Transition metal

Nanocages

Oxygen evolution

Physical chemistry

Catalysis

Valence (chemistry)

Tafel equation

Electrode

Organic chemistry

Inorganic chemistry

Chemistry

Overpotential

Metallurgy

Materials science

Spinel

Oxide

Electrochemistry

Biochemistry

Journal of the American Chemical Society

A major challenge that prohibits the practical application of single/double-transition metal (3d-M) oxides as oxygen evolution reaction (OER) catalysts is the high overpotentials during the electrochemical process. Herein, our theoretical calculation shows that Fe will be more energetically favorable in the tetrahedral site than Ni and Co, which can further regulate their electronic structure of binary NiCo spinel oxides for optimal adsorption energies of OER intermediates and improved electronic conductivity and hence boost their OER performance. X-ray absorption spectroscopy study on the as-synthesized NiCoFe oxide catalysts indicates that Fe preferentially dopes into tetrahedral sites of the lattice, which induces high proportions of Ni3+ and Co2+ on the octahedral sites (the active sites in OER). Consequently, this material exhibits a significantly enhanced OER performance with an ultralow overpotential of 201 mV cm-2 at 10 mA cm-2 and a small Tafel slope of 39 mV dec-1, which are much superior to state-of-the-art Ni-Co based catalysts.

Valence Engineering via Selective Atomic Substitution on Tetrahedral Sites in Spinel Oxide for Highly Enhanced Oxygen Evolution Catalysis