Preparation, characterization and photocatalytic activity of CeO2 nanocrystalline using ammonium bicarbonate as precipitant
Introduction
It is well known that rare-earth oxides have been applied widely in many fields. Among them, cerium dioxide (CeO2) finds numerous applications in catalysts [1], catalyst supports [2], cosmetics materials [3], ceramic materials [4], oxygen gas sensors [5], solid oxide fuel cells [6] and fluorescent materials [7]. Moreover, nano-sized materials have been studied vigorously in recent years because their significant properties are different from the bulk [8]. Therefore, the studies on the preparation and properties of CeO2 nanocrystalline have attracted extensive interests during the last few years.
CeO2 nanocrystalline has been prepared by sol–gel process [9], sonochemical synthesis [10], gas condensation [11] and hydrothermal synthesis [12]. These methods have defects in the complex process and expensive raw materials, so the cost of production is very high and it is difficult to be realized in industrial production.
In this paper, CeO2 nanocrystalline has been obtained as a final decomposition product of hydrated cerium carbonate formed by using ammonium bicarbonate as precipitant. The composition and decomposition course of hydrated cerium carbonate, the formation process of CeO2 and the dispersity of the particles have been investigated by IR, TG, XRD and SEM. For the first time, CeO2 nanocrystalline was utilized as a photocatalyst for the photocatalytic degradation and decolorization of the dye.
Section snippets
Synthesis of CeO2 nanocrystalline
Ce2(CO3)3·nH2O (Industrial Product), nitric acid (65%, A.R.), ammonium bicarbonate (A.R.), and polyethylene glycol 1000 (A.R.) were used as the starting ingredients.
Ce2(CO3)3·nH2O was dissolved in hot nitric acid to form Ce(NO3)3 aqueous solution. The accurate concentration of the Ce(NO3)3 solution was determined by EDTA complexing titrimetry. The experimental temperature was kept at 40 °C by a thermostat. 0.5 mol/L ammonium bicarbonate aqueous was dropped slowly into the Ce(NO3)3 aqueous
IR analysis
The FT-IR spectrum of the precursor is shown in Fig. 1. The strong absorption band between 1300 and 1600 cm− 1 is due to carbonate ion stretching vibration, the sharp absorption peaks between 600 and 900 cm− 1 are due to carbonate ion bending vibration, and the absorption band between 3000 and 3750 cm− 1 is due to –OH group of H2O. These prove that the precursor is hydrated cerium carbonate (Ce2(CO3)3·xH2O), not the mixed salts of cerium and ammonium carbonates.
TG analysis
Fig. 2 shows the TG curve of the
Conclusion
- (1)
Using cerium nitrate as raw material, NH4HCO3 as precipitant and polyethylene glycol 1000 as dispersant, pure cubic phase CeO2 nanocrystalline has been prepared by the cerium carbonate precursor calcined at 400 °C for 2 h. The advantages of this method are that raw materials are low-cost, operation is easy, and it is easy to be realized in industrial production. The composition of the cerium carbonate precursor is Ce2(CO3)3·2.5H2O.
- (2)
The average crystallite size of CeO2 nanocrystalline increases
Acknowledgments
This work was supported by the Doctoral Program Foundation of Education Agency of Hebei Province (No. B2004205) and the Research Foundation of Hebei University in P.R. China.
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