Construction of a g-C3N4/PANI/α-MnO2 direct Z-scheme heterojunction with oxygen-rich vacancies for enhancing photocatalytic degradation of tetracycline hydrochloride under visible light

Abstract

This work involved the in situ chemical polymerization of aniline at ambient temperature using a simple hydrothermal method to synthesize a novel ternary photocatalyst for wastewater treatment. The Z-scheme heterojunction features of this ternary nanocomposite (20 wt%-g-C₃N₄/0.5 wt%-PANI/α-MnO₂) led to exceptional photocatalytic activity. In comparison to the pure nanomaterials g-C₃N₄ (15.5 m² g⁻¹) and α-MnO₂ (18.5 m² g⁻¹), the surface area of the catalyst dramatically increased (40.5 m² g⁻¹) after being modified by PANI. Tetracycline hydrochloride (TCH) photodegradation was examined using pure g-C₃N₄ and α-MnO₂, g-C₃N₄/α-MnO₂ binary nanocomposite (with varying weight% of g-C₃N₄), and ternary nanocomposite (with varying weight% of PANI). After one hour, TCH (50 mg L⁻¹) was degraded by a maximum of 96% with the ternary nanocomposite, which is much more than those of 20-g-C₃N₄/α-MnO₂ (75%), g-C₃N₄ (35%) and α-MnO₂ (20%). Even after five consecutive cycles, the modified ternary photocatalyst continued to function well and sustained almost 86% of its degrading efficiency. The large surface area and quenching of photoluminescence, which result in efficient separation of electron/hole pairs and consequent reduction in the rate of recombination of charge carriers, are the main causes of the ternary catalyst's strong photocatalytic activity. This study offers a method for enhancing photocatalytic activity using conductive polymers.