Polyelectrolyte modified black phosphorus/titania nanosheet heterojunction enhanced photocatalysis: Synergistic enhancement effect of interface affinity and electron transport channel

The instability and high electron-hole recombination have limited the application of black phosphorus (BP) as an excellent photocatalyst. To address these challenges, poly dimethyl diallyl ammonium chloride (PDDA), poly (allylamine hydrochloride) (PAH), and polyethyleneimine (PEI) are introduced to the functionalization of BP (F-BP), which can not only enhance its stability, but also boost the carrier transfer. Furthermore, a high-performance heterojunction photocatalyst is fabricated using F-BP and titania nanosheets (TNs) via a layer-by-layer self-assembly approach. The experimental outcomes unequivocally indicate that F-BP exhibits fast charge migration compared to BP. The density functional theory (DFT), in situ Kelvin-probe force microscopy (KPFM) and other advanced characterization techniques collectively unfold that PDDA modified BP can notably boost separation and propagation of charges, along with an enhanced carrier abundance. In summary, this novel strategy of using polyelectrolytes to enhance the electron transfer and the stability of BP permits immense potential in building next-generation BP-based high efficiency photocatalysts.

Photocatalytic degradation of tetracycline hydrochloride by a Fe3O4/g-C3N4/rGO magnetic nanocomposite mechanism: modeling and optimization

The photocatalytic degradation of antibiotics requires a good separation efficiency of photogenerated electron-hole pairs and a wide visible light absorption range. Current studies have discussed the successful preparation of ferroferric oxide/graphite carbon nitride/reduced graphene oxide (Fe₃O₄/g-C₃N₄/rGO). The phase structure and morphology of the Fe₃O₄/g-C₃N₄/rGO composites were characterized by XRD, HR-TEM, SEM, and EDS. The obtained composites were used to degrade tetracycline hydrochloride (TCH) to evaluate its photocatalytic activity. The effects of four variables on the degradation of TCH were analyzed by the response surface method and artificial intelligence (gradient regression tree, random forest, artificial neural network, etc.). The results showed that the graphite carbon nitride in the catalyst maintained its original structure and that the photocatalytic activity was significantly improved. The degradation rate of TCH was 86.7% under the optimal conditions (the Fe₃O₄/g-C₃N₄/rGO dosage was 0.1 g, pH = 7.0, the initial concentration of TCH was 20 mg/L, and the visible light irradiation time was 60 min). At the same time, the degradation rate of TCH changed little after the material was used five times, which indicates that the stability and recyclability of the Fe₃O₄/g-C₃N₄/rGO photocatalyst were excellent. Finally, a possible photocatalytic mechanism of the Fe₃O₄/g-C₃N₄/rGO photocatalyst is proposed in this paper.

Self-assembled micro-flowers of ultrathin Au/BiOCOOH nanosheets photocatalytic degradation of tetracycline hydrochloride and reduction of CO2

The low separation efficiency of carriers and weak light response of photocatalysts severely limit the application of photocatalysis technology. Herein, we prepared a visible light responsive self-assembled micro-flowers of ultrathin bismuth oxide formate nanosheets supported by gold nanoparticles (Au/BiOCOOH) composite photocatalyst via hydrothermal method. The physicochemical and photoelectric properties of obtained-photocatalysts were completely analyzed via a range of characterization means. Compared with bare BiOCOOH, the photocatalytic activity of Au/BiOCOOH was significantly improved. 2.0%Au/BiOCOOH possessed the highest rate constant of 0.0054 min^-1 for degradation of tetracycline hydrochloride (TC-HCl), which was nearly 13.5 times higher than that of BiOCOOH. The intermediate products were analyzed by 3D EEM and HPLC/MS, and the antibacterial ability of intermediate products with 2.0%Au/BiOCOOH significantly descended. In order to explore the potential of practical applications, photocatalytic experiments were also implemented through different water sources and solar light irradiation. Furthermore, the photocatalytic activity was also investigated by photocatalytic reduction of carbon dioxide (CO₂). The excellent photocatalytic activity owed to the enhanced separation of charge carriers and light absorption ability by the surface plasmon resonance (SPR) effect of Au nanoparticles. The work may provide a feasible strategy to obtain efficient BiOCOOH-based photocatalyst.