Superior Supercapacitive Performance of Grass-like CuO Thin Films Deposited by Liquid Phase Deposition Technique
In the current study copper oxide (CuO) thin films are deposited on stainless steel substrates (flat and mesh) by a binder free liquid phase deposition technique. Copper hydroxide thin films are deposited by means of a ligand-exchange equilibrium reaction of metal-fluoro complex ions and fluoride ions consuming reaction by means of boric acid as a scavenging agent. These films are annealed at 300, 400 and 500 °C to get CuO thin films. The films are characterized by different techniques in order to check their phase, morphology and wettability. The supercapacitive performance of the CuO film is found to be best in KOH electrolyte. Specific capacitance is calculated from cyclic voltammetry (at several scan rates), charging-discharging (at different current densities) and electrochemical impedance spectroscopy. The highest value of specific capacitance at 3 mV s-1 in 6 M KOH electrolyte is 552 and 849 F g-1 on flat and mesh stainless steel, respectively. The supercapacitive performance is significantly improved when CuO thin films are deposited on mesh substrate as compared to flat substrate due to higher surface area. Also, symmetric device of CuO on mesh stainless steel is fabricated and tested.