Synergistic redox enhancement: silver phosphate augmentation for optimizing magnesium copper phosphate in efficient energy storage devices and oxygen evolution reaction

The implementation of battery-like electrode materials with complicated hollow structures, large surface areas, and excellent redox properties is an attractive strategy to improve the performance of hybrid supercapacitors. The efficiency of a supercapattery is determined by its energy density, rate capabilities, and electrode reliability. In this study, a magnesium copper phosphate nanocomposite (MgCuPO(4)) was synthesized using a hydrothermal technique, and silver phosphate (Ag(3)PO(4)) was decorated on its surface using a sonochemical technique. Morphological analyses demonstrated that Ag(3)PO(4) was closely bound to the surface of amorphous MgCuPO(4). The MgCuPO(4) nanocomposite electrode showed a 1138 C g(−1) capacity at 2 A g(−1) with considerably improved capacity retention of 59% at 3.2 A g(−1). The increased capacity retention was due to the fast movement of electrons and the presence of an excess of active sites for the diffusion of ions from the porous Ag(3)PO(4) surface. The MgCuPO(4)–Ag(3)PO(4)//AC supercapattery showed 49.4 W h kg(−1) energy density at 550 W kg(−1) power density and outstanding capacity retention (92% after 5000 cycles). The experimental findings for the oxygen evolution reaction reveal that the initial increase in potential required for MgCuPO(4)–Ag(3)PO(4) is 142 mV, indicating a clear Tafel slope of 49 mV dec(−1).