Typical Synthesis and Environmental Application of Novel Ti Nanoparticles - Advanced Materials for Agriculture, Food and Environmental Safety - page 443

O 2

O 2 / HO 2

e - e -

CB

hv CB

Pollutant

CO 2 / H 2 O

3.24 eV

2.82 eV

HO + H +

h +

h +

VB VB

H 2 O

Bi 2 Ti 4 O 11

NMBT1

Figure 15.16 General mechanistic representation of the photocatalytic activity of NMBT
on MO solution under UV-irradiation.

in Figure 15.16 [89, 152, 153]. h e NMBT can be excited by the photons
with the wavelengths under 409-439 nm for dif erent compositions and
produces the photogenerated electron/hole pairs, following photocatalytic
activity. In the case of Bi 2 Ti 4 O 11 with the band gap energy of 3.24 eV, which
theoretically requires the photons of wavelengths 382 nm, little photocata-
lytic activity is shown under UV-light compared to the NMBT photocata-
lyst. On the other hand, NiMoO 4 powder shows photocatalytic activity,
which is better than Bi 2 Ti 4 O 11 but inferior to NMBT photocatalysts under
similar experimental conditions. Of the three compositions of NM x BT 1−x (x
= 0.01, 0.05, 0.1) composite, the sample having x = 0.01 shows maximum
photocatalytic activity. h is is probably due to ei cient generation of elec-
tron and hole, where electron resides in the conduction band and the hole
is captured forming Ni 3+ . With an increase of dopant concentration of Ni 2+
(for x = 0.01-0.1) the band gap increases and the rate of reaction decreases
due to inei cient formation of hole and electron. h e NMBT is capable
of localizing electron in the conduction band and hole in Ni 3+ more ei -
ciently than individual components [153]. Moreover, the high surface area
of NMBT produced at lower temperature helps to produce more active
centers for photocatalytic reaction.

References

1. S.G. Anju, K.P. Jyothi, J. Sindhu, Y. Suguna, and E.P. Yesodharan, Res. J.
Recent Sci., Vol. 1 (ISC-2011), pp. 191-201, 2012.

2. R. Zouaghi, B. David, J. Suptil, K. Djebbar, A. Boutiti, and S. Guittonneau,
Ultrason. Sonochem. , Vo l . 18, pp. 1107-1112, 2011.

3. M. Ying-Shih, S. Chi-Fanga, and L. Jih-Gaw, J. Hazard. Mater., Vol. 178, pp.
320-325, 2010.