Electroactive and Conformal Coatings of Oxidative Chemical Vapor Deposition Polymers for Oxygen Electroreduction

Polymer from 3,4-ethylenedioxythiophene (EDOT) was synthesized using oxidative chemical vapor deposition (oCVD). To enable the synthesis of PEDOT, two different oxidants, antimony pentachloride (SbCl5) and vanadium oxytrichloride (VOCl3), were utilized. The effect of deposition temperature on the polymer electroactivity and conductivity was evaluated by measuring the overpotential for the oxygen reduction reaction and film electrical conductivity, respectively. PEDOT films with conductivity values of ∼2000 S/cm were deposited in a single step coating and doping process. X-ray photoelectron spectroscopy revealed that the residual metalloid within polymer films, in the case of SbCl5, is contributing to the hole conductivity. The electrocatalytic activity of deposited material in oxygen reduction reaction (ORR) was studied; the results indicate a direct relationship between the conductivity values and the electrocatalytic activities of the deposited films. The unique potential offered by oCVD to coat PEDOT conformally enabled us to apply a coat of electroactive polymers on complex structures of a gas diffusion layer fabric, carbon cloth. Using our approach, we imparted stable electrocatalytic activity to carbon cloth electrodes and fabricated all-organic electrodes for ORR.