Facile Construction of 2D/2D g-C3N4/BiOIO3 Z-Scheme Heterojunctions with Strong Built-In Electric Field for Efficient Ciprofloxacin Photodegradation

The escalating pollution of aquatic ecosystems by antibiotics has triggered substantial public concerns, with ciprofloxacin (CIP) being a representative pollutant. Bismuth iodate (BiOIO 3 ), a novel 2D bismuth-based polar photocatalyst, is a promising material for the photodegradation of antibiotics. However, its practical application is hindered by its wide bandgap and rapid charge recombination. Therefore, this study aims to construct a 2D/2D g-C 3 N 4 /BiOIO 3 Z-scheme heterojunction (CNB) via a one-step hydrothermal method to overcome these limitations. The optimal CNB-2 (5   wt% g-C 3 N 4 ) achieved 91% CIP degradation within 60   min (rate constant k=0.04369   min -1 ), 3.8-fold and 2.9-fold higher than pure g-C 3 N 4 and BiOIO 3 , respectively, with a 62% total organic carbon (TOC) removal rate. The degradation pathways primarily involve the ring opening of the piperazine ring and decarboxylation of the quinolone structure. Radical trapping and EPR tests identified that ·OH and ·O 2 - were the main active species. CNB-2 maintained >90% degradation efficiency over pH 3-9 and retained 86.8% activity after 5 cycles, showing excellent stability. Its superior performance arose from the 2D heterostructure’s large specific surface area and Z-scheme charge transfer, which enhanced carrier separation while preserving strong redox capacity. This work offers a practical strategy for designing efficient photocatalysts to remediate antibiotic contaminated water.