Abstract
Two physical vapor deposition (PVD) processes, magnetron sputtering (MS) and arc plasma deposition (APD), were investigated to prepare oxygen reduction reaction (ORR) catalysts for proton exchange membrane fuel cells (PEMFCs). The catalysts are composed of Pt or Pt alloy on a NbOx decorated carbon support (NbOx/C). The combination of these materials results in tunable structures and electronic properties and a commensurate increase in lifetime (>60% retention after 30,000 cycles) and initial MEA mass activities of over 300 AgPt−1. In situ x-ray absorption spectroscopy (XAS) shows that there exists direct interaction between Pt and the O in the non-stoichiometric NbOx in Pt on NbOx/C catalyst. The introduction of Co leads to shortened Pt–Pt bond distance as confirmed by XAS, and a beneficial Pt on NbOx strain effect. The relationship between Pt and NbOx loading is discussed based on rotating disk electrode (RDE) data.
