Covalent Organic Framework-Coupled and Gold-Decorated BiVO₄ Nanosheets For Enhanced Photocatalytic Dye Removal

The development of efficient photocatalysts is crucial for environmental remediation of toxic organic dyes. In this work, covalent organic framework (BTTA COF)-coupled, Au-incorporated BiVO₄ nanosheets (BTTA/Au-BVNS) were synthesized and applied for the degradation of methylene blue (MB) and malachite green (MG). Compared to BiVO₄ nanoparticles, BiVO₄ nanosheets exhibited superior photocatalytic activity, which was further enhanced by the incorporation of Au and BTTA COF. The optimized 3BTTA/3Au-BVNS nanocomposite achieved a 3.36-fold increase in MB degradation and a 3.0-fold increase in MG degradation relative to pristine BiVO₄ nanosheets. The presence of Au reduced the band gap from 2.23 to 2.01 eV through surface plasmon resonance, while BTTA COF coupling increased surface area and facilitated charge separation. Electrochemical analyses confirmed improved charge transfer and stability of the composite. These synergistic modifications significantly enhanced photocatalytic performance, underscoring the potential of COF-supported, plasmonic-assisted BiVO₄ systems as advanced materials for wastewater treatment and sustainable environmental protection.