Graphitic carbon nitride (g-C 3 N 4 ) nanotubes were produced by using salicylic acid-mediated melamine successfully. The obtained long g-C 3 N 4 nanotube possesses a large specific surface area and a parallel channel structure. Salicylic acid and its decomposition products present in g-C 3 N 4 influenced its formation process and inhibited the crystal growth of g-C 3 N 4 . A possible mechanism is proposed: Salicylic acid and its decomposition products facilitated the formation of g-C 3 N 4 nanosheet, and then the nanosheet coiled to form a nanotube. The tube-like structure facilitates the increase in photocatalytic activities, which are 6.7 and 2.4 times that of pristine g-C 3 N 4 in 2-propanol decomposition and CO 2 photoreduction, respectively. The enhanced photocatalytic performance was contributed by the large specific surface area, better photogenerated charge carrier transmission, and the porous nanotube structure. This research provides an easy synthetic method for the large-scale production of g-C 3 N 4 nanotubes applied in the photocatalytic field.
Due to their ease of preparation, low cost and environmentally-friendly characteristics, zinc-type photocatalysts have attracted a lot of interest with regards to the photocatalytic degradation of organic pollutants. In this study, K+ doped ZnO (KZO) microcrystals were prepared from zinc acetate dehydrate and potassium hydroxide. X-ray diffraction analysis revealed the structure of the hexagonal wurtzite and the substitution of potassium ions in zinc oxide. A scanning electron microscope image showed the nanorod microstructure of prepared KZO crystallites. UV–visible analysis showed that the light absorption of KZO crystals expanded to the visible region and possessed a narrower band gap. In addition, the photocatalytic performance of KZO nanoparticles was evaluated. The results show that KZO possesses enhanced activity which is 3.45 times that of pure ZnO. This high performance in the photocatalytic degradation of organic pollutants can be ascribed to the band gap reduction, large surface area and improved transmission of charge carriers.
Large specific surface area porous g-C3N4 nanosheets were prepared by utilizing acetaldehyde-mediated melamine. The synthetic processes adopted two-step thermal treatments which are in N2 and then in an air atmosphere. The introduced acetaldehyde made melamine condensation incompletely and generated body defects in g-C3N4 when heated in N2. Further heating in air realized pores formation at sites of body defects, thus increase the specific surface area of g-C3N4. Notably, the introduction of acetaldehyde is beneficial to generate high concentration defects, which are active sites for thermal oxidative etching, and increase the yield of g-C3N4 by inhibiting the sublimation of melamine. The photocatalytic performance of obtained g-C3N4 was evaluated by the degradation of 2-propanol under visible light irradiation ([Formula: see text][Formula: see text]nm). The porous g-C3N4 exhibits excellent photocatalytic performance than bulk g-C3N4. The addition of trace acetaldehyde significantly increased the specific surface area and enhanced photocatalytic activity, providing a new idea for the development of simple, low-cost and high active g-C3N4 photocatalyst.
In this study, Fe 3 O 4 @silica nanotubes (Fe 3 O 4 @SiNTs) were synthesized through a co-axial electrospinning of a shell-liquid consisting of tetraethoxysilane, polyvinyl pyrrolidone, ethanol and hydrogen chloride and Fe 3 O 4 nanoparticles (NPs) and a core-liquid of paraffin. Their microstructure and drug delivery property were evaluated. SEM observations showed that Fe 3 O 4 @SiNTs had the tubular hollow structure. The presence of magnetic component caused a magnetic separability of Fe 3 O 4 @SiNTs. After soaked in the solution of tetracycline hydrochloride (TH, one of the representative antibiotics), Fe 3 O 4 @SiNTs supported the adsorption of TH with the loading efficiency of 64±5% to produce TH-loaded Fe 3 O 4 @SiNTs. TH-loaded Fe 3 O 4 @SiNTs presented a sustained release behavior for TH after soaked in the phosphate buffer saline. After incubation with Escherichia coli (E. coli, one of the most widely used bacteria), TH-loaded Fe 3 O 4 @SiNTs exhibited strong anti-bacterial property to inhibit the growth of E. coli, indicating that the released TH was biologically active.
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