Hydrogen electrosorption into Pd–Pt–Au ternary alloys

Thin layers of Pd–Pt–Au alloys were prepared by metal codeposition at constant potential from chloride solutions. The process of hydrogen electrosorption into Pd–Pt–Au alloys was investigated in acidic solution (0.5 M H2SO4) using cyclic voltammetry and chronoamperometry, also coupled with the electrochemical quartz crystal microbalance. It was found that Pd alloying with both Pt and Au decreases the maximum hydrogen solubility, but improves the kinetics of absorbed hydrogen oxidation, which is mirrored in a negative shift of the potential of hydrogen desorption peak and shorter hydrogen desorption time. In Pd–Pt–Au alloys the effect of absorption/desorption hysteresis and the stresses connected with hydrogen absorption are reduced in comparison with pure Pd. After prior hydrogen absorption in Pd–Pt–Au alloys, surface oxides are formed and reduced at potentials even by 200 mV lower than before hydrogen treatment.