Tandem Catalysis for pH-Universal Hydrogen Oxidation in Fuel Cells

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Minimizing platinum-group metal (PGM) usage is crucial for reducing the cost of anion-exchange membrane fuel cells (AEMFCs) and proton-exchange membrane fuel cells (PEMFCs).
• High PGM loadings are currently required for efficient hydrogen oxidation reaction (HOR) kinetics, especially in AEMFCs, hindering commercial viability.
• Nickel-based catalysts present a cost-effective alternative but suffer from low activity and poor oxidative stability.

Purpose of the Study:

• To develop a novel, low-PGM catalyst for enhanced fuel cell performance.
• To overcome the limitations of traditional nickel-based catalysts in terms of activity and stability.
• To provide a general strategy for designing efficient tandem electrocatalysts for multi-step reactions.

Main Methods:

• Fabrication of a core-shell nanoreactor with Ni nanoparticles encapsulated in N-doped graphitic carbon (NC) embedded with atomic Ru and Ni.
• Testing the catalyst's performance in AEMFC and PEMFC configurations.
• Conducting mechanistic studies in alkaline media to elucidate the catalytic pathway.

Main Results:

• Anodes utilizing the novel catalyst achieved peak power densities of 2.36 W cm⁻² (AEMFC) and 3.26 W cm⁻² (PEMFC) with ultralow Ru loading (1 µg cm⁻²).
• The catalyst demonstrated excellent stability, with negligible structural changes after 200 hours of continuous operation at 1 A cm⁻².
• Mechanistic studies revealed a tandem catalytic pathway involving H₂ dissociation and H* spillover.

Conclusions:

• The developed Ni-NC@Ru,Ni catalyst offers a highly efficient and stable alternative to PGM catalysts in fuel cells.
• The core-shell nanoreactor design and tandem catalytic mechanism provide a promising strategy for future electrocatalyst development.
• This approach significantly reduces PGM requirements, paving the way for more cost-effective fuel cell technologies.