Boosted photocatalytic activity via photothermal-assisted triphase photocatalysis over an electrospun interpenetrating mat

Photocatalysis has been extensively researched as a promising environmental technology in the past years. Despite great efforts have been made in catalyst engineering, the core challenge in the photocatalytic process still lies in achieving efficient light absorption and interfacial carriers’ transfer. In this study, we propose a “self-floated” interpenetrating fiber system for photothermal-assisted triphase photocatalysis, consisting of commercial P25-TiO₂ nanoparticles (NPs) and carbon black (CB) NPs by employing hydrophobic polymethyl methacrylate (PMMA) fibers as support. The photons beyond the bandgap of P25-TiO₂ NPs are converted to facilitate a localized heating effect which promotes free radical reaction, meanwhile a fast oxygen diffusion is realized at the solid (photocatalysts)-liquid(water)-gas(air) triphase interface by functionalizing surface of fibers. Removal of the polyvinyl pyrrolidone (PVP) component facilitates exposure of hydrophilic P25-TiO₂ NPs on the hydrophobic PMMA fibers. This, in turn, enhances the wetting properties and increase the specific surface area available for photocatalytic reaction. Based on the photothermal effect, effective exposure of the catalytic active sites and construction of the triphase reaction interface, the proposed system exhibits ∼19 times increase of first-order kinetic reaction rate constant (k) for salicylic acid (SA) degradation. The interpenetrating fibers also perform superior stability over 10 times cycling tests with a degradation efficiency >90 % and feasible use of sunlight, demonstrating potentials for scale-up photocatalytic applications by combing with a large-scale and convenient electrospinning.