In this study, density functional theory (DFT)-based calculation has been performed on activated carbon sheet doped with silicon atom. In a two-dimensional activated carbon sheet, carbon atoms are replaced by silicon atom and the structural and electronic properties are investigated. The result of structural analysis explains the depth of an activated carbon (AC) sheet, total width as well as changes in the bond lengths with the doping of Siatoms. AcSi$_1$ (single silicon-doped activated carbon) and AcSi$_2$ (double silicon-doped activated carbon) exhibit lesser binding energy than pristine AC sheet and AcSi$_3$ (triple silicon-doped activated carbon). The result of the projected density of states (PDOS) explains s–p hybridisation of all the systems. The analysis of crystal orbital overlap population (COOP) explains the antibonding states in all the systems. There is also a probability to get higher values of transport properties in pristine sheet and AcSi$_3$ sheet rather than in AcSi$_1$ and AcSi$_2$ sheets.