替位型掺杂三氧化钨载铂催化剂的设计合成及其电催化性能研究

Tungsten trioxide (WO3) has been widely studied as an electrode material for direct methanol fuel cell (DMFC) because of its special electrochemical properties and high stability in acid solution. In view of the problems of poor conductivity and slow methanol oxidation kinetics of Pt/WO3 catalyst as anode of DMFC at present, a new method to regulate the electronic structure of WO3 by substituting doping with non-metallic atom is proposed in this project. At the same time, the micro-pore structure which can promote the insertion/extraction of hydrogen is formed, thus speeding up the methanol oxidation kinetics. Based on the first principle of density functional theory and methanol electrooxidation as probe reaction, Pt/m-WO3 catalysts with core-shell structure are synthesized by plasma technique and gas-solid reaction and so on. The relationship between the micropore channels , the electronic structure and electrocatalytic performance of m-WO3 are established. The influence of the composition, morphology and structure of the catalyst on the electrocatalytic performance of methanol are revealed. The synergistic mechanism between noble metal and m-WO3 is also clarified. The DMFC with Pt/m-WO3 catalyst as anode is then designed and assembled based on the half-cell reactions, which will further enhance its energy conversion efficiency and service life. The problems of the current WO3 fuel cell catalyst above mentioned are effectively solved.

三氧化钨（WO3）具有特殊的电化学性质和酸性溶液中稳定性高等优点，作为直接甲醇燃料电池（DMFC）电极材料而被广泛研究。本项目针对目前Pt/WO3作为DMFC的阳极存在导电性差和甲醇氧化动力学缓慢等问题，提出一种通过非金属原子（m）替代掺杂方式调控WO3的电子结构，同时形成可促进质子嵌脱的微观孔道结构，从而加快甲醇氧化动力学过程的研究新思路。以基于密度泛函的第一性原理为理论指导，甲醇氧化反应为探针反应，采用等离子技术和气固相反应等方法可控合成具有核壳结构的Pt/m-WO3催化剂，建立m-WO3体相的微观孔道、电子结构与其电催化性能之间关系，揭示催化剂的组成、形貌和结构对甲醇电催化性能的影响规律，阐明贵金属和m-WO3之间协同作用机理。在半电池反应研究基础上，设计和组装一种以Pt/m-WO3催化剂为阳极的DMFC装置，提升其能量转换效率和使用寿命，有效解决WO3燃料电池催化剂面临的上述问题。

贵金属和WO3之间具有氢溢流效应和双功能机理，在直接甲醇燃料电池研究领域得到广泛研究，然而WO3存在导电性能差以及比表面积小等问题。本项目通过氮掺杂方法调控WO3的微孔结构与电子结构，提升电导率的同时加快甲醇氧化动力学过程，从而提高对甲醇氧化反应的电催化性能。研究成果共发表SCI论文8篇，申请和授权发明专利2项，培养硕士研究生8名，项目组成员参加线上下学术交流4次。在项目执行中取得的主要代表性成果如下：1）以尿素作为氮源，偏钨酸铵微球为前驱体，采用喷雾干燥法制备氮掺杂WO3微球，借助改进的液相还原法得到Pt/N-WO3催化剂。研究结果表明氮掺杂在减小WO3的带隙、提高电子迁移率以及为催化反应提供活性位点等方面发挥了重要作用；2）在上述研究基础上，采用水热法合成了具有纳米片层结构的Pt /N-WO3催化剂，结果发现纳米片层结构的存在有利于甲醇在其表面电催化氧化过程的发生；3）采用第一性原理计算方法对Pt /N-WO3体系的吸附能、氢迁移能和电子结构等方面展开研究，为实验研究提供了强有力的理论研究基础。