Center for Electrochemical Science and Engineering, Department of Chemical and Biological Engineering, Illinois Institute of Technology, Chicago, IL 60616.
Proc Natl Acad Sci U S A. 2014 Jan 7;111(1):45-50. doi: 10.1073/pnas.1319663111. Epub 2013 Dec 23.
We report a unique and highly stable electrocatalyst-platinum (Pt) supported on titanium-ruthenium oxide (TRO)-for hydrogen fuel cell vehicles. The Pt/TRO electrocatalyst was exposed to stringent accelerated test protocols designed to induce degradation and failure mechanisms identical to those seen during extended normal operation of a fuel cell automobile-namely, support corrosion during vehicle startup and shutdown, and platinum dissolution during vehicle acceleration and deceleration. These experiments were performed both ex situ (on supports and catalysts deposited onto a glassy carbon rotating disk electrode) and in situ (in a membrane electrode assembly). The Pt/TRO was compared against a state-of-the-art benchmark catalyst-Pt supported on high surface-area carbon (Pt/HSAC). In ex situ tests, Pt/TRO lost only 18% of its initial oxygen reduction reaction mass activity and 3% of its oxygen reduction reaction-specific activity, whereas the corresponding losses for Pt/HSAC were 52% and 22%. In in situ-accelerated degradation tests performed on membrane electrode assemblies, the loss in cell voltage at 1 A · cm(-2) at 100% RH was a negligible 15 mV for Pt/TRO, whereas the loss was too high to permit operation at 1 A · cm(-2) for Pt/HSAC. We clearly show that electrocatalyst support corrosion induced during fuel cell startup and shutdown is a far more potent failure mode than platinum dissolution during fuel cell operation. Hence, we posit that the need for a highly stable support (such as TRO) is paramount. Finally, we demonstrate that the corrosion of carbon present in the gas diffusion layer of the fuel cell is only of minor concern.
我们报告了一种独特且高度稳定的电催化剂——负载在钛钌氧化物（TRO）上的铂（Pt），用于氢燃料电池汽车。Pt/TRO 电催化剂经受了严格的加速测试协议，这些协议旨在诱导与燃料电池汽车在延长正常运行期间相同的降解和失效机制，即车辆启动和关闭时的支撑物腐蚀，以及车辆加速和减速时的铂溶解。这些实验是在原位（在玻璃碳旋转圆盘电极上沉积的支撑物和催化剂上）和异位（在膜电极组件中）进行的。Pt/TRO 与最先进的基准催化剂——负载在高比表面积碳（Pt/HSAC）上的 Pt 进行了比较。在异位测试中，Pt/TRO 仅损失了其初始氧还原反应质量活性的 18%和氧还原反应比活性的 3%，而相应的 Pt/HSAC 损失分别为 52%和 22%。在原位加速降解测试中，在 100%相对湿度下以 1 A·cm(-2)进行的膜电极组件中的电池电压损失对于 Pt/TRO 来说可忽略不计，仅为 15 mV，而 Pt/HSAC 的损失过高，无法在 1 A·cm(-2)下运行。我们清楚地表明，燃料电池启动和关闭期间诱导的电催化剂支撑物腐蚀是比燃料电池运行期间的铂溶解更有效的失效模式。因此，我们假设需要高度稳定的支撑物（如 TRO）是至关重要的。最后，我们证明了燃料电池气体扩散层中存在的碳的腐蚀只是一个次要问题。
