Microwave-Assisted Photocatalytic Degradation of Organic Pollutants via CNTs/TiO2

Abstract

Introducing microwave fields into photocatalytic technology is a promising strategy to suppress the recombination of photogenerated charge carriers. Here, a series of microwave-absorbing photocatalysts, xCNTs/TiO2, were prepared by combining titanium dioxide (TiO2) with carbon nanotubes (CNTs) using a typical alcoholic thermal method to study the promotion of microwave-generated thermal and athermal effects on the photocatalytic oxidation process. As good carriers that are capable of absorbing microwaves and conducting electrons, CNTs can form hot spots and defects under the action of the thermal effect from microwaves to capture electrons generated on the surface of TiO2 and enhance the separation efficiency of photogenerated electrons (e−) and holes (h+). Excluding the influence of the reaction temperature, the athermal effect of the microwave field had a polarizing effect on the catalyst, which improved the light absorption rate of the catalyst. Moreover, microwave radiation also promoted the activation of oxygen molecules and hydroxyl groups on the catalyst surface to generate more reactive oxygen radicals. According to the mechanism analysis, the microwave effect significantly improved the photocatalytic advanced oxidation process, which lays a solid theoretical foundation for practical application.

Mechanism insight into the facet-dependent photoaging of polystyrene microplastics on hematite in freshwater

“…To evaluate the contribution of different radicals in the reaction, quenching experiments for different radicals were performed. The •OH, 1 O 2 , holes, and electrons during PS-MPs photoaging were quenched using tertiary butyl alcohol (TBA; 10 mM), furfuryl alcohol (FFA; 10 mM), ethylenediaminetetraacetic acid disodium salt (EDTA-2Na; 10 mM), and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ; 10 mM) as scavengers, respectively ( Li et al., 2017 ; Ren et al., 2022 ; Wang et al., 2022 ). The particle size reduction of PS-MPs was used to assess the effect of diverse radicals on PS-MPs photoaging.…”

Carbon Dot-Titanium Dioxide (CD/TiO2) Nanocomposites: Reusable Photocatalyst for Sustainable H2 Production via Photoreforming of Green Organic Compounds

“…Furthermore, by introducing a ZIF-67-derived Co 3 O 4 @C metal-free co-catalyst onto TiO 2, the same group achieved the significantly enhancement of H 2 evolution rates via photocatalytic water splitting [7]. Another successful approach to TiO 2 modification in order to overcome these limitations was the fabrication of composite heterostructures with carbonbased nanomaterials such as carbon nanotubes (CNTs) [5,8,9], graphene oxide (GO) [10,11], reduced graphene oxide (r-GO) [12][13][14][15], graphitic carbon nitride (g-C 3 N 4 ) [16,17], or more recently with carbon dots (CDs) [18,19]. CDs' structure involves a carbon core consisting mostly of sp 2 carbon domains connected by sp 3 carbon atoms and a large number of functional groups (-OH, -COOH, -NH 2 , etc.)…”