Electrochemical Reduction of Oxygen on Hydrophobic Ultramicroporous PolyHIPE Carbon

A new kind of polyHIPE (polymerized high internal phase emulsion)-based carbon derived from coreacted furfuryl alcohol and tannin was tested as an ORR catalyst. To understand the reduction process, the surface was extensively characterized from the point of view of texture and chemistry. The prepared materials show subtle differences in the chemistry but marked differences in the porosity. The best-performing sample had a very high volume of ultramicropores and the highest degree of defects on the surface. The oxygen was present on the surface mainly in epoxy and ether configurations. Those oxygen groups located in large pores promoted transfer of O₂ dissolved in water/electrolyte to small pores of the hydrophobic surface. There, a strong adsorption of oxygen was energetically favorable. This led to weakening of O–O bonds, subsequent dissociation of oxygen, and its reduction/protonation. The presented polyHIPE carbons show high electrochemical stability and better tolerance to methanol than Pt/C. High kinetic current density was measured on them