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.

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.