a b s t r a c tStrontium titanate nanocube-dispersed mesoporous silica (STO(NC)-MPS) nanocomposite was examined as a photocatalyst for the photoreduction of CO 2 . Copper (Cu) was examined as a co-catalyst, and the results showed that it was effective for the production of CO under a flow of CO 2 and UV irradiation in water. As confirmed by gas chromatography-mass spectrometry, 13 CO was produced in the presence of 13 CO 2 , thus demonstrating that CO was generated upon photoreduction of CO 2 . Simultaneous formation of O 2 suggested that water acted as a reductant in the photocatalysis process. Moreover, Cu supported on STO(NC)-MPS showed higher selectivity toward CO 2 reduction when compared with Cu-supported composite prepared from mesoporous silica and SrTiO 3 that was synthesized by conventional solid state reaction. Thus, the current findings highlight the characteristics and advantages of SrTiO 3 nanocubes and their nanocomposites with mesoporous silica as photocatalysts for CO 2 photoreduction.