A Highly-Efficient Boron Interstitially Inserted Ru Anode Catalyst for Anion Exchange Membrane Fuel Cells.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• High-performance electrocatalysts are essential for the commercialization of anion exchange membrane fuel cells (AEMFCs).
• The hydrogen oxidation reaction (HOR) is a key process in AEMFCs, and its kinetics are typically pH-dependent.

Purpose of the Study:

• To develop and evaluate a novel boron-interstitial ruthenium catalyst (B-Ru/C) as an anode catalyst for AEMFCs.
• To investigate the unusual pH-dependent behavior of HOR kinetics on the B-Ru/C catalyst.

Main Methods:

• Synthesis of boron interstitially inserted ruthenium on carbon support (B-Ru/C).
• Electrochemical testing of B-Ru/C as an anode catalyst in AEMFCs.
• Density functional theory (DFT) calculations to understand the catalytic mechanism.

Main Results:

• The B-Ru/C catalyst achieved a peak power density of 1.37 W cm⁻² in AEMFCs, comparable to commercial PtRu catalysts.
• An unexpected inflection point in pH-dependent HOR kinetics was observed, with superior activity in alkaline electrolytes.
• The mass activity of B-Ru/C was significantly higher than Ru/C and commercial Pt/C, indicating enhanced alkaline HOR performance.

Conclusions:

• Interstitial boron modification of ruthenium enhances HOR kinetics in alkaline electrolytes.
• The B-Ru/C catalyst shows great promise for commercializing anion exchange membrane fuel cells.
• The observed anomalous pH-dependent behavior is attributed to the upshifted d-band center of Ru and optimized adsorption/reaction energetics.