A method for manufacturing a graphitic sheet is used to obtain the graphitic sheet with similar characteristics to graphene. The method includes forming an octadecyltrichlorosilane (OTS) layer on a substrate to obtain a composite. The composite is annealed at 250-400° C. for 30-90 minutes, forming the graphitic sheet on the substrate via self-assembly of octadecyltrichlorosilane (OTS) in the OTS layer. The annealed composite is immersed in water, followed by being sonicated for 2 minutes with a frequency of 40 kHz and a power output of 200 W, to separate the graphitic sheet from the substrate.