12 Search Results

Unsupported iridium (Ir) nanoparticles, that serve as standard oxygen evolution reaction (OER) catalysts in acidic electrolyzers, were investigated for electrochemical performance and durability in rotating disk electrode (RDE) half-cells. Fixed potential holds and potential cycling were applied to probe the durability of Ir nanoparticles, and performance losses were found to be driven by particle growth (coarsening) at moderate potential (1.4 to 1.6 V) and Ir dissolution at higher potential (>/=1.8 V). Several different commercially available samples were evaluated and standardized conditions for performance comparison are reported. In conclusion, the electrocatalyst RDE results have also been compared to results obtained formore » performance and durability in electrolysis cells.« less

Low-temperature direct methane fuel cells (DMEFCs) offer the opportunity to substantially improve the efficiency of energy production from natural gas. This study focuses on the development of well-defined platinum organometallic complexes covalently anchored to ordered mesoporous carbon (OMC) for electrochemical oxidation of methane in a proton exchange membrane fuel cell at 80 °C. A maximum normalized power of 403 µW/mg Pt was obtained, which was 5 times higher than a modern commercial catalyst and two orders of magnitude greater than Pt black catalyst. The observed differences in catalytic activities for oxidation of methane are linked to the chemistry of themore » tethered catalysts, determined by X-ray photoelectron spectroscopy. The chemistry/activity relationships demonstrate a tangible path for the design of electrocatalytic systems for C-H bond activation that afford superior performance in DMEFC for potential commercial applications.« less