Photo‐reduction of CO₂ Using a Rhenium Complex Covalently Supported on a Graphene/TiO₂ Composite

Abstract

One of the promising solutions for decreasing atmospheric CO2 is artificial photosynthesis, in which CO2 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 TiO2 to fabricate a novel catalyst composite TiO2 -rGO-Re(PyBn)(CO)3 Cl for CO2 photo-reduction. This hybrid composite demonstrated high selectivity conversion of CO2 into CO under xenon-lamp irradiation. Compared with the unsupported homogeneous catalyst Re(PyBn)(CO)3 Cl, the covalent immobilized catalyst composite TiO2 -rGO-Re(PyBn)(CO)3 Cl enhanced the turnover number six times and significantly improved catalyst stability. During the process of CO2 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 CO2 photo-reduction by the TiO2 -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 CO2 photo-conversion.

Inorganic Photochemistry and Solar Energy Harvesting: Current Developments and Challenges to Solar Fuel Production

“…The most common materials employed as substrates are metal oxide semiconductors [202][203][204], but carbon nanostructures (graphene, nanotubes, etc.) have also been used [197,205]. The work principle of these hybrid systems is illustrated in Figure 5.…”

“…In a different strategy to increase the electron mobility in the semiconductor, Cui and coworkers reported TiO 2 / reduced graphene oxide (rGO) composites modified with the molecular Re(I) catalyst fac-[Re(Cl)(CO) 3 (PyBn)] (PyBn=1-(2-picolyl)-4-phenyl-1H-1,2,3-triazole) [197]. The PyBn ligand allows the Re(I) complex to be covalently bound to the graphene sheets.…”

“…In these systems, the molecular Re(I) catalyst is immobilized in suitable substrates that can act in different steps of the photocatalytic cycle in order to yield higher efficiencies and stability. Moreover, the heterogenized system could be easier recycled and used in different solvents or reaction conditions [72,[191][192][193][194][195][196][197][198].…”

Study of the Parameters Impacting the Photocatalytic Reduction of Carbon Dioxide in Ionic Liquids

“…Reduction of CO 2 to CO, CH 4 is also a proton‐assisted process that requires an H + donor agent if the ionic liquid is not to be consumed, [27–31] most common source of H + being water. Physical and chemical CO 2 sorption have a common characteristic in ionic liquid which is a strong decrease while increasing the amount of co‐solvent (water) added [14] .…”

Systematic Study of the Behavior of Different Metal and Metal-Containing Particles under the Microwave Irradiation and Transformation of Nanoscale and Microscale Morphology

“…Another important challenge concerns the interactions of supported metal-containing particles with carbon materials. Carbon supports, including graphitic structures, are used for many types of catalysts for a wide range of reactions [31,32,33,34,35,36,37,38]; they play a special role in the catalytic processes under microwave irradiation. Carbon supports work very well as a microwave radiation sensitizer: they are rapidly heated to high temperatures in a microwave oven.…”