Preparation and Characterization of Stable and Active Pt@TiO2 Core-Shell Nanoparticles as Electrocatalyst for Application in PEMFCs

PEMFCs are an established viable sustainable source of energy, especially for key sectors such as transportation and stationary and portable plants. Pt is their best performing electrocatalyst. However, Pt is affected by stability and durability issues from corrosion, leaching, particle size growth, poisoning, and deleterious byproducts effects. One promising approach to meeting these challenges is the use of metal oxides because of their high chemical and electrical stability. They are usually used in the form of composites or as support materials with some successes but with accompanying challenges of reduced surface area and parts of the surface of the active catalyst NPs still bare, exposing them to some levels of poisoning, leaching, and particle size growth. Hence, in this work Pt@TiO2 core-shell NPs were prepared, with the surface of the Pt completely covered by TiO2 to combat these challenges. Uniform size and shape Pt@TiO2 NPs, with Pt cores of 6.5 nm and TiO2 shells of 0.5 nm, were obtained using a microemulsion/sol-gel method and hot water treatment, with bare Pt and TiO2 NPs as controls. Heat treatment at various temperatures showed negligible NP size change up to 300 degrees C but effective particle size growth suppression by the TiO2 at >= 400 degrees C. The NPs showed BET SAs in the order TiO2 (137) > Pt@TiO2 (78) > Pt (16.3 m(2)/g), with their corresponding ECSAs as 0.02, 4.24, and 8.52 m(2)/g, respectively. A preliminary FC performance evaluation to investigate the feasibility of these NPs as electrocatalysts showed that Pt@TiO2 had the best performance and stability, compared to even a commercial catalyst, with power generations of 239, 239, and 257 mW/cm(2) at 150 degrees C for Pt, Pt@TiO2, and commercial catalyst, respectively. These results show a significant viable new approach for the application of metal oxides for durable FCs and present new research opportunities.