Morphology control of Co3O4 with nickel incorporation for highly efficient oxygen evolution reaction

Abstract

Co3O4 with different morphologies including nanomeshs, nanorods, and nanowires structures were prepared by one-step hydrothermal method using various precursors. The Co3O4 nanowires arrays showed the optimal oxygen evolution reaction (OER) performance with an overpotential of 394 mV at 20 mA cm−2 and Tafel slope of 112 mV dec−1 in alkaline electrolyte. Subsequently, the effect of Ni doping on OER activity of Co3O4 nanowires arrays was further studied under identical conditions. Notably, the as-prepared 12% Ni-Co3O4 (the molar ratio of Ni to Co is 12%) rendered the best activity with a low overpotential of 340 mV to achieve 20 mA cm−2 and Tafel slope of 60 mV dec−1, and superior stability, outperforming other Ni-Co3O4 samples. Density functional theory (DFT) calculations revealed that the theoretical overpotentials of Co3O4 and Ni-Co3O4 were calculated to be 1.70 V and 0.51 V, respectively, and the chemical conversion from OH* to O* is the rate-limiting step (RLS) with energy barrier of 1.74 eV for Ni-Co3O4. Therefore, this study provides a promising method for designing highly active and stable substitution for noble metal catalysts toward OER.