单中心原子催化剂的配位结构与CO2电化学还原反应调控研究

As CO2 is an abundant and inexpensive carbon resource in the chemical industry, recycling CO2 into fuels and high value-added chemical stocks via an electrochemical process represents a promising path to mitigate the energy crisis. Due to the high thermodynamic stability of CO2, the standard potential of CO2/CO2- couple is as negative as -1.9 V versus reversible hydrogen electrode (vs RHE) in water for the formation of highly energetic CO2 anion radicals. As such, the effective activation of CO2 plays a key role in CO2 electrochemical reduction. From both theoretical and experimental perspectives, the electron transfer to CO2 is generally considered as the critical step during the activation of CO2. To overcome this bottleneck, it is especially important to rationally design a highly active and robust electrocatalyst which possesses assistant electron-donation centers to capture CO2 molecules and activate the stable C=O non-polar bonds. The project mainly focuses on the controllable synthesis of single-site atomic catalysts (including single-atom catalysts and single-site molecular catalysts) towards CO2 electrochemical reduction. The surface electronic densities, charge transfer, and interfacial free energy for single-site atomic catalysts are regulated via manipulating the coordination structure of single-site atom, thereby realizing the effective activation and conversion of CO2 Diversified interfacial processes such as the adsorption of substrate molecule, the cleavage and transformation of chemical bonds will be explored from atomic/molecular level by means of in-situ infrared spectroscopy, ultrahigh-resolution quasi in-situ X-ray photoelectron spectroscopy (XPS), and quasi in-situ extended X-ray absorption fine structure spectroscopy (NEXAFS). With the help of the first principles calculation, the CO2 adsorption, as well as the bond formation and the bond change process between single-sites and key intermediates, could be directly predicted under different coordinate structrue down to the atomic/molecular scale. The project aims to construct a single-site atomic catalyst system with high activity for electroreduction of CO2 and demonstrate the effect of coordinate structure on activity, selectivity, and stability, leading to final understanding of structure-activity/selectivity relationship during CO2 electrochemical reduction. This project would provide a guideline for the rational design of novel and highly efficient single-site atomic catalyst towards CO2 electrochemical reduction by regulating coordinate structuresof catalysts.

将CO2通过电化学还原成CO、HCOOH、多碳产物等高能量密度的能源物质和化工原料，不仅有效解决CO2大量排放所造成的环境问题，还能为当前资源紧缺提供再生洁净能源。本项目选择单中心原子催化剂（单原子催化剂和单中心分子催化剂）为研究对象，着重调控中心原子的配位结构（中心原子直接相连的内配位和中心原子非直接相连的外配位），造就中心金属原子表面电子态密度、价态以及表面自由能的变化，实现对CO2分子的高效活化转化。借助合肥光源同步辐射原位红外光谱、准原位X射线光电子能谱、准原位软X射线近边吸收谱等技术手段监测CO2分子和单中心原子催化剂在反应中的演化过程，从原子分子层面研究单中心原子催化剂的配位结构与CO2分子发生的吸附、键的断裂和键变过程的内在作用，诠释单中心原子催化剂在CO2电化学还原过程中的构效关系。旨在通过研究构筑一类对CO2电化学还原具有高活性的单中心原子催化剂体系。

将CO2通过电化学还原成CO、HCOOH和多碳产物等高能量密度的能源物质和化工原料，不仅有效解决CO2大量排放所造成的环境问题，还能为当前资源紧缺提供再生洁净能源。本项目主要以探究单中心原子催化剂的配位环境与CO2电化学催化还原的内在作用机制为主要研究目标。项目执行过程中分别通过调控中心原子直接相连的内配位和中心原子非直接相连的外配位为主要研究内容，诠释了单中心原子催化剂的活性中心原子的电子自旋态、电子态密度和电子能级排布等电子态结构特征与CO2的活化催化转化的内在联系，借助多种同步辐射原位/准原位技术及第一性原理，从原子分子层面上深入研究了CO2分子在单中心原子催化剂表面的吸附、键的断裂和键变过程，给出了验证催化机理的直接证据，从机理上解析CO2电化学催化还原过程中分子键的微观机制，并为高效的CO2电化学还原单中心原子催化剂的设计奠定坚实的实验和理论基础。在本项目的资助下，项目负责人培养了博士后2名、博士生3名和硕士生2名。并以通讯作者身份在Nat. Commun.(2 篇)，Chem. Soc. Rev.（1篇），Nano Lett.（6篇），Appl. catal. B: Environ（2篇），ChemSusChem（2篇），Adv. Sci.（1篇），Green Chem.（1篇），Chem. Comm.（1篇），J. Mater. Chem. A（1篇），Sci. China Chem.（1篇），ChemNanoMat（1篇），Nano Research（1篇），Chin. J. Catal.（1篇）发表论文21篇，申请专利3项。