Coupled cobalt-doped molybdenum carbide@N-doped carbon nanosheets/nanotubes supported on nickel foam as a binder-free electrode for overall water splitting

ABSTRACT In an attempt to develop low-cost, non-noble-metal bifunctional electrocatalysts for water elec-trolysis in alkaline media, cobalt-doped molybdenum carbide@N-doped carbon nanosheets/nanotubes were fabricated by using C 3 N 4 as the carbon source on a 3D porous nickel foam substrate. Benefiting from the optimized electronic structure and enhanced mass and charge transport, as well as the 3D conducting pathway, Mo x Co y @N-CNS /CNT shows superior performance towards both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. The optimal electrocatalyst is Mo 2 Co 1 @N-CNS /CNT , which reveals a current density of 10 mA cm -2 at the low overpotentials of 99 mV and 300 mV for the HER and OER, respectively, and a relatively low cell voltage (1.63 V) for the overall water electrolysis. The method of optimizing the composition and nanostructure of a material provides a new avenue for the development and utilization of high-performance electrocatalysts.