Unconventional-phase engineering of RuGa intermetallics for boosting alkaline hydrogen-electrode reactions

Abstract

Constructing high-efficient Ru-based electrocatalysts for hydrogen electrode reactions, including the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER), is crucial for the development of hydrogen energy economy. However, the strong hydrogen adsorption at the Ru site leads to poorer HOR/HER kinetics than those of the commercial Pt catalysts. Herein, a RuGa intermetallic electrocatalyst with a unique body-centered cubic (bcc) phase was successfully synthesized to improve the HOR/HER performance. The deconvolution analysis of the hydrogen desorption peak indicated weak hydrogen adsorption and presence of a high proportion of highly active sites of the bcc-phased RuGa intermetallic. The in situ electrochemical attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) study further confirmed the enhanced interfacial water adsorption ability of the RuGa surface. As expected, the unconventional bcc-phased RuGa intermetallic exhibited superior HOR/HER performance. For the HOR, the RuGa intermetallic exhibited a mass activity of 1.84 mA μg_PGM⁻¹ at an overpotential of 50 mV, which was about 12-fold higher than the that of the conventional hcp-phased Ru/C and even 2-fold higher than that of the commercial Pt/C. For HER, only 18 mV and 72 mV overpotentials were needed to deliver 10 mA cm⁻² and 100 mA cm⁻² current density, respectively. Furthermore, the RuGa intermetallic exhibited significant catalytic durability and strong tolerance to CO poisoning. Thus, the unconventional-phase engineering strategy reported in this work is significant for the subsequent exploration and structural designing of high-performance electrocatalysts.