Highly Efficient Photocatalytic Reduction of CO₂ to CO by In Situ Formation of a Hybrid Catalytic System Based on Molecular Iron Quaterpyridine Covalently Linked to Carbon Nitride

Abstract

Efficient and selective photocatalytic CO2 reduction was obtained within a hybrid system that is formed in situ via a Schiff base condensation between a molecular iron quaterpyridine complex bearing an aldehyde function and carbon nitride. Irradiation (blue LED) of an CH3CN solution containing 1,3‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐benzo[d]imidazole (BIH), triethylamine (TEA), Feqpy‐BA (qpy‐BA=4‐([2,2′:6′,2′′:6′′,2′′′‐quaterpyridin]‐4‐yl)benzaldehyde) and C3N4 resulted in CO evolution with a turnover number of 2554 and 95 % selectivity. This hybrid catalytic system unlocks covalent linkage of molecular catalysts with semiconductor photosensitizers via Schiff base reaction for high‐efficiency photocatalytic reduction of CO2, opening a pathway for diverse photocatalysis.

Co-facial π–π Interaction Expedites Sensitizer-to-Catalyst Electron Transfer for High-Performance CO2 Photoreduction

“…For the examples of covalent connection, Ishitani et al have connected Ru/Ir/Os PSs with Re/Mn catalysts via covalent bonds to achieve ultrafast intramolecular electron transfer and boost apparent quantum efficiency (Φ) for CO 2 reduction. 30 − 32 On the other hand, for the heterogeneous systems, the covalent linking between g -C 3 N 4 and diverse molecular catalysts, including several metal porphyrins 25 , 33 , 34 or metal quaterpyridine catalysts, 25 , 26 has also achieved good activity in the photoreduction of CO 2 to CO. However, the conventional covalent linkers, such as acetylene or amide bonds, are vulnerable and can be cleaved during photocatalysis, leading to catalytic performances below expectation.…”

Development of heterogeneous photocatalystsviathe covalent grafting of metal complexes on various solid supports

“…34). 136 The results revealed that upon utilizing Feqpy-BA@C 3 N 4 for photocatalytic reduction of CO 2 , a high CO yield of up to 25.5 mmol and a TON of 2554 were attained, which is a 10-fold increase in activity compared to that of the unlinked Feqpy.…”

Covalent Modification of Iron Phthalocyanine into Skeleton of Graphitic Carbon Nitride and Its Visible-Light-Driven Photocatalytic Reduction of Nitroaromatic Compounds

“…In order to demonstrate the enhanced photoelectric performance after the addition of FePc into CN skeleton, the transient photocurrent response and EIS were measured. As presented in Figure 8a, the gCN-FePc-1 exhibited much higher photocurrent intensity than the gCN, indicating that much more photoexcited electron-hole pairs were generated and separated in the gCN-FePc-1 [24,59]. The EIS spectrum in Figure 8b shows that the gCN-FePc-1 possessed a smaller arc radius than gCN, representing a lower resistance and a higher charge transfer ability in the gCN-FePc-1 than the gCN [19,60].…”

“…In order to overcome the inherent limitations of gCN, research on bandgap engineering, copolymerization, elemental doping, morphology modulation, and heterojunction construction has been conducted [21][22][23]. Recently, Fe-doped gCN-based photocatalysts attracted numerous attention due to the high abundance of Fe element in earth's crust and the excellent catalytic activity in both energy and environmental catalysis [24,25]. For example, Tonda et al reported that Fe atom doping had a significant influence on the electronic structure and catalytic property of gCN [26].…”