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Published October 24, 2006 | public
Journal Article

Diffusion of Platinum Ions and Platinum Nanoparticles during Photoreduction Processes Using the Transient Grating Method

Abstract

The photoreduction process of PtCl_6^(2-) to Pt nanoparticles in poly(N-vinyl-2-pyrrolidone) solutions upon UV light irradiation was investigated by monitoring the change in the diffusion coefficient (D). The D values of chemical species during UV irradiation was measured by the laser-induced transient grating (TG) method. The TG signal of the PtCl_6^(2-) solution before UV irradiation was composed of three kinds of contributions, the thermal grating, the species grating due to the creation of PtCl_4^(2-), and the species grating due to the depletions of PtCl_6^(2-). Upon UV irradiation of the solution, the species grating signal due to PtCl_6^(2-) diminished and then the TG signal of Pt nanoparticles gradually appeared. This result indicates that the gradual clustering of Pt^0 atoms into Pt nanoparticles occurs after all PtCl_6^(2-) ions are photochemically reduced to PtCl_4^(2-) and subsequently transformed to Pt^0 atoms with a short delay. With increasing time of the UV irradiation, the TG signal intensity increased, while D of the Pt nanoparticles did not change. This suggests that the number of Pt nanoparticles increases, but the size of the Pt nanoparticles with the polymer layer is unchanged, in the course of the UV irradiation.

Additional Information

© 2006 American Chemical Society. Received 9 June 2006. Published online 27 September 2006. Published in print 1 October 2006. We are grateful to Prof. S. Isoda at the Institute for Chemical Research, Kyoto University, for the TEM observations. A part of this work was supported by the "Nanotechnology Support Project" of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

Additional details

Created:
August 19, 2023
Modified:
October 26, 2023