Rapid Exciton Migration and Amplified Funneling Effects of Multi-Porphyrin Arrays in a Re(I)/Porphyrinic MOF Hybrid for Photocatalytic CO₂ Reduction

Abstract

A porphyrinic metal–organic framework (PMOF) known as PCN-222­(Zn) was chemically doped with a molecular Re­(I) catalyst-bearing carboxylate anchoring group to form a new type of metal–organic framework (MOF)–Re­(I) hybrid photocatalyst. The porphyrinic MOF-sensitized hybrid (PMOF/Re) was prepared with an archetypical CO2 reduction catalyst, (L)­ReI(CO)3Cl (Re­(I); L = 4,4′-dicarboxylic-2,2′-bipyridine), in the presence of 3 vol % water produced CO with no leveling-off tendency for 59 h to give a turnover number of ≥1893 [1070 ± 80 μmol h–1 (g MOF)−1]. The high catalytic activity arises mainly from efficient exciton migration and funneling from photoexcited porphyrin linkers to the peripheral Re­(I) catalytic sites, which is in accordance with the observed fast exciton (energy) migration (≈1 ps) in highly ordered porphyrin photoreceptors and the effective funneling into Re­(I) catalytic centers in the Re­(I)-doped PMOF sample. Enhanced catalytic performance is convincingly supported by serial photophysical measurements including decisive Stern–Volmer interpretation.

Inorganometallic Photocatalyst for CO2 Reduction

“…60−62 We recently designed and prepared a new type of porphyrinic metal−organic framework (PMOF) functionalized with an archetypical molecular catalyst for CO 2 reduction, (L)-Re I (CO) 3 Cl (Re(I)) (L = 2,2-bipyridine-4,4′-dicarboxylate) (Figure 17a). 63 The new PMOF-sensitized hybrid system (PMOF/Re(I)) exhibited efficient and durable conversion of CO 2 to CO, attaining TONs of ≥1893 (1070 ± 80 μmol h −1 (g of MOF) −1 ) with no leveling-off tendency over 59 h. This high catalytic activity originates from efficient exciton migration between highly ordered porphyrin units, which is in agreement with the experimentally determined exciton hopping time (∼1 ps), and effective funneling into the Re(I) catalytic centers doped in the PMOF sample (Figure 17b,c).…”

“…As an alternative to inorganic scaffolds, the introduction of an ordered molecular array system, the configuration of which remains unchanged following energy or electron transfer, is beneficial for assessing the sustainability of light harvesters. − The intrinsic advantages of metal–organic frameworks (MOFs), including high porosity, chemical stability, and synthetic tunability, make them a judicious choice for the effective immobilization of photosensitizing units. − We recently designed and prepared a new type of porphyrinic metal–organic framework ( PMOF ) functionalized with an archetypical molecular catalyst for CO 2 reduction, (L)­Re I (CO) 3 Cl (Re­(I)) (L = 2,2-bipyridine-4,4′-dicarboxylate) (Figure a) . The new PMOF -sensitized hybrid system ( PMOF /Re­(I)) exhibited efficient and durable conversion of CO 2 to CO, attaining TONs of ≥1893 (1070 ± 80 μmol h –1 (g of MOF) −1 ) with no leveling-off tendency over 59 h. This high catalytic activity originates from efficient exciton migration between highly ordered porphyrin units, which is in agreement with the experimentally determined exciton hopping time (∼1 ps), and effective funneling into the Re­(I) catalytic centers doped in the PMOF sample (Figure b,c).…”

“…(c) Energetics and interfacial ET processes in the PMOF /Re­(I) hybrid. Adapted from ref . Copyright 2021 American Chemical Society.…”

Z‐Scheme In2S3/NU‐1000 Heterojunction for Boosting Photo‐Oxidation of Sulfide into Sulfoxide under Ambient Conditions

“…In recently, photoactive MOFs constructed by light‐responsive tissue components, have attracted much research interest and been used as promising photocatalyst‐based platforms. Thus far, some photoactive MOFs, especially PCN‐222, [14] NU‐1000, [15] UiO‐66, [16] MIL‐101, [17] ZIF‐8 [18] etc., exhibit outstanding semiconductor properties and have been used in photocatalytic reactions, such as H 2 O splitting, [19] CO 2 reduction, [20] photodegradation of pollutants, [21] organic transformation reactions [22] . More importantly, combining their high porosity and photoactivity, the construction of heterojunction photocatalysts by integration of MOFs with inorganic semiconductors has been proved as an ideal strategy for robust photocatalysts by some groups including ours [23–26] .…”

Postsynthetic Modification of Metal−Organic Frameworks for Photocatalytic Applications

“…Such a strategy not only regulates the light absorption ability, but also introduces active sites into MOFs for photocatalysis. [50][51][52][53] For example, NU-1000 was functionalized with photosensitizer molecules such as boron-dipyrromethene (BODIPY) on the Zr 6 nodes, demonstrating outstanding activity for detoxification of the sulfur mustard stimulant. [51] Similarly, Zr 6 nodes of PCN-222 (PMOF) were decorated with fac-[Re(4,4 0 -bis(dicarboxylic acid)-2,2 0 -bipyridine)(CO) 3 Cl] (ReCA) to give a new PMOF/Re hybrid.…”