Rapid synthesis of nanostructured copper oxide for electrochemical supercapacitor based on novel [HPMIM][Cl] ionic liquid

• Nanostructured CuO electrode prepared by simple and cost effective hydrothermal method.
• A novel [HPMIM][Cl] ionic used as an electrolyte for CuO based supercapacitor.
• The highest specific capacitance of 60 F g−1 and energy density of 1.18 Wh kg−1 is observed.

Nanostructured Copper Oxide (CuO) thin films were rapidly deposited on stainless steel substrates by hydrothermal method. To study the concentration effect of copper sulfate (CuSO4) on the specific capacitance of CuO, concentration of CuSO4 was varied from 0.1 to 0.5 M. The monoclinic phase of CuO is confirmed using X-ray diffraction technique. Surface morphology was examined by Scanning Electron Microscopy (SEM) which showed nanobuds with bunch of nanopetals-like CuO structure at lower concentration of CuSO4 and overgrowth of nanopetals onto the background of nanobuds of CuO for higher concentration of CuSO4. The supercapacitive behavior of the electrodes was tested in three electrode system with 0.1 M 3-(1′-hydroxypropyl)-1-methylimidazolium chloride [HPMIM][Cl] ionic liquid electrolyte by using cyclic voltammetry and charge discharge. The highest specific capacitance of 60 F g−1 at 10 mV s−1 and energy density of 1.18 Wh kg−1 at 0.1 mA cm−2 is observed for CuO thin films deposited at 0.2 M concentration of CuSO4. This is the primary successful step towards development of ecofriendly CuO based supercapacitors in task specific IL synthesized by green technology.