Bifunctional Pt/TiO2-Ov catalysts for enhanced electron transfer and CO tolerance in acidic HOR and ORR

Hydrogen fuel cells, especially proton exchange membrane fuel cells (PEMFCs), are gaining traction as zero-emission power sources for electric vehicles. However, PEMFCs face challenges like the corrosion of carbon supports in platinum (Pt) catalysts and contamination from impurities such as CO and H₂S, which can deactivate the catalysts.

A recent study, "Bifunctional Pt/TiO₂-O_v catalysts for enhanced electron transfer and CO tolerance in acidic HOR and ORR," presents a novel non-carbon supported catalyst, Pt/TiO₂-O_v, enriched with oxygen vacancies (O_v). This catalyst was synthesized using a microwave-assisted method, leveraging the electronic metal-support interaction (EMSI) to enhance electron transfer between Pt and Ti atoms.

The research team, led by authors from Fuzhou University and Shanghai University, optimized the synthesis process of TiO₂-O_v by etching TiO₂/SiO₂ samples with varying HF concentrations and high-temperature hydrogen annealing. Pt nanoparticles were then immobilized onto the TiO₂-O_v support through ethylene glycol reduction and microwave heating.

The Pt/TiO₂-O_v catalyst demonstrated superior performance in both hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR). In a 0.1 mol/L HClO₄ electrolyte, its normalized Pt mass activity and specific activity were 1.24 times higher than commercial Pt/C. Notably, it showed remarkable CO tolerance, with a significantly higher relative retention rate than Pt/C under a H₂/(1000×10^–6) CO atmosphere.

The catalyst also exhibited excellent durability. After 5000 cycles of accelerated durability tests, it showed an exceptionally low half-wave potential loss of only 7 mV for ORR and a minimal current density decay of 13.44% after a 24-hour HOR test.

This study underscores the importance of the strong metal-support interaction between reducible oxide supports and noble metal Pt in improving long-term performance and CO poisoning resistance. The Pt/TiO₂-Ov catalyst’s exceptional performance and durability offer a promising alternative to conventional carbon-supported catalysts, paving the way for more efficient and practical PEMFC applications.

This work provides valuable insights into the design of noble metal-loaded electrocatalysts with oxygen-rich reducible oxide supports, which can enhance catalytic efficiency in energy conversion reactions and improve resilience against CO poisoning.