Electrochemical Behavior of a Pd Thin Film Electrode in Concentrated Alkaline Media

Abstract

Pd limited volume electrodes (LVE) were obtained electrochemically from the PdCl 2 aqueous solution. Hydrogen absorption was performed using cyclic voltammetry and chronoamperometry in concentrated (6 M) alkaline solutions (KOH, NaOH, the mixture of 2M LiOH + 4M KOH) and results were compared with 0.5 M H 2 SO 4 . It was found that hydrogen pretreatment procedure is crucial for further examination of hydrogen absorption in Pd electrodes. After many cycles of hydrogen absorption/desorption in Pd, these processes become electrochemically more reversible-faster than in a freshly prepared electrode. Results obtained for Pd electrodes in different concentrated alkaline media subjected to hydrogen pretreatment procedure are comparable with those for an acidic solution (e.g., α→β phase transition potential equals to ca. 0.050 V vs. RHE). The continuous Pd electrode cycling does not affect significantly the amount of absorbed hydrogen (ca. 0.72-0.74). The surface roughness factor in basic solutions decreases after multiple hydrogen sorption as in case of an acidic solution.

Tuning hydrogen sorption properties of Pd by its alloying with Ru, Rh, and Pt: the study of binary alloys in concentrated alkaline media

“…The implementation of the HPP In previously published research, concerning the behavior of Pd-LVE electrode in concentrated alkaline media, the authors ascertained the impact of HPP on hydrogen sorption properties of the Pd electrodes [51]. The implementation of similar procedures has been checked in case of Pd-binary alloys containing Rh, Ru, and Pt.…”

“…Hydrogen electrosorption experiments were carried out in a three electrode system: Pd-M (M = Rh, Ru, Pt) LVE [51] was the working electrode, Pt gauze was the auxiliary electrode, Hg|HgO|6 M OH − was the reference electrode. LVE electrodes were electrodeposited from the PdCl 2 solution with either H 2 PtCl 6 , RhCl 3 , and RuCl 3 solutions according to the procedures described in details in [12][13][14][15].…”

“…All potentials were calculated in reference to RHE. The potential recalculation into RHE was done with the use of Hydroflex electrode [38,39,51].…”

“…Recently, the authors have published the results concerning hydrogen electrosorption in Pd-LVE (limited volume electrode) electrode immersed in concentrated alkaline media [51]. It was noticed that neither the type of concentrated electrolyte (KOH, NaOH, mixed KOH and LiOH, 0.5 M H 2 SO 4 ) nor long cycling in hydrogen region affected the maximum hydrogen capacity of Pd (H/Pd).…”

Methanol Electrooxidation at Electrodes Made of Exfoliated Graphite/Nickel/Palladium Composite

“…4) after reaching the 26 cycle can be caused by the undesired impact of alkaline solution. It is known that in some cases the concentrated electrolyte involving even trace impurities may have unfavorable effect on the electrode behavior [33,34]. Owing to the considerable higher activity of Pd it can be assumed that the unwanted problem of electrode poisoning by CO is mainly associated with Pd component of the investigated system.…”