(d) Activation energy of CO oxidation to CO2 decreases with
increase in the effective charge on Pd ion in these oxides.
(e) A dual site mechanism with CO and O2 adsorption on Pd
ion and oxide ion vacancies respectively on the oxide surfaces
is proposed and the model fits well with the experimental
observations.
15 A. Gayen, K. R. Priolkar, P. R. Sarode, V. Jayaram, M. S. Hedge, G. N.
Subbanna and S. Emura, Chem. Mater., 2004, 16, 2317.
16 T. Baidya, A. Marimuthu, M. S. Hegde, N. Ravishankar and G. Madras,
J. Phys. Chem. C, 2007, 111, 830.
17 J. A. Wang, L. F. Chen, M. A. Valenzuela, A. Montoya, J. Salmones
and P. D. Angel, Appl. Surf. Sci., 2004, 230, 34.
18 R. D. Shannon, Acta Crystallogr. A, 1976, 32, 751.
19 James E. Huheey, Inorganic Chemistry, 3rd Edition, Harper Interna-
tional SI Edition, p. 195.
20 X. Gonze, J. M. Beuken, R. Caracas, F. Detraux, M. Fuchs, G. M.
Rignanese, L. Sindic, M. Verstraete, G. Zerah, F. Jollet, M. Torrent, A.
Roy, M. Mikami, Ph. Ghosez, J. Y. Raty and D. C. Allan, Comp. Mater.
Sci., 2002, 25, 478.
21 S. Goedecker, SIAM J. Sci. Comp., 1997, 18, 1605.
22 P. Hohenberg and W. Kohn, Phys. Rev., 1964, 136, 864B.
23 S. Goedecker, M. Teter and J. Huetter, Phys. Rev. B, 1996, 54,
1703.
Acknowledgements
The authors gratefully acknowledge financial support from the
Department of Science and Technology, Government of India.
References
24 W. Kohn and L. Sham, J. Phys. Rev., 1965, 140, 1133A.
25 M. C. Payne, M. P. Teter, D. C. Allan, T. A. Arias and J. D.
Joannopoulos, Rev. Mod. Phys., 1992, 64, 1045.
1 H. C. Yao and Y. F. Yao, J. Catal., 1984, 86, 254.
2 A. Trovarelli, Catalysis by Ceria and Related Materials, Imperial
College Press, UK, 2002, p. 236.
26 X. Gonze, Phys. Rev. B, 1996, 54, 4383.
3 P. Fornasiero, R. di Monte, G. Ranga Rao, J. Kasˇpar, S. Meriani, A.
Trovarelli and M. Graziani, J. Catal., 1995, 151, 168.
4 P. Fornasiero, E. Fonda, R. di Monte, G. Vlaic, J. Kasˇpar and M.
Graziani, J. Catal., 1999, 177, 187.
5 E. Mamontov, T. Egami, R. Brezny, M. Koranne and S. Tyagi, J. Phys.
Chem. B, 2000, 104, 11110.
6 Y. Nagai, T. Yamamoto, T. Tanaka, S. Yoshida, T. Nonaka, T.
Okamoto, A. Suda and M. Sugiura, Catal. Today, 2002, 74, 225.
7 G. Dutta, U. V. Waghmare, T. Baidya, M. S. Hegde, K. R. Priolkar and
P. R. Sarode, Catal. Lett., 2006, 108, 165.
27 H. J. Monkhorst and J. D. Pack, Phys. Rev. B, 1976, 13,
5188.
28 F. L. Hirshfeld, Theor. Chim. Acta (Berlin), 1977, 44, 129.
29 K. R. Priolkar, P. Bera, P. R. Sarode, M. S. Hegde, S. Emura, R.
Kumashiro and N. P. Lalla, Chem. Mater., 2002, 14, 2120.
30 S. Roy, A. Marimuthu, M. S. Hegde and G. Madras, Appl. Catal. B:
Environ., 2007, 73, 300.
31 H. Lieske and J. Volter, J. Phys. Chem., 1985, 89, 1842.
32 A. F. Diwell, R. R. Rajaram, H. A. Shaw and T. J. Truex, Stud. Surf.
Sci. Catal., 1991, 71, 139.
¨
8 M. Luo, J. Chen, L. Chen, J. Lu, Z. Feng and C. Li, Chem. Mater.,
2001, 13, 197.
9 T. Baidya, A. Gayen, M. S. Hegde, N. Ravishankar and L. Dupont,
J. Phys. Chem. B, 2006, 110, 5262.
10 B. M. Reddy, P. Bharali, P. Saikia, A. Khan, S. Loridant, M. Muhler
and W. Griinert, J. Phys. Chem. C, 2007, 111, 1878.
11 T. Baidya, M. S. Hegde and J. Gopalakrishnan, J. Phys. Chem. B, 2007,
111, 5149.
33 B. Harrison, A. F. Diwell and C. Hallett, Platinum Metals Rev., 1988,
32, 73.
34 L. A. Bruce, M. Hoang, A. E. Hughes and T. W. Turney, Appl. Catal.
A: General, 1993, 100, 51.
35 L. Tournayan, N. R. Marcilio and R. Frety, Appl. Catal., 1991, 78,
31.
36 A. Trovarelli, G. Dolcetti, C. di Leitenburg and J. Kaspar, Stud. Surf.
Sci. Catal., 1993, 75, 2781.
12 P. Bera, K. R. Priolkar, P. R. Sarode, M. S. Hegde, S. Emura, R.
Kumashiro, V. Jayaram and N. P. Lalla, Chem. Mater., 2002, 14, 3591.
13 P. Bera, K. C. Patil, V. Jayaram, G. N. Subbanna and M. S. Hegde,
J. Catal., 2000, 196, 293.
14 P. Bera, K. R. Priolkar, A. Gayen, P. R. Sarode, M. S. Hegde, S. Emura,
R. Kumashiro, V. Jayaram and G. Subbanna, Chem. Mater., 2003, 15,
2049.
37 G. Dutta, U. V. Waghmare, T. Baidya and M. S. Hegde, Chem. Mater.,
2007, 19, 6430.
38 B. K. Cho, J. Catal., 1992, 138, 255.
39 D. Briggs, M. P. Seah, Practical Surface Analysis, John Wiley & Sons
Ltd., reprinted December 2004, p. 502.
40 Linus Pauling The Nature of Chemical Bond, 3rd edition, Oxford and
IBH Publishing Co., page 98.
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