Anion-cation-dual doped tremella-like nickel phosphides for electrocatalytic water oxidation

Abstract Designing high-active earth-abundant electrocatalysts for oxygen evolution reaction (OER) is still a challenge. Elemental doping is an essential strategy to improve catalyst activity. Recent studies have shown that appropriate anion-cation-dual doping could greatly promote performance enhancement of OER electrocatalyst due to the synergistic effect of different dopants. Herein, tremella-like N/Fe dual doping nickel phosphides (N/Fe-Ni2P/Ni12P5) are fabricated for the first time. The N-anion and Fe-cation co-doping synergistically modulate the electronic structure, surface states and microtopography of the sample. The electrochemical surface area and electronic conductivity of the N/Fe-Ni2P/Ni12P5 are thus greatly enhanced. In addition, the computational simulations demonstrate that anion-cation co-doping optimizes adsorption free energy towards oxygen-containing intermediates and thus enhances intrinsic electrocatalytic activity. Consequently, the as-prepared N/Fe-Ni2P/Ni12P5 exhibits splendid OER performances with a low overpotential of 217 mV at the current density of 10 mA cm−2 and an ultra-long durability for over 120 h at high current densities of 500 and 1000 mA cm−2 in 1 M KOH. This work proposes an effective strategy to prepare dual-doped-type phosphide OER electrocatalyst with the promising application potential for large-scale water splitting.