Visible-Light-Driven Photoelectrocatalytic Degradation of Tetracycline Using Dual Z-Scheme Bi2MoO6/GQDs/TiO2 Heterojunctions

Abstract

Photocatalysis offers an effective approach for the treatment of refractory tetracycline (TC) contamination. Conventional TiO2-based semiconductor photocatalysts for TC degradation are limited by their narrow spectral response range and rapid electron-hole recombination. In this study, ternary Bi2MoO6/graphene quantum dots/TiO2 nanotube arrays (BGT) photocatalysts with dual Z-scheme heterojunctions were designed and synthesized to overcome these limitations. The removal efficiency of TC by BGT-2 photocatalysts in photoelectrocatalytic degradation reached 79.72% within 120 minutes, with an enhanced apparent reaction rate constant (Kapp= 13.62×10-3 min-1), representing a 2.41-fold enhancement compared to TiO2 (5.65×10-3 min-1). The optimized photocatalyst, BGT-2, exhibited a photocurrent density of 9.96 μA cm-2 and a carrier density of 7.18×1020 cm-3, demonstrating high charge separation efficiency. This enhanced photoelectrochemical performance was attributed to the formation of dual Z-scheme heterojunctions, which maintain the strong redox potentials of photogenerated carriers and reduce recombination losses. This work presents a novel material construction strategy for developing high-performance photocatalysts to address persistent antibiotic contamination.