Improvement of Photocatalytic Performance by Building Multiple Heterojunction Structures of Anatase–Rutile/BiOI Composite Fibers

Abstract

In this study, multiple heterojunction structures of anatase–rutile/Bismuth oxyiodide (BiOI) composite fibers are designed by the combined method of electrospinning and hydrothermal techniques. The influence of different Ti/Bi atomic ratios ([Ti/Bi]) on the nanostructures and photocatalytic properties are investigated. It is found that the morphology of BiOI covered on the TiO2 fiber surface changed with [Ti/Bi] from nanosheets to submicron spheres structures. Additionally, the crystallization of the composite fibers including the phases of anatase, rutile, and BiOI is identified, theses phases are in close contact with each other, and the interfacial effects are helpful to form the multiple heterojunctions which lead to blue shifts on the chemical state of Ti. The absorption of visible light has been improved by compositing BiOI on TiO2, while the band gap values of the composite fibers are significantly reduced, which can enhance the generation and separation of electrons and holes. For the case of [Ti/Bi] = 1.57, the photodegradation rate of anatase–rutile/BiOI composite fibers is about 12 times that of pure TiO2. For the photocatalytic mechanism, the synergistic s-type heterojunctions increase the content of active oxides which have a positive effect on the degradation rate.

Coaxial Electrospun Porous Core–Shell Nanofibrous Membranes for Photodegradation of Organic Dyes

“…Organic dyes, as common pollutants, can lead to reduced oxygen levels, increased toxicity, and excessive nutrient contents in water bodies. Photocatalysis induces oxidation–reduction reactions in semiconductor materials [ 4 , 5 , 6 , 7 , 8 , 9 ] to degrade organic pollutants and is now a highly regarded green and sustainable development strategy. Heterostructures formed by two or more photocatalytic materials often exhibit a wider range of light absorption wavelengths compared with single photocatalysts [ 10 , 11 , 12 , 13 ].…”

Fe- and S-Modified BiOI as Catalysts to Oxygen Evolution and Hydrogen Evolution Reactions in Overall Photoelectrochemical Water Splitting

“…For example, the photocatalytic activity and stability of BiOI in organic degradation was significantly enhanced by covering it with Bi 2 O 2 CO 3 [ 26 ]. The adsorption capacity of visible light and the charge separation efficiency of BiOI were improved by compositing BiOI with kaolinite [ 27 ] and TiO 2 [ 28 ]. Moreover, the performance of other photocatalysts such as g-C 3 N 4 can also be boosted by the modification of BiOI, by which the conversion efficiency of CO 2 reduction to CH 4 was increased to 39.43 µmol g −1 from 4.09 µmol g −1 of the bulk g-C 3 N 4 [ 29 ].…”

Highly Efficient Photo-Fenton Ag/Fe2O3/BiOI Z-Scheme Heterojunction for the Promoted Degradation of Tetracycline

“…Bismuth oxyiodide (BiOI) is a layered structure of (Bi 2 O 2 ) 2+ layers interleaved with double slabs of I atoms with a band gap of 1.77–1.92 eV and thus can absorb visible light [ 15 ]. However, the rapid recombination of photo-generated carriers makes the BiOI exhibit poor photocatalytic activity [ 16 ]. The preparation of the heterogeneous photocatalyst has been proven to be an efficient way to address this issue [ 17 , 18 ].…”