Non-precious metal high-entropy electrocatalysts (Al0.5NiCoCr-X0.5) for OER application

Abstract

The high entropy alloy electrocatalysts demonstrate exceptional efficiency in the production of hydrogen through water electrolysis. Consequently, the development of durable and economically efficient electrocatalysts has become an urgent objective to accomplish. In order to achieve this goal, a bulk non-precious metal high-entropy alloy, Al0.5NiCoCr-X0.5 (Mo, Mn, Cu, V, Fe), was synthesized and characterized in this study through physical phase analysis and electrochemical property test. To explore the reasons for the influence of the five added elements on the catalytic performance of high entropy alloys in this system and to find the OER electrocatalyst with the best catalytic performance. Electrochemical performance tests were performed in 1 M KOH electrolyte. At a current density of 10 mA·cm−2, the overpotential of the high-entropy alloy catalyst Al0.5NiCoCrMo0.5 was lower than that of the high-entropy alloy with the addition of the other four elements respectively, which was only 327 mV, and lower than that of the conventional noble metal catalyst RuO2, which had an overpotential of 342 mV. This is attributed to the addition of Mo element, which makes Al0.5NiCoCr produce a large number of HCP phases on top of the original FCC phase and a very small number of BCC phases, which is more conducive to the generation of active sites on the surface of the catalysts, and thus improves the OER activity, and the stability can be maintained for at least 20 hours. Therefore, Al0.5NiCoCrMo0.5 high-entropy alloy catalysts can be used in industrial hydrogen production instead of the traditional precious metal catalysts, and it has a rather broad application prospect, and at the same time, it lays a solid foundation for the application of transition metals in catalysts.