A novel organic-inorganic hybrid polymerization strategy for titanium oxide/polymer nanocomposites with supercapacitive properties

A titanium oxide/carbon-based nanocomposite was synthesized via a unique organic-inorganic hybrid polymerization process. Radical polymerization of acrylonitrile and condensation polymerization of titanium isopropoxide (TTIP) were balanced in an acid-assisted, one-pot synthesis. The resulting hybrid polymer exhibited intermediary properties of its organic and inorganic components, indicating a successful harmonization of the competing organic and inorganic polymerizations. It is suggested that the acid-protonated nitriles from the organic polymer were the sites for hybrid polymerization with the inorganic polymer. In the proposed mechanism, some of the acetone (medium for the radical organic polymerization) might have undergone acid-catalyzed aldol condensation and water elimination during synthesis. The gradual release of water promoted the hydrolysis of TTIP and resulted in a more controlled inorganic polycondensation. With acetone being used in this manner, its role as the medium supporting the organic radical polymerization was also controlled, thereby achieving a balance between the two competing reactions. Ultimately, the hydrogen of the protonated nitriles in polyacrylonitrile bonded with the oxygen of the titanium-oxo network, which zipped up the organic and inorganic polymerizations. When annealed at 900 degrees C, the hybrid polymer transformed into a polycrystalline graphitic carbon/titanium oxycarbonitride nanocomposite with supercapacitive properties. It demonstrated satisfactory electrochemical performance, with good specific capacitance of 55.5 F/g at a current density of 1 A/g, low charge-transfer resistance of 0.23 Omega, and an excellent cycling stability with no loss in capacitance even after 10,000 cycles. A symmetric device fabricated from this nanocomposite also showed fair performance with a low charge-transfer resistance of 0.44 Omega, specific capacitance of 25.5 F/g at 1 mV/s, energy density of 1Wh/kg, and power density of 900 W/kg, highlighting its potential for energy storage applications.