Photoirradiation-Induced Capacitance Enhancement in the h-WO₃/Bi₂WO₆ Submicron Rod Heterostructure under Simulated...

Recently, photoassisted charging has been demonstrated as a green and sustainable approach to successfully enhance the capacitance of supercapacitors with low cost and good efficiency. However, their light-induced capacitance enhancement is relatively low and is lost quickly when the illumination is off. In this work, a novel active material system is developed for supercapacitors with the photoassisted charging capability by the decoration of a small amount of Bi₂WO₆ nanoparticles on an h-WO₃ submicron rod surface in situ, which forms a typical type II band alignment heterostructure with a close contact interface through the co-sharing of W atoms between h-WO₃ submicron rods and Bi₂WO₆ nanoparticles. The photogenerated charge carrier separation and transfer are largely enhanced in the h-WO₃/Bi₂WO₆ submicron rod electrode, which subsequently allows more charge carriers to participate in its photoassisted charging process to largely enhance its capacitance improvement under simulated solar illumination than that of the h-WO₃ submicron rod electrode. Furthermore, the h-WO₃/Bi₂WO₆ submicron rod electrode could retain its photoinduced capacitance enhancement in the dark for an extended period of time from the photocatalytic memory effect. Thus, our work provides a solution to the two major drawbacks of reported supercapacitors with the light-induced capacitance enhancement property, and supercapacitors based on active materials with the photocatalytic memory effect could be utilized in various technical fields.