Environmentally Friendly Carbon-Preserving Recovery of Noble Metals From Supported Fuel Cell Catalysts

Significance Statement

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.

 

Environmentally Friendly Carbon-Preserving Recovery of Noble Metals From Supported Fuel Cell Catalysts .Renewable Energy Global Innovations 

Journal Reference

ChemSusChem, Volume 8, Issue 11, pages 1926–1934, 2015.

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)

Abstract

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).

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

 

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About the author

Ger J.M. Koper obtained his PhD (1990) in theoretical physics from the Leiden University. In 2000 he was appointed associate professor at the TU Delft working in the field of physical chemistry focusing on self-assembly processes.

He specializes in the application of statistical and irreversible thermodynamics to mesoscopic phenomena such as (nano)particle deposition, ligand binding to macromolecular systems, drying of colloidal films, stick-slip transition in nanopores, heterogeneous catalysis in nano-colloidal systems and self-assembly. 

About the author

Dr. Roman Latsuzbaia is a recent PhD graduate from Delft University of Technology and currently is employed on a position of a Scientist in a Dutch Organisation for Applied Scientific Research, TNO. He is mainly working on development of electrochemical routes for production of chemicals. His main interests are in electrochemistry, colloid chemistry, nanotechnology and fuel cells. 

About the author

Dr. Emanuela Negro obtained her PhD in material science from TU Delft in 2014 with a  dissertation focussed on the synthesis of more performing nanomaterials for fuel cell catalysts.

She is currently working as R&D engineer at Sulzer Chemtech where she researches on electrostatic separation of liquid-liquid systems.  Her main interests are sustainable energy production and management in chemical processes.

 

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