Supercapacitor and dye-sensitized solar cell (DSSC) applications of shape-selective TiO2 nanostructures

Abstract

Shape-selective TiO₂ nanomaterials with different morphology, namely wire-like, flake-like and flower-like, have been synthesized by utilizing a simple wet chemical route by the reaction of titanium isopropoxide with ethanol and water mixture in the presence of cetyltrimethylammonium bromide. The shape of the particles can be easily tuned by altering the concentration of surfactant relative to the metal salt and changing the other reaction parameters. The formation mechanism of different shapes has been elaborated in detail. The shape-selective TiO₂ nanomaterials have been utilized for electrochemical supercapacitor and DSSC applications. It was observed that TiO₂ nanomaterials with various shapes showed different specific capacitance (C_s) values, and the order of C_s values is as follows: wire-like > flower-like > flake-like. The highest C_s of 3.16 F g⁻¹ and better cycling stability was observed for TiO₂ nanomaterials having wire-like shapes. At a high scan rate 150 mV s⁻¹, the capacitance retention of wire-like TiO₂ electrode remains at about 90% after 5000 cycles. DSSC study results show that all the differently shaped TiO₂ nanomaterials can be used as potential anode materials, and, among the different shapes, the flower-like morphology shows better photo-conversion efficiency. The presented synthesis process is fast, cost-effective and environmentally friendly and could be utilized for other applications like gas sensors, photo-catalysts or elimination of pollutants from contaminated soils.