新型介孔膦酸钴基电催化剂及其电化学析氧性能研究

Electrochemical oxygen evolution reaction (OER) has attracted considerable attention due to the indispensable role for developing electrochemical energy conversion devices, such as metal–air batteries and fuel cells. The most efficient catalysts for the sluggish OER are still noble metals, that is, Ir- and Ru-based materials. To replace expensive Ir and Ru, numerous efforts have been undertaken toward using transition-metal alternatives, for instance, cobalt-based materials. However, the major challenges associated with this catalytic system are the unfavorable catalytic activity, low surface area, interior porosity, unsatisfactory crystallization, and lack of reaction mechanism. Accordingly, this project is aimed to develop novel mesoporous cobalt phosphonate hybrid electrocatalysts for efficient oxygen evolution on the basis of our previous works. By monitoring the formation process, deep insights into the structural characteristics at the molecular or atomic scale can be achieved, which can provide strong support and theoretical basis for the synthesized mesoporous cobalt phosphonate catalysts with high crystallization, well-defined mesoporosity, adjustable mesophases, and thus high catalytic performance. The influence of mesoporosity and the distribution status of organophosphonic moieties are investigated to understand the structure-performance relationship of the catalysts and the concerned catalytic theories, which is combined with the in-situ strategies and theoretical calculation. The optimized model of mesoporous hybrid catalyst system is established on the obtained experimental results, and a further step can realize the right catalytic sites and reaction mechanisms. Moreover, the attempts of modification, preparation of macroscopic mesoporous cobalt phosphonate hybrid catalysts, and direct conversion to mesoporous cobalt phosphate counterparts can provide new perspectives for the development and practical application of this new catalyst system with high activity and strong durability.

本项目针对当前有机-无机金属膦酸盐析氧电催化剂研究中所存在的电化学活性较低、孔性差、比表面积低、结晶度不高、反应机理研究缺乏等科学问题，开展新型高效介孔膦酸钴基电催化剂研究。在前期有关金属有机膦酸盐多孔杂合材料工作基础上，对介孔膦酸钴合成过程进行实时监测，研究形成过程和结构特性，在分子或原子水平上对形成机制和结构性能有更深入全面的认识，着力开发提高这类新颖杂合电催化剂孔壁结晶度和孔径及孔结构的方法，制备出新型孔结构和高性能的介孔膦酸钴材料。深入研究有机基团的分布状况以及这种分布对电化学活性的影响，获得催化剂的构效关系及相关催化理论规律性认识，根据实验结果对催化剂体系进行模型优化，确定催化剂活性中心，结合原位追踪检测和理论计算，深入理解电化学析氧反应机理。再进一步对其进行多功能修饰和改良，制成宏观块体材料，并基于介孔膦酸钴开发介孔磷酸钴催化剂，为新一代析氧电催化剂开发、应用提供理论指导。

本项目开展新型高效介孔膦酸钴基电催化剂研究，并扩展到其他金属膦酸盐材料及其衍生的金属磷酸盐和磷化物及多孔碳基材料电催化体系的构筑与性能研究。利用金属有机膦酸盐多孔杂化材料的结构和组成可调的特点，着重构建系列金属膦酸盐/磷酸盐/磷化物等复合催化剂，考察它们的电催化析氧和析氢等性能，并探讨它们的催化性能与催化剂组成、结构的内在联系，揭示复合催化剂内在组分之间的相互作用、催化作用机制和调控机制；进一步，借助有机膦酸的独特的鳌合/配位效应，制备出系列杂原子掺杂碳材料及碳-金属复合材料，系统研究它们的电催化性能及构效关系。本项目在执行过程中很好地探究了既定的研究内容，并在计划内容的基础上，进一步拓展了研究范围，获得系列高效电催化剂体系。主要进展包括：（1）采用不同有机膦酸，及引入其它导电载体（如石墨烯、碳纳米管等）等，合成出有机膦酸骨架桥连的介孔金属膦酸钴基材料，表征其结构和性质，考察其电催化析氧性能，理解其构效关系和催化机制。（2）利用不同气氛处理金属膦酸盐材料，制备出系列磷酸钴、磷酸镍、磷化钴、磷化镍等材料及其碳基复合催化剂，并考察它们的电催化析氧和析氢性能，以及全电解水产氢性能；发现借助有机膦酸分子能够实现碳材料的原位生成，提高获得金属颗粒的分散性和导电性，从而有效提升催化剂的电催化活性。（3）基于有机膦酸基团对金属离子的络合效应，以及膦酸盐在高温条件下升华形成的磷与金属离子发生磷化反应，原位生成高分散态的金属磷化物纳米颗粒负载的碳纳米片、碳纳米棒，以及自支撑结构材料，且其在电催化领域表现出优异的催化活性，并成功应用于电解水、锌-空气电池等能源装置。（4）基于有机酸-碱相互作用原理，选用合适的有机酸类和含氨基有机物制备出系列多孔（类）有机聚合物，经高温处理后生成系列杂原子共掺杂多孔碳材料，表现出优良的电催化氧还原和氧析出活性。项目已在Adv. Funct. Mater.，J. Mater. Chem. A，ACS Appl. Mater. Interfaces，ACS Sustainable. Chem. Eng.,等期刊发表基金标注的SCI收录论文54篇，应邀在国际和全国性学术会议作邀请报告和Keynote报告多次。