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

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.