Efficient photocatalytic degradation of petroleum oil spills in seawater using a metal-organic framework (MOF)

Photocatalysis is a green approach that has appeared to be a viable option for the degradation of a variety of organic contaminants. This work outlines the process of preparing the titanium-based metal-organic framework (MIL-125) photocatalysts using a simple solvothermal method. Structural, morphological, and optical analysis of samples (MT18 and MT48) was carried out by XRD, FT-IR, Raman, SEM, TGA, BET, and UV-Vis. Results indicated that the sample prepared at 150 °C and reaction time of 48 h (MT48) has a low crystal size of 7 nm with an optical band gap of 3.2 eV and a surface area of 301 m² g^-1. Under UV-visible light irradiation, the as-prepared MOFs proved to upgrade photocatalytic activity in degrading crude oil spills in saltwater. Effects of catalyst dosage and exposure time on the degradation of an oil spill in seawater were studied and analyzed using UV-Vis spectrophotometry and gas chromatography (GC-MS) which emphasized that the use of 250 ppm of MT48 photocatalyst under UV-Vis irradiation can degrade about 99% of oil spills in water after 2 h of exposure. The study's data revealed that MIL-125 could be used to photocatalyzed the cleanup of crude oil spills.

[Fe2S2-Agx]-Hydrogenase Active-Site-Containing Coordination Polymers and Their Photocatalytic H2 Evolution Reaction Properties

Three [Fe₂S₂-Ag_x]-hydrogenase active-site-containing coordination polymers (CPs), {[Fe₂S₂-Ag₁](4-cpmt)₂(CO)₆(ClO₄^-)}_n (1), {[Fe₂S₂-Ag₂](4-cpmt)₂(CO)₆(OTf^-)₂(benzene)}_n (2), and {[Fe₂S₂-Ag₂](3-cpmt)₂(CO)₆(ClO₄^-)₂}_n (3), were obtained by a direct synthesis method from ligands [FeFe](4-cpmt)₂(CO)₆ [L1; 4-cpmt = (4-cyanophenyl)methanethiolate] and [FeFe](3-cpmt)₂(CO)₆ [L2; 3-cpmt = (3-cyanophenyl)methanethiolate] with silver salts. 1-3 represent the first examples of [FeFe]-hydrogenase-based CPs. It was worth noting that the Ag-S bonding between the Ag centers and S atoms of a [Fe₂S₂] cluster produced a novel [Fe₂S₂-Ag_x] (x = 1 or 2) catalytic site in all three polymers. The results of photochemical H₂ generation experiments indicated that 2 and 3 containing [Fe₂S₂-Ag₂] active sites showed obviously improved catalytic performances compared with ligands L1 and L2 and [Fe₂S₂-Ag₁]-containing 1. This work provides a pioneering strategy for the direct synthesis of [Fe₂S₂]-based CPs or metal-organic frameworks.

CO Guest Interactions in SDB-Based Metal-Organic Frameworks: A Solid-State Nuclear Magnetic Resonance Investigation

Metal-organic frameworks (MOFs) are promising materials for greener carbon monoxide (CO) capture and separation processes. SDB-based (SDB = 4,4^'-sulfonyldibenzoate) MOFs are particularly attractive due to their remarkable gas adsorption capacity under humid conditions. However, to the best of our knowledge, their CO adsorption abilities have yet to be investigated. In this report, CO-loaded PbSDB and CdSDB were characterized using variable-temperature (VT) ¹³C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. These MOFs readily captured CO, with the adsorbed CO exhibiting dynamics as indicated by the temperature-dependent changes in the SSNMR spectra. Spectral simulations revealed that the CO simultaneously undergoes a localized wobbling about the adsorption site and a nonlocalized hopping between adjacent adsorption sites. The wobbling and hopping angles were also found to be temperature-dependent. From the appearance of the VT spectra and the extracted motional data, the CO adsorption mechanism was concluded to be analogous to that of CO₂. To gain a better understanding on the gas adsorption properties of these MOFs and their CO capture abilities, we subsequently compared the motional data to those reported for CO₂ in SDB-based MOFs and CO in MOF-74, respectively. A significant contrast in adsorption strength was observed in both cases because of the different physical properties of the guests (i.e., CO vs CO₂) and the MOF frameworks (i.e., SDB-based MOFs vs MOFs with open metal sites). Our results demonstrate that SSNMR spectroscopy can be employed to probe variations in binding behavior.