Authors : a*G.S. Gaikwad, b S. R. Thakare, c N.T. Khati, d A. V. Wankhade, aS.K. Patle, aK. Gour
Page Nos : 346-357
Description :
Photocatalytic degradation of organic pollutants by metal oxide has attracted significant
attention by researchers because of its usefulness in handling environmental
contaminants. Due to the fact that the photo-generated holes in the valence band and
the photo-generated electrons in the conduction band of an excited semiconductor
could serve as the oxidation and the reduction species respectively, photocatalysts
having strong oxidation–reduction power are widely studied for environmental cleaning
and for hydrogen generation from water splitting. TiO2 based photocatalyst are often
studied for degradation of dyes . Titanium dioxide is one of the most widely studied
semi-conducting photocatalysts for the degradation of organic contaminants from
water and air, because of its physical and chemical stability, high catalytic activity, high
oxidative power, low cost and ease of production . However, though it is a good catalyst,
its wide band gap (3.2 eV) limits TiO2 use in UV region. Since only about 4% of the solar
spectra falls in the UV range, it is appealing to develop efficient visible light-sensitive
photocatalysts in view of the better utilization of solar energy.
Highly photocatalytically active nano silver Zirconate has been prepared by Coprecipitation
method and the effect of silver modification was studied. The structural
and optical properties were characterized by X-ray diffraction, Fourier transform IR,
SEM, TEM and UV- VIS diffuse reflectance spectroscopy. The sharp peaks in the XRD
patterns indicate a well crystalline of the prepared samples. The average particle size
was determined from XRD powder pattern according to Debey–Scherrer’s equation (DXRD
=k · λ /β · cos θ)where DXRD is the average particle size, k is a constant , λ is the X-ray
wave-length equal to 0.15406 nm and β is the half-peak width. The average particle
size was 40-50 nm. The particle size and morphology of samples were examined by SEM
technique shows agglomerate and spongy nature . TEM micrographs of sample shows
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Ag2ZrO3 powder calcined at 400 0C was uniform, with a well-distributed spherical
particle with a size about 50 nm.
The photocatalytic activity of these materials were studied by analyzing the
degradation of an organic dye, methylene blue (MB) and it is found that silver zirconate
calcined at 400 °C shows higher rate of degradation than that of commercial TiO2
photocatalyst Degussa P-25. We attribute these observations to the extent of valence
band hole production and the role of silver in trapping the conduction band (CB)
electrons . The sensitizing property of the dye and electron scavenging ability of silver
together constitute to the interfacial charge transfer process in such a way to utilize the
photoexcited electrons.
