Electrocatalytic Properties of Metal Phthalocyanine Tetrasulfonate Intercalated in Metal Layered Simple Hydroxides (Metal: Co, Cu, and Zn).
Résumé
A series of hybrid metal (Zn, Cu, and Co) layered simple hydroxides (LSH) functionalized by surfactants, namely, dodecylsulfonate (DS0) or dodecylsulfate (DS–) and by tetrasulfonato metal (Cu, Co)-phthalocyanines, was synthesized by anionic exchange reactions and characterized by ancillary techniques. The electrochemical properties of these compounds were investigated by cyclic voltammetry in phosphate buffer solutions over a wide potential range including that suitable for oxygen reduction. The electroactivity of intralayer metal cations (Cu and Co) was evidenced as a function of the phosphate buffer pH. The redox properties of Co- and Cu-PcTS0 grafted in LSH (Zn, Co, and Cu) were also investigated in neutral pH solution, under argon, air, or O2 atmospheres. Interestingly, these hybrid compounds display an electrocatalytic behavior toward the reduction of oxygen. In particular with CoPcTS0-LSH, a sharp electrocatalytic reduction wave is observed at −0.40 V/Ag-AgCl with an intensity that depends on the oxygen concentration. The formation of a CoPc-O2 grafted species in the presence of oxygen was confirmed by electron paramagnetic resonance spectroscopy.