Diffusion of platinum ions and platinum nanoparticles during photoreduction processes using the transient grating method
Diffusion of platinum ions and platinum nanoparticles during photoreduction processes using the transient grating method
复制标题
DOI：
10.1021/la061663i
复制
发表时间：
2006-10-24
期刊：
影响因子：
3.9
通讯作者：
Terazima, Masahide
中科院分区：
文献类型：
--
作者：
Harada, Masafumi;Okamoto, Koichi;Terazima, Masahide
通过测量扩散系数（D）的变化，研究了PtCl 62-在聚（N-乙烯基-2-吡咯烷酮）溶液中的光还原过程.采用激光诱导瞬态光栅（TG）法测量了紫外光照射过程中化学物种的D值。紫外光照射前PtCl_（62-）溶液的TG信号由三种贡献组成：热光栅、由于PtCl_（42-）的产生而产生的物种光栅和由于PtCl_（62-）的耗尽而产生的物种光栅。在紫外光照射下，PtCl_（62-）引起的物种光栅信号减弱，然后逐渐出现Pt纳米颗粒的TG信号。该结果表明，在所有PtCl 62-离子被光化学还原为PtCl 42-并随后以短延迟转化为Pt-0原子之后，Pt-0原子逐渐聚集成Pt纳米颗粒。随着紫外光照射时间的增加，Pt纳米颗粒的TG信号强度增加，而D值没有变化。这表明在UV照射过程中，Pt纳米颗粒的数量增加，但具有聚合物层的Pt纳米颗粒的尺寸不变。
The photoreduction process of PtCl62- 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 PtCl62-solution before UV irradiation was composed of three kinds of contributions, the thermal grating, the species grating due to the creation of PtCl42-, and the species grating due to the depletions of PtCl62-. Upon UV irradiation of the solution, the species grating signal due to PtCl62- 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 PtCl62- ions are photochemically reduced to PtCl42- 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.