An excellent corrosion-resistant and good conductivity coating is desired for metal bipolar plate (BP) in proton exchange membrane fuel cell (PEMFC). In this view, a novel strategy to achieve this aim by introducing AlO into CrN film. AlO/CrN nanocomposite coatings are first prepared by co-sputtering. Subsequently, the microstructure, electrochemical corrosion resistance, interfacial contact resistances (ICR) and contact angle are systematically investigated. As a result, AlO/CrN nanocomposite coating shows a low corrosion current density of 0.084 μA/cm in room temperature and a low corrosion current density of 0.39 μA/cm at 70 °C, which highly meets the requirement of U.S. DOE 2025 targets. Besides, AlO/CrN nanocomposite coating displays a superior durability to pure Au film. It is revealed that AlO can hinder the growth of CrN columnar crystals and result in coating amorphization, which is the mechanism of AlO-promoted the CrN corrosion resistance. Furthermore, AlO/CrN coating also exhibits an excellent electrical conductivity, featuring a smaller ICR of 3.09 mΩ cm. Inspired by these results, introducing AlO into CrN coatings can provide enlightening insights to design new non-noble-metal coatings for metal BP in future PEMFC manufacturing.

中文翻译：

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PEMFC金属双极板Al2O3/CrN涂层的高耐腐蚀性和导电性：Al2O3阻碍CrN柱状晶体的生长

质子交换膜燃料电池（PEMFC）中的金属双极板（BP）需要优异的耐腐蚀性和良好的导电性涂层。有鉴于此，通过将 Al2O3 引入 CrN 薄膜中来实现这一目标的新颖策略。首先通过共溅射制备Al2O3/CrN纳米复合涂层。随后，系统地研究了微观结构、电化学耐腐蚀性、界面接触电阻（ICR）和接触角。结果表明，Al2O/CrN纳米复合涂层在室温下表现出0.084 μA/cm的低腐蚀电流密度，在70 ℃时表现出0.39 μA/cm的低腐蚀电流密度，高度满足美国DOE 2025目标的要求。此外，Al2O/CrN纳米复合涂层表现出比纯Au薄膜更优越的耐用性。结果表明，Al2O3会阻碍CrN柱状晶的生长，导致涂层非晶化，这是Al2O3促进CrN耐蚀性的机制。此外，Al2O/CrN涂层还表现出优异的导电性，其ICR较小，为3.09 mΩ·cm。受这些结果的启发，将 Al2O3 引入 CrN 涂层中可以为未来 PEMFC 制造中的金属 BP 设计新型非贵金属涂层提供启发性见解。