Study of electrochemical palladium behavior by the quartz crystal microbalance. I. Acidic Solutions

Anodic oxidation of Pd alloys with Pt and Rh

“…1b). In the former case frequency decreases in the anodic scan and after reversing polarization frequency reaches a steady value, increasing only when Rh surface oxide starts to be reduced, while in the latter case the frequency rise is observed, which is continued in the cathodic scan before Pd surface oxide reduction (Pd cathodic dissolution has already been reported in the literature [37,40,[42][43][44]). Therefore, different mechanisms of dissolution are expected for each metal.…”

“…Earlier investigations on that phenomenon [3,10,[35][36][37][38][39][40][41][42][43][44][45][46] have shown that the extent to which noble metals dissolve depends on the kind of metal, potential, scan rate, tem- Pd-Pt-Rh (below 22% Rh). After two cycles in a fixed potential limit anodic vertex potential was increased by 50 mV.…”

Electrochemical quartz crystal microbalance study on carbon oxides adsorption in the presence of electrosorbed hydrogen on Pd alloys with Pt and Rh

“…The frequency lowering in the hydrogen region probably results from stresses connected with hydrogen absorption [72,82]. However, it is also possible that this behavior reflects changes in hydrofilicity of the electrode surface caused by the presence of weakly adsorbed hydrogen (strongly interacting with water molecules) or a shift of the pzc value, similarly to the case of pure Pt-EQCM electrode [47,74,77,78,80].…”

“…The characteristic feature of the frequency response is its lowering in the hydrogen region caused by absorption of a large amount of hydrogen accompanied by stresses induced in the alloy lattice [72,82]. After CO adsorption the frequency is additionally diminished due to the presence of adsorbed CO.…”

“…In general, the EQCM response for noble metals and their alloys under conditions of an cyclic voltammetric experiment can be affected by several factors [46][47][48][49][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82]: (a) mass changes connected with electrosorption of hydrogen (both adsorption and absorption) and oxygen (surface oxide formation), (b) mass changes connected with the electrochemical dissolution and subsequent redeposition of metals, (c) mass changes connected with specific adsorption of ions and adsorption of water molecules, (d) changes in density and viscosity of the solution layer adjacent to the electrode surface caused by non-specific adsorption of ions and changes in interactions between electrode surface and solution, (e) stresses in metal lattice during hydrogen absorption and surface oxide formation, (f) effects connected with the changes in the electrode roughness.…”