A novel p–n junction Ag3PO4/BiPO4-based stabilized Pickering emulsion for highly efficient photocatalysis

Abstract

This study demonstrates a new kind of photocatalytic system via utilization of the superior specific properties inherent in Pickering emulsion. We designed the new photocatalytic system using a novel p–n heterojunction Ag₃PO₄/BiPO₄ (AB) as a photocatalytic active component, multiwalled carbon nanotubes (MWCNTs) and graphene (GR) as a hydrophobic conducting nanostructure to form the stabilized Pickering emulsion. The photocatalytic activity of the as-prepared stabilized Pickering emulsion-based system (Pe-bp system) was studied by monitoring the change in Acid Blue 92 dye (AB92) concentration under both visible and UV light irradiation. The results revealed that the Pe-bp system exhibits a noticeable improvement in both efficiency and rate of AB92 photodegradation in comparison with the traditional solution-dispersed photocatalytic system. The observed results are discussed in terms of (1) the self-assembled nanohybrid at the water/oil (w/o) interface provides a large surface area, (2) the use of MWCNTs and GR promotes the generation of amphiphilic nanostructures self-assembled at the w/o interface, reducing the charge recombination by shuttling and capturing photogenerated electrons and (3) the great separation of the products from the reactants during the photocatalytic reactions facilitates these processes. A possible mechanism explaining the origin of enhanced performance of formed nanohybrids in the Pe-bp system is also proposed. In addition to the high efficiency, the rapid and simple procedures used for demulsifying and re-emulsifying crucially make the Pe-bp system technically simple and practically applicable for environmental remediation.