Photocatalytic CO₂Reduction to Formate Using a Mn(I) Molecular Catalyst in a Robust Metal–Organic Framework

Abstract

A manganese bipyridine complex, Mn(bpydc)(CO)3Br (bpydc = 5,5'-dicarboxylate-2,2'-bipyridine), has been incorporated into a highly robust Zr(IV)-based metal-organic framework (MOF) for use as a CO2 reduction photocatalyst. In conjunction with [Ru(dmb)3](2+) (dmb = 4,4'-dimethyl-2,2'-bipyridine) as a photosensitizer and 1-benzyl-1,4-dihydronicotinamide (BNAH) as a sacrificial reductant, Mn-incorporated MOFs efficiently catalyze CO2 reduction to formate in DMF/triethanolamine under visible-light irradiation. The photochemical performance of the Mn-incorporated MOF reached a turnover number of approximately 110 in 18 h, exceeding that of the homogeneous reference systems. The increased activity of the MOF-incorporated Mn catalyst is ascribed to the struts of the framework providing isolated active sites, which stabilize the catalyst and inhibit dimerization of the singly reduced Mn complex. The MOF catalyst largely retained its crystallinity throughout prolonged catalysis and was successfully reused over several catalytic runs.

Rhenium(i) trinuclear rings as highly efficient redox photosensitizers for photocatalytic CO2 reduction

“…38,46 However, the efficiencies of the photocatalytic systems are not very high ( Φ HCOOH = 0.05 to 0.14).…”

Electrocatalytic Reduction of Carbon Dioxide by Mn(CN)(2,2′-bipyridine)(CO)3: CN Coordination Alters Mechanism

“…) In recent work, manganese(I) catalysts have also been utilized to mediate photochemical CO 2 reduction to formate. 35,36 The most widely investigated manganese catalyst is MnBr-(bpy)(CO) 3 where bpy = 2,2′-bipyridine. Some variation of the supporting bidentate ligand has been reported, including the extension of bpy with tert-butyl, 26 mesityl, 27 and phenol moieties.…”

Electrocatalytic and Solar‐Driven CO2 Reduction to CO with a Molecular Manganese Catalyst Immobilized on Mesoporous TiO2

“…Consequently, the few reports of Mn‐based CO 2 reduction photocatalysis use monochromatic or narrowly filtered light to prevent decomposition of the catalyst 14, 25a, 26. This photo‐instability was observed for TiO 2 | MnP , which displayed a significantly lower CO production of 0.39±0.16 μmol (12±3 % FE) when CPE was performed under UV‐filtered 1 sun illumination ( λ >420 nm to avoid TiO 2 band‐gap excitation in this experiment) at −1.7 V versus Fc + /Fc for 2 h (Figure S7).…”