Enhanced oxygen evolution activity in NiFe layered double hydroxides via Ce doping and oxygen vacancy engineering

초록

The overall pace of water electrolysis is governed by the comparatively slow oxygen evolution step, and rational electronic-structure control of transition-metal hydroxides offers a direct route to accelerate OER kinetics. Using density-functional theory (DFT), this study elucidates how cerium (Ce) doping and oxygen vacancies (Vo) jointly reshape the electronic structure and the oxygen-evolution pathway of NiFe layered double hydroxide (NiFe-LDH). Ce substitution downshifts the O-2p and Ni/Fe-3d bands, stabilizing metal–oxygen bonding, while hybridization among Ce-4f, O-2p, and Ni/Fe-3d (a d–p–f network) drives electron redistribution. The presence of Vo promotes polaronic charge transfer via hopping rather than band-like conduction. In this context, the electronic structure is consistent with metal-centered localized states associated with oxygen vacancies and Ce dopants, rather than band-like itinerant carriers. These electronic rearrangements mitigate antibonding interactions in M–O bonds, enhance electronic connectivity for polaron hopping, and reduce the highest computed free-energy barrier along the sequence of surface-bound intermediates in the oxygen-evolution pathway. Across the compositions and defect configurations examined, the barriers decrease, and the preferred active site shifts from Ni to Fe when Vo is present. Overall, dopant-triggered d–p–f electronic redistribution, coupled with defect-mediated charge control, offers a practical handle for regulating the reactivity of transition-metal hydroxide catalysts.

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