双碳限域的过渡金属单原子/团簇设计及电催化析氧反应性能研究

Developing highly efficient and robust electrocatalyst based on non-precious metals for oxygen evolution reaction (OER) is vital for sustainable and clean energy technologies, e.g. water splitting and metal-air batteries. The proposed project aims to explore a series of high-performance OER electrocatalysts consisting of atomically dispersed transition metal (TM, TM=Fe, Co, Ni) species co-confined by nitrogen-doped carbon nanotubes (N-CNTs) and reduced graphene oxide (rGO), through freeze drying and pyrolysis of a preformed GO-wrapped core-shell bimetallic zeolitic imidazolate frameworks (ZIFs) template, followed by the acid leaching process. Through changing the experimental conditions, the effects of the composition and structure of ZIFs, pyrolysis temperature, reaction time and acid leaching on the distribution and content of TMs, N-doping and microstructure of electrocatalyst (TM@N-CNTs@rGO) were thoroughly investigated. The relationship between the OER electrocatalytic performance and the morphology, microstructure, phase composition, TM coordination environment and surface property will be established by a series of electrocatalytic studies (e.g. overpotential, exchange current density, Tafel plot, turnover frequency and operation stability at all PH values). The electronic structure of TM-N-C and the interactions between the TM and the N-CNTs@rGO will be investigated using the density function theory. Based on these results, the structure-activity relationship of TM@N-CNTs@rGO in electrocatalysis as well as the OER catalytic mechanism will be revealed at an atomic level.

发展高活性和高稳定性的非贵金属析氧反应(OER)电催化剂对于可持续清洁能源技术十分关键。本项目将利用氧化石墨烯包覆的核壳沸石咪唑酯骨架材料作为前驱体，通过冷冻干燥、热还原裂解和酸滤，原位制备一系列氮掺杂碳纳米管(N-CNTs)和石墨烯(rGO)双碳限域的过渡金属单原子/团簇(TM@N-CNTs@rGO, TM=Fe, Co, Ni)复合材料OER电催化剂。通过改变前驱体成分和结构、反应温度及酸滤时间和浓度等实验条件，研究这些因素对复合材料中TM的分布、含量、N掺杂及CNTs@rGO微观结构的影响规律。通过比较过电位、塔菲尔斜率、转换频率以及在酸碱操作环境下的稳定性等，揭示电催化剂OER性能与其形貌、微观结构、单原子配位环境、表面性质间的相互关系。分析TM单原子/团簇的电子态结构及与双碳载体的相互作用，从原子态揭示催化机理，建立TM@N-CNTs@rGO单原子催化结构与催化活性的构效关系。

发展高性能的非贵金属析氧反应电催化剂对于可持续清洁能源技术十分关键。本项目通过设计MOFs核壳结构以及引入石墨烯、溶菌酶对MOFs前驱体表面进行功能化，辅以同步的碳化和/磷化/碲化前驱体，可控制备了系列碳载金属（化合物）复合材料（如多孔碳/碳纳米管负载的钴单原子、多孔碳片/碳纳米管/锌单原子/钴纳米颗粒、多孔碳/石墨烯/镍量子点、多孔碳-吡啶氮-钴单原子、多孔碳/碳纳米管/磷化钴、多孔碳/碳纳米管/正交相碲化钴等）。通过微观结构表征、电化学测试以及理论计算，分析了双碳限域的过渡金属基复合材料电催化析氧性能及电催化机理，阐明了微观结构、相成分、单原子配位环境等催化性能的影响规律。 i）低温碳化石墨烯包裹的二维Ni-ZIF可以制备石墨烯和多孔碳共限域的富含缺陷的Ni量子点，该结构有助于活性位点的高暴露，同时能优化中间体的吸附能。ii）通过SiO2改性的沸石咪唑酯前驱体策略，构筑了交联碳片自组装三维碳分级结构的Co-N4复合体系，该体系赋予界面丰富的催化活性位点，加速了氧化还原反应进行。iii）单原子钴的配位环境可以通过调控碳基体进行优化，双碳限域的Co-N3能降低反应中间体的能垒，提升反应动力学。iv）通过阴离子掺杂调控双碳耦合的二碲化钴使其从热力学稳定相到亚稳相，提升其电子传导能力，优化中间吸附能。通过控制磷化条件和后续的硫化处理，利用多种杂原子掺杂增强双碳耦合磷化钴复合材料的界面电荷的转移能力。在此基础上，本项目还探索了MOFs衍生的碳载过渡金属（化合物）单原子/团簇/纳米颗粒复合材料在储锂以及电催化电催化析氢及氧还原性能方面的研究。