Jian Hua Wang,Yao Ming Liu,Jian Bin Chao,Yu Wang,Hui Wang,Shao Min Shuang
A new phenazine-imidazole based Schiff base (PIS) fluorescent probe has been developed for the ratiometric detection of Cd2+ ions in aqueous media at physiological pH. PIS upon binding with Cd2+ ions shows red shifted fluorescence and thereby, permits ratiometric detection of Cd(II) ions. A detection limit down to 2.10 × 10−8 M was determined for Cd2+ quantitation. Also, the accompanying apparent fluorescence color change (from yellow to orange red) is noticeable to the naked eye under a UV-lamp. The sensing mechanism could be attributed to the 1 : 1 PIS–Cd complexation, followed by extension of the conjugation due to better planarity and modulation of the charge transfer efficiency in the probe. This was complemented by solvatochromism and density functional theory calculations. Furthermore, PIS was used to detect Cd2+ in Oxya chinensis cells, zebrafish larvae and live tissues of Arabidopsis thaliana under a fluorescence microscope, showing great potential in analyzing living biosystems.
The Ni-rich layered oxide cathode (LiNi 0.8 Co 0.1 Mn 0.1 O 2 , NCM811) suffers from serious interfacial side reactions and phase transition during high-voltage cycling (4.7 V), causing the poor rate capability and sharp capacity fading. Herein, a beneficial strategy is proposed, combining rigid/flexible chains, to exploit an endurable poly(imide-siloxane) (PIS) binder with transitable ion channel by structural tailoring and copolymerization. The in-situ formed nanoscale PIS layer on the NCM811 particle surface provides stern resistance to extreme conditions and strong attractive interactions, which enable a firm cathode-electrolyte interface and facile ion transfer path during charge-discharge process. The fabricated PIS-based cathodes under 4.3 V cutoff voltage exhibit higher capacity retention (83% vs. 69%, 1.0C, 500 cycles) and higher rate capacity (137.6 mAh g −1 vs. 123.6 mAh g −1 , 5.0C), in contrast to the cathodes with polyvinylidene fluoride (PVDF) binder. Further test under 4.7 V cutoff voltage indicates the rate capacity of PIS-based cathodes is superior than that of PVDF-based cathodes (163.2 mAh g −1 vs. 119.7 mAh g −1 , 5.0C), as well as superior capacity retention (74 % vs. 34%, 0.2C, 100 cycles). This work provides a valuable guideline for designing a polymer binder by focusing on stabilizing high-voltage cathode structure and facilitating ion diffusion.
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