质子交换膜燃料电池阴极电化学反应路径分析

Analysis of the Electrochemical Reaction Path at the Cathode of a PEM Fuel Cell

质子交换膜燃料电池阴极电化学反应对其性能有至关重要的影响。论文基于二电子反应机理,模拟了质子交换膜燃料电池阴极氧和质子电化学反应路径,分析了电化学反应过程中各个步骤能量变化规律和氢氧键形成机制。研究发现,氧分子还原过程中,4个质子逐个接近氧分子,形成氢氧键,最终生成2个水分子;第一个质子采用和氧分子氢氧键102°夹角的方向接近其中一个氧原子,形成第一个氢氧键;当第二个质子和另一个氧原子构成氢氧键时,需要很大的活化能,这是氧还原反应的控制步骤,生成中间产物过氧化氢。研究结果为理解质子交换膜燃料电池电化学反应原理,推动质子交换膜燃料电池的应用具有重要意义。

Electrochemical reaction in the cathode plays a very important role on the performance of proton exchange membrane（PEM） fuel cell.In this paper,the electrochemical reaction path of the reduction in the cathode of PEM fuel cell is simulated based on the two-electron reaction mechanism.The behavior of energetic change on each reaction step of this reduction and the mechanism of the formation of H-O bond are analyzed.The results show that in the process of reduction of oxygen,four protons approach the O_2 molecule one by one,and then four H-O bonds form,two H2_O molecules form finally.The first proton approaches the O_2 molecule in the direction of 102 degrees with the O-O bond and the first H-0 bond forms.The most active energy must be given to form the second H-O bond,and the H_2O_2 forms.This indicate that the second reaction step of this reduction is the control step.The results will be very helpful for understanding of the principle of electrochemical reaction in PEM fuel cell,and promoting its application.