Center for Electrochemical Science and Engineering, Department of Chemical and Biological Engineering, Illinois Institute of Technology, 10 W, 33rd Street, Chicago, Illinois 60616, USA.
ACS Appl Mater Interfaces. 2012 Oct 24;4(10):5098-102. doi: 10.1021/am3016069. Epub 2012 Sep 25.
Nonstoichiometric CeO(2) and Ce(0.25)Zr(0.75)O(2) nanoparticles with varying surface concentrations of Ce(3+) were synthesized. Their surface Ce(3+) concentration was measured by XPS, and their surface oxygen vacancy concentrations and grain size were estimated using Raman spectroscopy. The surface oxygen vacancy concentration was found to correlate well with grain size and surface Ce(3+) concentration. When incorporated into a Nafion polymer electrolyte membrane (PEM), the added nonstoichiometric ceria nanoparticles effectively scavenged PEM-degradation-inducing free radical reactive oxygen species (ROS) formed during fuel cell operation. A 3-fold increase in the surface oxygen vacancy concentration resulted in an order of magnitude enhancement in the efficacy of free radical ROS scavenging by the nanoparticles. Overall, the macroscopic PEM degradation mitigation rate was lowered by up to 2 orders of magnitude using nonstoichiometric ceria nanoparticles with high surface oxygen vacancy concentrations.
具有不同表面 Ce(3+)浓度的非化学计量 CeO(2)和 Ce(0.25)Zr(0.75)O(2)纳米粒子被合成。通过 XPS 测量了它们的表面 Ce(3+)浓度，通过拉曼光谱估计了它们的表面氧空位浓度和晶粒尺寸。发现表面氧空位浓度与晶粒尺寸和表面 Ce(3+)浓度密切相关。当将其掺入 Nafion 聚合物电解质膜 (PEM) 中时，添加的非化学计量氧化铈纳米粒子有效地清除了燃料电池运行过程中形成的导致 PEM 降解的自由基活性氧物质 (ROS)。表面氧空位浓度增加 3 倍，导致纳米粒子清除自由基 ROS 的效率提高了一个数量级。总体而言，使用具有高表面氧空位浓度的非化学计量氧化铈纳米粒子，宏观 PEM 降解缓解率降低了 2 个数量级。
