Development of benzoporphyrinic compounds as electrocatalysts for carbon dioxide reduction

Abstract

This research studies on an electrochemical reduction of carbon dioxide (CO₂) by using metallobenzoporphyrin derivatives as electrocatalysts. The benzoporphyrin derivatives have phenyl groups at meso positions and fused with benzo rings at β-positions of the pyrrolic units in order to extend the conjugated system. In this study, the central metals of the benzoporphyrin derivatives of interest are cobalt(II), copper(II), nickel(II), tin(IV) and zinc(II). The formation of the benzoporphyrin derivatives were confirmed by spectroscopic techniques and their electrocatalytic activity for the reduction of CO₂ was studied by means of cyclic voltammetry. The cyclic voltammetric experiments were performed under saturated nitrogen and saturated CO₂ conditions, and with and without radiation by a tungsten-halogen lamp. Based on cyclic voltammatric results, free base and the metallated benzoporphyrin derivatives exhibited catalytic effect on electrochemical reduction of CO₂. Considering the reduction potential and the current enhancement, it was found that copper(II)-tetraphenyltetrabenzoporphyrin exhibited the highest catalytic activity with the current enhancement at the second reduction of 154%, while tin(IV)-tetraphenyltetrabenzoporphyrin showed the least catalytic activity for the reduction of CO₂.