Studies On Electrocatalysis Reduction Of Oxygen With Macrocyclic Complexes

Transition metal macrocyclic complexes have high electrocatalytic activities for oxygen reduction. Three electrode systems are built to determine the activities for oxygen reduction, which include modified electrode or gas diffusion electrode as working electrode, SCE as reference electrode, platinum as auxiliary electrode. Cyclic voltammetry and stable polarization curve method are used to study electrochemical performance of modified electrode or gas diffusion electrode.The catalytic reduction behavior of oxygen on the electrode modified with 5, 10, 15, 20-Tetrakis (pentafluorophenyl)-21H-23H-porphine iron(â…¢) chloride (TPPFeCl) in H₂SO₄ solution is studied by cyclic voltammetry method. The influences of porphore iron TPPFeCl electrode modified with Nafion on the catalytic activity and stability of electrode are discussed. The reaction rate constant and diffusion coefficient of TPPFeCl on the electrode are 4.34×10^-5cm/s and 4.43×10^-6cm/s respectively.The behavior of catalytic reduction on three types of modified electrodes is studied using cyclic voltammetry. The first electrode modified with industrial dyestuff Direct Light Turquoise GL (denoted as GL) has notable catalytic activity, two reduction peaks of O₂ appear on CV curve (E_p is -0.25V and -0.40V respectively), but its stability is poor. The second electrode modified with poly (4-vinyl-pyridine) and GL shows a good catalytic performance. Both activity and stability are much better than those of the first electrode, i_p in the CV curve equals 200ï¼…of that of the first electrode and the E_p for the first peak has shifted positively about 0.05V. The catalytic performance of the third electrode modified with Nafion and GL is a little bid better than that of the first electrode, but is much worse than that of the second electrode. The reason of difference in the catalytic performances of these electrodes are discussed.The electrocatalytic reduction of oxygen on the gas diffusion electrode coated with cobalt phthalocyanine(CoPc) were studied systematically by stable polarization curves. The effects on electrocatalytic reduction of oxygen are discussed such as pressure of electrode preparation, content of CoPe, addition of PVP.The electrocatalytic reduction of dioxygen on the gas diffusion electrode of Nation modified by macrocyclic complexes of cobalt are studied systematically by stable polarization curves method. The effects of electrostatic interaction between the complex coating and Nation film on electrocatalytic rduction of oxygen under the catalyst of CoTMAP and CoTsPc are discussed.