TiO-supported RuIr alloy as an efficient and CO-resistant catalyst for hydrogen oxidation

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Ruthenium (Ru) is a promising catalyst for hydrogen oxidation reaction (HOR) due to its favorable hydrogen binding energy and oxygen affinity.
• Challenges for Ru catalysts include limited intrinsic activity and poor tolerance to carbon monoxide (CO) poisoning.
• Developing efficient and durable HOR catalysts is crucial for advancing fuel cell technology.

Purpose of the Study:

• To design and synthesize an efficient and durable catalyst for alkaline HOR using a RuIr alloy supported on titanium oxide (RuIr/TiO).
• To investigate the catalytic performance and CO tolerance of the RuIr/TiO catalyst compared to commercial platinum catalysts.
• To elucidate the underlying mechanisms responsible for the enhanced catalytic activity and durability.

Main Methods:

• Synthesis of RuIr alloy nanoparticles supported on titanium oxide (TiO).
• Electrochemical characterization including cyclic voltammetry and chronoamperometry to evaluate HOR activity and durability.
• Experimental characterizations (e.g., X-ray diffraction, X-ray photoelectron spectroscopy) and density functional theory (DFT) calculations to analyze catalyst structure and electronic properties.

Main Results:

• The RuIr/TiO catalyst exhibited a mass activity of 10.36 A mg^-1_PGM at 50 mV overpotential, significantly outperforming commercial Pt/C (4.84 times higher).
• RuIr/TiO demonstrated excellent CO tolerance, with only a 6.85% drop in current density after prolonged electrolysis under 1000 ppm CO/H₂, compared to 27.84% for Pt/C.
• DFT calculations and characterizations revealed that alloying and strong metal-support interactions modulate the electronic structure of Ru sites, optimizing H adsorption and OH binding, and promoting CO oxidation.

Conclusions:

• The RuIr/TiO alloy catalyst is highly efficient and durable for alkaline HOR.
• Alloying Ru with Ir and strong metal-support interaction with TiO are key strategies to enhance catalytic activity and CO tolerance.
• This work provides a promising pathway for developing advanced electrocatalysts for fuel cells and other electrochemical energy conversion systems.