Abstract
Integrating high-valence metal sites into transition metal-based oxygen evolution reaction (OER) catalysts turns out to be a prevailing solution to replacing noble metal-based electrocatalysts. However, stabilizing the thermodynamically unfavorable high-valence metal sites within the electrocatalyst remains challenging. Hereby, a general strategy is proposed that evokes cooperative geometric and electronic interactions at nanometer coherent interfaces, which effectively stabilizes interfacial high-valence metal sites within homogeneously distributed heterostructures and significantly enhances electrocatalytic activity. As a proof-of-concept study, by derivatizing multicomponent isoreticular hybridized metal-organic frameworks with separated sigma- or pi-bonded moieties, bimetal Ni-Fe selenides heterostructures with nanoscopic compositional and structural homogeneity are grafted. Such heterostructures entail nanometer-sized coherent interfaces that accommodate large geometric distortions and cooperatively stabilize the energetically unfavorable Jahn-Teller active electronic states of high-valence interfacial Ni sites. The presence of high-valence interfacial Ni sites and associated collective Jahn-Teller distortions greatly facilitate the Ni oxidation cycling through Ni3+/Ni4+ transition and stabilizes the *O key intermediate at Ni-Se dual sites, both of which synergistically lowers down the overall OER overpotential.