A Hydrothermal Route to the Synthesis of CaTiO3 Nanocuboids Using P25 as the Titanium Source

Yang

et al. 2019

Journal of Elec Materi

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The NaBH 4 reduction method has been used to engineer the surface of flakelike Bi 2 WO 6 (BWO) crystals with the aim of creating disordered surface structure and enhancing the photocatalytic activity. The disorder-engineered BWO samples were investigated by means of x-ray powder diffraction, fieldemission scanning electron microscopy, field-emission transmission electron microscopy, x-ray photoelectron spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, photoluminescence, electrochemical impedance spectroscopy and photocurrent response. Simulated sunlight, UV light and visible light were separately used as the light source to evaluate the photocatalytic activity of the samples toward the degradation of rhodamine B in aqueous solution. It is demonstrated that 0.03 M-BWO treated at 0.03 M NaBH 4 solution exhibits the highest photocatalytic activity, ca. 2.4 times higher than pristine BWO under simulated sunlight irradiation. The significant increase in the photocatalytic activity is observed at UV irradiation, which can be explained by the fact that the disordered surface states (formed in the forbidden gap of BWO) can act as electron acceptors to facilitate the separation of photogenerated electron/hole pairs. A slightly enhanced photocatalytic activity is observed under visible light irradiation, which is attributed to the enhanced visible light absorption induced by the disordered surface states. In addition, it is found that the treatment with high NaBH 4 concentrations is detrimental to the photocatalytic activity due to the creation of bulk defects in BWO crystals.

Section: Introductionmentioning

confidence: 99%

Surface Disorder Engineering of Flake-Like Bi2WO6 Crystals for Enhanced Photocatalytic Activity

Yang

et al. 2019

Journal of Elec Materi

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“…The existence of other oxidation states can be excluded since no additional binding energy peaks are detected on the Bi 4f and Ti 2p XPS spectra. On the O 1s XPS spectrum (Figure 8d), the binding energy at 529.7 eV is attributed to the crystal lattice oxygen of Bi 4 Ti 3 O 12 , whereas the binding energy at 531.5 eV could arise from chemisorbed oxygen species [58,59]. The C 1s XPS spectrum (Figure 8e) presents two peaks at 284.8 and 287.7 eV.…”

Section: Resultsmentioning

confidence: 99%

“…The C 1s XPS spectrum (Figure 8e) presents two peaks at 284.8 and 287.7 eV. The peak at 284.8 eV arises from the C–C sp 2 -hybridized carbon of CQDs and adventitious carbon that is used to calibrate the binding energy scale [59,60]. The peak at 287.7 eV is attributed to the presence of C–O–C or C=O [60].…”

Section: Resultsmentioning

confidence: 99%

Growth Process and CQDs-modified Bi4Ti3O12 Square Plates with Enhanced Photocatalytic Performance

et al. 2019

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Bi4Ti3O12 square plates were synthesized via a hydrothermal route, and their growth process was systematically investigated. Carbon quantum dots (CQDs) were prepared using glucose as the carbon source, which were then assembled on the surface of Bi4Ti3O12 square plates via a hydrothermal route with the aim of enhancing the photocatalytic performance. XRD (X-ray powder diffraction), SEM (scanning electron microscopy), TEM (transmission electron microscopy), UV-vis DRS (diffuse reflectance spectroscopy), XPS (X-ray photoelectron spectroscopy), FTIR (Fourier transform infrared spectroscopy), PL (photoluminescence) spectroscopy, EIS (electrochemical impedance spectroscopy) and photocurrent spectroscopy were used to systematically characterize the as-prepared samples. It is demonstrated that the decoration of CQDs on Bi4Ti3O12 plates leads to an increased visible light absorption, slightly increased bandgap, increased photocurrent density, decreased charge-transfer resistance, and decreased PL intensity. Simulated sunlight and visible light were separately used as a light source to evaluate the photocatalytic activity of the samples toward the degradation of RhB in aqueous solution. Under both simulated sunlight and visible light irradiation, CQDs@Bi4Ti3O12 composites with an appropriate amount of CQDs exhibit obviously enhanced photocatalytic performance. However, the decoration of excessive CQDs gives rise to a decrease in the photocatalytic activity. The enhanced photocatalytic activity of CQDs-modified Bi4Ti3O12 can be attributed to the following reasons: (1) The electron transfer between Bi4Ti3O12 and CQDs promotes an efficient separation of photogenerated electron/hole pairs in Bi4Ti3O12; (2) the up-conversion photoluminescence emitted from CQDs could induce the generation of additional electron/hole pairs in Bi4Ti3O12; and (3) the photoexcited electrons in CQDs could participate in the photocatalytic reactions.

“…4c. The absorption edge can be determined from the peak wavelength in the derivative spectra [53]. It can be seen that the light absorption edge of bare Ag 3 PO 4 is located at ~ 527 nm, corresponding to the bandgap energy ( E g ) of ~ 2.35 eV.…”

Section: Resultsmentioning

confidence: 99%

Facile Synthesis and Enhanced Visible-Light Photocatalytic Activity of Novel p-Ag3PO4/n-BiFeO3 Heterojunction Composites for Dye Degradation

Yang

Tang

et al. 2018

Nanoscale Res Lett

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In this work, Ag3PO4 microparticles were decorated onto the surface of BiFeO3 microcuboids through a precipitation method to obtain p-Ag3PO4/n-BiFeO3 heterojunction composites. The composites were employed for the degradation of acid orange 7 (AO7) under visible-light irradiation. It is found that the composites exhibit much higher photocatalytic efficiency than bare BiFeO3. Meanwhile, the intrinsical visible-light-driven photocatalytic activity of Ag3PO4/BiFeO3 composites was further confirmed by the degradation of phenol. In addition, the photo-Fenton-like catalysis property of the composite was also evaluated. The photocurrent analysis indicates that the combination of BiFeO3 with Ag3PO4 leads to the inhibition of recombination of photoinduced electrons and holes. The obvious enhancement in the photocatalytic activity of the composite is mainly ascribed to the efficient photogenerated charge separation and interfacial charge migration caused by the formation of Ag3PO4/BiFeO3 p-n heterojunctions.