Hierarchically Z-scheme photocatalyst of {010}BiVO4/Ag/CdS with enhanced performance in synergistic adsorption-photodegradation of fluoroquinolones in water

In this work, the sheet-like BiVO4 with a higher exposure ratio of {0 1 0} facets was synthesized by the addition of TiCl3, and the ratio of (04 0)/(0 1 1) on {01 0}BiVO4 was 2.85 times higher than that of normal decahedral BiVO4. Accordingly, the {01 0}BiVO4/Ag/CdS all-solid-state Z-scheme heterojunction was further constructed by photoreduction of Ag and chemical deposition of CdS on the well prepared {01 0}BiVO4 successively. The performance and mechanism of {01 0}BiVO4/Ag/CdS in synergistic adsorption-photodegradation of fluoroquinolones (FQs) from water were investigated in detail. The adsorption-photodegradation could be divided into three processes: adsorption, surface degradation, and solution degradation, with the rate constants of 0.118, 0.029, and 0.012 min(-1), respectively. Accordingly, the adsorption was a rapid process due to the combined CdS in this composited photocatalyst had a high affinity to FQs to achieve an adsorption equilibrium on the surfaces < 30.0 min. Besides, {01 0}BiVO4/Ag/CdS had a better separation efficiency of photogenerated electron hole pairs than BiVO4/Ag/CdS, because the enriched {010} facets of {01 0}BiVO4 caused more BiVO4/Ag/CdS ternary structure formed, and > 90% photodegradation efficiency for five FQs (C-0 = 0.062 mmol/L) was thus obtained within 60.0 min. The radical trapping and EPR results showed that holes and superoxide radicals were the main active species for FQs photodegradation. In summary, {01 0}BiVO4/Ag/CdS achieved an enhanced performance in synergistic adsorption and photodegradation of organic contaminants from water, and a talented photocatalyst was thus provided in water and wastewater treatment.