Amorphous Co2B Grown on CoSe2 Nanosheets as a Hybrid Catalyst for Efficient Overall Water Splitting in Alkaline Medium.

In this work, we synthesized a novel hybrid catalyst (Co2B/CoSe2) by growing amorphous Co2B on the surface of CoSe2 nanosheets. Benefiting from the prominent coupled effects between Co2B and CoSe2 nanosheets, an efficient oxygen evolution reaction catalyst Co2B/CoSe2 exhibits a very low overpotential of 320 mV @ 10 mA cm-2 with a Tafel slope of 56.0 mV dec-1 in alkaline medium. An overpotential of 300 mV can also be achieved by Co2B/CoSe2 at the same condition for hydrogen evolution reaction. Notably, at the applied potential of 1.73 V, the electrocatalyst Co2B/CoSe2 demonstrates a current density of 10 mA cm-2 for overall water splitting and displays an outstanding long-term stability. The faradaic efficiencies of Co2B/CoSe2 for both hydrogen and oxygen evolution are close to 100%.