A photoelectrochemical supercapacitor based on a single BiVO4-RGO bilayer photocapacitive electrode

A single photo-capacitive bilayer electrode using BiVO4-RGO was fabricated to develop a photoelectrochemical supercapacitor, integrating photoelectric conversion and energy storage. The capacitive behavior of the electrode was initially studied by cyclic voltammetry and galvanostatic charge-discharge. The BiVO4-RGO electrode displayed typical EDLC behavior and good performance as a supercapacitor exhibiting a specific capacitance of 141.8F.g−1 measured at a current density of 0.2A.g−1 demonstrating BiVO4’s facile charge transfer capability during electrical charging and discharging operations. Subsequently, the bilayer electrode was assembled into a photo-supercapacitor which was photocharged in the open circuit condition, generating a photovoltage of 340 mV and capable of delivering a specific discharge capacity of 4.1 mAh.g−1, the highest reported value for such electrode configuration till-date. In order to gain more insight about the charge transfer mechanism across the electrode-electrolyte interface, electrochemical impedance spectroscopic (EIS) analysis was performed for the BiVO4-RGO bilayer electrode under dark and light conditions, along with a durability test.