Insights into the role of reactive oxygen species in photocatalytic HO generation and OTC removal over a novel BN/ZnInS heterojunction.

Developing photocatalysts with superior performance to generate hydrogen peroxide (HO) and degrade oxytetracycline (OTC) is an effective strategy for the treatment of energy crisis and water purification. Herein, BN nanosheets were anchored onto the ZnInS microspheres for the research. Experimental and density functional theory (DFT) results demonstrate that due to different work functions and unique 2D/2D contact, the electron is spatially separated in BN/ZnInS nanocomposite, which increases the electron transfer efficiency from 43.7% (ZnInS) to 55.6% (BN/ZIS-4). As a result, BN/ZIS-4 with optimal ratio of BN and ZnInS exhibits the highest OTC degradation efficiency (84.5%) and HO generation rate (115.5 μmol L) under visible light illumination, which is 2.2 and 2.9 times than that of pristine ZnInS. HO generation is dominated by two pathways: two-step single-electron process (O → ∙O → HO) and another way (O → ∙O → O → HO). In the process of degrading OTC, ∙O, O and ∙OH are regarded as the main active species. This work offers a new insight for designing efficient, stable and reusable photocatalysts to solve current environmental conundrums.