Effect of Substituent Groups in Rhenium Bipyridine Complexes on Photocatalytic CO2 Reduction

Abstract

Abstract:We synthesized four different rhenium complexes, Re(bpy-R)(CO) 3 Cl (bpy = 2,2′-bipyridine and R = H, CH 3 , COOH, or CN), as photocatalysts that selectively reduce CO 2 to CO and investigated the effect of substituent groups (Rs) on the absorption and photocatalystic properties for CO 2 reduction under 365-nm light irradiation. The Re(bpy-R)(CO) 3 Cl (R = H or CH 3 or COOH) reduced CO 2 to CO in CO 2 -saturated DMF-triethanolamine solution, which was irradiated with 365-nm light. The amount of CO produced by CO 2 reduction differed, depending on the introduced Rs in the bipyridine moiety. We found that the ability of Re(bpy-R)(CO) 3 Cl (R = H or CH 3 or COOH) to produce CO has a linear relationship to molar absorption coefficients of rhenium complexes at the irradiated light wavelength. Introduction of the COOH group, which has the highest molar absorption coefficient among four rhenium complexes, enhanced CO 2 -to-CO reduction capacity (6.59 mol/cat-mol⋅2h) five times that of Re(bpy-H)(CO) 3 Cl with no R.

Constructing a rhenium complex supported on g-C3N4 for efficient visible-light-driven photoreduction of CO2 to CO via a novel Z-scheme heterojunction

“…5a. Ono et al reported the total amount of CO production of Re(bpy-COOH) reached TON CO = 6.59 for 2 h. 58 In our experiment, the TON CO of Re(bpy-COOH) obtained was lower than that in the Ono report, which can be explained by the low-intensity irradiation used. The amount of CO formation increased significantly when Re(bpy-COOH) was anchored to g-C 3 N 4 (increased by 5.6 times at 240 min of irradiation), indicating that Re(bpy-COOH) and g-C 3 N 4 combination enhanced the efficiency of the PCO2R.…”

“…[Re(CO) 3 (N–N)Cl] complexes presented high CO selectivity (greater than 90%), and the CO selectivity of Re(bpy-COOH) under low-intensity irradiation was evaluated to be 99.4% that agreed with previous studies. 58 The CO selectivity of the hybrid system was greater than that of the homogeneous catalyst, and thus combining Re(bpy-COOH) with g-C 3 N 4 improved the photocatalytic performance and the selectivity of CO.…”

Photocatalytic CO2 Reduction by Re(I) Polypyridyl Complexes Immobilized on Niobates Nanoscrolls

“…fac -[ClRe­(CO) 3 (dcbH 2 )] ( 1 ) was prepared with some modifications to literature procedures. , Initially, 0.19 g (0.5 mmol) of [ClRe­(CO) 5 ] and 0.11 g (0.6 mmol) of dcbH 2 were suspended in 10 mL of ethanol, and the mixture was heated to reflux for 7 h. The crude product precipitated as an orange solid, which was collected by filtration. Recrystallization was performed by suspending the solid in 90 mL of acetone.…”

Increase in CO2 reduction rate via optical near-field effect

“…We used Reðbpy-COOHÞðCOÞ 3 Cl (bpy-COOH ¼ 2;2 0 -bipyridine-4,4′-dicarboxylic acid), abbreviated as Re(bpy-COOH), 23 as an Re-complex (metal complex) to investigate the ONF Second, to attach Re(bpy-COOH) to the alumina sphere with gold clusters, Re(bpy-COOH) was dissolved in acetonitrile. Then, the Re(bpy-COOH) solution was mixed with the alumina-containing solution, and the mixture was allowed to stand still for 8 h in a manner similar to that of a previous study.…”