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This study aims to synthesize and evaluate the photocatalytic activity of bismuth terephthalate material (Bi-BDC) synthesized by solvothermal (ST) and microwave-assisted solvothermal (MW) methods. Differences in the crystal structure and crystal shape were assessed by analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectrum, X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption, Raman spectrum, and thermal gravimetric analysis (TGA). From XRD, IR, Raman, and XPS results, the fully crystallized Bi-BDC materials were achieved regardless of the preparation router. Bi-BDC-MW exhibited spherical-like morphologies, producing between stacked lamellar, while Bi-BDC-ST method exhibited a heterogeneous structure. The TGA data indicated that Bi-BDC is thermally stable up to 300 °C, suggesting the excellent thermal stability of Bi-BDC. The surface area and pore volume of Bi-BDC-MW (18 m2/g and 85 × 10−3 cm3/g) are higher than those of Bi-BDC-ST (16 m2/g and 52 × 10−3 cm3/g), which is due to its well-defined lamellar microstructure and homogeneity of the crystals. Compared to Bi-BDC-ST, Bi-BDC-MW has a higher value in the content of oxygen vacancy. Moreover, the photocatalytic efficiency of Bi-BDC-MW was significantly higher than that of Bi-BDC-ST, in which 99.44% rhodamine B (RhB) is removed after 360 min of irradiation. The improved photocatalytic efficiency of Bi-BDC-MW is ascribed to the morphology, specific surface area, and oxygen defects, which exhibited the good separation of electrons and holes, as confirmed by the photoluminescence (PL). The results should open a new approach to enhancing the photocatalytic activity of bismuth terephthalate materials. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) has received much interest as a visible-light-driven photocatalyst for degrading pollutants such as organic dyes and antibiotics. However, g-C3N4 bulk activity could not meet expectations due to its rapid recombination of photogenerated electron–hole pairs and low specific surface area. In our study, melamine was thermally treated one-step in the presence of NH4Cl to produce g-C3N4 nanosheets. The characterizations of surface morphology and optical properties of all g-C3N4 samples were investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), and UV–visible diffuse reflectance spectroscopy. Compared to bulk g-C3N4, g-C3N4 nanosheets demonstrated excellent photocatalytic activities, with approximately 98% RhB removal after 210 min of visible light irradiation. Furthermore, the effect of catalyst dosage, pH, and RhB concentration on the removal percentage dye of g-C3N4 nanosheets was also investigated. h+ and •O2− species were demonstrated as the key reactive species for the RhB. Besides, ECN exposed a tetracycline degradation efficiency of 80.5% under visible-light irradiation for 210 min, which is higher than BCN (60.8%). The improved photocatalytic activity of g-C3N4 nanosheets is due to the restriction of the recombination of photogenerated electrons/hole pairs, as provided by photoluminescence spectra and Nyquist plot. As a result, our research may offer an effective approach to fabricating g-C3N4 nanosheets with high photocatalytic activity and high stability for environmental decontamination. [ABSTRACT FROM AUTHOR]

In this study, the g-C3N4 with simultaneous isotype heterojunction and porous structure showed superior photocatalytic decomposition of tetracycline hydrochloride (TCH) under white LED light irradiation fabricated via a thermal polycondensation method using melamine and thiourea as precursors and NH4Cl as soft-template. X-ray diffraction and transmission electron microscopy demonstrated the successful fabrication of the heterojunction between two different phases of g-C3N4 metal-free semiconductor. Besides, the increase in surface area as well as the porosity of g-C3N4 isotype heterojunction compared with CN-M (the g-C3N4 was synthesized using melamine as precursor) or CN-T (the g-C3N4 was synthesized using thiourea as precursor) was confirmed through nitrogen adsorption–desorption isotherms. The improved photocatalytic degradation of TCH over CN-MT (the g-C3N4 was synthesized using melamine and thiourea as precursors and NH4Cl as soft-template) compared to CN-M and CN-T could be assigned to the visible light absorption expansion, the increase in surface area as well as the porosity and reduction of photo-generated electron–hole pair recombination. Specifically, the CN-MT-1:1 isotype heterojunction revealed the highest photocatalytic activity for TCH degradation (81.55%) within 180 min. Furthermore, this catalyst can be recycled four times, which demonstrates the potential of CN-MT as a visible light-sensitive catalyst for organic pollutant removal. [ABSTRACT FROM AUTHOR]

The effects of the substitution of V5+ with Ni2+ at the corresponding sites in BiVO4 on the crystal structures, optical properties, and photocatalytic efficiency of BiVO4 was investigated. Ni2+ cations doped at the V5+ sites in BiVO4 was confirmed by X-ray diffraction, Raman, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflectance spectra, and photoluminescence spectra. Ni-doped BiVO4 exhibited excellent degradation of crystal violet (CV) compared with the bare BiVO4. For optimal Ni2+ doping of 5%, the degradation rate of CV, which reached about 95% within 180 min of LED light irradiation, was obtained. Ni doping can introduce advantageous defect states that significantly increase the separation and diffusion efficiency of the photo-induced charge carriers, thereby boosting the photocatalytic activity of crystal structures. [ABSTRACT FROM AUTHOR]

Nano Fe-BTC/graphene oxide (GO) composites were successfully synthesized by hydrothermal treatment with a microwave-assisted method. Samples were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N2 adsorption–desorption, Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS). SEM image of Fe-BTC/GO-30 showed the particle size of 30–50 nm on the GO surface. From the UV–Vis diffuse reflectance spectra, it revealed that nano Fe-BTC/GO composite absorbed the wavelengths in the visible light region with a low bandgap energy of 2.2–2.45 eV. Fe-BTC/GO nanocomposites were tested for the photocatalytic degradation of reactive yellow 145 (RY-145) in aqueous solution. Fe-BTC/GO composites exhibited high photocatalytic activity. Thus, at pH of 3 and high initial concentration of 100 mg RY-145/L, removal efficiency reached the value of 98.18% after 60 min. of reaction. In comparison with Fe-BTC/GO synthesized by the solvothermal method, nano Fe-BTC/GO showed much higher RY-145 removal efficiency. Moreover, this Fe-BTC/GO-30 showed high catalytic activity stability and could be reused, opening the high potential application of this promising photo-Fenton catalyst in photocatalytic degradation of organic pollutants from aqueous solution. [ABSTRACT FROM AUTHOR]

Fe/graphene oxide and Cu–Fe/graphene oxide nanocomposite were synthesized by the atomic implantation method to study the photocatalytic degradation of dichlorodiphenyltrichloroethane (DDT). The synthesized nanocomposites were characterized by the XRD, N2 isotherms, SEM with EDX, TEM and XPS analysis. Characterization results have reported that oxides of Cu and Fe were uniformly distributed on graphene oxide and exited in the form of Cu+ and Fe2+ ions in Cu–Fe/graphene oxide nanocomposite. The high photocatalytic DDT removal efficiency 99.7% was obtained for Cu–Fe/graphene oxide under the optimal condition of 0.2 g/L catalyst, 15 mg/L H2O2 and pH 5. It was attributed to the reduction of Fe3+ to Fe2+ by Cu+ ions and –OH radicals formation. However, it was dropped to 90.4% in the recycling study by leaching of iron and without a change in phase structure and morphology. [ABSTRACT FROM AUTHOR]