Density functional theory-based analysis on O2 molecular interaction with the tri-s-triazine-based graphitic carbon nitride

► O2 molecule interaction with g-C3N4 surface is physisorbed. ► The interaction is mainly between VBT of the surface and LUMO of the molecule. ► g-C3N4 surface provides stronger O2 molecular adsorption than graphene. ► g-C3N4 surface has less tendency to be oxidized by adsorbate than graphene. ► g-C3N4 surface is a better catalyst for ORR than graphene sheet.