Self-supported nickel-cobalt nanowires as highly efficient and stable electrocatalysts for overall water splitting.

The development and design of highly active and stable electrocatalysts based on cheap and Earth-abundant materials is critically important to enable water splitting as a desirable renewable energy source. Herein, we fulfill the significant electrochemical water splitting enhancement in both electrocatalytic activity and durability by constructing self-supported nickel-cobalt nanowire catalysts with abundant oxygen vacancies. Specifically, the rich oxygen vacancies can largely promote the oxygen evolution reaction (OER) activity of optimal Ni1Co1O2 NWs with a relatively low overpotential of 248 mV to drive a current density of 10 mA cm-2. More significantly, after the phosphorization of Ni1Co1O2 NWs, the resultant Ni1Co1P NWs can also display excellent electrocatalytic hydrogen evolution reaction (HER) performances with an overpotential of only 101 mV to achieve a current density of 10 mA cm-2. Furthermore, benefiting from the unique 1D nanowire structure, the synergistic effect, and the optimal Gibbs free energy for hydrogen evolution evolved from the phosphorization, the Ni1Co1O2 NWs//Ni1Co1P NWs couple is thus highly active and stable for overall water electrolysis with a low voltage of 1.58 V at 10 mA cm-2, showing extraordinary promise for practical overall water splitting electrolysis.