Abstract
In the present article, electrodes containing a composite of platinum on top of a plasma-oxidized multi-layer graphene film are investigated as model electrodes that combine an exceptional high platinum utilization with high electrode stability. Graphene is thereby acting as a separator between the phosphate-based electrolyte and the platinum catalyst. Electrochemical impedance measurements in humidified hydrogen at 240 °C show area-normalized electrode resistance of 0.06 Ω·cm−2 for a platinum loading of ∼60 µgPt·cm−2, resulting in an outstanding mass normalized activity of almost 280 S·mgPt−1, exceeding even state-of-the-art electrodes. The presented platinum decorated graphene electrodes enable stable operation over 60 h with a non-optimized degradation rate of 0.15% h−1, whereas electrodes with a similar design but without the graphene as separator are prone to a very fast degradation. The presented results propose an efficient way to stabilize solid acid fuel cell electrodes and provide valuable insights about the degradation processes which are essential for further electrode optimization.
Highlights
Solid acids are an alternative and interesting class of proton conducting electrolytes for fuel cell applications
After Haile [1,2,3,4] demonstrated the general concept employing CsH2PO4 (CDP) in solid acid-based fuel cells (SAFCs) they were further developed by a number of researchers [1,3,5,6,7,8,9,10,11,12,13,14,15] and appreciated for their intermediate operating temperature (230–260 ◦C) in comparison to polymer electrolyte membranes fuel cells (PEMFCs)
Local hotspots were reported to cause local phase transitions [23]. Unwanted processes such as agglomeration of platinum nanoparticles (NPs) [20] or phosphate-associated catalyst poisoning are known for high-temperature PEMFCs and might occur as well in SAFCs [24,25]
Summary
Solid acids are an alternative and interesting class of proton conducting electrolytes for fuel cell applications. Carbon black is currently the most widely used support material to boost platinum activity towards the oxygen reduction reaction (ORR) These developments, in which a carbon support is employed, do not solve the second major problem, namely, the degradation and a lack of long-term stability. Tennyson et al [27] reported 1.3 mg·cm−2 platinum loaded on different carbon allotropes such as CNTs, carbon black, and graphene flakes They reported that platinum-decorated boron-doped graphene-like flakes exhibit higher stability toward oxidation during the aggressive SAFCs operating conditions, in comparison to CNT and polyhedral graphitic platelets. These hybrid materials showed a promising way for reducing anode and cathode catalyst loading with the enhancement of the platinum performance on the different carbon allotropes supports
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
