Blue TiO₂ nanosheets as a high-performance electrode material for supercapacitors

We are reporting the use of blue titanium oxide (b-TiO₂) nanostructures as advanced electrode material for high performance supercapacitor for the first time. A one-pot hydrothermal route was employed for the oxidation of layered titanium diboride (TiB₂) into b-TiO₂ nanosheets. The b-TiO₂ nanosheets are prepared via hydrothermal oxidation of TiB₂. Physico-chemical characterizations such as X-ray diffraction, UV-visible, photoluminescence spectroscopy, electron spin resonance spectroscopy, laser Raman spectrum, X-ray photoelectron spectroscopy, and morphological studies revealed the formation of sheet-like b-TiO₂ nanostructures. The energy storage properties of the b-TiO₂ electrode were examined using aqueous and organic electrolytes. The cyclic voltammetry and charge-discharge analysis of b-TiO₂ electrode using 1 M Na₂SO₄ revealed their pseudocapacitive nature with a high specific capacitance (∼19 mF cm^-2). The b-TiO₂ based symmetric supercapacitor (SSC) device using organic liquid (1 M TEABF₄) works over a wide operating potential window (3 V) and delivered a high specific capacitance (6.67 F g^-1 or 3.58 mF cm^-2), possess high energy density and power density with excellent cyclic stability over 10,000 cycles. Collectively, these studies demonstrated the usefulness of b-TiO₂ as a novel electrode material for high performance supercapacitor.