MoS_(2)/八面体Fe_(3)O_(4)复合界面催化电化学海水提铀的性能与机理研究

Performance and Mechanism of MoS_2/Octahedral Fe_3O_(4) Composite Interface Catalytic Electrochemical Seawater Extraction of Uranium

电化学海水提铀是一种可持续补充核燃料的有效策略,但由于海洋中铀的浓度极低(铀质量分数为3.3×10^(-9))与复杂的环境干扰,高活性电催化剂的合理设计仍然是一个挑战。本工作提出界面键合策略,通过简单水热法制备MoS_(2)/八面体Fe_(3)O_(4)复合材料,通过X射线光电子能谱(XPS)、高分辨透射电镜(HRTEM)等一系列表征,表明成功将八面体Fe_(3)O_(4)的{2 2 2}晶面与MoS_(2)的{0 0 2}晶面进行键合。在模拟溶液中,经过7 h的电化学提取,铀提取效率可以达到96%。同时,共存离子下的铀提取实验结果表明,MoS_(2)/Fe_(3)O_(4)对铀具有良好的选择性和对共存离子的抗干扰性。在10 L天然海水中进行电化学提取,提取到27.2μg的铀,提取容量为5.44 mg/g。通过对催化剂与提铀性能之间构效关系的研究,验证了界面键合面向电化学海水提铀的可行性。机理探究揭示了界面键合策略对降低Fe_(3)O_(4)的电荷转移电阻、提高电子在界面处的转移速率与Fe_(3)O_(4)的循环稳定性的促进作用,对电化学海水提铀的催化剂设计与开发提供了思路。

Extracting uranium from seawater is an effective strategy for sustainable nuclear fuel supplementation.Uranium in seawater mainly exists in the form of hexavalent uranyl(U(Ⅵ)),although the total amount is large,the mass fraction of U(Ⅵ) is only 3.3×10^(-9),and many metal ions coexist with uranium.Extracting uranium from seawater is extremely challenging.Electrochemical seawater uranium extraction has become an emerging method for seawater uranium extraction due to its advantages over physical and chemical adsorption processes,such as fast reaction rate,strong anti-interference ability,and simple desorption.However,due to the lack of research on the structure-activity relationship between catalysts and uranium extraction performance,the rational design of highly active electrocatalysts remains a challenge.In this work,we proposed an interface bonding strategy by using a simple hydrothermal method to bond the {2 2 2} fact of octahedral Fe_(3)O_(4) to the {0 0 2} fact of MoS_(2).This significantly improves the electron transfer rate at the interface and the cycling stability of Fe_(3)O_(4),verifying the feasibility of interface bonding for the electrochemical extraction of uranium from seawater.After 7 hours of electrochemical extraction in a simulated solution,the extraction efficiency of uranium can reach 96%.Meanwhile,the experimental results of coexisting ion extraction of uranium indicated that MoS_(2)/Fe_(3)O_(4) has good selectivity for uranium and anti-interference ability against coexisting ions.Electrochemical extraction is also performed in 10 L natural seawater with a yield of 27.2 μg.The extraction amount of uranium is 5.44 mg/g.A series of characterizations such as XPS and HRTEM,show that Fe_(3)O_(4) is dispersed on the surface of MoS_(2) and effectively bound through interfacial interactions.This dispersion effectively solves the aggregation problem of Fe_(3)O_(4),and the stability of MoS_(2) structure ensures the cycling stability of Fe_(3)O_(4).By combining the MoS_(2) and Fe_(3)O_(4) at the interface,an efficient electron transfer channel can be constructed,accelerating electron transfer and achieving the goal of simultaneously improving the selectivity,stability,and electron transfer rate of the catalyst.Therefore,the interfacial regulation strategy proposed in this work utilizes the synergistic effects of different components in the composite material to achieve stability and the cyclicity of the catalyst in seawater uranium extraction.At the same time,the interface control strategy will also provide a feasible solution for achieving efficient reduction and extraction of uranyl in a series of complex environments such as seawater.And the electron transfer path and the species change of uranium during catalytic reduction need to be further explored in the mechanism analysis in this work.