金属-有机框架衍生的中空碳材料及其在电化学能源存储与氧还原领域中的应用

金属-有机框架材料(metal-organic frameworks,MOFs)是一类由金属离子或金属团簇与有机配体通过配位键连接形成的具有周期性网络结构的多孔配位聚合物。这类材料通常具有孔道规整、比表面积大、孔隙率高、结构可设计及孔壁易修饰等特点,诸多的优点使得MOFs的研究从配位化学跨越到多个学科领域,成为当前多学科交叉前沿热点之一。近来的研究发现,以MOFs为前驱体碳化后制得的碳材料可保留MOFs的大比表面积和多孔结构,同时可以实现均匀的杂原子(如N、P、S、B等)掺杂,而且通过选择合适的MOFs前驱体可调控产物的组成和形貌尺寸,这些显著的结构特征使其具备了成为高性能功能性材料的潜力。最近,以MOFs为模板或前驱体制备的中空碳材料引起了人们的广泛关注,这主要是因为中空结构可有效缓解材料在电化学过程中产生的体积变化及受到的冲击,而且中空结构可暴露出更多的活性位点,具有快速的传质过程,使得材料发挥出最优性能,故而此类材料可被用在二次电池、电容器、电催化等多种电化学器件和多个领域中。基于此,本文综述了MOFs衍生的中空碳材料在储能器件及电催化领域的研究进展,主要包括锂离子电池、锂硫/硒电池、钠离子电池、超级电容器、电催化氧还原等领域,并对这类材料当前面临的挑战及未来的发展趋势进行了阐述。

Metal-Organic Framework-Derived Hollow Carbon Materials for Electrochemical Energy Storage and Oxygen Reduction Reaction

Metal-organic frameworks (MOFs) are porous coordination polymers with periodic network structures constructed from metal ions/clusters and organic ligands through coordination interactions. Typically, MOFs always have advantageous features of regular pore structures, large specific surface areas, high porosity, designable structures and modifiable pore walls. By virtue of these unique characteristics, the study of MOFs is moving from the coordination chemistry to a broad range of academic disciplines, which is becoming one of the hot topics in intercrossed multi-disciplines. Recent studies show that MOFs are promising candidate precursors for functional carbon materials. On the one hand, the specific surface area and porosity are still kept in the MOF-derived carbon materials and various heteroatoms (e.g., N, S, P, and B) can be uniformly doped into the prepared carbon frameworks. On the other hand, the composition, morphology and size of the resultant carbon materials can also be tuned precisely by choosing the appropriate MOF precursors. Currently, MOF-derived hollow carbon materials have drawn widespread attention, mainly because the hollow structures are favorable for alleviating the volume change and impact in the electrochemical processes. Furthermore, hollow structures are more likely to achieve maximum performance benefiting from the fast mass transport and full exposure of active sites. As a result of these properties, MOF-derived hollow carbon materials have shown many applications in a variety of energy devices and areas, such as secondary batteries, capacitors, and electrochemical catalysis. Here, a comprehensive overview of recent developments of MOF-derived hollow carbon materials is provided, including their preparation processes and applications in lithium-ion batteries, lithium-sulfur/selenium batteries, sodium-ion batteries, supercapacitors, and oxygen reduction reaction. Finally, the current challenges and development trends in the future of MOF-derived hollow carbon materials are also discussed.