Polymer blending and nanophotocatalyst loading synergy in visible light‐driven photocatalytic PES/SPSf mixed matrix membranes

Abstract

Abstract The synergy of polymer blending and loading photocatalytic titania–amorphous carbon nanotubes (TiO 2 –aCNT) in tailoring the morphological, surface, and optoelectrical properties of membranes is investigated. High energy band gap ( E g ) polyethersulfone (PES), and low E g sulfonated polyethersulfone (SPSf) polymer blends were loaded with TiO 2 –aCNT nanocomposite fillers. SEM reveals membranes consisting of a selective layer, a dense sublayer and a spongy layer with the latter two consisting of a network of nanofibers whose diameters decrease with increasing TiO 2 –aCNT loading. The downshifting in the wavenumbers of sulfonyl and sulfone peaks in Fourier transform infrared and Raman spectra confirms bonding of TiO 2 –aCNT with PES/SPSf via these groups. Blending PES with SPSf decreases the E g of the membranes while loading TiO 2 –aCNT produces a second band edge corresponding to = 2.8 eV. Suppression of charge recombination in membranes is realized at 1.2 filler wt.%. Charge separation occurrs via shuttling of the positive holes to the aCNTs and valence band of TiO 2 while electrons are shuttled to the conduction bands of PES and SPSf. Electron impedance spectroscopy shows TiO 2 –aCNT loading reduces polymer membrane resistance to charge transport. Dye degradation up to 85% is realized under direct sunlight irradiation accompanied by mineralization.