A step-by-step strategy to design active and stable quaternary intermetallic compounds for the hydrogen evolution reaction

Abstract

Multinary intermetallic compounds with rich chemical compositions enable one to achieve a logical design for desired materials based on the required function. In this work, we have demonstrated a step-by-step strategy to design a quaternary intermetallic compound that exhibits highly active and stable performance for the hydrogen evolution reaction (HER). With binary intermetallic TaCo₂ as the starting point, the minor inclusion of a ductile Cu element in TaCo₂ to form ternary TaCu_0.25Co_1.75 can substantially lower the degradation rate from ca. 20% to 5% after sintering treatment (i.e., enhance connectivity between particles). However, the overpotential at a current density of 10 mA cm⁻² (η₁₀) increases by ca. 20 mV from TaCo₂ to TaCu_0.25Co_1.75. Further incorporation of a HER active Ru element to cast quaternary TaCu_0.125Ru_0.125Co_1.75 can decrease ca. 70 mV of η₁₀ while maintaining long-term stability. This proves that one can design functional intermetallic compounds intentionally, which may be extended to different fields of application.