One-step induced porous graphitic carbon sheets as supercapacitor electrode material with improved rate capability

•Porous GCS were prepared by one-step in-situ KOH chemical activation process.•Excellent textural parameters (high surface area) and graphene-like structure.•GCS-2 supercapacitor electrode displayed 85% capacitance retention at 50 A g−1.•The electrode showed excellent cyclic stability over 10,000 cycles at 1 A g−1.