Findings

Ru-O-Mo sites exhibit tenfold stronger H2O adsorption than Ru.

Achieved a record-low overpotential of 16 mV at 10 mA/cm².

Catalysts maintained performance over 40 hours without decline.

Abstract

Electrocatalytic hydrogen evolution reaction (HER) in alkaline media is a promising electrochemical energy conversion strategy. Ruthenium (Ru) is an efficient catalyst with a desirable cost for HER, however, the sluggish H2O dissociation process, due to the low H2O adsorption on its surface, currently hampers the performances of this catalyst in alkaline HER. Herein, we demonstrate that the H2O adsorption improves significantly by the construction of Ru-O-Mo sites. We prepared Ru/MoO2 catalysts with Ru-O-Mo sites through a facile thermal treatment process and assessed the creation of Ru-O-Mo interfaces by transmission electron microscope (TEM) and extended X-ray absorption fine structure (EXAFS). By using Fourier-transform infrared spectroscopy (FTIR) and H2O adsorption tests, we proved Ru-O-Mo sites have tenfold stronger H2O adsorption ability than that of Ru catalyst. The catalysts with Ru-O-Mo sites exhibited a state-of-the-art overpotential of 16 mV at 10 mA cm-2 in 1 M KOH electrolyte, demonstrating a threefold reduction than the previous bests of Ru (59 mV) and commercial Pt (31 mV) catalysts. We proved the stability of these performances over 40 hours without decline. These results could open a new path for designing efficient and stable catalysts.