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A novel fluorinated diamine monomer (FPMDA ) was synthesized from p-fluorobenzaldehyde and 2, 6-dimethylaniline, and then reacted with pyromellitic anhydride to obtain a fluorinated polyimide (FPI). The structures of the synthesized FPMDA diamine monomer and polyimide were characterized by FTIR, nuclear magnetic hydrogen spectroscopy, and mass spectrometry (MS) ;the thermal properties of the polyimide film were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The results showed that FPI has excellent solubility in solvents such as DMF, NMP, and THF. FPI also shows good thermal stability, under nitrogen environment, with thermal decomposition temperature Td5% of 550 °C, Td10% of 580 °C, and char yield of 58.7% at 1 000 °C, its glass transition temperature is greater than 400 °C . [ABSTRACT FROM AUTHOR]

Due to the advantages of non-toxicity, high chemical stability, high activity and low cost, TiO2 is deemed as ideal material for photocatalytic degradation. However, due to its relatively high band-gap energy, anatase TiO2 can only absorb UV light and light with higher energy. In this work, the anatase TiO2 particles were decorated with two organic photosensitizers hemin and eosin Y. The morphology and chemical structure of the composites were verified by SEM, XRD patterns and Raman spectra, the light absorption ability and generation of free radicals were also investigated. The band-gap energy of TiO2, hemin/TiO2 and EY/TiO2 were found to be 2.82 eV, 0.72 eV and 0.95 eV, respectively. Additionally, absorption of more visible light and generation of more superoxide radicals were achieved after decoration of photosensitizers. Consequently, the photocatalytic degradation activity was largely improved, when the TiO2 particles was decorated with 3% of hemin, the degradation rate of methyl blue reached 76.89% and 63.82% in 120 min under UV light and visible light, respectively, which were 1.86 and 1.84 times that of neat TiO2. Comparatively, the ferric ions in hemin may capture the electrons generated by TiO2 and then deliver the electrons to oxygen to generate more superoxide radicals, thus hemin/TiO2 exhibits higher photocatalytic degradation activity than EY/TiO2. [ABSTRACT FROM AUTHOR]

Peroxy radicals (HO2 and RO2) play a significant role in the formation of ozone andsecondary organic aerosols, and in controlling the atmospheric oxidation capacity. Themeasurement of total peroxy radical RO2* (RO2* = HO2 + ΣRO2) by the PERCA (PEroxyRadical Chemical Amplification) technique is achieved by converting HO2 and RO2 to NO2by their reaction with NO and reforming HO2 in a flow reactor in the presence of a chaincarrier such as CO, which has been widely used in atmospheric chemistry field studies due toits low-cost and portability. The number of radical reformation cycles before being lost, defined as the chain length(CL), is a critical parameter determining the accuracy and sensitivity of PERCA instruments.For CO-based chemical amplification, the wall loss and water dependent gas phase reactionsare the most important chain termination processes that control CL. Compared to dryconditions, the reported CL value is reduced by half at 40% sample inlet relative humidity(RHinlet) and by a factor of 4 at 70% RHinlet. The strong dependence of CL on sample RHfor different instruments makes accurate correction of water vapor effect a realchallenge. In this presentation, we report our progresses made in PERCA by using a large diameterNafion dryer (18 mm inner diameter, MD-700, Perma Pure) as an amplifier to minimize theimpact of water vapor on the chain length (CL). We demonstrate (1) that the Nafion dryerreactor can achieve a higher CL (1.6 times better) than the commonly used PFA tube reactorand (2) that there is a relatively small decrease in CLwet over a wide sample RH (about a 10%reduction at 87% RH). The water sensitivity was strongly suppressed in the Nafiondryer reactor and improved the overall PERCA system performance in quantifyingRO2* concentrations with high sensitivity and high accuracy under most (even veryhumid) ambient conditions. We suggest that this is a simple and attractive approachfor research groups to determine peroxy radical chemistry in field and chamberapplications. References: 1, Chen, Y., Yang, C., Zhao, W., Fang, B., Xu, X., Gai, Y., Lin, X., Chen, W., and Zhang,W.: Ultra-sensitive measurement of peroxy radicals by chemical amplification broadbandcavity-enhanced spectroscopy, Analyst, 141, 5870-5878, 2016. 2, Fang, B., Zhao, W., Xu, X., Zhou, J., Ma, X., Wang, S., Zhang, W., Venables, D. S.,and Chen, W.: Portable broadband cavity-enhanced spectrometer utilizing Kalman filtering:application to real-time, in situ monitoring of glyoxal and nitrogen dioxide, Opt. Express, 25,26910-26922, 2017. 3, Yang, C., Zhao, W., Fang, B., Xu, X., Zhang, Y., Gai, Y., Zhang, W., Venables, D.S., and Chen, W.: Removing water vapor interference in peroxy radical chemicalamplification with a large diameter Nafion dryer, Anal. Chem., 90, 3307-3312,2018. 4, Yang, C., Zhao, W., Fang, B., Yu, H., Xu, X., Zhang, Y., Gai, Y., Zhang, W., Chen, W.,and Fittschen, C.: Improved chemical amplification instrument by using a Nafion dryer as anamplification reactor for quantifying atmospheric peroxy radicals under ambient conditions,Anal. Chem., 91, 776-779, 2019. [ABSTRACT FROM AUTHOR]

Modulating the electronic structure of the electrocatalyst plays a vital role in boosting the electrocatalytic performance of the oxygen evolution reaction (OER). In this work, we introduced a one-step solvothermal method to fabricate 1,1-ferrocene dicarboxylic acid (FcDA)-decorated self-evolved nickel sulfide (Ni 3 S 2 ) nanosheet arrays on a nickel foam (NF) framework (denoted as FcDA-Ni 3 S 2 /NF). Benefiting from the interconnected ultrathin nanosheet architecture, ligand dopants induced and facilitated in situ structural reconstruction, and the FcDA-decorated Ni 3 S 2 (FcDA-Ni 3 S 2 /NF) outperformed its singly doped and undoped counterparts in terms of OER activity. The optimized FcDA-Ni 3 S 2 /NF self-supported electrode presents a remarkably low overpotential of 268 mV to achieve a current density of 10 mA cm -2 for the OER and demonstrates robust electrochemical stability for 48 h in a 1.0 M KOH electrolyte. More importantly, in situ electrochemical Raman spectroscopy reveals the generation of catalytically active oxyhydroxide species (NiOOH) derived from the surface construction during the OER of pristine FcDA-Ni 3 S 2 /NF, contributing significantly to its superior electrocatalytic performance. This study concerns the modulation of electronic structure through ligand engineering and may provide profound insight into the design of cost-efficient OER electrocatalysts.