Spin-State Transition Represses the Surface Reconstruction for Efficient Water Oxidation

Spin-state manipulation holds great potential for navigating the reconstructed behavior during the oxygen evolution reaction (OER) due to the modified d–p orbital hybridization. Herein, we proposed a spin-state transition repressed surface reconstruction strategy by fabricating the iridium (Ir)-doped NiCo hydroxide with low spin-state Co sites as an efficient and stable OER catalyst. Ir doping induces spin asymmetry to be broken, alters the Co spin state from eg2 to eg0.6, and changes the orbital hybridization of Co(Ni)-O, effectively reducing the oxidation of metal sites in the catalytic reaction due to the alleviated accumulation of OH– on the surface, thus repressing the surface reconstruction. Notably, the stable Ir-NiCo LDH exhibited a low overpotential (245 mV at 10 mA cm–2) and steadily operated for over 100 h. The enhanced performance resulted from the introduction of high-active Ir and the up-shifted Co d-band center, which promote the generation of key *OOH intermediates. This work supplies a new platform for the development of effective OER catalysts based on the relationship between the electronic spin-state and surface reconstruction.