Display omitted •Multi-layered T6100 surface shows high activity towards ORR.•Role of dangling σ bond and π electron network.•Operating potential is significantly high (0.48V) considering C1 as an active site.•Si-substitution shows over activity with a high overpotential value. The electrocatalytic activity of T6100 surface containing both sp3 (C1) and sp2 (C2) hybridized carbon atoms is explored using first-principles density functional theory based approach. The top layered C1 atom of the surface is found to be more active towards the oxygen reduction reaction (ORR), as compared to that of C2 atom. This is attributed to the presence of dangling σ bond in the corresponding C1 atom, leading to the high electron density near the Ferrmi level. Whereas, the π electron in the top layered C2 atom forms a weak out of plane network. As estimated from free energy profile, the overpotential is much lower when C1 is considered as the active site and the final step i.e desorption of final OH− ion is found to be the potential determining step. We have also reported the effect of Si dopant on the catalytic activity of T6100 surface and explained the origin of high overpotential value in this case. Thus in this report, we propose a new metal-free catalyst i.e T6100 surface, having both sp2 (maintains the high metallicity needed to reduce ohmic loss) and sp3 (helps in capturing the upcoming molecules) hybridized carbon atoms, as a potential candidate for ORR.