Abstract:

An orthogonal test scheme L9 (3⁴) was designed considering four main factors, anode catalyst (IrO₂) loading, cathode catalyst (Pt/C) loading, anode nafion proportion and cathode nafion proportion with three levels. The water electrolysis properties of different membrane electrode assembly (MEAs) were characterized using polarization curve under 60℃. The current density at 2V was used to assess the performance. The MEA had the best performance when the anode catalyst loading was 2.0mg/cm², cathode catalyst loading was 1.0mg/cm², anode nafion proportion was 20% and cathode nafion proportion was 25%. Polarization curve measurement, hydrogen yield calculation and stability test was conducted on the MEA with optimal condition. Under a constant current mode, the electrolytic voltage increased from 1.78V to 2.06V during the stability test. The electrochemical impedance spectroscopy (EIS) indicated that the total resistance of electrolyser and charge transfer resistance both increased. Scanning electron microscopy (SEM) revealed that the cathode catalytic layer was peeled off from the membrane after testing. The water in tank was analyzed by inductively coupled plasma mass spectrometry (ICP-MS) every ten hours, the result showed that there was an obvious accumulation of the Ir and Pt elements in the feed water with the process of water electrolysis.

Key words: electrolysis, orthogonal test, membrane electrode assembly, hydrogen production, stability

摘要：

以阳极催化剂（IrO₂）、阴极催化剂（Pt/C）含量、阴极Nafion质量分数和阳极Nafion质量分数为考察的因素，进行了四因素三水平的正交试验，以电解槽电解电压在2V时的电流密度为衡量标准，确定了配置催化剂浆料的最优配比为：阳极催化剂IrO₂担载量2.0mg/cm²，阴极催化剂Pt担载量1.0mg/cm²，阳极催化剂浆料中Nafion质量分数20%，阴极催化剂浆料中Nafion质量分数25%。使用最优配比配制催化剂后制备膜电极，对该膜电极进行极化曲线测试、产氢量计算及稳定性测试，发现运行80h后，膜电极的电解性能下降，在0.6A/cm²时，电解电压从1.78V升高到2.06V。使用交流阻抗分析稳定性测试前后的各部分电阻变化，发现各部分电阻均有增加。扫描电镜发现测试后阴极催化层与膜发生明显剥离。对稳定性测试期间的循环水进行电感耦合等离子体质谱（ICP-MS）测试，发现长时间运行后，水中Ir和Pt的含量增加。

关键词: 电解, 正交试验, 膜电极, 制氢, 稳定性