Efficient Photoelectrochemical Reduction of CO2 on Pyridyl Covalent Bonded Ruthenium(II) Based-Photosensitizer.

Photo/electrochemical CO 2 reduction using pyridine was feasible to produce methanol via the formation of pyridiniumformate intermediate. To improve the reduction efficiency, a pyridyl bonded ruthenium (II)-based photosensitizer catalyst (Ru-Py) was designed for photoelectrochemical CO 2 conversion. The photocurrent density on Ru-Py modified electrode in CO 2 saturated solution was 0.103 mA cm −2 higher than that without illumination. The total Faradaic efficiency (f) reached 83.1%, whereas the turnover number (TON) for methanol was 38.4 in aqueous solution after 8 h irradiation. The methanol production was 24.1 μmol which was higher than the published literatures (less than 8 μmol) in similar systems could be attributed to the efficient electron transfer between the photosensitizer and the pyridyl active site covalently linked by C-C bond, as well as the strong and wide absorption up to 610 nm resulted from the large conjugated structure of the ligands. The mechanism investigation revealed that the N atom in pyridyl as catalytic active sites played significant role in CO 2 conversion by forming the pyridiniumformate intermediate which was confirmed by the simulation reaction. Meanwhile, in order to realize the reduction process intuitively, the density functional theory (DFT) was applied to simulate the structure of Ru-Py and the pyridiniumformate intermediates. [ABSTRACT FROM AUTHOR]