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等优点，是化石燃料的潜在替代品，可作为汽车和固定应用的能源。尽管有这些优点，质子交换膜燃料电池仍然面临着成本高和耐久性较差的问题，限制了其广泛使用。这些成本与它们对铂 (Pt) 基电催化剂的依赖以及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）合金组成的电催化剂来减少 Pt 的需求。这种方法不仅降低了材料成本，而且由于这些合金的 ORR 活性比纯 Pt 更高，因此已被证明可以提高燃料电池性能。尽管如此，Pt 负载量仍然远高于美国能源部 (DOE) 设定的目标，并且这些 Pt 合金催化剂的稳定性存在问题。 该研究旨在应用电沉积技术来制备具有改善的 ORR 活性和稳定性的 Pt-Co 催化剂薄膜，同时减少 Pt 的负载量。尽管电沉积有一些优点并且在过去已经取得了成功，但它并没有像其他方法那样广泛用于制造铂基催化剂。本研究的目的是通过应用新颖的调制和脉冲技术来更充分地探索这些优势，这些技术提供比直流电镀更多的操作变量来控制合金成分和沉积形态。将开发一种新颖且简单的方法，利用观察到的 Pt-Co 沉积行为来制造具有可调成分分布的催化剂薄膜，然后分析其 ORR 活性和稳定性。如果成功，这可以提高 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.