Synthesis of a Porous CoS2-CN/MWCNTs Composite Derived from ZIF-67 for Electrochemical Hydrogen Storage Applications

The porous CoS2/nitrogen-doped carbon (CoS2-CN) polyhedrons were prepared using metal-organic framework as the precursor. After the carbonization of zeolitic imidazolate framework ZIF-67 and the heat treatment with sulfur, the CoS2-CN composite was obtained. Multi-walled carbon nanotubes (MWCNTs) were introduced and evenly intertwined with the CoS2-CN. Eventually, CoS2-CN and Co-CN exhibited good discharge capacities of 498.3 mAh/g and 402.2 mAh/g, respectively. For electrochemical hydrogen storage, more electrochemical active sites could be provided owing to the extraordinary porous nanostructure and large specific surface area inherited from ZIF-67. The N-doped carbon could enhance the conductivity of the materials. The CoS2-CN electrode revealed higher discharge capacity than Co-CN due to the introduction of sulfur species. Moreover, the discharge capacity further increased to 542.8 mAh/g for CoS2-CN/MWCNTs. The loaded MWCNTs could further enhance the conductivity and electrocatalytic activity of CoS2-CN. The high-rate dischargeability, kinetic properties and corrosion resistance were also improved after MWCNTs modification.