铂铜合金催化甲醇电氧化的机理研究

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...

Mechanistic insight into methanol electro-oxidation catalyzed by PtCu alloy

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.