Around the world efforts are made to harness energy from hydrogen for various applications using fuel cell technology. Fuel cells are already being utilized for residential power supply and the fuel cell vehicles appeared on the market. However, the price of the energy generated using fuel cells is still relatively expensive due to pricy fuel cell components. Noble metals, such as Pt, Pd, Au or their alloys are utilized in hydrogen fuel cells to convert chemical energy of hydrogen into an electrical energy. Therefore, it is important to develop efficient methods for recovery or regeneration of fuel cell catalysts in order to reduce the costs.
The electrochemical dissolution of platinum can be used as an environmentally friendly way to recover or regenerate platinum fuel cell catalyst. In our recent article published in ChemSusChem we present a simple technique to recycle Pt catalyst from a fuel cell electrode in a sustainable fashion. We managed to fully dissolve platinum nanoparticles from a fuel cell electrode under very mild conditions without damaging other parts of the electrode, such as the carbon support. This offers two significant opportunities:
- In-situ regenerate fuel cell catalyst, this will multiply the lifetime and avoid platinum losses during its handling in in the nanoparticle deposition and recovery processes.
- Recovery of the degraded platinum nanoparticles from the fuel cell in a simple and environmentally friendly manner. Conventional methods are either very energy-consuming or use very corrosive substances such as aqua regia.
We reported complete dissolution of fuel cell catalyst, platinum nanoparticles, under mild conditions: at room temperature in 0.1 M HClO4 and 0.1 M HCl by electrochemical potential cycling between 0.5 – 1.1 V and at a 50 mV s-1 scan rate. Dissolution rates as high as 22.5 μg cm-2 cycle-1 were achieved, which ensured a relatively short dissolution timescale of 3 – 5 hours for a platinum loading of 0.35 mg cm-2 on carbon, which is typically used in hydrogen fuel cells. The influence of chloride and oxygen in the electrolyte on the dissolution was investigated and a mechanism was proposed based on the experimental observations and on available literature. During the dissolution process the carbon support corrosion processes were minimal.
Presently, we are continuing this research along a variety of tracks: (partial) dissolution of core-shell materials, compatibility with novel membrane materials, etc.
Dr. R. Latsuzbaia, Dr. E. Negro , Dr. G. J. M. Koper*
Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands)
The dissolution of noble-metal catalysts under mild and carbon-preserving conditions offers the possibility of in situ regeneration of the catalyst nanoparticles in fuel cells or other applications. Here, we report on the complete dissolution of the fuel cell catalyst, platinum nanoparticles, under very mild conditions at room temperature in 0.1 m HClO4 and 0.1 m HCl by electrochemical potential cycling between 0.5–1.1 V at a scan rate of 50 mV s−1. Dissolution rates as high as 22.5 μg cm−2 per cycle were achieved, which ensured a relatively short dissolution timescale of 3–5 h for a Pt loading of 0.35 mg cm−2 on carbon. The influence of chloride ions and oxygen in the electrolyte on the dissolution was investigated, and a dissolution mechanism is proposed on the basis of the experimental observations and available literature results. During the dissolution process, the corrosion of the carbon support was minimal, as observed by X-ray photoelectron spectroscopy (XPS).
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