Thin film micro-solid oxide fuel cells (mSOFCs) utilizing nanoporous ruthenium (Ru) anodes were fabricated and investigated for direct methane operation for the first time. The mSOFCs consist of 8 mol % yttria-stabilized zirconia (YSZ) thin film electrolytes, porous platinum (Pt) cathodes and porous Ru anodes, fabricated on silicon platforms by physical vapor deposition. The fuel cells, tested with methane as the fuel and air as the oxidant, exhibited an open circuit voltage (OCV) of 0.71 V and a peak power density of 450 mW cm À2 at 500 C without visually detectable carbon deposition. Structural investigations revealed that the morphology evolution in nanoporous Ru anodes was strongly dependent on the fuels (namely, methane or hydrogen) used, and possible mechanisms leading to the observations are discussed. Results presented here project insights to enable direct use of hydrocarbons with high performance, and are of potential relevance to advancing low temperature micro-fuel cell technology for portable power.
This proceedings manuscript describes in brief representative results on porous Ru anodes incorporated into thin film solid oxide fuel cells (SOFCs). Thin film of 8 mol% yttria-stabilized zirconia (YSZ) was fabricated as free-standing electrolytes, with porous platinum (Pt) and porous Ru deposited as cathode and anode electrodes, respectively. μSOFCs were tested with methane as the fuel and air as the oxidant, exhibiting an open circuit voltage of 0.71 V and a peak power density of 450 mW/cm2 at 500 °C. Anode electrodes were investigated for structural change and was found that morphology evolution in anode electrodes were strongly dependent on the fuels used. Auger electron spectroscopy was carried out on Ru anodes before and after methane operation, and revealed minimal amount of carbon existing on Ru surface, possibly being reaction intermediates. On-going studies on Ru-CGO composite anodes are discussed.
This manuscript describes representative results of thin film microsolid oxide fuel cells (µSOFCs) utilizing nano-porous ruthenium (Ru) and Ru -gadolinia doped ceria (CGO) nano-composite anodes, investigated for operation with various fuels. 8 mol% yttria-stabilized zirconia (8YSZ) and compositionally graded CGO-8YSZ thin films were fabricated on silicon substrates as selfsupported electrolytes. Performance of devices integrating such electrodes and electrolytes are presented with methane and natural gas as fuels. Oscillations in fuel cell current were observed when nano-porous Ru and Ru-CGO anode µSOFCs were operated at constant voltage with methane. Degradation mechanisms of pure metallic electrodes are then compared to composite electrodes at the intermediate temperature range of 300 -500 °C. New synthesis methods to realize percolating ultra-thin composite electrodes is highlighted as a promising research direction.
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