Direct Z-scheme Cu₂O/WO₃/TiO₂ nanocomposite as a potential supercapacitor electrode and an effective...

This paper presents the synthesis of visible light-responsive ternary nanocomposites composed of cuprous oxide (Cu₂O), tungsten trioxide (WO₃), and titanium dioxide (TiO₂) with varying weight percentages (wt.%) of the Cu₂O. The resulting Cu₂O/WO₃/TiO₂ (CWT) nanocomposites exhibited band gap energy ranging from 2.35 to 2.90 eV. Electrochemical and photoelectrochemical (PEC) studies confirmed a reduced recombination rate of photoexcited charge carriers in the CWT nanocomposites, facilitated by a direct Z-scheme heterojunction. The 0.50CWT nanocomposite demonstrated superior photodegradation activity (2.29 × 10^-2 min^-1) against Reactive Black 5 (RB5) dye under visible light activation. Furthermore, the 0.50CWT nanocomposite exhibited excellent stability with 80.51% RB5 photodegradation retention after five cycles. The 0.50CWT electrode achieved a maximum specific capacitance of 66.32 F/g at 10 mA/g current density, with a capacitance retention of 95.17% after 1000 charge-discharge cycles, affirming its stable and efficient supercapacitor performance. This was supported by well-defined peaks in cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) curves, indicating pseudocapacitive properties.