Pulsed electrodeposition of nickel/palladium globular particles from an alkaline gluconate bath. An electrochemical, XPS and SEM investigation

Nickel oxide species, palladium metal and complex Ni–Pd particles were deposited on the glassy carbon electrode by pulsed electrochemical conditions from 0.5 M NaOH solution containing 5 mM gluconate ion, 0.5 mM Ni(NO3)2 and/or 2 mM Pd(NO3)2. The electrodeposition process was performed using the following potentials and pulse durations: E1 = −1.0 V and E2 = +0.8 V vs. SCE, t1 = 50 ms and t2 = 50 ms for the relevant times of 600 s. The nickel oxide particles were deposited during the anodic pulse of potentials, while the palladium particles were deposited during the cathodic sequence of the potential pulses. The Ni–Pd system shows an acceptable character of electrochemical reversibility and a high affinity for oxygen adsorption. The XPS and SEM techniques were used in order to define the surface chemical composition and the actual morphology of the deposited material. An average surface chemical composition of Pd0.5Ni was established and the composite appears formed of well dispersed single globular particles having an average size comprised between 50 nm and 150 nm of diameter.

► Pulsed electrochemical deposition of Ni and Pd particles.
► Use of gluconate ligant (free cyanide systems) in alkaline medium.
► Electrochemical chraracterization of the Ni–Pd electrodic system.
► XPS characterization of electrodeposited Ni–Pd composite.
► SEM characterization of electrodeposited Ni–Pd composite.