TY - JOUR
T1 - CeO 2 surface oxygen vacancy concentration governs in situ free radical scavenging efficacy in polymer electrolytes
AU - Trogadas, Panagiotis
AU - Parrondo, Javier
AU - Ramani, Vijay
PY - 2012/10/24
Y1 - 2012/10/24
N2 - Nonstoichiometric CeO 2 and Ce 0.25Zr 0.75O 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
AB - Nonstoichiometric CeO 2 and Ce 0.25Zr 0.75O 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
KW - free radical scavenging
KW - nonstoichiometric cerium oxide
KW - PEM degradation
KW - reactive oxygen species
UR - https://www.scopus.com/pages/publications/84867905722
U2 - 10.1021/am3016069
DO - 10.1021/am3016069
M3 - Article
AN - SCOPUS:84867905722
SN - 1944-8244
VL - 4
SP - 5098
EP - 5102
JO - ACS Applied Materials and Interfaces
JF - ACS Applied Materials and Interfaces
IS - 10
ER -