基于分子模拟的HT-PEMFC阴极反应路径及温度影响

Influence of HT-PEMFC Cathode Reaction Path and Temperature Based on Molecular Simulation

目的研究高温质子交换膜(HT-PEM)燃料电池阴极氧还原反应特性,分析不同温度对反应系统能量、键长、键角和反应粒子运动速度的变化规律.方法建立HT-PEM燃料电池阴极催化剂Pt(1 1 1)表面及氧分子模型,运用分子动力学原理,根据密度泛函理论和第一性原理,模拟HT-PEM燃料电池阴极氧分子在催化剂Pt(1 1 1)表面的吸附和4个氢离子依次与氧分子反应等过程.结果氧分子的吸附和第1个氢离子与氧分子反应的时间最长;反应生成物水分子的键长为0.099 nm,H-O-H键角为104.5°,与实际测量值相符.结论各步反应中,键长达到平衡需要的时间比键角达到平衡需要的时间短;随着温度的提高,各个反应粒子运动速度加快,系统能量达到平衡时需要的时间缩短,导致电化学反应速度提高.

In order to study the oxygen reduction reaction on the cathode of high temperature proton exchange membrane（ HT-PEM） fuel cell,the surface of HT-PEMfuel cell cathodic catalyst Pt（ 1 1 1） and the oxygen molecular model were established. Based on the theory of molecular dynamics,the adsorption of the cathodic oxygen molecules of HT-PEMfuel cell on the Pt（ 1 1 1）surface and the reaction of four hydrogen ions with oxygen molecules were simulated according to the density functional theory and the first principle. The effects of temperature on the energy,bond length,bond angle and velocity of the reactive particles were analyzed. The results showthat the adsorption of oxygen molecules and the reaction time of the first hydrogen ion and oxygen molecules are the longest. The bond length of the reaction product water is 0. 099 nm and the bond an-gle of H-O-H is 104. 5°,which is in accordance with the actual detection value. In the reaction,the time required for the bond length to reach the equilibrium is shorter than the time required for the bond angle to reach equilibrium. As the temperature increases,the velocity of each reaction particle is accelerated and the time required for the system to reach equilibrium is shortened,which leads to an increase in the electrochemical reaction rate.