Hollow S-doped carbon spheres from spherical CT/PEDOT composite particles and their CO₂ sorption properties

Chemically functionalizable shape-controlled poly(3,4-ethylenedioxythiophene) (PEDOT)-derived conducting copolymers, C1(C4)-CT/PEDOT/PSS-20APS and C1(C4)-CT/PEDOT/PSS-10APS, were prepared through oxidative polymerization of 3,4-ethylenedioxythiophene (EDOT) and 3-thiophenecarboxylic acid (C1-CT) or 4-(3-thienyl)butyric acid (C4-CT) in the presence of acid-labile mesoporous ZnO/Zn(OH)2 hard template. The mesoporous ZnO/Zn(OH)2 hard template could be removed by mild acid etching. The morphology of these polymeric microparticles was dependent on the concentration of ammonium persulfate (APS, (NH4)2S2O8) catalyst and the type of CT monomers. Hollow capsular C1-CT/PEDOT/PSS-20APS copolymer spheres with a large surface opening were obtained when the amount of oxidizing agent APS was 20mmol under the same experimental conditions. Because C1(C4)-CT/PEDOT/PSS-xAPS copolymers contain S-rich moieties in the polymer backbone, they are suited for the preparation of S-doped carbonaceous materials. Therefore, we carbonized C1-CT/PEDOT/PSS-20APS at several different temperatures in a high-purity nitrogen atmosphere to easily prepare hollow S-doped carbon spheres (HSCSs). The level of S-dopants in carbon spheres was strongly dependent on the carbonization temperature. Lower carbonization temperature led to a higher content of S-dopants but lower BET surface area. These carbon spheres were further analyzed by TEM, SEM, PXRD, and XPS. Gas sorption analyses were also performed to study gas sorption with different amount of S-dopants.