A two-birds-one-stone strategy: Fabrication of ultrahigh-surface-area CuS/Bi2S3/carbon aerogel from cotton linter via KOH activation and in-situ sulfurization for efficient photocatalytic removal of tetracycline and Cr(VI)

As typical emerging pollutants, antibiotic residues and heavy metal contamination urgently require highly efficient, multifunctional treatment materials. Photocatalytic technology is clean, sustainable, and harnesses solar energy, offering great promise for environmental remediation. Using cotton linters as raw material, we prepared a carbon aerogel (BiCuS/CA-KOH) with a high specific surface area (1298.19 m 2 /g) and uniformly loaded CuS/Bi 2 S 3 nanostructures through KOH activation coupled with in-situ sulfidation. This material features a microporous–mesoporous hierarchical structure, a well-defined CuS/Bi 2 S 3 heterointerface, and a three-dimensional conductive carbon framework that facilitates electron transport. Under visible light and at pH = 3, the catalyst achieved a 98.51% degradation rate of tetracycline (87.31% TOC mineralization) and a 97.98% reduction rate of Cr(VI) within 80 min. Mechanistic studies indicate that ·OH and ·O 2 − are the primary active species in the oxidation of tetracycline, while photo-generated electrons dominate the reduction of Cr(VI). After five cycles, the material retained over 90% of its removal efficiency toward both pollutants, and no significant structural damage was observed. The study demonstrates that BiCuS/CA-KOH can achieve both the efficient degradation of tetracycline and the reduction of Cr(VI).