Improved porosity and ionic sorption capacity of carbon particles prepared by spray pyrolysis from an aqueous sucrose/NaHCO3/TEOS solution

Abstract

Porous carbon spheres were synthesized by spray pyrolysis from an aqueous solution containing sucrose and sodium bicarbonate. Tetraethyl orthosilicate (TEOS) was tested as a porogen agent, and the microstructure and the porosity of carbon particles were investigated with changing TEOS content. According to the TEM and element mapping analysis, Si elements are uniformly distributed throughout the carbon matrix, and most of them are easily removed by ultrasonic washing with purified water. As a result, the surface area was increased by introducing TEOS into the spray solution. In particular, the external surface area of carbon can be largely increased by using TEOS, about 2.4 times larger than that of carbon produced without TEOS. The microstructure of carbon spheres was also influenced by the use of TEOS, which was discussed based on TEM, element mapping and XRD analysis. According to the evaluation of the electrochemical properties, the carbon prepared using TEOS exhibited enhanced specific capacitance, mainly due to an increase of the external surface area. The ion-sorption capacitance or the ion diffusion coefficient of carbon prepared by changing the TEOS content was found to have a linear relationship with the external surface area. These results demonstrate experimentally that adding TEOS to the precursor solution in the spray pyrolysis is a simple and effective way of producing highly mesoporous carbon spheres with improved electrochemical properties.