Xiangjie Gong,Tao Yang,Yan Song,Xiaodong Tian,Zihui Ma,Zhanjun Liu
MOFs-reinforced electrospun carbon nanofibers offer a wide range of applications in the field of energy storage. In this study, ZIF-67 nanoparticles were produced and combined with polyacrylonitrile for electrospinning before being stabilized and carbonized to form a carbon nanofiber. BET, FT-IR, EA, DSC , and other techniques were used to investigate the stabilizing behaviors of PAN electrospun fiber with varying ZIF-67 concentrations at different temperatures. Under the same stabilizing settings, it was discovered that PAN electrospun fiber containing ZIF-67 nanoparticles could absorb more oxygen, promoting a higher degree of cyclization and crosslinking. Therefore, it was preferred to prepare carbon nanofibers at a lower stabilization temperature. Importantly, the degree of stability and disorder of the PAN/ZIF-67 stabilized fiber has been described by the FT-IR and the Raman spectra . This research deepens understanding about the formation of MOF-reinforced carbon nanofibers and expands our knowledge of the stability of PAN/MOF hybrid fibers.
The deposited dust provides a large surface for heterogeneous ozone uptake reactions in urban regions. Prior studies have barely considered the effect of the photothermal conversion of deposited dust and underlying surface on ozone uptake. In this study, Fe 2 O 3 , TiO 2 , α-Al 2 O 3 , and SiO 2 were selected as model mineral dusts (MDs) to evaluate the photothermal effect. With an irradiation intensity of 100 mW/cm 2 , the uptake coefficients of ozone by Fe 2 O 3 , TiO 2 , α-Al 2 O 3 , and SiO 2 were 2.4, 30, 2.72, and 2.83 times higher than those in a dark condition. For SiO 2 and α-Al 2 O 3 , the increase in the uptake coefficient was due to the temperature increase induced by photothermal conversion. For Fe 2 O 3 and TiO 2 , photoelectric and photothermal conversion simultaneously participated in ozone uptake reactions. At 70 °C, the contribution of thermal catalysis to ozone uptake over Fe 2 O 3 and TiO 2 was approximately 55.4 % and 55.0 %, respectively. The temperature increase induced by photothermal conversion also promoted MDs' activity for ozone uptake after removing the light source (after sunset). This work proves that the ozone uptake induced by the photothermal effect of deposited MDs and the underlying surface was the primary ozone elimination pathway in urban atmospheres.
Previous artificial oxygen carriers mainly rely on the reversible combination of five coordination of porphyrin iron and oxygen to achieve oxygen carrying function. However, another oxygen-carrying mode, the competitive binding between oxygen and other ligands, has rarely been studied. In this study, heme dimethyl ester [HDME(II)] was used as the oxygen-carrying component to study the oxygen-carrying properties of its hexacoordinated complexes. The oxygen absorption capacity of the hexacoordinated complexes was determined by gas absorption method. At the same time, the oxygen absorption capacity was used as an indicator to investigate its s oxidation rate. The results show that in the five and six complexes of HDME(II), when there is a strong ligand, the hexa-coordinated complexes can effectively coordinate oxygen. When there is a strong ligand and a weak ligand at the same time, the oxygen binding capacity of the hexa-coordinated complexes is significantly improved. In addition, when the weak ligand is fixed and the strong ligand is changed, it can be observed that the coordination ability of the strong ligand has a significant effect on the oxygenation curve of the system. In addition, the long hydrophobic chain of the axial ligand in the HDME(II) hexacoordinated complexes helps to slow down the oxidation rate of the hexa-coordinated complexes. When the axial ligand has a certain reducibility, the oxidation rate of the hexacoordinated complexes is further reduced. Therefore, the oxygen carrier mode of the heme derivative is expected to become an effective oxygen carrier.
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