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.