Enhancing Activity and Pt Utilization in Pt-CsH2PO4 Composite Electrodes for Solid Acid Fuel Cells

The performance and stability of solid acid fuel cells have been improved dramatically in recent years, but the continued reliance of these devices on Pt as a catalyst hinders wide-scale adoption. Electrospray fabrication of CsH₂PO₄-based electrodes has been shown to produce structures with high surface area, a feature which presumably provides a high number density of triple phase boundaries between the gas, catalyst, and the electrolyte. Here, high activity anodes with only 14 μg cm^-1 of Pt were formed by electrospray deposition of a solution of Pt-decorated CNTs and CsH₂PO₄. The carbon nanotubes serve as interconnects to the current collector as well as a platform for interaction between the Pt and CsH₂PO₄. Using AC Impedance Spectroscopy and cyclic voltammetry, proton reduction and hydrogen oxidation were observed to occur at the low summed electrode overpotential of 0.1 V (or 0.05 V per electrode) with a current density of 42 mA cm^-2. Furthermore, these Pt-CNT-CsH₂PO₄ composites have the highest Pt utilization to date for solid acid-based electrodes at 61 S mg^-1, a 3-fold improvement over the state-of-the-art electrodes with a 50x decrease in Pt loading. We are also using electrospray techniques to form stable Pt-CsH₂PO₄-polymer composite cathodes. The inclusion of a polymer prevents electrolyte agglomeration and provides long-term stability under normal operating conditions.