Xingyan Liu,Jinfeng Zhao,Jie Hao,Ying Zhang,Weiyi Cui,Dawei Lou,Xiyue Wang
The solvothermal approach was used to create a three-dimensional covalent organic framework (TP-PA) using p-phenylenediamine (PA), 1,3,5-triformyl phoroglucinol (TP), and anhydrous ethanol as the solvent. It was utilized as a coating material for needle trap devices (NTD) to determine five polychlorinated biphenyls (PCBs) from milk coupled with gas chromatography (GC). The results displayed that TP-PA presented excellent extraction performance to PCBs owing to its abundant micro/mesopores structure, high specific surface area and good chemical and thermal stability. The proposed needle-type micro-extraction (NTME)-GC method had wide linearity (0.025–200 μg L −1 ) with R 2 ≥ 0.9928, low limits of detection (0.0072–0.0146 μg L −1 ), and good single device repeatability and device-to-device reproducibility with the relative standard deviations (RSDs) below 7.07 %. It was applied to detect five trace PCBs in milk, and satisfactory spiked recoveries were obtained (79.7 %∼96.4 %) with relative standard deviations less than 11.9 %. The above results indicated that the method has excellent application potential for detecting PCBs in food.
Covalent organic frameworks (COFs) as new photocatalysts for hydrogen evolution have aroused considerable interest over the past few years. However, most of COF-based photocatalysts require expensive and rare Pt co-catalysts to achieve a high hydrogen evolution rate. Here, a series of Tp-Pa-2-COF-based photocatalyst materials with porous 2D conductive metal–organic framework (MOF) Cu3(HHTP)2 as a noble metal-free co-catalyst are successfully prepared by an easy handling and green mechano-chemical method. Remarkably, after optimizing the ratio of the COF and MOF, the Tp-Pa-2/Cu3(HHTP)2 hybrid composite with a mass ratio of 3 : 1 exhibits the highest hydrogen evolution rate of 7.71 mmol h−1 g−1 under visible-light irradiation, while the hydrogen evolution rate of the pure Tp-Pa-2 is only 0.026 mmol h−1 g−1. Based on the detailed experiments and calculations, the improved performance can be mainly explained by the porous crystalline Cu3(HHTP)2 co-catalyst in the resulting composites efficiently promoting the utilization rate of the photogenerated charge-carriers, thus contributing to the high hydrogen generation performance.
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