Enhanced photocatalytic degradation of methylene blue using a ZnO-TiO2/rGO nanocomposite under UV irradiation

Abstract

This study reports the development of ZnO-TiO₂/rGO ternary nanocomposites synthesized via a simple hydrothermal strategy, exhibiting enhanced photocatalytic efficiency for the degradation of methylene blue (MB) under UV irradiation. The photocatalytic performance of the ZnO-TiO₂/rGO nanocomposites was evaluated under various conditions, including different pH levels, catalyst amount, and irradiation times. The ternary nanocomposite achieved ≈100% MB degradation after 120 min, surpassing the performance of individual ZnO, TiO₂, ZnO-TiO₂, and rGO photocatalysts. Reactive species analysis identified hydroxyl radicals and superoxide radicals as the primary active species, confirmed through scavenger studies. The proposed photocatalytic degradation mechanism highlights the role of reactive oxygen species (ROS) and the synergistic effect of the composite components. Additionally, the ZnO-TiO₂/rGO nanocomposite demonstrated excellent stability and reusability over multiple cycles, making it a promising candidate for environmental remediation. This study presents a rational design concept for developing highly efficient photocatalysts for wastewater treatment applications.