Perovskite solar cells have become stars in photovoltaics due to their rapidly increased efficiency. However, their stability is still below par due to moisture permeation from grain boundaries and defects. To conquer both problems at once, a passivation agent 3,4,5,6-tetrafluorophthalicacid (TFPA) is rationally designed to heal both for not only improved cell efficiency but also better stability. It is found that the TFPA is prone to distribute along grain boundaries and has little influence within the bulk of the perovskite film. In addition, it appears that the TFPA helps to reduce the film roughness, to adjust the energy level, to facilitate hole transporting from perovskite to spiro-OMeTAD, and to increase the hydrophobicity of the perovskite film, as it is demonstrated by the inhibited nonradiative recombination and prolonged carrier lifetime. Owing to strong interactions between F, -COOH, and Pb, the device with TFPA shows outstanding efficiency and stability. A perovskite solar cell with TFPA modification delivers a champion efficiency of 23.70% and a significantly enhanced stability that the device maintains 90% of its initial efficiency after 5200 h, among the best ambient stability. Herein, an effective strategy of grain boundary passivation is provided to improve the stability of perovskite solar cells.
In this paper, a novel robust TFPA–TTA–COF coating with nano pores was grafted to the gully-like surface of stainless steel fibers (GS-SSF). The GS-SSF were prepared using a two-step electrochemical etching method, and the covalent organic framework (COF) TFPA–TTA–COF coating was chemically bonded to the gully-like surface via in situ growth. The prepared metal fibers were applied as the headspace solid-phase microextraction (HS-SPME) fibers and combined with gas chromatography (GC) to develop a detection method for phenolic compounds (PCs) in water. The developed method gave the limits of detection (S/N = 3) from 0.07 µg·L −1 to 0.52 µg·L −1 with enrichment factors from 243 to 2405. The relative standard deviations for inter-day study (n = 5) and fiber-to-fiber were from 3.94% to 8.89% and 2.17% to 8.05%, respectively. The prepared fiber could stand at least 180 cycles without remarkable loss of extraction efficiency. The developed method was successfully employed for the determination of trace PCs in environmental water with recoveries from 84.76% to 124.84%.
Haijuan Jiang,Xiaoming Wu,Hongjian Miao,Shaoxiang Yang,Hongyu Tian,Baoguo Sun
Tetrabromobisphenol A (TBBPA) was a widely used brominated flame retardant , and had attracted widespread attention from researchers due to its potential adverse effects on ecosystems and human health. Therefore, to eliminate the negative effects of TBBPA, methods for the adsorption and removal of TBBPA are urgently needed. In this work, the fluorine-functionalised magnetic covalent organic frameworks (Fe 3 O 4 @TFAPT-TFPA@COF) were first prepared through a simple and rapid ultrasound method to efficiently adsorpt and remove TBBPA. Firstly, a pre-modification strategy was used to modify fluorine functional groups onto amine monomers via superacid catalyzed trimerization . Then, amine and aldehyde monomers undergo Schiff base reaction smoothly to form a COF layer coated on the surface of Fe 3 O 4 nanoparticles . The characterisation results indicated that the prepared Fe 3 O 4 @TFAPT-TFPA@COF had a high surface area , porosity, crystallinity and abundant F-containing binding sites . Additionally, the adsorption process of prepared Fe 3 O 4 @TFAPT-TFPA@COF complied with pseudo-second-order kinetics and the Langmuir adsorption model. It had a large adsorption capacity (107.5 mg g −1 ), could effectively remove tetrabromobisphenol A within 4 minutes and had excellent regeneration ability within eighth repetitions. Finally, tetrabromobisphenol A was efficiently removed by a small separation column loaded with Fe 3 O 4 @TFAPT-TFPA@COF, achieving levels below the detection limit (< 0.05 mg L −1 ) and providing practical application value for the real-time removal of TBBPA. The main mechanisms promoting the excellent adsorption performance of TBBPA were through halogen bonds , electrostatic interactions , π-π stacking, and hydrogen bonding interactions, providing potential reference value for the adsorption ability and mechanism of TBBPA in other applications.
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