Application of the cyclic semi-integral voltammetry and cyclic semi-differential voltammetry to the determination of the reduction mechanism of a Ni-porphyrin

In this work, the combination of the cyclic semi-integral voltammetry (CSIV) and cyclic semi-differential voltammetry (CSDV) methods with cyclic voltammetry (CV) has been used. Therefore. a quick and precise mechanistic interpretation of the experimental results is obtained. The procedure has been applied to the electrochemical reduction of Ni-meso-tetra(4-N-methylpyridyl) porphyrin (Ni-TMPyP) in acidic aqueous solution (pH 4.3). where this compound exhibits two reduction waves and one or two oxidation waves as a function of the scan rate in CV. Moreover. the electrode process is affected by the adsorption of an intermediate reduction product and by a chemical reaction following the first reduction wave. Finally, in order to confirm the proposed mechanism, numerical simulations of the CV and the CSDV were performed, (C) 2002 Elsevier Science B.V. All rights reserved.