Bifunctional hierarchical WO3 nanorods@Br-doped g-C3N4 Z-scheme heterojunctions for efficient tetracycline photodegradation: Optimization of key parameters, toxicological assessment, and electrocatalytic hydrogen evolution reaction

초록

In this study, graphitic carbon nitride (CN) and tungsten trioxide (WO3) were successfully incorporated into bromine (Br)-doped graphitic carbon nitride (BCN) using an in-situ hydrothermal method. The photocatalytic efficiency of the resulting WO3/Br-doped CN (WBCN) composites for the removal of tetracycline (TC) antibiotics under sunlight irradiation was evaluated. The mass ratio of WO3 to Br-doped CN (BCN) significantly influenced TC adsorption and photocatalytic degradation, with an optimal ratio of 9:1. The synthesized catalyst exhibited exceptional performance, achieving 98% TC detoxification under sunlight, attributed to enhanced light absorption, efficient charge separation, and reduced electron-hole (e_/h+) recombination facilitated by BCN doping. Trapping experiments and ESR analysis identified center dot O 2 _ and center dot OH as the primary reactive species in TC decomposition, with h+ radicals playing a secondary role. Reusability tests further confirmed the high stability of the photocatalyst. The Z-scheme charge transfer mechanism was elucidated, highlighting the crucial role of Br doping in enhancing synergistic interactions between WO3 and CN. Additionally, the nickel foam (NF) electrode supported by the WBCN-2 composite demonstrated remarkable electrocatalytic activity for hydrogen evolution, achieving a minimum overpotential of 99 mV and a Tafel slope of 108 mV/dec at a current density of 10 mA/ cm2. The WBCN-2@NF composite catalyst also achieved excellent performance, with a low cell voltage of 1.77 V at 10 mA/cm2. Chronopotentiometry (CP) tests revealed remarkable long-term stability, with minimal current loss over 15 h of continuous operation. Overall, the WBCN composite exhibits excellent photocatalytic and electrocatalytic performance, making it a promising candidate for practical environmental remediation and sustainable energy production.

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