Nickel oxide films were synthesized by electrochemical precipitation of Ni(OH)2 followed by heat-treatment in air at various temperatures (200-600 °C). Their structure and electrochemical properties were studied by cyclic voltammetry, X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). XRD results showed that the nickel oxide obtained at 250 °C or above has a crystalline NiO structure. The specific capacitance of the oxide depends on the heat-treatment temperature, showing a maximum value at 300 °C. XAS results revealed that the non-stoichiometric nickel oxide (Ni1-xO) approached the stoichiometric NiO structure with increasing heat-treatment temperature due to the defect healing effect. The defective nature of the nickel oxide could be utilized to improve its specific capacitance for supercapacitor application.
Bibliographical noteFunding Information:
This study was supported by Korea Science and Engineering Foundation (KOSEF) Research Project (no. 2001-6-301-07-2) and the Brain Korea 21 Project. The authors are grateful to authorities at the Pohang Light Sources for X-ray absorption spectroscopic measurements.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)