Hybrid electrocatalysts for oxygen reduction reaction: Integrating enzymatic and non-platinum group metal catalysis

For the first time, oxygen reduction reaction has been demonstrated on a system which integrates enzymatic and non-platinum based catalysts simultaneously. This achievement is of a great importance as it offers the possibility of exploring concomitantly two very different types of catalysts, combining the advantages of both in enhancing oxygen reduction reaction rate. The engineered catalytic hybrid material not only possesses lower overpotentials compared to the purely non-PGM catalyst, but also is capable of achieving higher current densities in comparison to purely enzymatic catalyst. The hybrid catalyst undergoes oxygen reduction with the desired 4 electron transfer process, leading to the formation of water as a final product. The achieved current density of 1.2 mA cm^-2 is believed to be the highest reported for bilirubin oxidase -based gas-diffusion cathode reported so far.