Abstract
Fuel cells have been poised to enter the energy market as a viable alternative to non-renewable resources for years, but due to prohibitive costs and reliability concerns they remain commercially untenable. One of the primary concerns facing PEMFCs today are the platinum group metals (PGM) catalysts which represent a significant portion of the total manufacturing cost of these devices. Recovery programs could provide an alternative source for the metals, but current processes are expensive, hazardous, and environmentally unsound. We propose an alternative methodology based on electrochemical assisted dissolution in halide solutions, with a specific focus on platinum and ruthenium recovery in strong iodide solutions.
An electrochemical quartz crystal microbalance (EQCM) was used to accurately determine the change in mass of the system during the initial stages of the project. Using an EQCM a controlled deposition of the target metals was achieved. This new electrode was then placed into varying halide solutions at room temperature in order to determine the effective dissolution rate at differing pHs and electrical potentials. Rotating ring disk electrode experiments were also conducted in order to determine if a recovery process from halide solution would be possible. Results suggest native pH solutions are likely unsuitable for Ru dissolution, but acidified solutions are more suitable, as predicted by E-pH diagrams. Surface oxide or halide complex formation complicates recovery process as these moieties must be removed before dissolution can occur. Rotating ring disk experiments show that the dissolution process is possible at ambient conditions, but may progress too slowly for a viable industrial process. Future work will investigate dissolution processes at elevated temperature.
