Cu₂O/ZnO-PANI ternary nanocomposite as an efficient photocatalyst for the photodegradation of Congo Red dye

In this research, a novel Cu2O/ZnO-PANI ternary nanocomposite was synthesized via a facile one-pot solvothermal method and in-situ polymerization of aniline at room temperature. The ternary composite Cu2O/ZnO-PANI having Z-scheme heterojunction properties displayed outstanding adsorption properties, super-fast photocatalytic activities as well as enhanced stability. The modification with PANI led to the increase of the surface area of the composite to 45.32 m2 g-1 as compared with that of Cu2O (8.82 m2 g-1) and Cu2O/ZnO (35.66 m2 g-1). The photodegradation of Congo Red dye was studied with pure Cu2O, Cu2O/ZnO, and Cu2O/ZnO-PANI composite photocatalysts and serves as a model photocatalytic reaction for the composite. The highest degradation efficiency by Cu2O/ZnO-PANI was up to 100% after 30 min, much higher than that of Cu2O (81%), and Cu2O/ZnO (94%). The optimized composite was still active in the subsequent photocatalytic degradation of Congo Red, retaining more than 92% of the initial degradation efficiency even after the fifth cycle. This interesting activity can be attributed to the large surface area of the catalyst and the quenching of the photoluminescence, which led to the effective separation of electron/holes and subsequent reduction in the rate of recombination of the charged carriers. Likewise, the photocorrosion of Cu2O was successfully prevented, thereby forming a stable ternary photocatalyst. This work can provide a technique to improve the photocatalytic activity of photocatalysts through the processing of ternary nanocomposites utilizing conductive polymers.