Synthesis and Optical Properties of Transition Metal Doped ZnO ...

Transform (FFT) and inverse FFT to the
transmission electron micrographs. The
measured lattice spacing of 2.81Å and 1.9 Å
correspond to the (100) and (102) planes of
the Wurtzite structure [22, 23].
Modification in the band gap
structure of ZnO through manganese doping
has been reported to cause ferromagnetic
ordering [24]. We therefore assume that
doping of ZnO with metal and transition
metals add tails within the conduction and
valence band. Thus visible light energy will
be enough to excite electrons from tails state
to the conduction states. Further, ZnO doped
with Mn 2+ is more effective than
ZnO:Cu 2+ in absorbing visible light This
highest absorption intensity of Mn 2+ doped
ZnO is attributed to the lowest dopant level
of Mn 2+ with in the band gap of ZnO as
compared to that of Cu 2+ ion.
5. Conclusion
In summary we have shown that manganese
doping of ZnO nanoparticles have decrease the native
band gap of ZnO and created more defects sites on
the ZnO surface. The nanoparticles synthesized by
co-precipitation techniques have poly crystalline
structure with average particles size of 37 nm. The
increased surface defects are capable to absorb more
visible light. This newly synthesized manganese
doped ZnO will have applications in
electrophotochemical hydrogen production and
heterogeneous photocatalysis. It will make the
photocatalyst capable to work with only visible light
irradiation and will eliminate the need of UV light.
The preliminary results suggest that manganese
doped ZnO nanoparticles can be used as immobilized
photocatalysts for water and environmental
detoxification from organic compounds.
6. Acknowledgment
The author gratefully acknowledge the
financial and intellectual support from Asian
Institute of Technology Bangkok, Thailand
7. References
[1] J. H. He, C. L. Hsin, J. Liu, L. J. Chen
and Z. L. Wang, Advanced Materials,
19(2007) 781-784
[2] C. Y. Lee, Y.T. Haung, W. F. Su, C. F.
Lin, App. Phy. Lett., 89 (2006) 231116
[3] W. Shen, Z. Li, H. Wang, Y. Liu, Q.
Guo, Y. Zhang,Journal of Hazardous
Materials (2007) (in press)
[4] M. A. Garcia, J. M. Merino, E. F. Pinel,
A. Quesada, J. d. Venta, M. L. R. Gonza,
G. R. Castro, P. Crespo, J. Llopis, J. M.
G. Calbet and A. Hernando, Nano letter
7 (2007) 1489-1494
[5] T. Makino, K. Tamura, C. H. Chia, Y.
Segawa, M. Kawasaki, A. Ohtomo, and
H. Koinuma, Phy. Review B, 65 (2002)
121201-121204
[6] X. Liu, G. Li, Y. Luo, Z. Quan, H.
Xiang, and J. Lin, J. Phys. Chem. B 110
(2006) 9469-9476
[7] M. Miyauchi, A. Nakajima, T.
Watanabe and K. Hashimoto, Chem.
Mater. 14(2002) 2812-2816
[8] K. Vanhesuden, W. L. Warren, J. A.
Voigt, C. H. Seager and D. R. Tallant,
Impact of Pb doping on the optical and
electronic properties of ZnO powders,
Applied Physics letter, 67(1995) 1280-
1282
[9] R. Wang, J. H. Xin, Y. Yang, H. Liu, L.
Xu and J. Hu, Applied Surface Science
227 (2004) 312-317
[10] R. Viswanatha, S. Sapra, S. S. Gupta,
B. Satpati, and P. V. Satyam, J. Phys.
Chem. B, 108 (2004) 6303-6310
[11] S. Sakthivel, B. Neppolian, M.V.
Shankar, B. Arabindoo, M.
Palanichamy, and V. Murugesan, Solar
Energy Materials & Solar Cells 77
(2003) 65–82
[12] T. F. Jaramillo, S. Baeck, A. K.
Shwarsctein, K. S. Choi, G. D. Stucky,
and E. W. McFarland, J. Comb. Chem. 7
(2005) 264-271
[13] K. Vanheusden. W. L. Warren, J. A.
Voigt, C. H. Seager, and D. R. Tallant,
Appl. Phys. Lett. 76 (1995) 1280-1282
310