Amorphous CoB Grown on CoSe Nanosheets as a Hybrid Catalyst for Efficient Overall Water Splitting in Alkaline Medium.

In this work, we synthesized a novel hybrid catalyst (CoB/CoSe) by growing amorphous CoB on the surface of CoSe nanosheets. Benefiting from the prominent coupled effects between CoB and CoSe nanosheets, an efficient oxygen evolution reaction catalyst CoB/CoSe exhibits a very low overpotential of 320 mV @ 10 mA cm with a Tafel slope of 56.0 mV dec in alkaline medium. An overpotential of 300 mV can also be achieved by CoB/CoSe at the same condition for hydrogen evolution reaction. Notably, at the applied potential of 1.73 V, the electrocatalyst CoB/CoSe demonstrates a current density of 10 mA cm for overall water splitting and displays an outstanding long-term stability. The faradaic efficiencies of CoB/CoSe for both hydrogen and oxygen evolution are close to 100%.