Facile synthesis of CoSe nanoparticles encapsulated in N-doped carbon nanotubes-grafted N-doped carbon nanosheets for water splitting

Rationally designing a high-efficiency, inexpensive and stable electrocatalyst is important in the renewable energy field. Herein, a one-step strategy is adopted to synthesize 3D hybrid of CoSe nanoparticles encapsulated nitrogen-doped carbon nanotubes graft onto nitrogen-doped carbon nanosheets (denoted as [email protected]/NCN) with excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity in acidic and alkaline solutions, respectively. Benefiting from the unique morphology, the large surface area and good conductivity, the hybrid exhibits excellent electrocatalytic HER activity in 0.5 M H2SO4 solution, which is a low overpotential of 197 mV at a current density of 10 mA cm−2 with a Tafel slope of 43 mV dec−1. Meanwhile, it presents a low overpotential of 301 mV at a current density of 10 mA cm−2 with a Tafel slope of 75 mV dec−1 in 1 M KOH solution for OER. The good electrocatalytic property is comparable to most of the previously reported Co-based electrocatalysts and the synthetic method is low toxic and simple, which may be expanded to other transition metal dichalcogenides. The strategy provides a possibility for preparation for effective nonprecious high performance HER and/or OER electrocatalysts.