Photocatalytic reduction of CO2 with H2O on highly dispersed Ti-oxide catalysts as a model of artificial photosynthesis

•Photocatalytic reduction of CO2 with H2O preceded on tetrahedrally coordinated Ti-oxide species•Under UV light irradiation tetrahedral Ti species produces CH3OH, CH4, and O2 as well as CO.•Photocatalytic decomposition of H2O into H2 and O2 proceeded on TiO2 thin film photocatalyst under sunlight.•The hybridization of natural and artificial photosynthesis using thin film photocatalysts is proposed.•Hybridized system produces H2, sugars and O2 from wastewater with excretions from the roots of the vegetables in plant factory.

The results of investigations on the photocatalytic reduction of CO2 with H2O to produce CH4, CH3OH and O2, artificial photosynthesis, obtained on the highly active tetrahadrally-coordinated Ti-oxide species with TiO4 units constructed within micro- and meso-porous framework structures are summarized. The yields of these products were found to change remarkably depending on the reaction conditions such as the ratio of H2O/CO2 ratio. Advanced metal ion-implantation method to modify the catalysts to enable the absorption and operation under visible light was shown to open the way to more innovative possibilities in artificial photosynthesis as well as in the use of clean, unlimited and sustainable solar light to produce useful organic compounds such as CH3OH from CO2 and H2O. The hybridization of natural photosynthesis in green plants and artificial photosynthesis realized by the utilization of thin film photocatalysts is proposed to be promising to produce H2, sugars and O2 from wastewater with excretions from the roots of the vegetables in plant factory under sunlight irradiation.

Graphical abstractPhotocatalytic reduction of CO2 with H2O to produce CH3OH, CH4, and O2 as well as CO proceeds on highly dispersed tetrahedrally coordinated Ti-oxide single site catalyst constructed within zeolite framework structure (artificial photosynthesis).Figure optionsDownload full-size imageDownload as PowerPoint slide