The dinuclear rhenium(I) complex [ReCl(CO) 3 ( l -tptzH)Re(CO) 3 ] (where tptz-H is 2,4,6-tri(pyridine-2-yl)-
2H-1,3,5-triazine-1-ide) was used as an electrocatalyst for the homogeneous and heterogeneous reduction
of CO 2 . The electrochemical behavior of the complex in solution and at the surface of an electrode after its
adsorption was studied for the reduction of CO 2 on a carboxylated multiwall carbon nanotubes modified
(CMWCNTs) pencil graphite electrode (PGE) using cyclic voltammetric methods. The reduction potential
of CO 2 in homogenous studies was
853 mV versus NHE in acetonitrile. The results show that methanol
(MeOH) as a weak Brönsted acid enhances the rate of the catalytic process for the reduction of CO 2 in ace-
tonitrile. Under heterogonous conditions, the dinuclear complex was only casted on the CMWCNTs–PGE
and investigated in an acidic solution of MeOH. In comparison with the homogeneous catalyst, the hetero-
geneous catalyst shows a higher cathodic current and a lower over potential (about 650 mV).