Promoted adsorption-photocatalysis synergistic removal of contaminants via surface regulation by a tree-like nanofiber membrane substrate

Abstract

Photocatalysis represents a promising strategy for wastewater treatment, but the widely used powder photocatalysts are still limited by sluggish interfacial mass transfer and chemical processes. In this study, a tree-like PVDF nanofiber membrane (T-PVDF) was explored to enhance the photocatalytic activity of TiO2 and TiO2/BiOI heterojunction through different pathways. TiO2 was first integrated into the T-PVDF substrate via a one-step electrospinning method. The dendritic architecture greatly favored the contaminant adsorption on the catalytic surface and thus boosted the photodegradation of RhB under UV or visible light irradiation. Especially for the visible light driven dye-sensitive photocatalysis, the integrated TiO2@T-PVDF outperformed the powder TiO2 and pristine PVDF membrane anchored TiO2 by 17.9 and 2.4 times, respectively. In addition, the construction of TiO2/BiOI heterojunction on the T-PVDF substrate was realized by further growing BiOI nanosheets via a solvothermal method. The irregular growth of BiOI on the multiscale nanofiber substrate formed a rough surface with unexpected high hydrophobicity, which allowed the accumulation of high-concentrated O2 at the catalytic interfaces. This greatly boosted the O2 reduction and inhibited the competitive H2 evolution under visible light irradiation, resulting in 3.8-fold higher reaction kinetics than that obtained for hydrophilic powder TiO2/BiOI heterojunction.