Precursor solution concentration-dependent electrochemical supercapacitive behavior of spray-deposited RuO2 films using aqueous/organic solvent mixtures

RuO2 electrodes are spray-deposited with various precursor solution concentrations using aqueous/organic solvent mixtures. RuO2 has a preferential growth along the (110) plane of the rutile tetragonal crystal structure with porous morphology. The bandgap decreases from 2.05 to 1.77 eV with increasing precursor solution concentrations. Electrical resistivity of 0.12 x 10(4) omega cm has been observed for RuO2 films prepared with a 50 mM precursor solution concentration. RuO2 film showed a specific capacitance of 893 Fg(-1) at a scan rate of 5 mVs(-1) and 964 Fg(-1) at 0.5 Ag-1 with 93.67% capacitance retention over 1000 cycles. As a RuO2 electrode supercapacitor device, the energy density reaches 76.56 Whkg(-1) at a power density of 1701 Wkg(-1). The solution resistance is about 0.32 omega for the RuO2 electrode prepared with a precursor solution concentration of 50 mM. The use of an aqueous/organic mixture as solvent improves the electrochemical supercapacitive performance of RuO2 electrodes. [GRAPHICS]