直接甲醇燃料电池(DMFC)可以将甲醇的化学能转化为电能.甲醇在室温下是一种液体,很容易运输和低风险储存.在常用燃料中,甲醇热值较高且价格便宜,其单位价格热值甚至高于汽油.更重要的是,甲醇可以通过二氧化碳催化加氢制得.因此可以将可再生能源转化为氢气,并高效地存储在甲醇分子中.而燃料电池消耗甲醇后,产物只有二氧化碳和无污染的水.在未来,这种利用甲醇进行的碳回收过程可以实现接近零碳排放.基于上述优点,DMFC已成为近年来最有前途并有望应用于移动车辆的燃料电池之一.在DMFC中,最关键的步骤是甲醇的电催化氧化反应.本文通过密度泛函理论(DFT)计算,研究并比较了由铂、铂铜合金和铜的甲醇电催化氧化反应机理.通过系统研究复杂反应网络,包括反应中间体脱氢、水分子解离和抗毒反应等基元反应步骤,探索了该反应的催化过程.在pH=0和零电位条件下,在纯铜电极表面,吸附后甲醇的大部分脱氢步骤是吸能的,这使其在甲醇电催化氧化中需要更高的电势,因而活性较低.而对于铂和铂铜合金,其甲醇脱氢步骤主要是放能的,比较容易进行.但甲醇脱氢后产生的一氧化碳中间体在铂原子上结合太强,会在活性位点积累,最终毒化催化剂.因此,对铂及其合金催化剂,其最大的挑战在于如何消耗掉快速累积的一氧化碳.作为甲醇电催化氧化中另一个反应物,水分子会在催化剂表面电化学解离为羟基,而一氧化碳可以与这些羟基结合并消耗,完成催化剂的抗毒反应.但该抗毒反应是一个热力学基元反应,较难直接通过改变电势直接促进,主要由催化剂本身的性质所决定.DFT计算表明,相比于纯铂电极,铂与铜的合金化不仅可以降低一氧化碳和羟基之间结合的自由能能垒,而且可以帮助水分子解离产生更多的羟基来提升催化剂抗中毒的能力.这使得实验中铂铜合金比纯铂电极具有更高的催化活性.以上结果揭示了在铂和其合金电催化剂表面,吸附一氧化碳消耗的抗毒反应和水分子解离在甲醇电催化氧化反应中的重要性.这些反应机理将助力更高活性合金电催化剂的理性设计,促进直接甲醇燃料电池技术的发展及其在生产生活中的应用.“,”In this work, we have performed density functional theory (DFT) calculations to investigate the methanol electro-oxidation reaction (MOR) catalyzed by the Pt, PtCu alloy and Cu. The complex reaction networks, including the intermediate dehydrogenation, water dissociation and anti-poison reaction steps, are systematically investigated to explore the mechanisms. At the standard condition of pH = 0 and zero potential, for Cu, most dehydrogenation steps along the favorable pathway are endergonic, making it less active in MOR. For the Pt and PtCu alloy, their dehydrogenation steps are mainly exergonic, but the formed CO intermediate binds too tightly on Pt, that can accumulate on active sites to poison the electro-catalyst. The CO can be consumed by the thermodynamic reaction with OH*, which comes from water dissociation. DFT calculation shows alloying the Pt with Cu could not only reduce the free energy barrier for binding between CO* and OH*, but also assist the water dissociation to produce more OH* for that anti-poison reaction. That makes the PtCu alloy more active than the pure Pt electrode in experiment. The results reveal the importance of an-ti-poison reaction and water dissociation in MOR, which could be applied to the rational design of more active alloy electro-catalysts in future.