ABSTRACT 18O/16O isotope effects were observed at the cathode of a polymer electrolyte membrane fuel cell at 25 and 35°C. Results of experiments in which the 18O/16O isotope ratios of the oxygen gases supplied to and exhausted from the cell were measured revealed that the lighter isotope 16O reacted more preferentially to form water molecules at the cathode than the heavier one, 18O. The value of the oxygen isotope separation factor, S1, defined as the ratio of the 18O/16O isotope ratios of the oxygen gases supplied to and exhausted from the cell, ranged from 1.0030 to 1.0139, and tended to decrease with decreasing rate of oxygen utilisation (θ) and with increasing flow rate of the feed oxygen gas (DF). The value of another separation factor, S2, defined as the ratio of the 18O/16O isotope ratios of the exhausted oxygen gas and oxygen having reacted to form water molecules at the cathode, ranged from 1.0049 to 1.0304. The S2 value was much less affected by the change in θ and DF than the S1 value with the majority of the S2 value being in the range of 1.0240–1.0304.

中文翻译：

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聚合物电解质膜燃料电池阴极18O/16O同位素效应的观察

摘要 在 25°C 和 35°C 下，在聚合物电解质膜燃料电池的阴极观察到 18O/16O 同位素效应。测量供应到电池和从电池排出的氧气的 18O/16O 同位素比的实验结果表明，较轻的同位素 16O 比较重的同位素 18O 更优先在阴极反应形成水分子。氧同位素分离因子 S1 的值定义为供应到电池和从电池排出的氧气的 18O/16O 同位素比的比值，范围从 1.0030 到 1.0139，并且随着氧气利用率的降低而减小(θ) 并且随着进料氧气 (DF) 的流速增加。另一个分离因子 S2 的值，定义为排出的氧气与在阴极反应形成水分子的氧气的18O/16O同位素比之比，范围从1.0049到1.0304。S2 值受 θ 和 DF 变化的影响比 S1 值小得多，大部分 S2 值在 1.0240-1.0304 的范围内。