Performance of palladium nanoparticle–graphene composite as an efficient electrode material for electrochemical double layer capacitors

•Single step synthesis of palladium nanoparticles decorated-graphene nanocomposite.•Improved electron transfer kinetics and superior capacitive performance.•High specific capacitance of 637Fg−1at a current density of 1.25Ag−1.•Retention of 91.4% of its initial capacitance after 10000 cycles of testing.