Incorporation of graphene quantum dots into magnesium copper phosphate (GQDs-MgCuPO₄) for supercapattery and electrocatalysis applications

Abstract We efficiently synthesize magnesium copper phosphate nanoparticles (MgCuPO 4 ) doped with graphene quantum dots (GQDs) using a hydrothermal method for supercapattery and oxygen evolution reactions in KOH electrolyte. The GQDs-MgCuPO 4 electrode has a high specific capacity (1188 Cg −1 at 1.0 Ag −1 ) and a high rate capability (67%). The symmetric supercapattery (GQDs-MgCuPO 4 //GQDs-MgCuPO 4 ) provides a staggering energy density of 46 Wh-kg −1 , as well as a high power density of 1300 W-kg −1 and a high cyclic stability of 93% after 10,000 cycles. Furthermore, it demonstrates high efficiency in the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), with corresponding low overpotentials of 181 mV and 119 mV. The GQDs-MgCuPO 4 stands out as a capable solution for various energy storage and conversion difficulties.