Gadolinium‐Induced Activation of CoNiO ₂ for Efficient Oxygen Evolution: A Structural and Electronic Modulation Approach

Multicomponent transition metal oxides (TMOs) incorporating rare‐earth (RE) elements have emerged as promising materials for the oxygen evolution reaction (OER). However, knowledge of how to regulate the structure of TMO‐based nanomaterials through RE incorporation to enhance catalytic performance remains limited. Here, we report a simple one‐step microemulsion method for synthesizing cobalt‐nickel oxide (CoNiO 2 ) alloys with gadolinium‐induced structural modulation, yielding a pronounced multimetallic synergistic effect that enhances the OER. Notably, Gd incorporation into CoNiO 2 induces the formation of a two‐dimensional morphology (2D‐GdCoNiO x ), which fine‐tunes the electronic structure, generates tensile strain, increases oxygen vacancies, and promotes electron accumulation around oxygen sites. Consequently, 2D‐GdCoNiO x exhibits high electrochemical performance, delivering an overpotential of 219 mV at 10 mA cm −2 , along with excellent stability over 250 h at both 10 and 100 mA cm −2 . In situ Raman spectroscopy and X‐ray absorption spectroscopy, together with Bader charge analysis, reveal that Gd incorporation regulates the local microenvironment and induces electron accumulation at metal–oxygen units within asymmetric Gd‐O‐Ni/Co sites. This effect originates from the polarized ionic character of the Gd‐O bond and enables multiple adjacent sites to more effectively adsorb OH − intermediates during the OER, thereby optimizing adsorption energies at segmentally synergistic sites and enhancing catalytic activity. Theoretical calculations further confirm that Gd inclusion modifies the electronic structure, increases electrical conductivity, and promotes catalytic activity. Overall, this study presents a new strategy for designing highly efficient two‐dimensional multicomponent TMOs incorporating RE elements for the OER.