Highly selective and efficient electroreduction of CO_(2) in water by quaterpyridine derivative‐based molecular catalyst noncovalently tethered to carbon nanotubes

A disubstituted quaterpyridine based cobalt complex non‐covalently tethered to multiwalled carbon nanotube(MWCNT)substrate,forming a hybrid catalyst,Co‐qpyCOOH/CNT,catalyzed the conversion of CO_(2) to CO under aqueous conditions.At an optimal and uniform loading,it exhibited remarkable catalytic activity,near‐exclusive selectivity,and high stability towards the formation of CO.At a mere cathodic potential of−0.65 V versus RHE(η=0.54 V),it achieved a high partial current density of−6.7 mA/cm^(2) and a F.E.CO=100%.In addition,with 20 h of stable operation,hydrogen evolution remained practically undetected.Its hybrid structure due to noncovalent immobilization on MWCNT imparted the intrinsic activity and much‐needed stability in performance whereas‒COOH groups may stabilize the intermediates by acting as H‐bond donors,promoting catalytic activity.Tethering to a conductive solid substrate and tuning of the second sphere of coordination played an important role in its performance to achieve desired reduction product with high selectivity and activity.

Heavy-Atom-Free Photosensitizers for High-Yield CO_(2)-to-CO Conversion

Heavy-Atom-Free photosensitizers(HAFPs)with abundant resources showgreat potential to construct noble metal-free and high-yield CO_(2)photoreduction systems,but have rarely been achieved due to their poor intersystem crossing(ISC)efficiency.Herein,a library of HAFPs(B-1-B-8)were rationally designed by coupling various anthracene donors and boron dipyrromethene acceptors to break the short-lived excited state limitation of pure organic chromophores.The special orthogonal geometry between electron donor and acceptor contributes totriggering spin-orbit charge transfer-induced ISCs to achieve long-lived triplet and reduced states,which can facilitate consecutive intermolecular electron transfers to further boost CO_(2)reduction.Impressively,the reduced HAFP B-8 can efficiently sensitize iron catalysts to construct noble metal-free photocatalytic systems for highly efficient and selective CO_(2)-to-CO conversion with 1311μmol yield.Experimental and theoretical investigations clearly illustrate the structure-activity relationship,highlighting a new avenue to develop highly efficient organic photosensitizers to boost CO_(2)photoreduction.

Co porphyrin-based metal-organic framework for hydrogen evolution reaction and oxygen reduction reaction

Constructing molecule@support composites is an attractive strategy to realize heterogeneous molecular electrocatalysis.Herein,we synthesized metal-organic framework(MOF)-supported molecular catalysts for hydrogen evolution and oxygen reduction reaction(HER/ORR).Ligand exchange strategy was used to prepare molecule@support hybrids due to the same functional group.A series of hybrids were obtained using Co porphyrin(1)and different MOFs including MIL-88(Fe),MOF-5(NiCo)and UIO-66(Zr).The1@MOF-5(NiCo)had the best HER and ORR activity compared with 1@MIL-88(Fe)and 1@MOF-5(NiCo).These hybrids also exhibited tunable selectivity for ORR with four-electron process,which can be attributed to the synergistic effect of porphyrin molecules and MOFs.This work provides a possibility for molecular catalysts to improve activity of HER and tune selectivity of ORR.

Iodine-catalyzed N-sulfonylation of benzotriazoles with sodium sulfinates under mild conditions

A new and convenient procedure is developed for the preparation of N-sulfonylbenzotriazoles from sodium sulfinates and benzotriazoles using molecular iodine as catalyst via the S-N bond formation reaction. This catalytic radical sulfonylation proceeds efficiently in air at room temperature under neutral conditions, and in short reaction time, to afford the corresponding N-sulfonylbenzotriazoles in good yields, thus extending the catalytic application of molecular iodine in organic synthesis.