Co-construction of oxygen doping and van der walls heterojunction in O-CB/ZnIn2S4 promoting photocatalytic production and activation of H2O2 for the degradation of antibiotics

Abstract

The in situ production of H₂O₂ by photocatalysis have shown a sustainable strategy for water remediation, but the peroxide evolution capacity are still unsatisfactory. Herein, we ingeniously design oxygen-doped carbon black/zinc indium sulfide (O-CB/ZnIn₂S₄) composites for photocatalytic production and activation of H₂O₂ to degrade antibiotics. The rich oxygen dopants and van der walls heterojunction between O-CB and ZnIn₂S₄ promoted charge transfer, oxygen adsorption and reduction for peroxide generation. The optimized O-CB/ZnIn₂S₄-2 composites exhibited ultrahigh H₂O₂ production rate (1985 μmol/g/h) in pure water (pH=7) without sacrificial reagents and aeration assistance, which was 2 times, 3 times, and 12 times higher than CB/ZnIn₂S₄-2, ZnIn₂S₄ and O-CB, respectively. Additionally, O-CB/ZnIn₂S₄-2 composites exhibited considerable amount of OH of 30 μmol/L in 60 min, which was originated from the reduction of innergenerate-H₂O₂ by photogenerated electrons and direct photolysis. The degradation and quenching experiments shows that the innergenerate-H₂O₂ contributed to the rapid degradation and deep mineralization of tetracycline antibiotics(tetracycline, oxytetracycline, chlortetracycline hydrochloride). Moreover, intermediates analysis and toxicity estimation further confirm the significant mineralization and toxicity decrease during the degradation of oxytetracycline by O-CB/ZnIn₂S₄-2. The work provides deep insights into the crucial role of dopants and heterojunction in promoting H₂O₂ production and activation.

Keywords: Degradation; Peroxide; Photocatalysis; Tetracycline; ZnIn(2)S(4).