An Efficient H₂S-Tolerant Hydrogen Oxidation Electrocatalyst Enabled by a Lewis Acid Modifier for Fuel Cells

Area of Science:

• Catalysis
• Electrochemistry
• Materials Science

Background:

• Industrial hydrogen fuel contains hydrogen sulfide (H2S), which poisons platinum catalysts in fuel cells.
• Removing H2S to parts per billion levels is crucial but difficult and expensive.

Purpose of the Study:

• To develop a hydrogen oxidation reaction (HOR) catalyst that is tolerant to H2S.
• To achieve high performance comparable to platinum catalysts.

Main Methods:

• Chemical grafting of chromic oxide (Cr2O3) onto a molybdenum-nickel (MoNi4) alloy.
• Investigating the mechanism of H2S tolerance using catalyst surface interactions.

Main Results:

• The composite Cr2O3/MoNi4 catalyst demonstrated excellent H2S tolerance.
• The catalyst achieved HOR performance comparable to commercial platinum on carbon (Pt/C).
• A fuel cell with the composite catalyst survived 5 ppm H2S without deactivation.

Conclusions:

• The Cr2O3 coating prevents H2S poisoning by repelling sulfide ions.
• Adsorbed hydroxyl ions on the catalyst surface enhance HOR kinetics.
• This novel catalyst offers a promising alternative for H2S-contaminated hydrogen fuel applications.