RESUMO
Cu(II) supramolecular assemblies [Cu2(tipe)2(H2O)2](NO3)4·2.5H2O (CuN4) and [Cu2Cl4(tipe)(CH3CN)]·H2O (CuN2Cl2) (tipe = 1,1,2,2-tetrakis(4-(imidazole-1-yl)phenyl)ethene) were synthesized and utilized for photocatalytic CO2 reduction. CuN4 exhibits CO production of up to 891 µmol gcat-1 with a selectivity of 79.9%, while CuN2Cl2 gives low CO production of 206 µmol gcat-1 but with a high selectivity of >99.9% in 5 h. The experimental and DFT calculation results indicate that the coordination environment and non-covalent interactions within the assemblies have a great impact on the photocatalytic CO2 reduction behavior. This work provides useful insights on Cu(II) assembly catalyzed CO2 photoreduction.
RESUMO
Metal-organic frameworks (MOFs) can be used as electrocatalysts for the CO2 reduction reaction (CO2RR) because of their well-dispersed metal centers. Silver is a common electrocatalyst for reduction of CO2 to CO. In this study, two Ag-MOFs with different structures of [Ag8O2(TIPE)6](NO3)4 (Ag-MOF1) and [Ag(TIPE)0.5CF3SO3] (Ag-MOF2) [TIPE = 1,1,2,2-tetrakis(4-(imidazol-1-yl)phenyl)ethene] were synthesized and used for CO2 electroreduction. The results show that Ag-MOF2 is superior to Ag-MOF1 and exhibits high CO faradaic efficiency (FE) of 92.21% with partial current density of 29.51 mA cm-2 at -0.98 V versus reversible hydrogen electrode (RHE). The FECO is higher than 80% in the potential range of -0.78 to -1.18 V. The difference may be caused by different framework structures leading to different electrochemical active surface areas and charge transfer kinetics. This study provides a new strategy for designing and constructing CO2 electroreduction catalysts and provides potential ways for solving environmental and energy problems caused by excessive CO2 emission.
RESUMO
Three novel fluorescent Zn(II) frameworks, namely [Zn(DPA)(NDA)]2·2DMF (1), [Zn2(DPA)(OBA)2]·2DMF·4H2O (2) and [Zn(DPA)(HNTB)]·H2O (3) (DPA = 2,5-di(pyridin-4-yl)aniline, H2NDA = 1,4-naphthalenedicarboxylic acid, H2OBA = 4,4'-oxydibenzoic acid, H3NTB = 4,4',4''-nitrilotribenzoic acid, DMF = N,N-dimethylformamide), were successfully fabricated and structurally characterized. Due to the variety of organic linkers, 1-3 exhibit varied topologies: 1 is a 4-c three-dimensional (3D) framework with {65·8} topology, 2 is a 6-c 3D net with point symbol of {44·610·8}, and 3 is a 4-c two-dimensional network that further stacks into a 3D structure by hydrogen bonding interactions with {44·62} topology. Experiments related to fluorescence show that 1-3 can be utilized to quickly identify specific anions of CrO42-/Cr2O72-, and organic molecules such as 2,4,6-trinitrophenol and benzaldehyde.