Mo-Migration-Induced Secondary Surface Reconstruction Enables Highly Efficient Oxygen Evolution Reaction

Developing efficient and stable catalysts by exploiting dynamic structural changes during the oxygen evolution reaction (OER) remains a significant challenge. In this work, we engineer atomically dispersed Mo sites within an FeNiOOH catalyst through Mo-migration-induced reconstruction. Synchrotron radiation spectroscopy reveals the bridged Mo–O moiety in FeNiOOH, which effectively modulates the local structure of (oxy)hydroxides. Moreover, this structural adjustment can further drive the phase transformation from routine γ-FeNiOOH to the more active β-FeNiOOH, as identified by in situ Raman spectroscopy. The effective Mo-FeNiOOH catalyst achieves a remarkably low overpotential of 184 mV for the OER at 10 mA cm –2 for over 100 h. By integration with Pt/C, the Mo-FeNiOOH || Pt/C cell exhibits a low voltage of 1.42 V at 10 mA cm –2 in overall water splitting. This secondary reconstruction strategy advances the rational design of high-efficiency OER catalysts for eco-friendly energy technologies.