Synthesis of quantum dot-based CuO/Fe3O4@g-C3N4 dual Z-scheme ternary composite from Aloe vera

• Quantum dot CuO and Fe 3 O 4 metallic oxides were embedded on g-C 3 N 4. • The bandgap energy of g-C 3 N 4 was successfully reduced from 2.66 to 1.67 eV. • The charge carrier recombination rate of g-C 3 N 4 was substantially mitigated. • Enhanced photocurrent response indicated potential photocatalytic application. CuO/Fe 3 O 4 @g-C 3 N 4 ternary composite was synthesised via an ex-situ hydrothermal method by using Aloe vera leaf extract as a reducing and stabilising agent. Morphological investigations of CuO/Fe 3 O 4 @g-C 3 N 4 showed spherical-shaped quantum dot-sized (3.34 ± 0.98 nm) metallic oxides uniformly dispersed on g-C 3 N 4 . Incorporating CuO and Fe 3 O 4 quantum dots onto g-C 3 N 4 resulted in a dual Z-scheme heterostructure with decreased bandgap energy (2.66 to 1.67 eV). This work is significant as it demonstrated a simple, one-step ex-situ green synthesis of a dual Z-scheme CuO/Fe 3 O 4 @g-C 3 N heterostructure. It is known in literature that g-C 3 N 4 suffers from quick recombination of photoexcited charges and over the years these have been improved using modification strategies such morphologies regulating, element doping and heterojunctions construction. Dual Z-scheme heterojunctions have advantageous properties such as reduced bandgap energy, increased separation rate of photogenerated electron-hole pairs and efficient redox reactions, compared to other heterojunctions that suffer from limitations such as low charge separation efficiency. It is envisaged that this dual Z-scheme ternary composite will be incorporated into a hollow fiber membrane for application in the degradation of antiviral drugs, which will be addressed separately and is not included in the present manuscript.