Electrochemical reduction of CO2 at hanging mercury drop electrode by nickel (II) macrocyclic complex of 1,3,6,8,12,15-hexaazatricyclo [13.3.1.1] eicosane

Cyclic voltammetry, Control-potential electrolysis, and gas chromatographic techniques were employed to investigate the electrochemical behavior of the complex [NiL] (ClO4)(2), where L = 1,3,6,8,12,15 - Hexaazatricyclo [13.3.1.1]eicosane in water and in water mixtures of acetonitrile and dimethylformamide under nitrogen and carbon dioxide atmospheres. The complex exhibited a reversible one-electron reduction at hanging mercury drop electrode. In the presence of CO2, the cathodic current increases in all solvent systems studied. Gas chromatographic analysis of the electrolyzed solution showed that CO and hydrogen were found as gaseous products and photometric analysis revealed the formation of trace amounts of formic acid in solution phase. Catalytic efficiency of the complex in various solvent systems are compared and discussed.