Study On Synthesis And Electrochemistry Application Of TiO₂-carbon Aerogels

Carbon aerogel (CA) is a most promising material as an electrode for electrical double-layer capacitor (EDLC), as it allows an interconnected three-dimensional network structure, a high specific surface area, good electrical conductivity and a suitable pore size distribution for common electrolytes. Titania as a metal dopant was doped carbon aerogel, which it can change pore structure of aerogel and be effective for the considerable enhancement of its capacitive deionization (CDI) performance and decrease its physical adsorption.Carbon aerogels doped with TiO2 were synthesized by sol-gel polymerization of a mixture of resorcinol, formaldehyde and tetrabutyl orthotitanate, followed by gelation and supercritical drying and carbonization in N2 gas atmosphere. Ethanol was selected as solvent instead of water in sol-gel polymerization process. The morphology and microstructure characteristic of TiO2-mounted carbon aerogel sample was obtained by thermogravimetric (TG), TEM, SEM, BET, and X-ray diffraction (XRD) methods. It was found that the total pore volume and average pore sizes increased by TiO2 addition. The titania phase in anatase form was more homogeneously distributed in carbon aerogels at 900℃. The anatase-rutile transformation didn't take place at carbonization temperatures from 500℃to 1100℃. TiO2 can catalyze the partial graphitization of the carbon aerogel structure.Electrochemical properties of TiO2-doped carbon aerogel sample were obtained by Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge/discharge experiment. Cyclic voltammetry measurements showed it exhibited good reversibility and high specific capacity as the electrode material and the anatase in the structure did not take part in redox reactions. Electrochemical impedance spectroscopy demonstrates that the carbon aerogel electrode exhibited showing a good capacitor behavior with lower resistance. The specific capacitance of 20% TiO2-doped carbon aerogel electrodes has been improved to 165F/g, the decay diacharge time is only 8% and the charge/discharge efficiency remains at 100% after 10000 cycles.Carbon aerogel electrodes applicable to the CDI process on NaCl solution were examined. The effects of TiO2, flow rate, voltage and consistency on the electrosorption performance were investigated in this study. From the CDI process on NaCl solution, the incorporation of titania on CA is effective for the considerable enhancement of its CDI performance and decrease its physical adsorption. The electrosorption amount of 20% TiO2-doped CA is 4.5 times for CA.