三维BCN@C的仿生构筑、能级调控及其对铀的光催化还原机制

放射性废水中铀的吸附和光催化还原是放射化学领域最受关注的前沿问题之一。本项目以含有机物放射性废水中的铀为研究对象，针对放射性废水处理过程中面临的可溶性有机物会与铀发生络合而增加处理难度、光催化剂上有限的活性位点容易被铀的还原产物占据和粉末状催化剂难回收等问题，提出构建集吸附和光催化功能耦合的宏观尺度碳掺杂氮化硼/生物炭（BCN@C）仿生组装体，使BCN上的光电子引入到含大量吸附位点的生物质衍生炭上，促进铀的可持续还原。重点围绕BCN@C的仿生组装以及BCN与生物炭之间能级匹配度的精细调控，利用同步辐射X射线吸收精细结构技术研究BCN@C仿生组装体上铀的配位环境、化学价态和键合模式，进而在分子水平上揭示吸附剂/半导体能级匹配度与铀吸附-催化还原的构效关系。最后，在有机物存在的情况下，探究有机物的光氧化对铀的吸附-催化还原的作用机制。预期成果有望为含有机物的放射性废水的处理提供理论参考。

The adsorption and photocatalytic reduction treatment of uranium in radioactive wastewater is one of the most concerned frontier issues in the field of radiochemistry. However, the soluble organics coordinate with uranium and thus severely decrease the adsorption efficiency. Meanwhile, the limited active sites on the photocatalyst are easily occupied by the reduction products of uranium and the difficulty of recovering the powdery catalyst also limits the further application of the catalyst. Herein, we propose to construct a 3D macroscale carbon-doped boron nitride@bio-charcoal (BCN@C) bionic assembly with adsorption-photocatalytic function, so that the photoelectrons on BCN will be introduced to bio-charcoal with a large number of adsorption sites, and promote the continuous reduction of uranium. In this project, we focus on the assembly of the BCN@C bionic assembly and the fine adjustment of the energy level matching between BCN and bio-charcoal. Synchronous radiation X-ray absorption fine structure technology is used to study the coordination environment, chemical valence state and bonding mode of uranium on the BCN@C bionic assembly. Furthermore, we will provide the correlation between the energy-level matching of adsorbent/semiconductor and the adsoption-reduction performance in the molecular level. Meanwhile, the influence of photo-oxidation of organics on the adsoption-reduction of uranium will be illuminated. This project is expected to provide theoretical references for the treatment of organic radioactive wastewater.