Synthesis of transparent Ti-containing mesoporous silica thin film materials and their unique photocatalytic activity for the reduction of CO2 with H2O

Photocatalytic Hydrogenation on Semiconductor Particles

“…The charge-transfer excited state of these species played an important role in the selectivity for producing CH3OH, in contrast to the different selectivity giving CH4 on bulk TiO2 photocatalyst. Ti-incorporated mesoporous silica also exhibited high activity in the photoreduction of CO2 with water to generate CH3OH and CH4 under UV irradiation [55]. Methanol was also selectively produced by employing CaFe2O4 [56] and NiO-loaded InTaO4 [47] under visible light irradiation.…”

“…Therefore, the photocatalytic hydrogenation of CO2 upon semiconductor powders has received much attention [9][10][11][44][45][46][47][48][49][50][51][52][53][54][55][56]. Among the earliest studies on the photocatalytic hydrogenation of CO2, Inoue et al examined a wide range of semiconductors (WO3, TiO2, ZnO, CdS, GaP, and SiC in 200 -400 mesh) in aqueous solution [44].…”

CO2 Splitting by H2O to CO and O2 under UV Light in TiMCM-41 Silicate Sieve

“…of irradiation to the presence of residual H 2 O in the sieve. Infrared monitoring of 13 CO 2 + H 2 O photolysis revealed the formation of some 12 CO gas along with the 13 CO product, with the 12 CO growth fluctuating erratically between experiments. This points to the presence of small amounts of carboneous residues that react with oxidizing intermediates formed during the photochemical reaction.…”

“…Such carboneous residues are known to be difficult to remove completely from the high-surface area mesoporous silicates. 28,29 The origin of 12 In order to determine whether single or multiple photons are required for the CO production, we examined the laser power dependence of the 13 CO absorbance in 13 CO 2 + D 2 O experiments. Figure 5a shows the growth of the ro-vibrational line of 13 CO at 2117 cm -1 that was used for the analysis.…”

“…Development of framework Ti-containing mesoporous silicate films that are optically transparent (as opposed to the light-scattering pressed wafers of crystallites) has allowed the determination of the quantum efficiency, which is around 0.3% (300 nm). 11,12 UV photolysis of CO 2 and H 2 O gas mixtures loaded into the sieve was typically conducted at moderately elevated temperature (around 325 K) and monitored by GC analysis of the products. Methanol and methane were the main products, along with trace amounts of CO, O 2 , C 2 H 4 , and C 2 H 6 .…”