NiSe2 Anchored N, S-Doped Graphene/Ni Foam as Free-Standing Bi-Functional Electrocatalyst for Efficient Water Splitting

It is still challengeable to develop nonprecious free-standing bi-functional electrocatalysts with high efficiencies for hydrogen and oxygen evolution reactions. Herein, for the first time, we present a novel hybrid electrocatalyst synthesized via a facile hydrothermal reaction, which is constructed by ultrafine NiSe2 nanoparticles/nanosheets homogenously anchored on a 3D graphene/nickel foam (NiSe2/3DSNG/NF). This hybrid delivers superior catalytic performances for hydrogen/oxygen evolution reactions and overall water splitting: it shows an ultra-small Tafel slope of 28.56 mV dec-1 for hydrogen evolution in acid, and a low Tafel slope of 42.77 mV dec-1 for oxygen evolution reaction; particularly, in a two-electrode setup for water splitting, it requires an ultra-small potential of 1.59 V to obtain 10 mA cm−2 with nearly 100% faradaic efficiencies for H2 and O2. This study presents a new approach of catalyst design and fabrication to achieve highly efficient and low-cost water electrolysis.