Functionalized TiO2 Supported Pt Nanocatalysts for Oxygen Reduction Reaction in PEMFCs

The activity and durability of the catalysts used for the oxygen reduction reaction (ORR) are crucial to the commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Pt is still the most common catalytic material for the PEMFCs. Many factors, such as the catalyst’s composition, size, shape, support, and adsorbates, are related to the catalyst’s performance; such matters have been extensively studied over the past several decades in pursuit of high ORR activity, long term stability, and reduced Pt consumption. Titanium oxidebased materials compared to traditional carbon supports have been seen as promising supports for nanosized catalysts in electrochemical applications because of their low cost, nontoxicity, and high stability in acidic and oxidative environments1,2. In this presentation, dual doping of anatase TiO2, used as a Pt catalyst support, both augments resistance against the carbon corrosion that commonly occurs in oxygen reduction reaction (ORR) Pt/C catalysts and promotes the generation of oxygen vacancies that allow better electron transfer from the nanosupport to Pt, thereby facilitating the oxygen dissociation reaction. The effects of the oxygen vacancies within the doped TiO2 nanosupport on ORR activity and stability are investigated both experimentally and by density functional theory analysis. The mass activity of Pt supported doped anatase TiO2 is shown to be 9.1 times higher than that of a commercial standard Pt/C catalyst after hydrogen reduction3. The oxidesupported nanocatalysts also show improved stability against Pt sintering under during cycling, because of strong metal−support interactions (SMSI). References 1. VTT Ho, BJ Hwang et al., “Nanostructure Ti0.7Mo0.3O2 Support Enhances Electron Transfer to Pt: Used as High Performance Catalyst for Oxygen Reduction Reaction”, 2011, J. Amer. Chem. Soc., 133, 11716–11724. 2. CJ Pan, BJ Hwang et al., “Tuning/exploiting Strong MetalSupport Interaction (SMSI) in Heterogeneous Catalysis”, 2017, J. Taiwan Inst. Chem. Eng., DOI.org/10.1016/j.jtice.2017.02.012. 3. MC Tsai, BJ Hwang et al., “Interplay between Molybdenum Dopant and Oxygen Vacancies in a TiO2 Support Enhances the Oxygen Reduction Reaction”, 2016, ACS Catalysis, 6 (10), 6551–6559.