Pd基金属间化合物及其表面结构调控对直接甲醇燃料电池阴极氧还原活性和耐久性的影响

The development of non/low-Pt cathode catalysts with high catalytic activity, long-term durability and high methanol tolerance for direct methanol fuel cell is current research focus. This proposal will focus on the development of palladium based intermetallic compounds and their modified surface layer as methanol tolerant oxygen reduction reaction (ORR) catalysts due to the good structural stability and relatively low cost of palladium based intermetallic compounds. Research efforts include: (1) to prepare different Pd based intermetallic compounds; (2) to explore the effect of composition, structure and morphology on both activity and durability of the catalysts; (3) to elucidate the lattice matching, electronic effect and ligand effect between the shell and Pd based intermetallic compound on the mechanism of improvement for activity and durability. Research emphasis will be placed on the exploration of the effects of the interaction between Pd based intermetallic core and modified shell to elucidate the relationships between the structure and performance of the catalysts and to design a new durable catalyst for the DMFCs.

非/低Pt，具有高催化活性和长耐久性，抗甲醇的纳米电催化剂是直接甲醇燃料电池阴极催化剂的研究热点。借助Pd基金属间化合物良好的结构稳定性和相对低的成本，项目提出开展Pd基金属间化合物作为抗甲醇氧还原电催化剂的研究，重点研究金属间化合物制备方法、组成、结构和形貌对催化剂活性和耐久性的影响规律。同时通过Pd基金属间化合物非金属元素掺杂和表面富Pt调控其表层结构，探索Pd基金属间化合物内核与表层的晶格匹配，以及催化剂的电子效应和配体效应等对氧还原催化活性和耐久性提高的机制，阐明Pd基金属间化合物及其表面结构调控催化剂结构与活性和耐久性间的“构~效”关系，丰富有关电催化理论。

直接甲醇燃料电池作为一种清洁、高效的新能源，在便携式移动电源上具有广阔的应用前景，但阳极甲醇容易渗透到阴极，在阴极产生过电位，降低电池性能。理想的直接甲醇燃料电池催化剂是非/低Pt，具有高催化活性和长耐久性，抗甲醇等特性。本课题借助Pd基金属间化合物良好的结构稳定性和对甲醇催化氧化基本无活性，开展了Pd基金属间化合物作为抗甲醇氧还原电催化剂的研究，通过一步法在无表面活性剂、低温条件下制备了Pd2Sn金属间化合物，发现其电催化活性相比于Pd催化剂明显提高，但比铂催化剂略低；进一步地通过Co掺杂的Pd2Sn金属间化合物，发现掺杂以后金属间化合物的晶格收缩和电子结构发生变化，其氧还原活性是铂碳催化剂的2.1倍，且其耐久性明显提升；另外通过对Pd基催化剂表面富Pt调控其表层结构增强其氧还原性能，其电催化活性是铂催化剂的1~3倍，铂的利用率提高到5~10倍，并且耐久性也显著提升。