Enhancing the Photocatalytic Performance of CuBi2O4 Through Graphene Oxide Incorporation

Copper bismuth oxide (CuBi2O4) was produced through a domestic microwave-assisted synthesis using water as an environmentally friendly solvent, whereas graphene oxide (GO) was obtained using a modified Hummers’ method. Structural characterization by XRD confirmed the formation of a pristine tetragonal CuBi2O4 phase, with no shift in diffraction peaks after GO incorporation, although a slight reduction in crystallinity was observed. FESEM analysis revealed the characteristic sheet-like morphology of GO and spherical CuBi2O4 particles. EDS analysis verified the elemental composition of the prepared composites. Incorporating GO into CuBi2O4 narrowed the optical band gap from 2.4 to 2.2 eV and suppressed electron–hole recombination, as evidenced by the lower photoluminescence intensity. Furthermore, BET measurements showed that the specific surface area increased markedly from 3.79 m2/g for pristine CuBi2O4 to 16.49 m2/g for the composite. This enhancement may provide additional adsorption sites for malachite green (MG) molecules, promoting their adsorption onto the composite surface before exposure to visible light. The composite achieved 86.5% MG removal within 150 min, with nearly twice the rate constant of pristine CuBi2O4. Reactive species trapping experiments indicated that photogenerated holes (h+) and superoxide radicals (•O2−) played major roles in the photocatalytic process. Meanwhile, the removal efficiency of pristine CuBi2O4 declined by approximately 40% after four consecutive reuse cycles.