Besides semiconductors with mesoporous structures, mesoporous
silica with 1D hexagonal pore (SBA-15) has been studied
as a catalyst support for photocatalytic reduction of CO2 [100].
For example, Ce-doped TiO2 nanoparticles supported on SBA-15
mesoporous silica remarkably enhances photocatalytic activity for
reduction of CO2 into CO and CH4 under UV–vis illumination, relative
to Ce-TiO2, where Ce-TiO2/SBA-15 with a Ti:Si ratio of 1:4
demonstrates 8-fold enhancement in CO production and 115-fold
enhancement in CH4 production. It is mainly ascribed to the more
effective diffusion and adsorption of CO2 through the ordered 1D
pores in SBA-15.