Facile route to achieve N, S-codoped carbon as bifunctional electrocatalyst for oxygen reduction and evolution reactions

Zn-air batteries with high theoretical energy density and low cost are potential devices for future energy storage technology. Whereas, the performance of the battery is dependent on the catalyst on the air cathode. Efficient catalysts can advance the kinetics of oxygen reduction and oxygen evolution (ORR/OER) reactions. Polydopamine is a commonly used carbon source with a simple and non-toxic synthetic route. Here, the N, S-codoped carbon composite is prepared by carbonizing the mixture of polydopamine/sodium dodecyl sulfate precursors. The obtained sample displays an onset potential of 0.876 V vs. RHE, a half wave potential of 0.805 V, and a current retention of 94% after 20000s chronoamperometric response. Meanwhile, it shows a good OER catalytic property with the overpotential of 0.545 V. Owing to the favorable dual function catalytic ability of the sample, the sample can be used as an air–cathode catalyst to construct rechargeable Zn–air batteries. The battery exhibits an open circuit voltage of 1.526 V and a 54.1% round trip efficiency. Moreover, it also presents satisfactory durability and benign charge and discharge stability over long cycles.