Cobalt coated electrodes for high efficiency PEM fuel cells by plasma sputtering deposition

Proton exchange membrane (PEM) fuel cell electrodes coated with ultra-thin Co layer have been successfully fabricated via plasma sputter-deposition. In order to investigate the influence of Co layers on the oxygen reduction reaction, a series of Co layers with different nominal thickness have been deposited into the cathode-membrane interface. The polarization curves confirmed visible enhancement in cell performance when a 5 nm Co layer on cathode gave rise to a high current density of 750 mA cm(-2) at 0.6 V. Scanning electron microscopy showed that the sputter deposited 5 nm Co layer formed nanosized island structures on the porous electrode, while electrochemical impedance spectra confirmed that a reduction in the total impedance of the electrode led to the improvement of the membrane electrode assembly (MEA) performance.