Carbon monoxide powered fuel cell towards H₂-onboard purification

Area of Science:

• Electrochemistry
• Catalysis
• Materials Science

Background:

• Proton exchange membrane fuel cells (PEMFCs) are susceptible to carbon monoxide (CO) poisoning at low concentrations (<10 ppm).
• CO adsorption blocks active sites on the catalyst surface, significantly reducing fuel cell performance and lifespan.

Purpose of the Study:

• To investigate the use of atomically dispersed Rh catalysts (Rh-N-C) for CO oxidation in PEMFCs.
• To demonstrate the potential of CO as a fuel in PEMFCs using these novel catalysts.
• To explore the application of this technology for selective CO removal from hydrogen gas streams.

Main Methods:

• Fabrication of atomically dispersed Rh catalysts supported on nitrogen-doped carbon (Rh-N-C).
• Electrochemical testing of PEMFCs utilizing pure CO as fuel.
• Performance evaluation of CO oxidation and CO2 generation.
• Analysis of CO removal efficiency from H2/CO mixtures.

Main Results:

• CO oxidation to CO2 initiated at 0 V with Rh-N-C catalysts.
• Achieved an unprecedented power density of 236 mW cm-2 with pure CO fuel.
• Demonstrated a maximum CO turnover frequency of 64.65 s-1 at 363 K, surpassing existing catalysts.
• Reduced CO concentration by one order of magnitude in a H2 gas stream using a single PEMFC cell while generating electricity.

Conclusions:

• Atomically dispersed Rh catalysts enable efficient CO oxidation and utilization as a fuel in PEMFCs.
• This approach offers a dual benefit of power generation and selective CO removal from hydrogen.
• The observed catalytic activity is attributed to weak CO adsorption and co-activation of H2O by adjacent Rh sites.