Development of an aqueous zinc ion rGH//Bi2MoO6 photo-assisted charging supercapacitor

Abstract

The rapid economic development in recent decades has led to the non-renewability of traditional fossil fuels and environmental problems. Therefore, the search for clean and renewable sources of energy has become imminent. Among the known renewable energy sources, solar energy has received considerable attention due to its environmental benefits and abundant availability. The transformation of solar energy into electrical energy, along with its efficient storage and utilization through advanced energy harvesting and storage systems, has emerged as a prominent research focus in recent years. In this study, a new type of integrated photo-assisted charging rGH//Bi₂MoO₆ supercapacitor, which converts solar energy into electrical energy, was constructed using Bi₂MoO₆ as the photoanode (negative electrode), a reduced graphene oxide hydrogel (rGH) as the cathode (positive electrode), and a Zn(CF₃SO₃)₂ aqueous solution as the electrolyte. The results show that under photoelectric collaborative charging conditions (light intensity = 95 mW cm⁻², current density = 0.1 A g⁻¹), the specific capacity of the capacitor reached 236.9 F g⁻¹, representing a 31.8% increase compared with electric charging alone. Under photocharging only conditions, the specific capacity of the supercapacitor reached 31.09 F g⁻¹. The coulombic efficiency of the supercapacitor with electric charging and photoelectric collaborative charging was 100% after 10 000 cycles, and the corresponding capacity retention rates of the supercapacitor were 92% and 118%, respectively. The developed supercapacitor has potential for applications in fields such as wearable electronics and off-grid power supply.