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

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 TaCo 2 as the starting point, the minor inclusion of a ductile Cu element in TaCo 2 to form ternary TaCu 0.25 Co 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 ( η 10 ) increases by ca. 20 mV from TaCo 2 to TaCu 0.25 Co 1.75 . Further incorporation of a HER active Ru element to cast quaternary TaCu 0.125 Ru 0.125 Co 1.75 can decrease ca. 70 mV of η 10 while maintaining long-term stability. This proves that one can design functional intermetallic compounds intentionally, which may be extended to different fields of application.