Carbon Dioxide Capture in Homogeneous and Heterogeneous Surfaces of Porous Silica Glass

Experimental and simulation studies for carbon dioxide (CO2) adsorption on porous silica glass were performed to reveal how surface heterogeneity can affect the adsorption mechanism of CO2. In performing the simulation, the structure of porous silica glass was modeled as a slit pore consisting of parallel walls of connected SiO4 units. The adsorption isotherms of CO2 at 283 K were generated for a series of pore widths using a Monte Carlo ensemble. The defective surfaces created by random removal of surface atoms and the surfaces containing hydroxyl functional groups were chosen to represent the surface heterogeneity for the simulation tasks. The isotherms derived for the defective surfaces showed a rapid adsorption at low pressures because of the stronger interaction between the rough nonuniform surfaces and CO2 molecules. For the role of surface functional groups, the adsorption isotherms dramatically increased with an increasing number of functional groups. The amount of CO2 adsorbed for randomly placed functional groups was greater than that for the presence of functional groups at the pore edges. The proper control of surface heterogeneity by manipulating both the amounts of hydroxyl surface groups and surface defects should help enhance the efficient capture of CO2 in porous silica glass.

Synthesis of Graphitic Carbon Nitride in Porous Silica Glass

We developed and studied facile synthesis of graphitic carbon nitride in macroporous silica glass matrix. Melamine was used as a precursor. The synthesis was performed in a closed air ambience at 400–600∘C. It was found that the synthesized material was characterized with a broadband room-temperature photoluminescence in the range of 350–750[Formula: see text]nm with the peak shifting from to 445[Formula: see text]nm to 702[Formula: see text]nm when the temperature of the synthesis was increased from [Formula: see text]C to [Formula: see text]C while the intensity of the luminescence was decreased. The nature of the luminescent centers and possible applications of the synthesized material are discussed.