Starch built TiO2 nanoarchitecture with mixed anatase and rutile phase for high energy density supercapacitor electrode

Abstract

TiO2 nanoparticles are generally known to have low capacity and poor cycle life when used for supercapacitor electrodes. This work improved the overall energy storage ability of TiO2 nanoparticles by growing them on an activated starch template, which creates polyhydroxylated points that act as nucleation sites for stable nanoparticle growth. The calcined products were studied for phase changes using XRD, TEM, and Raman. Consequently, a balance between the anatase and rutile phase in the TiO2 nanoparticles led to the highest energy storage capacity. The calcination resulted in lowered crystallite sizes, and the activated starch template imparted surface oxygen groups that contributed to enhanced supercapacitive performances. In this work, the TiO2 synthesized on an activated starch template is referred to as A-TiO2, the TiO2 grown on un-activated starch was U-TiO2, while the reference TiO2 synthesized without a template was referred to as unsupported-TiO2. A-TiO2, which has 72% anatase and 28% rutile, had the best result and showed specific capacitance as high as 388 Fg−1, energy density as high as 194 Wh Kg−1, a power density of 4473 W Kg−1, ESR of 0.53 ohms, and retention capacity of 99% after 20,000 cycles.