Abstract: Disclosed is a catalytic system for the reduction of carbon dioxide to carbon monoxide. The catalytic system includes an iridium (Ir) photosensitizer and a TiO2/Re(I) complex catalyst. No additional process is required to anchor the molecule-based dye compound on TiO2 in the synthesis of the catalytic system. This enables the synthesis of the catalytic system in a relatively easy manner for groups of photosensitizer candidates. In addition, the catalytic system can be utilized as a platform for more easily evaluating the abilities of photosensitizers. Furthermore, the catalytic system can find application in various fields due to its ability to selectively produce carbon monoxide gas with high efficiency.