2D Platinum Network ORR Catalyst on Carbon and Niobium Oxide Hybrid Support

Tuesday, 7 October 2014: 17:40
Sunrise, 2nd Floor, Galactic Ballroom 7 (Moon Palace Resort)
C. Xu, J. Yang, B. Pence, K. Gath, P. Pietrasz, M. Sulek (Ford Motor Company), K. Sun (University of Michigan), E. Sohm (ULVAC Technologies, Inc), and G. Meng (Ulvac-Riko, Inc)
2D platinum network catalyst on graphitic carbon and amorphous NbOx hybrid support has been synthesized by Arc Plasma Deposition (APD) method. The 2D platinum structure on the conductive, corrosion resistant amorphous metal oxide significantly increases the catalyst stability under RDE accelerated stress tests. RDE and 5cm2MEA single cell test results showed that the catalyst has higher specific and mass activities than those of conventionally prepared platinum on graphitic carbon (Pt/C) catalyst. The microstructures of the catalyst were characterized by transmission electron microscopy (TEM).

Amorphous NbOx conductive metal oxide was deposited from either Nb2O5 in Ar or Nb in a gas mixture of 30 vol.% of O2 in Ar onto carbon particles by using Arc Plasma Deposition (APD) system (Ulvac-Riko, Inc). The obtained NbOx on carbon particle are isolated amorphous islands, with the value of x between 1 and 2.5. When Pt was deposited onto the formed NbOx islands, a platinum 2D nano-network was obtained, as schematically shown in Figure 1. The platinum particles with about 5 nm size can be uniformly deposited on the support NbOx and carbon. Figure 2 shows the percentage change of ECSA and mass activity under AST using square wave 1.0V~1.5V for carbon corrosion (a) and 0.1V~1.0V for Pt (b). The specific (SA) and mass activities (MA) are about 400 m A/cm2Pt and 350A/gPt, respectively. The accelerated stress tests show that the durability of the catalyst is about 3~5 times higher than those of synthesized Pt on carbon catalyst through wet chemical methods under the same carbon corrosion and platinum stress conditions. The polarization curve and EIS data of Pt/C and Pt/NbOx/C on a 5 cm2 single cell are shown in Figure 3. Pt/NbOx/C cell with 0.07mg/cm2 Pt loading and Pt/C cells with 0.19mg/cm2 Pt loading have a similar polarization curve.