Construction of Mn2+-doped ZnCo2O4//rGH photoassisted charging supercapacitor

Photorechargeable supercapacitors were constructed using Mn 2+ - doped ZnCo 2 O 4 as the photoanode, reduced graphene oxide hydrogel (rGH) as the cathode and Zn (CF 3 SO 3 ) 2 as the electrolyte. The physical composition, microstructure, light absorption, chemical structure, and electrochemical performance of the supercapacitors were comprehensively characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HR-TEM), ultraviolet–visible (UV–Vis), X-ray photoelectron spectroscopy (XPS), and electrochemical workstation, respectively. The results show that under the photoelectric synergistic charging conditions (current density of 0.2 A g −1 and light intensity of 95 mW cm −2 ), the specific capacity of the 4 % Mn 2+ -doped ZnCo 2 O 4 //rGH supercapacitor is 256.4 F g −1 , which is 12 % higher than that of the electric charging, and 69 % higher than that of the ZnCo 2 O 4 //rGH supercapacitor. The 4 % Mn 2+ - doped ZnCo 2 O 4 //rGH supercapacitor shows Coulombic efficiency of 100 % for both electric and photoelectric synergistic charging after 10000 cycles, and the capacity retention rate of 78 % and 122 %, respectively, which are 28 % and 22 % higher than that of ZnCo 2 O 4 //rGH supercapacitor at the same conditions, suggesting that the 4 % Mn 2+ - doped ZnCo 2 O 4 //rGH supercapacitor has better photoelectrochemical performance than the ZnCo 2 O 4 //rGH supercapacitor.