Electrochemical Deposition for Electrochemical Energy Applications

质子交换膜燃料电池（PEMFC）由于其高能效、高功率密度、快速启动、低工作温度、连续运行、模块化、燃料灵活性和低温室气体排放而成为汽车和固定应用中化石燃料的潜在替代能源。尽管有这些优点，PEMFC仍然面临高成本和低于期望的耐久性的问题，这限制了它们的广泛使用。这些成本与它们对铂（Pt）基电催化剂的依赖和阴极催化剂层中所需的高Pt负载水平有关，以补偿氧还原反应（ORR）的缓慢动力学。 研究人员已经做出共同努力，通过使用由Pt与较便宜的过渡金属如Co、Fe和Ni合金化组成的电催化剂来减少Pt需求。这种方法不仅降低了材料成本，而且由于这些合金对ORR的活性高于纯Pt的活性，还显示出改善了燃料电池性能。然而，Pt负载量仍然远高于美国能源部（DOE）设定的目标，并且存在关于这些Pt合金催化剂的稳定性的问题。 该研究旨在应用电沉积技术制备具有改善的ORR活性和稳定性的Pt-Co催化剂膜，同时降低Pt负载。电沉积法虽然有一些优点，但并没有像其他方法那样广泛用于制备铂基催化剂，并且在过去已经取得了成功。提出的研究的目的是更充分地探索这些优势，通过应用新的调制和脉冲技术，提供更多的操作变量来控制合金成分和存款形态比可能与直流电镀。一种新的和简单的方法，利用所观察到的行为的Pt-Co沉积将开发制造催化剂膜与可调的组合物配置文件，然后将分析其ORR活性和稳定性。如果成功，这可以增加Pt利用率，足以将Pt负载降低到DOE目标水平，并且仍然能够提高ORR活性。

Proton exchange membrane fuel cells (PEMFC) are potential alternatives to fossil fuels as energy sources for automotive and stationary applications due to their high energy efficiency, high power density, quick start-up, low operating temperature, continuous operation, modularity, fuel flexibility and low greenhouse gas emissions. Despite these advantages, PEMFCs still face problems of high costs and less than desired durability that have limited their widespread use. These costs are linked to their reliance on platinum (Pt)-based electrocatalysts and the high Pt loading levels required in the cathode catalyst layer to compensate for the slow kinetics of the oxygen reduction reaction (ORR). Researchers have made concerted efforts to reduce the Pt requirement by using electrocatalysts consisting of Pt alloyed with less expensive transition metals such as Co, Fe and Ni. This approach not only reduces material costs, but also has been shown to improve fuel cell performance due to the higher activity of these alloys for the ORR than that of pure Pt. Nevertheless, the Pt loading is still much higher than the target set by the U.S. Department of Energy (DOE) and questions exist regarding the stability of these Pt alloy catalysts. The proposed research is aimed at applying electrodeposition techniques to fabricate Pt-Co catalyst films with improved ORR activity and stability, while reducing Pt loading. Electrodeposition is not as widely used to fabricate Pt-based catalysts as other methods although it has some advantages and has shown success in the past. The objective of the proposed research is to more fully explore these advantages by applying novel modulated and pulsed techniques that provide more operating variables to control alloy composition and deposit morphology than is possible with DC plating. A novel and simple method that takes advantage of the observed behaviour of Pt-Co deposition will be developed to fabricate catalyst films with tunable composition profiles which will then be analyzed for their ORR activity and stability. If successful, this could increase Pt utilization enough to lower Pt loading to the DOE target level and still be able to improve the ORR activity.