An Intermetallic CaFe ₆ Ge ₆ Approach to Unprecedented Ca−Fe−O Electrocatalyst for Efficient Alkaline Oxygen Evolution Reaction

Based on the low-cost and relatively high catalytic activity, considerable efforts have been devoted towards developing redox-active transition metal (TM)-oxygen electrocatalysts for alkaline oxygen evolution reaction (OER) while role of redox-inactive earth metals has often neglected in OER. Herein, first time, we developed a novel ternary intermetallic CaFe6Ge6 precatalyst, whose surface rapidly transforms into porous ultrathin Ca−Fe−O heteroshell structure during OER through oxidative leaching surficial Ge. Benefiting from synergistic effects, this highly efficient OER-active material with distinct layers large electrochemical area more exposed active Fe sites than Ca-free FeOx phase. Also, presence Ca is responsible enhanced transport activation hydroxyls related intermediate as unequivocally illustrated by combination quasi in-situ Raman spectroscopy various ex-situ methods.