Synergistic cation-anion dual-doping triggering accelerated phase reconstruction for efficient oxygen evolution reaction.

Abstract

Electrochemical reconstruction of precatalysts into active (oxy)hydroxides is essential to the oxygen evolution reaction (OER), yet achieving phase transformation with cation-anion co-modulation of the electronic structure remains challenging. Thus, we report S-Fe-NiMoO4 nanorod arrays as an OER precatalyst, in which the partial leaching of MoO42- and S species triggers structural destabilization and rapid reconstruction into the S-Mo/Fe-NiOOH active phase. Density functional theory (DFT) calculations indicate that the weakened intermediate adsorption in the *O → *OOH step on S-Mo/Fe-NiOOH reduces the energy barrier. The S-Fe-NiMoO4 precatalyst delivers outstanding OER activity with mere 238 mV at 100 mA cm-2. A low cell voltage of 1.52 V is required to drive 10 mA cm-2 in an asymmetric two-electrode alkaline electrolyzer of the S-Fe-NiMoO4||Fe-NiMoO4 couple, with sustained stability over 120 h and near-unity Faradaic efficiency. This work establishes a dual-doping dynamic phase engineering strategy for designing durable and high-performance OER electrocatalysts toward industrial-scale water electrolysis.