The results of investigations on the photocatalytic reduction of CO 2 with H 2 O to produce CH 4 , CH 3 OH and O 2 , artificial photosynthesis, obtained on the highly active tetrahadrally-coordinated Ti-oxide species with TiO 4 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 H 2 O/CO 2 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 CH 3 OH from CO 2 and H 2 O. 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 H 2 , sugars and O 2 from wastewater with excretions from the roots of the vegetables in plant factory under sunlight irradiation.