Understanding the interatomic electron transfer effect on boosting electrocatalytic water splitting over Nd-Co3O4 nanosheets self-supporting electrode

Abstract

Regulating the orbital spin-electron filling of metal centers via interatomic electron transfer in transition metal oxides is one promising approach to enhancing their electrocatalytic oxygen evolution reaction (OER) performances, while it is still a challenge due to lacking of efficient strategy and deep understanding. In this work, a facile strategy containing electrochemical deposition and annealing in air atmosphere has been proposed to introduce monodispersed neodymium (Nd) atoms into spinel Co₃O₄ nanosheets to trigger the electron transfer. Accordingly, the as-prepared Nd doped Co₃O₄ nanosheets (Nd/Co₃O₄) on nickel foam or carbon cloth showed greatly enhanced OER performances, with low overpotential of 284 and 396 mV at 10 mA cm⁻², small Tafel slope of 95 and 119 mV dec⁻¹ in 1.0 M KOH and 0.5 M H₂SO₄, respectively. The experimental and density function theory results coherently indicate that the charge transfer in the Nd-O-Co asymmetric configuration not only enhances the conductivity of Co₃O₄, but also regulates the filling degree of e_g orbitals of Co, leading to higher spin states, optimized adsorption ability, and accelerated H₂O dissociation process, thus achieving boosted OER activity.