Phosphorylation Modulation of the Electronic Structure of CoMn Aerogels for Enhanced Oxygen Evolution Reaction in...

Developing inexpensive, highly active and stable nonprecious metal-based electrocatalysts to improve the catalytic performance of oxygen evolution reaction (OER) is critical for realizing the large-scale implementation of electrochemical water splitting, metal air batteries, and other green energy devices. Herein, we report a facile phosphorylation approach that can modulate the electronic structure of CoMn aerogel to improve the OER performance in alkaline media. The as-prepared PO₄ ^3--CoMn-Aerogel catalyst exhibited excellent OER performance in 1 M KOH, evidenced by a low overpotential of 254.4 mV to afford a current density of 10 mA cm^-2 and a small Tafel slope of 101.98 mV dec^-1, superior to the RuO₂ benchmark catalyst. Moreover, PO₄ ^3--CoMn-Aerogel demonstrated robust long-term stability, as it was able to operate stably for 35 h without significant current decay. Multiple characterization techniques indicated that the phosphorylation dramatically modulates the electronic structure and local chemical microenvironment of the CoMn-Aerogel. Density functional theory calculations validated that, at the equilibrium potential of 1.23 V, the transformation of *O to *OOH constitutes the rate-determining step, and surface phosphorylation significantly lowers the associated free energy barrier to 0.82 eV. This study offers an effective strategy that can engineer the transition metal aerogel-based electrocatalysts with improved catalytic performance toward OER.