The electrocatalytic activity of T6[100] surface containing both sp 3 (C 1 ) and sp 2 (C 2 ) hybridized carbon atoms is explored using first-principles density functional theory based approach. The top layered C 1 atom of the surface is found to be more active towards the oxygen reduction reaction (ORR), as compared to that of C 2 atom. This is attributed to the presence of dangling σ bond in the corresponding C 1 atom, leading to the high electron density near the Ferrmi level. Whereas, the π electron in the top layered C 2 atom forms a weak out of plane network. As estimated from free energy profile, the overpotential is much lower when C 1 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 T6[100] 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 T6[100] surface, having both sp 2 (maintains the high metallicity needed to reduce ohmic loss) and sp 3 (helps in capturing the upcoming molecules) hybridized carbon atoms, as a potential candidate for ORR.