Electropolymerization of PGM-free molecular catalyst for formation of 3D structures with high density of catalytic sites

Precious group metal-free catalysts are considered essential for promotion of sustainable polymer electrolyte membrane fuel cells technology. The major advantage of molecular catalysts relative to still better performing materials based on pyrolysis of metallomacrocycles is that the catalytic center in the former is much more well-defined, which allows rational design and tuning of catalysts along with precise measurements of catalytic and degradation processes. We now report our approach that is aimed to gain the benefits of both molecular and material-based catalyst: electropolymerization of a molecular catalyst- 5,15-bis(p-aminophenyl),10-pentafluorophenylcorrolato cobalt (III), CoBAC. The polymeric material polyCoBAC is obtained in a three-dimensional cauliflower-like structure with ranging sizes of particles with beyond the state-of-the-art catalytic site density: 1.44*10²⁰ sites/cm [3]. A comparison between polyCoBAC and its precursor monomer CoBAC reveals that the catalytic activity regarding oxygen reduction reaction of the former is superior, in terms of both reaction mechanism and kinetics. The catalytic activity strongly depends on the polyCoBAC loading with a maximal activity obtained with less than 27 μg/cm² loading.