Bimetallic co-doping engineering over nickel-based oxy-hydroxide enables high-performance electrocatalytic oxygen evolution

Enhancing the electrocatalytic oxygen evolution reaction (OER) performance is essential to realize practical energy-saving water electrolysis and CO₂ electroreduction. Herein, we report a bimetallic co-doping engineering to design and fabricate nickel-cobalt-iron collaborative oxy-hydroxide on nickel foam that labeled as NiCoFeO_xH_y-NF. As expected, NiCoFeO_xH_y-NF exhibits an outstanding OER activity with current density of 10 mA cm^-2 at 194 mV, Tafel slope of 53 mV dec^-1, along with the robust long-term stability, which is significantly better than bimetallic NiCo and NiFe combinations. Comprehensive computational simulations and characterizations jointly unveil that the twisted ligand environment induced by heteroatoms ensures the balance strength between the metal-oxygen hybrid orbital states and the oxidized intermediates adsorption, thus lowering the oxygen cycling energy barriers for overcoming the sluggish OER kinetics. Moreover, a novel phase transition behavior is monitored by in-situ Raman spectra under OER operating conditions, which facilitates electron-mass transfer as well as boosts the exposure of activity sites. For practical applications, Ni₂P-NF || NiCoFeO_xH_y-NF and Cu || NiCoFeO_xH_y-NF couples were constructed to realize high-efficiency water electrolysis and CO₂ electrochemical reduction for the production of valuable H₂ and C₂H₄, respectively. This work elucidates a novel mechanism by which bimetallic co-doping improves the electrocatalytic OER activity of nickel-based hydroxides.