压电调制的软X射线吸收谱学技术及在N掺杂石墨烯体系研究中的应用

Element-doped two-dimensional (2D) ultrathin nanomaterials have been a very hot and active subject of research in physics, chemistry, material, etc., due to their fascinating physical, chemical properties and novel phenomena. Identifications of the microstructures (including local atomic and electronic structures) of the dopants are pivotal to the understanding of the novel phenomena and properties, as well as to the design and preparation of new 2D functional materials. In this project, we propose to setup a new piezo-modulated soft X-ray absorption spectroscopy (PM-SXAS) technique at the soft X-ray magnetic dichroism (XMCD) beamline of National Synchrotron Radiation Laboratory (NSRL). This will be achieved through a strategy of using a piezo-actuated chopper to render the sample drain current with a certain periodic frequency feature, together with the use of a lock-phase amplifying method. This PM-XAS technique can overcome the detection-of-limit of conventional soft X-ray absorption technique, and will act as a promising and powerful soft X-ray method to detect the microstructures of trace elements in complex functional materials. It will be used to explore the microstructure of N dopants in graphene and to study the C-O interactions between C atoms in graphene and residue O atoms. Combining this technique with magnetization measurements and real-space multiple-scattering calculations of XAS spectra, we will obtain the relationship between microstructures and macroscopic magnetism from the electronic/atomic viewpoints. These studies will allow us to gain new insights into the microscopic ferromagnetism mechnism in N-doped graphene.

掺杂二维薄层材料表现出的新奇物理现象和优异的物理化学性质是物理、化学和材料等领域的研究热点，而实现其掺杂原子的微结构（局域结构和电子结构）探测也成为人们理解这些新现象和设计、制备出新型二维薄层功能材料的关键和追求目标。本项目将依托合肥光源的软X射线磁圆二色站，通过研制基于压电效应工作的压电斩波器调制入射X射线赋予样品电流周期性频率结构的策略，结合锁相放大技术，建立压电调制的软X射线吸收谱学探测新方法（PM-SXAS），实现复杂功能材料中低掺杂浓度轻元素的微结构探测，为我国用户提供一个高质量的软X射线吸收谱学表征手段。利用PM-SXAS研究N掺杂石墨烯二维薄层材料中N原子、残留O原子和C原子的微结构及相互间的作用特点，结合磁性测量等常规表征手段以及实空间多重散射理论计算和第一性原理计算，在电子、原子水平上建立微结构和宏观磁性之间的内在联系，为明确N掺杂石墨烯具有铁磁性的微观机理提供理论依据。

掺杂二维薄层材料表现出的新奇物理现象和优异的物理化学性质是物理、化学和材料等领域的研究热点，而实现其掺杂原子的微结构（局域结构和电子结构）探测也成为人们理解这些新现象和设计、制备出新型二维薄层功能材料的关键和追求目标。本项目依托合肥光源的软X射线磁圆二色站，建立弱信号的软X射线吸收谱学探测新方法。在此基础上，基于同步辐射谱学实验方法研究了石墨烯、MoS2和V2C等二维量子功能材料的结构与磁性，揭示了这些低维量子材料中通过引入外来原子、缺陷和杂化促使这些非铁磁性材料具有室温本征铁磁性的内在机制，为在电子、原子水平上设计制备出低维量子磁性材料提供了理论依据。另一方面研究了MOF和铱基氧化物等量子材料，在光催化或电催化产氢、产氧和氮还原过程中，其微观结构与宏观催化性能之间的内在联系，揭示了微观结构在产氢、产氧过程中扮演的角色，为指导合成高效产氢、产氧的高活性催化剂提供了新思路。在该基金的支持下已发表SCI论文14篇，其中代表性文章为《自然•通讯》2篇、《美国化学会志》1篇、《德国应用化学》1篇。