Unraveling structure-related reconstruction during oxygen evolution reaction (OER) and its correlation with intrinsic electrocatalytic activity is of great significance for designing better catalysts but unfortunately remains elusive. Herein, ultrathin Ni-Fe layered-double-hydroxides (LDH) with inherent oxygen vacancies (V O ) are successfully fabricated via coprecipitation under a controlled manner, which accomplish a quite low overpotential of 230 mV at 10 mA cm −2 in 1.0 M KOH and perform among the best of recently reported nonprecious electrocatalysts. During the OER, inherent V O is experimentally and theoretically evidenced to boost surface reconstruction and the operando formation of p−n interfaces (i.e., γ-Ni-Fe LDH/α-Ni-Fe LDH) via deprotonation. On such reconstructed interfaces, the V O in both surface γ-Ni-Fe LDH and bulk α-Ni-Fe LDH can alter the electron densities of metal sites and subsequently optimize the free energies of a multistep OER pathway, which accounts for the boosted OER activity and, more importantly, identifies the correlation of electrocatalysis with both the catalyst surface and bulk.

Modulating the dynamic change of catalysts is significant for understanding the mechanism and exploiting better electrocatalysts but remains challenging in oxygen evolution reaction (OER). Herein, ceria-promoted reconstruction of Ni-X (X = S, P, and O) is investigated to unravel the correlation between the reconstructed surface and the OER performance, which further guides the design of prominent electrocatalysts. Interfacial CeO 2 promotes the in situ reconfiguration of Ni-X via strengthening hydroxyl adsorption, generating highly active CeO 2 -NiOOH interfaces. Moreover, rich oxygen vacancies formed after breaking Ni-S/P bonds and leaching S/P anions render Ni 3 S 2 and Ni 2 P superior to NiO with the same CeO 2 modification, highlighting another dependence on pre-catalyst materials chemistry. Theoretical analysis further confirms that the co-presence of CeO 2 -NiOOH interfaces and oxygen vacancies can harmoniously regulate intermediate chemisorption toward favorable OER kinetics. As a proof of concept, CeO 2 -modified Ni 3 S 2 exhibits low overpotentials of 251 and 364 mV at the current densities of 10 and 100 mA cm −2 in 1.0 M KOH, respectively, performing among the best of recently reported Ni-based counterparts.

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Single-layer CoFe layered-double-hydroxides (CoFe LDH-S) are successfully fabricated under a near-anhydrous condition, thanks to the weakened hydrogen bonds between monolayers. Benefiting from the single-layer structure with rich defects and disordered...