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

Abstract

The development of anti-corrosion and anti-poison electrocatalysts for both the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) is of great importance for effective applications of proton exchange membrane fuel cells (PEMFCs). In this study, a non-carbon supported catalyst, Pt/TiO₂-O_v, enriched with oxygen vacancies (O_v), is successfully synthesized using a microwave-assisted method. This catalyst is developed as a bifunctional electrocatalyst with superior contamination tolerance, enabling efficient HOR and ORR performance. The electronic metal-support interaction (EMSI) is leveraged to facilitate electron transfer between Pt and Ti atoms, induced by the formation of oxygen vacancy channels in the small-sized, high surface area TiO₂-O_v support. Notably, TiO₂-O_v has a lower bandgap than commercial TiO₂, enhancing its catalytic properties. In a 0.1 mol/L HClO₄ electrolyte, the normalized Pt mass activity (j_k,m) and specific activity (j_0,s) of Pt/TiO₂-O_v are 1.24 times higher than those of commercial Pt/C. Furthermore, Pt/TiO₂-O_v catalyst exhibits minimal current density decay after a prolonged durability testing under hydrogen and oxygen atmospheres. Remarkably, under a H₂/(1000×10^–6) CO atmosphere, the relative retention rate of Pt/TiO₂-O_v significantly exceeds that of Pt/C catalyst, demonstrating its superior CO tolerance and promising potential for practical applications in PEMFCs. This study highlights the critical role of the strong metal-support interaction between the reducible oxide support and the noble metal Pt in improving long-term performance and CO poisoning resistance.

Graphical abstract

Keywords

CO poisoning / hydrogen oxidation reaction / oxygen reduction reaction / proton exchange membrane fuel cells (PEMFCs) / Pt/TiO₂ catalyst

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