Silver Phosphate/Carbon Nanotube-Stabilized Pickering Emulsion for Highly Efficient Photocatalysis

Abstract

This study demonstrates a first exploitation of the unique properties inherent in Pickering emulsions to develop a new kind of photocatalytic system. We engineered the system by using silver phosphate (Ag3PO4) as a photocatalytic active metal oxide semiconductor and multiwalled carbon nanotubes (MWNTs) as a hydrophobic conducting nanostructure to form the Pickering emulsions. The photocatalytic activity of the as-formed Ag3PO4/MWNT-stabilized Pickering emulsion-based system is studied toward dye decomposition and oxygen evolution. Results imply that the Pickering emulsion-based photocatalytic system exhibits a much higher efficiency, as compared with traditional solution-dispersed photocatalytic system. This high efficiency is elucidated in terms of the unique properties inherent in Pickering emulsions including (i) the self-assembled Ag3PO4/MWNT nanohybrid at water/oil interface, well ensuring a large surface area of the photocatalyst, (ii) the use of MWNTs to facilitate the formation of amphiphilic nanostructures self-assembled at water/oil interface, promoting the charge separation of the semiconductor through the π–π network of MWNTs by shuttling and storing photogenerated electrons from the visible light irradiated Ag3PO4, and (iii) the separation of the product (e.g., O2 evolved from water oxidation) from the reactants during the photocatalytic process, well accelerating the photocatalytic reactions. In addition to the high efficiency, the fast and simple procedures employed for demulsifying (e.g., sonication or centrifugation) and re-emulsifying (e.g., shaking) essentially make our Pickering emulsion-based photocatalytic system technically simple and thus practically applicable. This study opens a new way to developing novel photocatalytic systems with high efficiency and good practical applicability based on Pickering emulsion science and technology.

Magnetically controllable Pickering emulsion prepared by a reduced graphene oxide-iron oxide composite

“…Up to date, there have been several examples of Pickering emulsions prepared by carbonaceous materials, including carbon nanotubes (CNTs) [13,16,17], graphene oxide (GO) [18][19][20][21][22][23][24], and GO-derived materials [15,25]. Pickering emulsions stabilized by GO have drawn significant attention owing to the unique 2-D structure and amphiphilic surface properties of GO [19,20].…”

Visible light driven degradation of methylene blue dye using Ag3PO4

“…This is because photocatalytic reactions are typically surface-based processes, and thus the photocatalytic efficiency is closely related to the morphology and micro-structure of a photocatalyst [18]. On the other hand, Ag 3 PO 4 based composites materials have been successfully synthesized by various techniques to improve the photocatalytic activity of Ag 3 PO 4 [19][20][21][22][23][24]. The pH dependent photocatalytic performances and reactions kinetics also investigated [25].…”

Decoratable hybrid-film-patch stabilized Pickering emulsions and their catalytic applications

“…Zhou et al exploited the Au-carbonaceous spheres formed Pickering emulsion to reduce p-nitroanisole by sulphide to p-anisidine with the conversion yield up to 96% within 5 h [15]. Other examples of the PE interfacial catalysis includes using Ru/CNT-TiO2 complex to catalyze benzyl alcohol to benzaldehyde [16], and Ag3PO4−MWNT complex to photocatalyze H2O to O2 [17].…”