多级孔结构亲CO2 MOFs模板负载的M@MOF电催化剂及其电催化转化CO2研究

Electrochemical reduction is an effective method to convert carbon dioxide (CO2) into hydrocarbon fuels under mild conditions. However, it is necessary to further improve the activity, selectivity, and stability of electrocatalyst. M@MOF, prepared using metal-organic frameworks (MOFs) as template for encapsulating active metal nanoparticles, is a promising electrocatalyst with good performance for electrocatalytic reduction of CO2. For this project, the hierarchically pore-structured MOFs with high CO2 adsorption selectivity are chosen to prepare the M@MOF electrocatalyst with large specific surface area, rich active sites and good stability through controlling the formation of metal nanoparticles by virtue of the pore size and functional difference of MOFs. The obtained electrocatalyst is used to assemble the M@MOF modified electrode and its performance for electrocatalytic reduction of CO2 will be assessed. The relationship between structure and performance of the M@MOF electrocatalyst will be established by structural characterization and qualitative/quantitative analysis of the products. In addition, the influence of channel (cavity) size/shape, adsorption sites, the CO2 adsorption enthalpy, metal ions and ligands of MOFs, the incorporated metal and ratio, as well as the encapsulate technique on the structure of the active metal nanoparticles and the activity/selectivity/stability of the M@MOF electrocatalyst will be revealed. The corresponding electrochemical reaction mechanisms will be explored by studying the evolution of structure and composition in the processes of electrocatalytic reduction of CO2. On the basis of works above, we will try to develop the M@MOF electrocatalyst with high performance and realize high efficiencies of electrocatalytic reduction of CO2.

电化学还原是温和条件下转化CO2为碳氢燃料的有效方法。然而，还原CO2电催化剂的活性、选择性、稳定性仍需进一步提高。金属有机骨架（MOFs）负载活性金属纳米粒子组装的M@MOF有希望成为性能优良的还原CO2电催化剂。本项目拟选择具有多级孔结构的亲CO2MOFs作为模板，通过孔道尺寸、功能化差异控制纳米粒子的形成，组装成具有高比表面积、高活性位点、高稳定性的M@MOF电催化剂；制备M@MOF修饰电极并评估其电催化性能；通过结构表征和产物定性、定量分析确立M@MOF的结构与其电催化性能的构效关系；揭示MOFs载体的孔道（空腔）大小、形状、吸附位点、CO2吸附焓、金属离子、配体，负载金属、负载比例及工艺对纳米粒子的结构、M@MOF催化剂活性、选择性以及稳定性的影响；探讨还原过程中组分、结构演变规律，探索其电化学反应机理。在此基础上，发展性能优良的M@MOF电催化剂，实现CO2的高效电催化还原。

本项目借助富含微-介孔多级孔道结构的MOFs材料作为模板，首次开展了MOFs担载Cu NPs及应用于电催化还原CO2(CO2RR)的研究。利用MOFs结构中孔道尺寸、功能化差异控制Cu纳米粒子的形成，组装高活性位点、高度有序的M@MOF催化剂；系统开展了以富含卟啉基活性分子催化剂的原生态MOFs—PCN–222(M) (M= Fe, Cu, Co, Zn, Mn, Ni)和PCN–224(M) (M= Zn, Cu) 与碳材料（活性炭、CNTs、GO）结合，组装高活性、高稳定性、对CO2具有高吸附选择性复合材料；以富含N的多微孔MOFs为前驱体衍生高M-Nx位点、高比表面积M-N-C复合材料。应用混合配体策略获得了富含介孔和高密度原子级Fe-NX分布活性位点的Fe-N-C材料，得到了具有超高稳定性、100% FECO%的单原子催化剂。