Preparation and electrochemical capacitance of graphene/titanium nitride nanotube array

Abstract

Two kinds of graphene composite electrode materials were synthesized on a titanium nitride nanotube array (TiN NTA) and a nickel foam (NF) substrate by a simple adsorption–reduction process, forming a graphene/titanium nitride (G/TiN) NTA and graphene/nickel foam (G/NF). Both the chemical reduction method and the thermal reduction method were used to convert graphene oxide into graphene, forming a G/TiN NTA and thermal reduction graphene/titanium nitride (TRG/TiN) NTA. The morphology and microstructure of the G/TiN NTA, G/NF and TRG/TiN NTA were characterized by scanning electron microscopy, Raman spectra and X-ray diffraction analysis. The electrochemical performance of G/TiN NTA, G/NF and TRG/TiN NTA were investigated by electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge–discharge measurements. The specific capacitances of G/NF and G/TiN NTA were 198.7 and 333.7 F g⁻¹, respectively, at a current density of 1 A g⁻¹ with respect to the mass of graphene. TiN NTA was more suitable as a substrate material for the graphene composite electrode and G/TiN NTA achieved a higher capacitance performance. Additionally, the specific capacitance of G/TiN NTA and TRG/TiN NTA was 230.7 and 197.9 F g⁻¹, respectively, at a current density of 4 A g⁻¹. This indicated that the chemical reduction method was effective for producing graphene composite electrodes with a higher capacitive performance. An all-solid-state flexible supercapacitor was also constructed using two symmetric G/TiN NTA electrodes and a gel electrolyte of polyvinyl alcohol–potassium hydroxide–potassium iodide, achieving an energy density of 34.2 W h kg⁻¹ and a power density of 11.3 kW kg⁻¹.