Influences of the (NH2)2CO concentration on magnetic photocatalytic composites.

Magnetic photocatalytic Fe 3 O 4 @TiO 2 composites have been fabricated by changing the concentration of (NH 2 ) 2 CO. Samples were named as low (NH 2 ) 2 CO concentration group which the (NH 2 ) 2 CO concentration in the synthesis process was below 2.25 mol/L and high (NH 2 ) 2 CO concentration group which the (NH 2 ) 2 CO concentration was above 2.5 mol/L. Photocatalytic degradation experiments of methyl orange showed that the final degradation rates of low (NH 2 ) 2 CO concentration group samples were higher than that of high (NH 2 ) 2 CO concentration group, even better than P25 at the same test conditions. And it was interesting that samples of low (NH 2 ) 2 CO concentration group had smaller values of BET surface areas than that of high (NH 2 ) 2 CO concentration group. It indicated that the improvement of photocatalytic activity which was effected by BET surface areas was not obvious. There were two main factors enhancing the photocatalytic property of low (NH 2 ) 2 CO concentration group: First, diffusing reflection spectra showed that the low (NH 2 ) 2 CO concentration group samples had lower reflectivity, this suggested that the structure improved the efficiency of light absorption; Second, NH 4 + would take up the active sites on the surface of the TiO 2 particles, the FT-IR test results showed that the samples of the low (NH 2 ) 2 CO concentration group samples bonded less NH 4 + , thus leading to the higher photocatalytic activity. It had enlightenment role for optimizing the performance of photocatalytic materials. [ABSTRACT FROM AUTHOR]