Regulating metal-oxygen covalency in reconstructed sulfurized high-entropy perovskite to activate and stabilize lattice oxygen for oxygen evolution reaction

Abstract

Switching adsorbate evolution mechanism (AEM) to lattice oxygen mechanism (LOM) can break the theoretical limit of catalytic activity for oxygen evolution reaction (OER). However, LOM-dominated catalysts are difficult to simultaneously obtain high activity and stability because of their trade-off relationship. Here, we report a reconstructed sulfurized high-entropy perovskite (S-LaNiFeCoCrMnO3) possesses excellent activity with an overpotential of 165 mV and has a high catalytic stability for 1800 h at 10 mA/cm2 toward the OER. Furthermore, the S-LaNiFeCoMnCrO3 as anode catalyst in anion exchange membrane water electrolyzer exhibits a high current density of 5.8 A/cm2 at the cell voltage of 2.0 V. On line differential electrochemical mass spectrometry results suggest that the increased reactivity of lattice oxygen in reconstructed S-LaNiFeCoCrMnO3 facilitates the enhancement of OER activity. X-ray absorption near-edge structure and in situ Raman spectroscopy results reveal that the local Ni-S bond in the sulfurized layer on the surface of S-LaNiFeCoCrMnO3 drives the generation of Fe-NiOOH active phase with NiO2 subunit layer and high-valent Ni4+ species. Furthermore, strong covalent Ni-O and weak covalent Fe-O bonds in the Fe-NiOOH active phase play a critical role of activating and stabilizing lattice oxygen, thus breaking the activity-stability trade-off relationship for the LOM.