Fabrication of high-performance 3D Biochar-Silica@BiOCl composites for photocatalytic degradation of tetracycline hydrochloride

A “waste-to-waste” strategy was adopted by pyrolyzing waste sugarcane bagasse to synthesize biomass-derived carbon (AC) and utilizing diatomite (DTE) as a substrate to construct a high-performance three-dimensional carbon–silica-based bismuth oxychloride (AC-DTE@BiOCl) photocatalyst. The three-dimensional structure effectively prevents the agglomeration of BiOCl while providing additional active sites. Experimental results demonstrate that AC-DTE@BiOCl efficiently degrades 96.2 % of tetracycline hydrochloride (TCH) within 90 min, exhibiting excellent photocatalytic performance. Infrared spectroscopy analysis reveals that the symmetric stretching vibration peak of Si-O (804 cm⁻¹) weakens and slightly broadens, while no characteristic peaks of TCH are detected, indicating its complete degradation. Density functional theory (DFT) calculations indicate that the carbonyl site in the TCH molecule exhibits the highest negative electrostatic potential, and O2, O4, O7, N1, O6, and O3 atoms are identified as the primary active sites for radical attack. Furthermore, the photocatalytic degradation of TCH mainly proceeds through hydroxylation, deamination, and ring-opening pathways. These findings provide valuable insights into the rational design and development of high-efficiency and stable photocatalytic materials for environmental remediation applications.