Constructing bundle-like Co-Mn oxides and Co-Mn selenides for efficient overall water splitting

Abstract

Making easy-to-make, cost-efficient, and durable electrocatalysts for overall water splitting to produce oxygen and hydrogen is of paramount significance for future renewable energy systems but is still a challenge. Herein, mesoporous CoMn and CoMnSe nanobundles are successfully constructed via a facile one-pot hydrothermal approach. It is discovered that the Mn introduction in Co oxides can simultaneously tune their electronic structure and modulate the nanobundle morphology. As a result, benefitting from the 3D open nanobundle structure, the self-supported Co₁Mn₁ oxide exhibits unprecedented oxygen evolution reaction (OER) activity with an ultralow overpotential of 221 mV at 10 mA cm⁻². Moreover, such a nanobundle-like structure also enables the Co₁Mn₁Se catalyst to exhibit outstanding hydrogen evolution reaction (HER) activity with a relatively low overpotential of 87.3 mV at 10 mA cm⁻², surpassing those of previously reported non-precious metal catalysts. More importantly, taking advantage of their excellent OER and HER activity, an advanced water electrolyzer through exploiting Co₁Mn₁ oxide and Co₁Mn₁Se nanobundles as the anode and cathode is fabricated, which gives an impressive water-splitting current density of 10 mA cm⁻² in 1.0 M KOH solution at 1.60 V with remarkable stability over 36 h, holding great potential for efficient overall water splitting electrocatalysis.