Defect enriched N, S-codoped carbon sheets as an efficient electrocatalyst to oxygen reduction reaction

A nitrogen and sulfur codoped carbon-based catalyst (Fe-NS-AG-C) to oxygen reduction reaction (ORR) is prepared by pyrolyzing a precursor from iron chloride, thiourea, anhydrous glucose and carbon black. Glucose is transformed to carbon sheets with defect-rich structures which are highly active to the anchoring of nitrogen and sulfur atoms. Correspondingly, the 3.35 at% and 0.63 at% contents of nitrogen and sulfur in Fe-NS-AG-C are heavily higher than the 0.71 at% and 0.26 at% in the controlled catalyst Fe-NS-C (without glucose). The edge-oriented pyridinic N is easily formed as ORR active sites with the C-S structure. A dual mesopore-dominated microstructure is also constructed by the carbon sheets to favor the mass transfer in the reaction process. As a result, the Fe-NS-AG-C presents outstanding ORR performance with more positive half wave potential, greater limiting current density, and better methanol tolerance than the benchmark Pt/C catalyst. The Zn-air battery assembled with Fe-NS-AG-C outputs 1.48 V of open circuit voltage, 156 mW cm−2 of maximum power density, and 1.26 V of work voltage, 785 mAh g−1Zn of specific capacity and 983 mWh g−1Zn of specific energy density at 10 mA cm−2 of discharge current density.