Highly Efficient Electrocatalytic Uranium Extraction from Seawater over an Amidoxime-Functionalized In-N-C Catalyst.
Highly Efficient Electrocatalytic Uranium Extraction from Seawater over an Amidoxime-Functionalized In-N-C Catalyst.
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高效的电催化性铀从海水中提取，这是在N-C催化剂中启用的。
DOI：
10.1002/advs.202201735
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发表时间：
2022-08
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海水中铀的浓度约为 3.3 ppb，因此是丰富且可持续的核燃料来源。在此，开发了一种用于从海水中提取铀的吸附-电催化平台，该平台包含锚定在用柔性偕胺肟部分（In-N x -C-R，其中R表示偕胺肟基团）功能化的空心氮掺杂碳胶囊上的原子分散的铟。 In–N x –C–R 表现出优异的铀酰捕获特性，可在 24 小时内实现 6.35 mg g−1 的铀去除率，是迄今为止报道的最好的铀萃取剂之一。重要的是，In–N x –C–R 相对于海水中的钒，表现出卓越的铀提取选择性（前者的选择性高出 8.75 倍）。 X射线吸收光谱（XAS）表明，偕胺肟基团可作为铀酰螯合位点，从而可以选择性吸附其他离子。 XAS和原位拉曼结果直接表明，通过涉及InN x 位点的可逆单电子转移过程，吸收的铀酰可以电催化还原为不稳定的U(V)中间体，然后以不溶性Na2O(UO3·H2O) x 的形式重新氧化为U(VI)以进行收集。这些结果在分子水平上提供了对铀提取过程的详细机制理解。这项工作为从海水中吸附电催化提取铀提供了路线图，为不断增长的从地球海洋中获取有价值金属的技术提供了补充。用柔性偕胺肟基团功能化的多孔铟氮碳胶囊可以实现从海水中高效提取铀。灵活的偕胺肟基团允许选择性吸附铀酰，而InN x 单原子位点提供可逆的单电子转移平台，用于通过U(V)中间体将铀酰转化为可收获的Na2O(UO3·H2O) x 沉淀物。
Seawater contains uranium at a concentration of ≈3.3 ppb, thus representing a rich and sustainable nuclear fuel source. Herein, an adsorption–electrocatalytic platform is developed for uranium extraction from seawater, comprising atomically dispersed indium anchored on hollow nitrogen‐doped carbon capsules functionalized with flexible amidoxime moieties (In–N x –C–R, where R denotes amidoxime groups). In–N x –C–R exhibits excellent uranyl capture properties, enabling a uranium removal rate of 6.35 mg g−1 in 24 h, representing one of the best uranium extractants reported to date. Importantly, In–N x –C–R demonstrates exceptional selectivity for uranium extraction relative to vanadium in seawater (8.75 times more selective for the former). X‐ray absorption spectroscopy (XAS) reveals that the amidoxime groups serve as uranyl chelating sites, thus allowing selective adsorption over other ions. XAS and in situ Raman results directly indicate that the absorbed uranyl can be electrocatalytically reduced to an unstable U(V) intermediate, then re‐oxidizes to U(VI) in the form of insoluble Na2O(UO3·H2O) x for collection, through reversible single electron transfer processes involving InN x sites. These results provide detailed mechanistic understanding of the uranium extraction process at a molecular level. This work provides a roadmap for the adsorption–electrocatalytic extraction of uranium from seawater, adding to the growing suite of technologies for harvesting valuable metals from the earth's oceans. Porous indium−nitrogen−carbon capsules functionalized with flexible amidoxime groups enable highly efficient uranium extraction from seawater. The flexible amidoxime groups allow selective uranyl adsorption, while the InN x single atom sites provide a reversible single electron transfer platform for uranyl conversion to a harvestable Na2O(UO3·H2O) x precipitate via a U(V) intermediate.