전도성 기판 위의 직접적 반도체 형성 및 전자저장장치로의 응용

Abstract

Electrodes of different morphology, i.e., nanospheres (NSs) and nanorods (NRs), made by chemically depositing indium oxide (In₂O₃) on indium-tin oxide substrates were investigated for their electrochemical supercapacitive properties. The presence of nanosized pores and voids in In₂O₃ electrode of NRs caused increase in redox reaction active sites, and ultimately, inner and outer charges than that of NSs In₂O₃ electrode. Due to the combined effect of double-layer and pseudocapacitance, the specific capacitance of In₂O₃ electrode composed of NRs was higher (105 F/g) than that of NS (7.6 F/g). Electrochemical supercapacitive (ES) properties of liquid-phase synthesized mesoporous (pore size distribution centered∼12 nm) and of 120m²/g surface area nickel hydroxide film electrodes onto tin-doped indium oxide substrate are discussed. The amounts of inner and outer charges are calculated to investigate the contribution of mesoporous structure on charge storage where relatively higher contribution of inner charge infers good ion diffusion into matrix of nickel hydroxide. Effect of different electrolytes, electrolyte concentrations, deposit mass and scan rates on the current-voltage profile in terms of the shape and enclosed area is investigated. Specific capacitance of ∼85 F/g at a constant current density of 0.03 A/g is obtained from the discharge curve. Di-(3-diaminopropyl)-viologen (DAPV) was used as a foreign molecule within electrolyte during electrodeposition of MnO₂(MnO₂-V) for the first time, wherein, higher oxygen evolution rate induced by DAPV showed increase in surface roughness and porosity. The MnO₂-V electrode showed a specific capacitance, SC of 229 F/g which was about five times higher than MnO₂without DAPV, MnO₂-N (48 F/g) at the scan rate of 10 mV/s. In presence of DAPV, at the MnO₂/current collector interface, lower contact resistance was obtained from electrochemical impedance spectroscopy measurement. Finally, diminished electrical conduction and interference of ion diffusion caused by residual MnO₂resulted in decrease of SC with an addition of deposition charges. Sustainable stability for electrochemical supercapacitor electrode was observed in MnO₂-V by investigating subsequent charge-discharge cycling.