Laser flash photolysis study of the photochemical formation of colloidal Ag nanoparticles in the presence of benzophenone
Laser flash photolysis study of the photochemical formation of colloidal Ag nanoparticles in the presence of benzophenone
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DOI：
10.1039/b205829d
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发表时间：
2002-01-01
影响因子：
3.3
通讯作者：
Yonezawa, Y
中科院分区：
文献类型：
--
作者：
Kometani, N;Doi, H;Yonezawa, Y
当AgClO 4、十二烷基硫酸钠（SDS）和二苯甲酮（BP）的混合物的水溶液用近紫外光照射时，发生Ag+离子的敏化光还原和随后的胶体Ag纳米颗粒的形成。在这项研究中，反应的机制和动力学进行了研究，通过纳秒激光灰光解，时间分辨发射光谱和稳态光解。二苯甲酮酮基自由基（BPK）是由二苯甲酮三重态（BPT）与SDS发生夺氢反应还原Ag+而形成的。结果表明，随着Ag+离子浓度的增加，银纳米粒子的生成率显著降低，表明Ag+离子对BPT的猝灭作用是有效的。在SDS胶束溶液中，BPK的氧化速率常数以及Ag+离子对BPT的猝灭速率常数比本体溶液中预期的速率常数大得多，这反映了Ag+离子和BP分子集中在SDS胶束中。胶体银纳米粒子的形成，V-Ag，和BP光漂白，V-BP，在稳态照射下与近紫外光（λ = 365 nm）的速率进行了评估和V-Ag和V-BP对Ag+离子浓度的依赖性定量解释的速率常数估计激光灰光解。
Sensitized photoreduction of Ag+ ions and subsequent formation of colloidal Ag nanoparticles take place when an aqueous solution of a mixture of AgClO4, sodium dodecylsulfate (SDS) and benzophenone (BP) is irradiated with near-UV light. In this study, the mechanism and kinetics of the reaction have been studied by means of nanosecond laser ash photolysis, time-resolved emission spectroscopy and also steady-state photolysis. Benzophenone ketyl radial (BPK) is formed by the hydrogen abstraction reaction of the benzophenone triplet (BPT) from SDS, which reduces Ag+ ions. It is found that the yield of colloidal Ag nanoparticle formation decreases remarkably with increasing concentration of Ag+ ions, indicating the efficient quenching process of BPT by Ag+ ions. Rate constants for the oxidation of BPK as well as the quenching of BPT by Ag+ ions in SDS micellar solution are considerably larger than those expected in the bulk solution, reflecting that Ag+ ions and BP molecules are concentrated in the SDS micelles. The rate of colloidal Ag nanoparticle formation, V-Ag, and BP photobleach, V-BP, under steady-state irradiation with near-UV light (lambda = 365 nm) were evaluated and the dependence of V-Ag and V-BP on the concentration of Ag+ ions is interpreted quantitatively in terms of rate constants estimated by laser ash photolysis.