ELECTROCHEMICAL HYDROGEN INSERTION INTO PALLADIUM AND PALLADIUM NICKEL THIN-FILMS

A generator-detector mode with the rotating ring-disk electrode has been used to determine the difference between Pd and Pt electrode behavior and the origin of the larger overpotentials at Pd-hydrogen evolving cathodes. The use of thin film Pd disk electrodes has allowed full hydrogen or deuterium charging of the metal phase in short times. The electrode system has made feasible simultaneous measurements of the hydrogen uptake in PdH(x) films where the maximum composition reached was PdH0.81. Alloying Ni into Pd decreases the maximum hydrogen absorption by solid solution Pd-Ni films to near zero at 17% Ni. The outgassing of hydrogen on open circuit from variously charged electrodes can be followed in real time and shows the losses associated with transfer of specimens to post-analysis (approximately 6% in 5 min).