PEO-b-PS Block Copolymer Templated Mesoporous Carbons: A Comparative Study of Nitrogen and Sulfur Doping in the Oxygen Reduction Reaction to Hydrogen Peroxide

Carbon materials slightly doped with heteroatoms such as nitrogen (N-RFC) or sulfur (S-RFC) are investigated as active catalysts for the electrochemical bioelectronic oxygen reduction reaction (ORR) to H 2 O 2 . Mesoporous carbons with wide, accessible pores were prepared by pyrolysis of a resorcinol-formaldehyde resin using a PEO-b-PS block copolymer as a sacrificial templating agent and the nitrogen and sulfur doping were accomplished in a second thermal treatment employing 1,10-phenanthroline and dibenzothiophene as nitrogen and sulfur precursors, respectively. The synthetic strategy allowed to obtain carbon materials with very high surface area and mesopore volume without any further physico-chemical post treatment. Voltammetric rotating ring-disk measurements in combination with potentiostatic and galvanostatic bulk electrolysis measurements in 0.5 M H 2 SO 4 demonstrated a pronounced effect of heteroatom doping and mesopores volume on the catalytic activity and selectivity for H 2 O 2 . N-RFC electrode was employed as electrode material in a 45 h electrolysis showing a constant H 2 O 2 production of 298 mmol g -1  h -1 (millimoles of H 2 O 2 divided by mass of catalyst and electrolysis time), with a faradic efficiency (FE) up to 61% and without any clear evidence of degradation. The undoped carbon RFC showed a lower production rate (218 mM g -1  h -1 ) but a higher FE of 76 %, while the performances drastically dropped when S-RFC (production rate 11 mmol g -1  h -1 and FE = 39 %) was used.