Abstract
Low-temperature Bi-Nb-O system photocatalysts were prepared by a citrate method using homemade water-soluble niobium precursors. The structures, morphologies, and optical properties of Bi-Nb-O system photocatalysts with different compositions were investigated deeply. All the Bi-Nb-O powders exhibit appreciably much higher photocatalytic efficiency of photo-degradation of methyl violet (MV), especially for Bi-Nb-O photocatalysts sintered at 750 °C (BNO750), only 1.5 h to completely decompose MV, and the obtained first-order rate constant (k) is 1.94/h. A larger degradation rate of Bi-Nb-O photocatalysts sintered at 550 °C (BNO550) can be attributed to the synergistic effect between β-BiNbO4 and Bi5Nb3O15. Bi5Nb3O15 with small particle size on β-BiNbO4 surface can effectively short the diffuse length of electron. BNO750 exhibits the best photocatalytic properties under visible-light irradiation, which can be attributed to its better crystallinity and the synergistic effect between β-BiNbO4 and α-BiNbO4. The small amount of α-BiNbO4 loading on surface of β-BiNbO4 can effectively improve the electron and hole segregation and migration. Holes are the main active species of Bi-Nb-O system photocatalysts in aqueous solution under visible-light irradiation.
Highlights
Recent years, much attention has been focused on the environmental remediation due to the increasing pollution problems caused by the industries
Low-temperature Bi-Nb-O system photocatalysts were prepared by the citrate method using homemade water-soluble niobium precursors
With the sintering temperature increasing to 550 °C, most of the Bi5Nb3O15 decomposes and Low-β forms as the major phase
Summary
Much attention has been focused on the environmental remediation due to the increasing pollution problems caused by the industries. In 1972, photosensitized decomposition of water into H2 and O2 using TiO2 semiconductor electrode was first reported by Fujishima and Honda [2]. A large number of semiconductor materials have been investigated as active catalysts for the reduction and/or elimination of environmental pollution in water and air due to their potential in the conversion of light energy. TiO2, as one of the most popular photocatalysts, can solely absorb the UV light, which accounts for only 4 % of the total sunlight.
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