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Adsorption of 2,2′-bipyridine at an Au(111)

par Siinor, Liis ;Siimenson, Carolin;Doneux, Thomas ;Buess Herman, Claudine
Référence Electrochemistry communications, 78, page (56-59)
Publication Publié, 2017

Article révisé par les pairs

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Résumé :

The adsorption of added 2,2′-bipyridine (2,2′-BP) from 1-ethyl-2,3-dimethyl imidazolium bis(trifluoromethanesulfonyl) imide (EMMImNTf2) at an Au(111) electrode has been investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Addition of 2,2′-BP to the ionic liquid clearly modifies the interfacial region as a result of the competition between 2,2′-BP and EMMImNTf2 to occupy the electrode surface. Within the region of ideal polarizability, the 2,2′-BP adlayer undergoes structural changes, shown by the presence of peaks in the CV curves. Between −0.2 V and +0.9 V, the capacitance–potential curves obtained from EIS data present a capacity maximum depending strongly on the ac frequency, which is typical pseudocapacitive behavior indicative of a reorganization of the interfacial layer. At more positive potentials a true capacity value close to 10 μF.cm−2 and invariant with the potential suggests that the 2,2′-BP molecules adopt a perpendicular orientation with the nitrogen atoms facing the electrode surface, similar to their adsorption on gold from aqueous solutions.