The increasing uranium containing wastes generated during uranium mining and finishing pose a huge threat to the environment and human health, and thus robust strategies for on-site monitoring of uranium pollutant are of great significance for environmental protection around uranium tailings. Herein, a facile “turn-on” colorimetric platform that can achieve uranium detection by spectrometry and naked eyes was developed based on the uranium-enhanced nanozyme activity of covalent organic framework (JUC-505). Thanks to the extended π-conjugated skeleton and donor-acceptor (D-A) structure, JUC-505 exhibited superior photo-activated nanozyme activity, which would be prohibited when the cyano group in JUC-505 skeleton was transformed to the amidoxime group. Further results elucidated that the coordination of uranium with amidoxime groups led to the electron transfer between uranium and the JUC-505-AO skeleton, and thus significantly restored the nanozymatic activity of JUC-505-AO with the subsequent remarkable color changes. Moreover, the uranium concentrations in uranium tailing wastewater detected by the present “turn-on” colorimetric method were well agreed with those by ICP-MS, demonstrating a high accuracy of the present method in real samples. The D-A structured JUC-505 with superior photocatalytic property and nanozymatic activity was applied to facilitate colorimetric detection of uranium, which displays the advantages of low detection limit, excellent selectivity, fast response and simple operation for uranium detection in real samples, and shows a great potential in on-site monitoring of uranium pollutant around uranium tailings as well as nuclear power plant.

中文翻译：

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基于供体-受体结构共价有机框架的增强纳米酶活性的先进“开启”比色铀平台

铀矿开采和精加工过程中产生的含铀废物不断增加，对环境和人类健康构成巨大威胁，因此强有力的铀污染物现场监测策略对于铀尾矿周围的环境保护具有重要意义。在此，基于共价有机框架（JUC-505）的铀增强纳米酶活性，开发了一种简便的“开启”比色平台，可以通过光谱法和肉眼实现铀检测。由于延伸的π共轭骨架和供体-受体（DA）结构，JUC-505表现出优异的光激活纳米酶活性，当JUC-505骨架中的氰基转化为偕胺肟基团时，这种活性将被抑制。进一步的结果表明，铀与偕胺肟基团的配位导致了铀与JUC-505-AO骨架之间的电子转移，从而显着恢复了JUC-505-AO的纳米酶活性以及随后显着的颜色变化。此外，本发明的“开启”比色法检测到的铀尾矿废水中的铀浓度与ICP-MS的检测结果非常吻合，表明本方法在实际样品中具有较高的准确性。 DA结构的JUC-505具有优异的光催化性能和纳米酶活性，用于铀的比色检测，在实际样品中的铀检测中表现出检出限低、选择性好、响应快、操作简单等优点，显示出良好的检测效果。铀尾矿和核电厂周围铀污染物现场监测的潜力。