Abstract
We have used STM to examine the effects of annealing time in the presence of different gaseous species (Ar, H2 and N2) on the morphological transformation of vacuum-vapor deposited Pt clusters on highly oriented pyrolytic graphite (HOPG). This study shows that the morphological transformation of the Pt clusters on HOPG is a function of both gaseous species and annealing time. Without annealing, the as-deposited platinum consists of an aggregation of smaller clusters. These clusters become more uniform and spherical after annealing for 4 h in the presence of Ar and H2. Further annealing shows a morphological transformation from spherical to elongated shape. Small amounts of hydrocarbon impurities in Ar or hydrogen might possibly explain the shape transformation of the Pt clusters. However, the morphological transformation of the Pt clusters is totally different when the sample is annealed in low sticking coefficient gas, n2, suggesting adsorbed gases (hydrocarbon or hydrogen) have profound effects on the shape transformation. These results indicate that pretreatment conditions are important factors in the shape transformation, which may have significant influence on catalytic activity and selectivity.
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T.P. Chojnacki, K. Krause and L.D. Schmidt, J. Catal. 128 (1991) 1419.
M. Komiyama, S. Morita and N. Mikoshiba, J. Microsc. 152 (1988) 197.
H.W. Salemink, H. Meir, R. Ellialtioglu, J.W. Gerritsen and P. Muralt, Appl. Phys. Lett. 54 (1989) 1112.
S. Gao and L.D. Schmidt, J. Catal. 115 (1989) 356.
G. Binnig, H. Rohrer, Ch. Gerber and E. Weibel, Phys. Rev. Lett. 49 (1982) 57.
E. Ganz, K. Sattler and J. Clarke, J. Vac. Sci. Technol. B9 (1988) 829.
M. Komiyama, J. Kobayashi and S. Morita, J. Vac. Sci. Technol. A8 (1990) 608.
U. Muller, K. Sattler, J. Xhie, N. Venkaswaran and G. Raina, J. Vac. Sci. Technol. B9 (1991) 829.
J. Xhie, K. Sattler, U. Muller, N. Venkaswaran and G. Raina, J. Vac. Sci. Technol. B9 (1991) 833.
X.C. Zhou and E. Gulari, Acta. Cryst. A47 (1991) 17.
K.L. Yeung and E.E. Wolf, J. Vac. Sci. Technol. B9 (1991) 798.
S. Lee, H. Permana and K.Y.S. Ng, J. Vac. Sci. Technol. B10 (1992) 561.
T. Wang, C. Lee and L.D. Schmidt, Surf. Sci. 163 (1985) 181.
T.P. Chojnacki and L.D. Schmidt, J. Catal. 115 (1989) 473.
M. Drechsler, in:Surface Mobilities on Solid Materials, ed. Vu Thien Binh (Plenum Press, New York, 1983).
R.T. Yang, in:Chemistry and Physics of Carbon, Vol. 19, eds. P.L. Walker Jr. and P.A. Thrower (Dekker, New York, 1984) pp. 163–210.
R.T.K. Baker, R.D. Sherwood and J.A. Dumesic, J. Catal. 66 (1980) 56.
J.W. Lyding, J.S. Hubacek, G. Gammie, S. Skala and R. Brockenbrough, J. Vac. Sci. Technol. A6 (1988) 365.
A.M. Baró, A. Bartolome, L. Vazquez, N. Garcia, R. Reifenberger, E. Choi and R.P. Andres, Appl. Phys. Lett. 51 (1987) 1594.
X. Chu, L.D. Schmidt, S.G. Chen and R.T. Yang, J. Catal. 140 (1993) 543.
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Lee, S., Permana, H. & Simon Ng, K.Y. Effects of annealing and gas treatment on the morphology of platinum cluster size on highly oriented pyrolytic graphite by scanning tunneling microscopy. Catal Lett 23, 281–292 (1994). https://doi.org/10.1007/BF00811363
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DOI: https://doi.org/10.1007/BF00811363