Deep Electronic Structure Modulation of the Self-Deposited Active Layer on FeNi intermetallic compounds via an Interfacial CeO2 Electron Pump for Efficient Oxygen Evolution Reaction

Although FeNi intermetallic compounds (IMCs) are promising pre-catalysts for the oxygen evolution reaction (OER) due to their ability to in-situ form a stable Ni 1-x  Fe x  OOH active layer, their activity is ultimately limited by the saturation of Fe 3+ incorporation into the lattice. To overcome this limitation, we introduce CeO 2 as an external electron regulator to construct a carbon-coated heterostructure (C@CeO 2 /FeNi). At the interface, CeO 2   acts as an electron pump, working synergistically with Fe 3+ to enable deep electronic modulation of the self-deposited active layer, thereby breaking through the performance ceiling of FeNi IMCs. The optimal C@CeO 2 /FeNi-0.3 catalyst achieves a low overpotential of only 211   mV at a current density of 10   mA   cm -2 and a small Tafel slope of 54   mV dec -1 in 1.0   M KOH, significantly surpassing its CeO 2 -free counterpart. In addition, it exhibits remarkable stability: after continuous electrolysis for 100   hours at overpotentials of 230 and 350   mV, the activity of this material decays by only 10% and 8.3%, respectively. This work demonstrates that interfacial electron-pump engineering is an effective strategy to push the performance boundaries of alloy-based OER catalysts.