ABSTRACT
Photocatalytic hydrogen evolution is desired to effectively alleviate the serious crisis of energy and the environment, and the utilization of low-cost photocatalysts, especially cobalt-based MOF catalysts, is meaningful, but rarely investigated. Herein, through a self-assembly strategy, we synthesized a Co clusters-based MOF (Co3-XL) by the ligand N,N'-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxdiimide bi(1,2,4-triazole), containing abundant carbonyl O atoms in the channels of the 3D skeleton, and a large porosity of 50.7%. The as-synthesized MOF can be stable in the pH range of 3-10 and shows a narrow band gap of 1.82 eV. Furthermore, its maximum amount of water absorption can reach 192 cm3/g. Under irradiation of simulated solar light, the rate of hydrogen evolution is 23.05 µmol·h-1·g-1 among 12 h with the presence of co-catalyst Pt and photosensitizer RhB. The reaction mechanism has been probed by the transient photocurrent response and steady-state photoluminescence spectra. Therefore, as a narrow band gap photocatalyst, the cobalt clusters-based MOF (Co3-XL) has potential applications for hydrogen evolution from water.
ABSTRACT
Benzene derivatives are seriously harmful to environment and human health, and sensitively detecting these compounds is of great significance but is a challenge. Hence, we designed and synthesized two luminescent lanthanide-organic frameworks, [{Ln(SIP)(H2O)4}]n, [Ln = Tb (1), Eu (2)], with high solvent and pH stability, which can be used as luminescent probes to detect toluene and benzaldehyde among various reagents, and the detection limit can reach up to 10-7 mol L-1 for toluene, and 10-6 mol L-1 for benzaldehyde. Regenerated experimental results indicate that both 1 and 2 can be used for at least five cycles with high precision. To the best of our knowledge, this is the first example of the two-dimensional regenerable luminescent sensor for toluene and benzaldehyde through luminescent quenching.
ABSTRACT
Two isostructural 2D MOFs ([Ln7(CDA)6(HCOO)3(µ3-OH)6(H2O)8] n, abbreviated as 1-Gd and 2-Dy) were successfully synthesized under solvothermal conditions. The self-assembly of lanthanide(III) nitrate and 1,1'-cyclopropane-dicarboxylic acid (H2CDA) resulted in wheel-like Ln18 cluster second building units (SBU), which are further linked to six neighboring wheels to generate a 2D ordered honeycomb array. Both 1-Gd and 2-Dy exhibit high thermal stability and decompose above 330 °C. Moreover, they have good solvent stability in ten common solvents and pH stability with pH values from 1 to 13. Magnetic studies reveal that 1-Gd exhibits weak antiferromagnetic coupling between adjacent Gd3+ ions and has a large magnetocaloric effect of 47.30 J kg-1 K-1 (Δ H = 7.0 T at 2 K), while 2-Dy shows ferromagnetic interaction between adjacent Dy3+ ions. Interestingly, 1-Gd and 2-Dy can catalyze the cycloaddition of CO2 to epoxides under mild conditions and can be reused at least five rounds with negligible loss of catalytic performance.
