Operando deciphering the activity origins for potential-induced reconstructed oxygen-evolving catalysts

Fe incorporated Ni-based electrocatalysts have emerged as one of the most active oxygen-evolving catalysts under alkaline conditions and deciphering the effect of iron incorporation in enhancing the activity is challenging but critical for the catalyst design. Herein, the as-prepared nanocube Ni-based catalysts underwent a reconstruction process and transformed from γ-NiOOH to β-NiOOH structure by iron incorporation under the applied bias, which was confirmed by in-situ Raman measurement. According to the methanol oxidation current response difference, the hydroxyl adsorption intensity was proposed to be regulated by iron incorporation and the rate-determining step would be the formation of *OOH for Fe-doped β-NiOOH, which was further supported by DFT calculation. This work reveals the effect of iron-doped on the phase structure transform and the regulation of intermediate species elaborately and offers new insight on the understanding of the activity origins for NiFe-based catalysts.