Study of the deposition and characterisation of a 5,10,15,20-tetrakis-(4-sulphonatophenyl)porphyrin Co(II) layer at gold surfaces in alkaline solution

Abstract

In this paper, the electrodeposition of Co(II)TSPor at gold electrodes is described. It was found that this deposition is initially controlled by kinetic parameters leading to a nearly 100% coverage of the electrode surface. However, once formed a reorganisation of the layer occurs. Experimental evidence that Co(II)TSPor is deposited was provided by using Raman spectroscopy.

Electrochemical deposition of 5,10,15,20-tetrakis-(4-sulphonatophenyl) porphyrin and its Co(II) derivative at a gold microelectrode array

“…In addition, the positions and bandwidth of the most intense Raman bands are similar to those of the pure crystalline substances (1528, 1451, 748 and 681 cm −1 ) [16]. Important to note is that the Raman spectrum of the H 2 TSPor modified gold electrode is more similar to the spectrum of CoTSPor than to that of H 2 TSPor powder.…”

“…The Raman spectroscopic analysis of a H 2 TSPor modified gold electrode (gold electrode cycled in a 8.01 × 10 −3 mol L −1 H 2 TSPor solution during 100 scans) shows identical Raman bands compared to the Raman spectrum of a CoTSPor modified electrode, which is shown and explained in literature [16]. In addition, the positions and bandwidth of the most intense Raman bands are similar to those of the pure crystalline substances (1528, 1451, 748 and 681 cm −1 ) [16].…”

“…The electrodeposition of 5,10,15,20-tetrakis-(4-sulphonatophenyl)porphyrin Co(II), tetrasodium salt (CoTSPor) at gold macroelectrodes in a pH 12 buffer solution has been the subject of intensive investigation [16]. It was found that this deposition is initially controlled by kinetic parameters leading to a nearly 100% coverage of the electrode surface in which the CoTSPor molecules form a chaotic multilayer.…”

“…After this initial stage, the adsorption is completed and followed by a slow reorganisation of the chaotic multilayer resulting in a thermodynamic more stable configuration (aggregation of CoTSPor molecules). A hypothesis regarding the electrodeposition of CoTSPor was based on the electrochemical observations made while following the currentpotential behaviour as a function of scan number and CoTSPor concentration [16].…”

“…Characterisation of the modified electrodes is done by electrochemical and spectroscopic methods, including Raman spectroscopy. The electrodeposition of CoTSPor, Co(II) incorporated into the ligand, onto a gold macro electrode has been already described [16]. It was found that this deposition is initially controlled by kinetic parameters leading to a nearly 100% coverage of the electrode surface.…”