Photo‐reduction of CO 2 Using a Rhenium Complex Covalently Supported on a Graphene/TiO 2 Composite

One of the promising solutions for decreasing atmospheric CO 2 is artificial photosynthesis, in which CO 2 can be photoconverted into solar fuels. In this study, a rhenium complex Re(PyBn)(CO) 3 Cl (PyBn=1‐(2‐picolyl)‐4‐phenyl‐1H‐1,2,3‐triazole) was covalently grafted onto the surface of reduced graphene oxide (rGO). This was further combined with TiO 2 to fabricate a novel catalyst composite TiO 2 –rGO–Re(PyBn)(CO) 3 Cl for CO 2 photo‐reduction. This hybrid composite demonstrated high selectivity conversion of CO 2 into CO under xenon‐lamp irradiation. Compared with the unsupported homogeneous catalyst Re(PyBn)(CO) 3 Cl, the covalent immobilized catalyst composite TiO 2 –rGO–Re(PyBn)(CO) 3 Cl enhanced the turnover number six times and significantly improved catalyst stability. During the process of CO 2 photo‐reduction, intermediate species with lifetimes longer than hundreds of microseconds were observed and the formation of CO products was revealed using timeresolved infrared spectroscopy. A plausible mechanism for CO 2 photo‐reduction by the TiO 2 –rGO–Re(PyBn)(CO) 3 Cl catalyst composite has been suggested. The obtained results have implications for the future design of efficient catalyst composites for CO 2 photo‐conversion.