In this work, two series of plasmonic S-type heterojunction photocatalysts containing Bi, TiO2, and biochar (Bi/TiO2@C) have been developed through a biomass-assisted hydrothermal-calcination strategy, utilizing grapefruit peel as a reducing agent and C resource. The calcination temperature and the mass ratio of biomass were optimized to obtain the optimal nanocomposite, which shows excellent adsorptive and visible-light photocatalytic performance in the removal of diverse antibiotic and dye pollutants, including tetracycline, oxytetracycline, ciprofloxacin, sulfamethoxazole, sulfisoxazole, malachite green, and rhodamine B. The remarkable performance can be attributed to the enhanced absorption of light absorption resulting from the localized surface plasmon resonance effect of the semimetal Bi, and the formation of heterogeneous interface between Bi and TiO2, which accelerates the transfer of photogenerated charge. Furthermore, trapping tests and electron spin resonance (ESR) analysis reveal that ∙O2- and h+ are the primary active species involved in the removal of tetracycline. A plausible charge transfer mechanism has been proposed.
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