Facile in-situ simultaneous electrochemical reduction and deposition of reduced graphene oxide embedded palladium nanoparticles as high performance electrode materials for supercapacitor with excellent rate capability

We have reported fast and simple synthesis of electrochemically reduced graphene oxide nanosheets (ErGO NSs)-embedded-palladium nanoparticles (Pd-E-ErGO) hybrids on nickel (Ni) sheet for high performance electrochemical supercapacitors (SCs) electrode. The Pd-E-ErGO hybrids material was successfully prepared by facile and one-pot in-situ electrochemical reduction and deposition using water as solvent in which palladium nanoparticles (Pd NPs) were uniformly embedded inside 2D-nanosheets of ErGO. During electrochemical reduction, graphene oxide nanosheets were reduced into ErGO NSs and PdCl₂ ionized to form Pd²⁺ which attracted to the negative oxygen containing functional groups of ErGO NSs then reduced to form Pd NPs which embedded completely between ErGO NSs structure. The surface/structural morphology of Pd-E-ErGO hybrids was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS) and Raman spectroscopy. The proportions of elements present in hybrids were determined by EDS and thermogravimetric analysis (TGA). As an application, the synthesized Pd-E-ErGO hybrids revealed enhanced electrochemical performance as high specific capacitance with excellent cycling stability which was very significant for electrochemical SCs. The Pd-E-ErGO hybrids electrode fulfills an approving specific capacitance value of 1524.7 F/g at a scan rate of 20 mV/s and improved cycling stability of 92.1% capacitance retention after 2000 cycles in the three-electrode setup. The electrochemical synthesis of Pd-embedded-graphene derivatives structure as well as improved electrochemical performance for SCs opens up a new idea to prepare electrode materials.