Search

The composites of BiVO4 and g-C3N4 (BiVO4/g-C3N4) were synthesised by the calcination of a mixture of monoclinic BiVO4 and bulk g-C3N4 at 300 °C for 4 h. Both components were previously prepared by the precipitation of Bi(NO3)3 with NH4VO3 and annealing of melamine. X-ray photoelectron spectroscopy (XPS) identified the presence of C–O and C=O bonds as well as metal nitrides which confirmed the formation of a heterojunction between BiVO4 and g-C3N4. The heterojunction was also indicated by UV–Vis diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy. The band gap energies were determined at 2.42–2.46 eV of BiVO4 and 2.75–2.82 eV of bulk g-C3N4. The specific surface area was 23–28 m2 g−1 of the composites and 6 m2 g−1 and 35 m2 g−1 of pure BiVO4 and g-C3N4, respectively. The photocatalytic activity of the composites was investigated by the decomposition of Acid Orange 7 (AO7) and nitrous oxide. In case of AO7, the BiVO4/g-C3N4 (1:3) composite was the most active one and the main role in the reaction was played by photoinduced holes forming hydroxyl radicals. At the decomposition of N2O, the most important species were the photoinduced electrons and the BiVO4/g-C3N4 (1:1) composite was the most active photocatalyst. [ABSTRACT FROM AUTHOR]

The composites of graphitic carbon nitride (g-C 3 N 4) and BiOIO 3 with different weight ratios of both components (1:1, 2:1, 4:1 and 6:1) were prepared by heating of their mechanical mixtures. Bismuth iodate was prepared by hydrothermal treatment of aqueous solutions of Bi(NO 3) 3 ·5H 2 O and I 2 O 5. Pure g-C 3 N 4 was prepared by thermal polycondenzation of melamine at 620 °C. All of the samples were characterized using X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), UV-VIS diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, X-ray photoelectron (XPS) and Fourier transformed infrared (FTIR) spectroscopy. The measurement of photocurrents was used for the study of photogenerated charge carriers and nitrogen physisorption for the evaluation of specific surface area (SSA) and pore size distribution of the samples. The photodegradation activity of the samples was tested by the UVA light photocatalytic decomposition of N 2 O. The highest photodegradation activity was observed for the 1:1 composite, which was 2 and 2.5 times higher in comparison to pure BiOIO 3 and g-C 3 N 4 , respectively. The enhanced photocatalytic activity was explained by a significant reduction of charge carriers' recombination due to the formation of a heterojunction between g-C 3 N 4 and BiOIO 3. [ABSTRACT FROM AUTHOR]