Graphene modified TiO2 composite photocatalysts have drawn increasing attention because of their high performance. Some significant advancements have been achieved with the continuous research, such as the corresponding photocatalytic mechanism that has been revealed. Specific influencing factors have been discovered and potential optimizing methods are proposed. The latest developments in graphene assisted TiO2 composite photocatalysts are abstracted and discussed. Based on the primary reasons behind the observed phenomena of these composite photocatalysts, probable development directions and further optimizing strategies are presented. Moreover, several novel detective technologies—beyond the decomposition test—which can be used to judge the photocatalytic performances of the resulting photocatalysts are listed and analyzed. Although some objectives have been achieved, new challenges still exist and hinder the widespread application of graphene-TiO2 composite photocatalysts, which deserves further study.

No abstract

No abstract

Hollow organosiliceous sphere (HOS) materials have been successfully synthesized by a co-condensation method with tetraethylorthosilicate (TEOS) and organosilane (1,2-bis(triethoxysilyl)ethane, BTSE) as mixed silica sources under acidic conditions. The application of HOSs as adsorbents for the volatile organic compound (VOC) abatement was demonstrated. The HOSs were characterized by transmission electron microscopy (TEM), N 2 sorption isotherms, FT-IR spectroscopy, thermogravimetric analysis (TGA) and Xray photoelectron spectroscopy (XPS). The results indicated that all samples showed a uniform hollow mesostructure and the organic groups were chemically incorporated into the walls of HOSs. The static adsorption and stability behaviors of water vapor, n-hexane and 93# gasoline on HOSs were investigated, with commercial silica gel (SG) and activated carbon (AC) as references. It was found that the sample with an initial molar ratio BTSE/(BTSE + TEOS) of 25% (HOS-25%) had the largest VOC adsorption capacity (1.36 g g À1 n-hexane and 1.35 g g À1 93# gasoline) and the smallest water vapor adsorption capacity (0.0120 g g À1 ) under static adsorption conditions. The dynamic adsorption behaviors of n-hexane on HOS-25% were evaluated via breakthrough curves. The dynamic adsorption capacities of n-hexane are in the following order: SG < AC < HOS-25% and the stability is in the order of AC < SG < HOS-25%. The larger dynamic VOC capacity of the HOSs may be attributed to the synergetic effect between the unique morphology and hybrid walls. The static and dynamic n-hexane and water vapor competitive adsorption results suggested that HOS-25% had a much higher adsorption tendency for VOCs over water vapor. The HOSs with high hydrophobicity, large VOC removal capacity and excellent recyclability show great potential for VOC controlling.

No abstract