Catalytic Activity of Polyaniline in the Molecular Oxygen Reduction: Its Nature and Mechanism

By comparing experiments in air and an inert atmosphere, additional evidence for the polyaniline catalytic action on the air oxygen electroreduction is obtained. The action is compared with that of graphite substrates under the same conditions. The effect of the oxygen supply method and the polyaniline film thickness (weight) on the oxygen reduction rate is evaluated. To elucidate the nature of the polyaniline catalytic activity, quantum-chemical modeling of polyaniline and its adsorption complexes with oxygen is carried out. According to calculations, molecular oxygen can be reversibly chemisorbed at the polyaniline surface that serves as a donor of electron density. The bonding order for the O2*molecules chemisorbed at polyaniline decreases by ∼30% and the bond length increases by 24%. Thus, oxygen molecules acquire higher activity in a chemisorbed state and can then participate in the reduction more actively.