Abstract:

Cobalt/polythiophene/carbon black composite catalysts(Co-PTh/C) were firstly synthesized by an oxidative chemical polymerization and then were tested as a reduction reagent in the gas diffusion electrode of zinc-air cells. The asprepared catalysts were characterized by means of SEM-EDX and TEM techniques, which showed that they dispersed uniformly and had a size range of 10 to 30 nm. The catalytic activity of the products towards ORR(oxygen reduction reaction) in a 6 mol/L KOH aqueous solution was evaluated by cathodic polarization curves(LSV) and electrochemical impedance spectroscopy(EIS). A current density of 0.152 A/cm2 at -0.20 V(vs.Hg/HgO) could be achieved on the electrode with CoPTh/C as catalyst, which is superior to 5%Pt/C. Using this electrode as a positive electrode and pure zinc as a negative electrode, a zinc-air cell could be assembled. The cell showed a stable voltage platform of 1.1 V with a constant current density of 0.075 A/cm2 when discharged in a 6.0 mol/L KOH solution.

Key words: polythiophene, Oxygen reduction, gas diffusion electrode,, current density