Facile one-step hydrothermal synthesis of noble-metal-free hetero-structural ternary composites and their application in photocatalytic water purification

The development of heterostructured and metal decorated photocatalysts using a relatively simple, efficient and economical one-step strategy is crucial for commercial applications. However, these materials are usually synthesized through two- or multi-step approach. Herein, a facile one-step hydrothermal method was used to fabricate a noble-metal-free heterostructural BiOCl/Bi₂MoO₆/Bi ternary composite from BiOCl for the first time. First, BiOCl was dispersed in ethylene glycol (EG), H₂O and glycerol (GLY) and the BiOCl/Bi₂MoO₆/Bi ternary composite was formed after Na₂MoO₄ was introduced into BiOCl in EG. However, only binary BiOCl/Bi₂MoO₆ and BiOCl/Bi photocatalysts were obtained from BiOCl in H₂O and GLY, respectively. Using the same synthetic route, BiOCl/Bi₂WO₆, BiOCl/Bi₂WO₆/Bi and BiOCl/Bi were also synthesized in H₂O, EG and GLY, respectively. The photocatalytic activities of as-prepared three samples were investigated by applying them for the photocatalytic disinfection of bacteria and organic pollutant degradation. Under visible-light irradiation, the BiOCl/Bi₂MoO₆/Bi ternary composite presented the highest photocatalytic activity in comparison with the other two binary samples; the water disinfection with 100% inactivation of bacteria was realized within 4 h. The intermediates of RhB photodegradation were qualitatively identified by liquid chromatography tandem mass spectrometry (LC-MS/MS) and a possible mechanism and detailed degradation pathway were proposed.