Electropreparation and characterization of polyNiTSPc films. An EQCM study

Study by XPS and UV−Visible and DRIFT Spectroscopies of Electropolymerized Films of Substituted Ni(II)-p-Phenylporphyrins and -Phthalocyanines

“…Table 2 shows some parameters obtained from CVs at scan rates (V) from 5 to 300 mV s -1 . As already reported, 9 for polyNiTSPc-modified GC electrodes d log(j p )/d log(V) decreases with increasing film thickness, from 0.85 to 0.50, indicating that, as could be expected, diffusion control was obtained for thicker films and higher scan rates. (This trend had been already noted by White and Murray.…”

“…The solutions of the sulfo monomers were prepared with deionized and twice-distilled water and stored in a dark bottle, their stability being checked before use by the invariance of the UV-vis spectra. The modified electrodes were prepared as described, 9 namely, a glassy carbon (GC) (Pine Instruments, 0.8 cm in diameter), indium tin oxide (ITO) (Delta Technologies Ltd.), or Pt foil (Aldrich) electrode was subjected to repetitive cyclic voltammetry (RCV) at 10 mV s -1 between the potential limits (vs mercurous sulfate electrode (MSE), 0.64 V vs SHE) and using the electrolyte solutions shown in Table 1, at room temperature and under nitrogen atmosphere. ITO electrodes were used for UV-vis spectroscopy and XPS, and a platinum sheet for specular reflectance FTIRS.…”

“…ITO electrodes were used for UV-vis spectroscopy and XPS, and a platinum sheet for specular reflectance FTIRS. It is known 9,10 that the nature of the substrate (GC, Pt, Au, or ITO) does not significantly affect the electrochemical behavior of the films.…”

“…15 The electrochemical equipment has been described. 9 For UV-vis spectroscopy, a double-beam Varian UV-vis spectrophotometer, model Cary 1E, was used. Spectra of the monomers in the pH 11 buffer were obtained with 1 cm silica cells, using the pH 11 buffer as a blank, and spectra of the films were obtained with spectroelectrochemical silica cells of 1.5 cm optical length with an ITO working electrode, a Pt wire auxiliary electrode, and a Ag/AgCl reference electrode (although the potential is referred to the MSE in order to facilitate comparison with the CVs with GC substrate) and using as blank an identical cell with an ITO electrode in the pH 11 buffer.…”

“…6 Repetitive cyclic voltammetry (RCV) in alkaline solution of a soluble macrocycle on an inert substrate yields at higher potentials, at which Ni(II) is oxidized to Ni(III) and the first steps of oxygen evolution occur, polymeric films that become firmly attached to the substrate. [7][8][9][10] Bukowska et al 11 found in surface-enhanced Raman spectra of roughened gold electrodes modified with Nitetraazamacrocyclic complexes a doublet at 480/570 cm -1 which appeared at high potentials only and which they assigned to the symmetric and antisymmetric O-Ni(III)-O stretching vibrations of oxo bridges connecting the layers of the macrocycles. Perez-Morales et al 12 found that the UV-visible absorbance spectrum of a polyNiTSPP film increased upon electrooxidation from the Ni(II) to the Ni(III) state.…”