Gas Permeable Inorganic Shell Improves the Coking Stability and Electrochemical Reactivity of Pt towards Methane Oxidation.

Solid oxide fuel cells produce electricity directly by oxidizing methane, which is the most attractive natural gas fuel, and metal nanocatalysts are a promising means of overcoming the poor catalytic activity of conventional ceramic electrodes. However, the lack of thermal and chemical stability of nanocatalysts is a major bottleneck in the effort to ensure the lifetime of metal-decorated electrodes for methane oxidation. Here, , this issue is addressed by encapsulating metal nanoparticles with gas-permeable inorganic shells. Pt particles of approximately 10 nm in size are dispersed on the surface of a porous LaSrCrMnO (LSCM) electrode wet infiltration and are then coated with an ultrathin AlO layer atomic layer deposition. The AlO overcoat, despite being an insulator, significantly enhances the immunity to carbon coking and provides high activity for the electrochemical oxidation of methane, thereby reducing the reaction impedance of the Pt-decorated electrode by more than two orders of magnitude and making the electrode activity of the Pt-decorated sample at 650C comparable with those reported at 800C for pristine LSCM electrodes. These observations provide a new perspective on strategies to lower the operation temperature, which has long been challenge related to hydrocarbon-fueled solid oxide fuel cells.