Towards rational electrode design: quantifying the triple-phase boundary activity of Pt in solid acid fuel cell anodes by electrochemical impedance spectroscopy
- 243 Downloads
Solid acid fuel cells based on CsH2PO4 as the electrolyte and Pt as the electrocatalyst are a promising intermediate temperature energy conversion technology. However, improving the electrode microstructure to achieve an optimal area-normalized resistance, while keeping or even lowering the Pt catalyst loading is particularly challenging due to the solid nature of the electrode components. Several architectures have been empirically developed, such as CsH2PO4 micro- or nanoparticles mixed with Pt nanoparticles or covered with thin-film Pt. For an optimal electrode design, a quantitative measurement of the fundamental parameter, namely the specific triple-phase boundary activity of Pt at the fuel cell operating conditions, is needed. Geometrically simple, well-controlled electrodes are typically fabricated for this purpose via lithography techniques. This approach however is not suitable for solid acids due to the water solubility of the electrolyte. Here we present a simple, water-free fabrication scheme to create a controlled electrode geometry consisting of a hole-patterned Pt thin film that allows measurements of the specific triple-phase boundary activity of Pt in an anodic environment. Based on electrochemical impedance spectroscopy measurements in a symmetric cell configuration, the triple-phase boundary activity of Pt is determined to be on the order of 1.3 kΩ m. This information is critical for the rational design of a solid acid fuel cell electrode without tedious empirical optimization.
KeywordsCatalysis Solid acid fuel cell Anode Specific activity Triple-phase boundary
The authors acknowledge Dietmar Hirsch and Andrea Prager for scanning electron microscopy and the funding through the ESF-Forschergruppe ‘Applied and theoretical molecular electrochemistry as a key for new technologies in the area of energy conversion and storage’.
- 2.Guenot B, Cretin M, Lamy C (2015) Clean hydrogen generation from the electrocatalytic oxidation of methanol inside a proton exchange membrane electrolysis cell (PEMEC): effect of methanol concentration and working temperature. J Appl Electrochem 45(9):973–981. doi: 10.1007/s10800-015-0867-3 CrossRefGoogle Scholar
- 4.Chisholm CRI, Boysen DA, Papandrew AB, Zecevic SK, Cha S, Sasaki KA, Varga Á, Giapis KP, Haile SM (2009) From laboratory curiosities to technological realization: the development path for solid acid fuel cells. Interface Mag 18:53–59Google Scholar
- 22.Wickman B (2010) Nanostructured model electrodes for studies of fuel cell reactions. Chalmers University of Technology, GöteborgGoogle Scholar