Designing highly-efficient oxygen evolution reaction FeCoNiCrMnOx electrocatalyst via coexisted crystalline and amorphous Phases: Experiment and theory

The design of phase structure was an effective method to improve the catalytic performance of catalysts. In this work, a new electrocatalyst of FeCoNiCrMn based high entropy oxide (HEO) with coexisted crystalline and amorphous phases was designed and analyzed by experimental and theoretical methods. The raising crystallization of specimen could effectively increase the d electron density and d band center of Ni2+ active ion, which contributed to increase the chemical activity of active ion and adjust the catalytic activity of HEO specimen. The designed HEO specimen with coexisted crystalline and amorphous phases exhibited the fairly low experimental oxygen evolution reaction overpotential of 219 mV at the current density of 10 mA cm -2 and 271 mV at the current density 100 mA cm -2 with the small Tafel slope of 42 mV dec -1, fast charge transfer rate, high intrinsic activity TOF of 0.078 s-1 at experimental overpotential of 350 mV and stable electrocatalytic activity, which were better than single crystalline or amorphous phase. This design strategy would be adopted to provide an effective enhancement scheme for HEO systems.