Designed synthesis of porous NiMoO4/C composite nanorods for asymmetric supercapacitors

Abstract

Porous and carbon composited binary transition metal oxide nanomaterials provide high ionic conductivity and electronic conductivity. However, it still remains a challenge to use a simple method to achieve in situ both composite and porous one-dimensional (1D) nanorods. In this paper, we have prepared porous NiMoO₄/C (NMO/C) composite nanorods using a solvothermal method and subsequent annealing step. In the solvothermal reaction, a simple organic solvent, cyclohexane, was introduced as a carbon source and pore-forming agent, realizing the controllable synthesis of porous 1D nanorods composited with heteroatoms via a simple strategy. This structure shows improved ionic and electronic conductivities and provides a large number of electrochemical reaction active sites, making it a possible candidate to be used as a high capacity electrode material for supercapacitors. On this basis, electrode materials with higher rate performance and utilization were prepared by mixing NMO/C with carbon nanotubes (CNTs) through simple physical mixing. Due to the 1D electrochemical synergistic effects of NMO/C and CNTs, the assembled NMO/C-CNT electrode shows a specific capacity of 325.1 F g⁻¹ (at a current density of 0.5 A g⁻¹) in a two-electrode system. At a high current density of 8 A g⁻¹, the specific capacity is still 182 F g⁻¹. This report provides a new strategy for the designed in situ synthesis of porous composite nanorods.