Multicomponent Composite Membrane with Three-Phase Interface Heterostructure as Photocatalyst for Organic Dye Removal

A multicomponent composite membrane (P-S-T/C) with three-phase interface heterostructure is ingeniously designed. A polydopamine (PDA)-modified conductive carbon fiber cloth (C_FC) is used as the substrate. Activated poly(vinylidene fluoride) (PVDF) with titanium dioxide (TiO₂) and a silicon dioxide (SiO₂) aerogel are electrospun as the top layer. The three-phase interface heterostructure was formed by TiO₂, conductive C_FC, and the SiO₂ aerogel. Its photocatalytic performance is validated by photodegradation of organic dyes in a low-oxygen (O₂) water environment. On combining with the capillary condensation of a bilayer structure, P-S-T/C exhibits excellent removal capability for anionic and cationic dyes. Moreover, P-S-T/C exhibits excellent stability and recyclability under simulated sunlight. The mechanism study indicates that the separated photogenerated carriers diffuse to the composite membrane surface rapidly on the three-phase interface of P-S-T/C. The abundant O₂ adsorbed on the porous SiO₂ aerogel surface acts as an electron (e^-)-trapping agent, which can also decrease the work function of the composite materials. Superoxide radicals (^•O₂ ^-) play a dominant role in the reaction of photodegradation supported by a free radical-trapping experiment. This work paves a way to design a membrane with photocatalytic performance by constructing the interface heterostructure.