MOF多孔碳载核壳结构Au基阳极纳米催化剂的可控制备及其在直接硼氢化钠燃料电池中的应用研究

High coulombic numbers nearly 8e- of BH4- electrooxidation can be obtained by using Au as anode electrocatalyst. So, Au anode electrocatalyst can enhance fuel efficiency and resolve security issues caused by H2 from BH4- hydrolysis in DBFC. However, the relatively low catalytic activity of Au anode catalyst limits the DBFC performance. In this proposal, we will focus on the design and synthesis of core-shell structure Au-based nanocatalysts (such as M@Au, M@Au-M, Au-M@Au, etc.). The transition metal (M) doping can improve the catalytic activity of Au catalysts due to synergistic effect between Au and M. Core-shell structure of Au catalysts not only can improve the utilization of Au, but also decrease the loss of M, which will lead to better stability for the Au-based catalysts. The Au-based nanocatalysts will be loaded on MOF porous carbon supporter with high specific surface area. The influence factors for the catalytic activity and stability of Au-based catalysts (such as chemical composition, microstructure and morphology, surface valence distribution, alloying degree, etc.) and supporter will be studied. We will try to reveal the inter-correlation among these factors, and the relationship between these factors and electrocatalytic performance of Au-based catalysts. Furthermore, the reaction mechanism of BH4- electrooxidation on Au-based cataysts will be studied by density functional theory (DFT). The above studies will provide theoretical foundation and technological instruction for design and synthesis of novel anode catalyst materials, and develop new anode electrocatalysts with low cost, good catalytic performance, and long-term durability for DBFC.

Au催化剂能使BH4-实现接近理论8e的氧化反应，用作直接硼氢化钠燃料电池(DBFC)阳极催化剂可解决燃料BH4-利用率低及其水解产生H2带来的安全问题。但Au相对较低的催化活性影响DBFC整体性能。本项目拟对Au催化剂进行过渡态金属(M)掺杂改性，利用金属间的协同效应提高其催化活性。设计制备以非贵金属或合金为内核，以贵金属或其合金为外壳的核壳结构Au基纳米催化剂，既可提高Au利用率，又可降低M流失，增强催化剂稳定性。通过制备高比表面积的MOF多孔碳作催化剂载体，进一步提高催化剂的催化活性和稳定性。研究催化剂和载体的组成、形貌、结构、表面价态分布、合金化程度等相互之间，及其与催化剂催化活性和稳定性之间的作用规律，结合对催化剂上BH4-氧化反应机理的理论研究，进一步揭示材料的构效关系，指导催化剂的制备、调控和优化，为高性能、低成本、长寿命的DBFC阳极催化剂的研发和应用提供理论基础与技术依据

直接硼氢化钠燃料电池(DBFC)主要以Pt、Au、Pd等贵金属作阳极催化剂，高的催化剂成本阻碍了DBFC的商业化。Au催化剂能使BH4-实现接近理论8e的氧化反应，用作DBFC阳极催化剂可解决燃料BH4-利用率低及其水解产生H2带来的安全问题。但Au相对较低的催化活性影响DBFC整体性能。本项目针对限制DBFC商业化的瓶颈问题，从贵金属Au催化剂掺杂改性和新型催化剂碳载体的研发两方面着手，提高催化剂性能，降低其成本。主要研究了以下内容：(1)设计制备了Co(OH)2@Au/C、Ni(OH)2@Au/C、Au/CoFe@NC/C、Au/Co2P@NC/C、Au/NiFe/NC、Au/FeMn@NC/C等6种核壳结构Au基纳米电催化剂；(2)以金属有机框架MOF材料ZIF-8作为前驱体制备了氮掺杂纳米多孔碳材料(NPC)；(3)以ZIF-8-NPC作为载体，制备了NPC载Au纳米粒子催化剂(Au/NPC)，NPC载Au-Fe双金属催化剂(Au/FeNPC)和NPC载Au-Co双金属催化剂(Au/CoNPC)等3种MOF多孔碳载Au基纳米电催化剂，以及石墨炔载Au(Au/eGDY)、石墨烯载Au(Au/G)、多壁碳纳米管载Au(Au/MWCNT)等3种Au催化剂。通过XRD测定了催化剂的物相组成，XPS分析了催化剂的表面组成，SEM、TEM观察和分析不同合成条件相应催化剂材料的形貌、微观结构、纳米粒子的粒径大小和分散情况，EDS测定催化剂材料的成分组成；采用线性电位扫描(LSV)、循环伏安(CV)、计时电流(CA)、计时电位(CP)等电化学测试技术研究了所制备的催化剂对BH4-电氧化反应(BOR)的催化性能，确定了催化剂的制备条件与催化剂的组成、结构、纳米粒子尺寸及电催化活性、催化剂稳定性之间的内在关系。研究结果表明，3d过渡态金属掺杂和采用新型碳材料(NPC和石墨炔等)作催化剂载体均可以明显提高Au催化剂对BOR的电催化性能。本项目的研究成果为高性能、低成本、长寿命的DBFC阳极催化剂的研发提供了一定的理论基础与技术依据。