Highly active and durable Pd-Cu catalysts for oxygen reduction in alkaline exchange membrane fuel cells

Abstract

A Pd-Cu catalyst, with primary B2-type phase, supported by VulcanXC-7R carbon was synthesized via a solvothermal method. The catalysts were physically and electrochemically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and both cyclic and linear sweep voltammetry using a rotating disk electrode (RDE). During the RDE testing, the half-wave potential of the Pd-Cu/Vulcan catalyst was 50 mV higher compared to that of commercial Pt/C catalyst for the oxygen reduction reaction (ORR) in alkaline media. The Pd-Cu/Vulcan exhibited a specific activity of 1.27 mA/cm2 and a mass activity of 0.59 A/mgPd at 0.9 V, which were 4 and 3 times greater than that of the commercial Pt/C catalyst, respectively. The Pd-Cu/Vulcan catalyst also showed higher in-situ alkaline exchange membrane fuel cell (AEMFC) performance, with operating power densities of 1100 MW/cm2 operating on H2/O2 and 700 MW/cm2 operating on H2/Air (CO2-free), which were markedly higher than those of the commercial Pt/C. The Pd-Cu/Vulcan catalyst also exhibited high stability during a short-term, in-situ AEMFC durability test, with only around 11% performance loss after 30 hours of operation, an improvement over most AEMFCs reported in the literature to date.