Sulfonated poly(ether ether ketone)/poly(vinyl alcohol) sensitizing system for solution photogeneration of small Ag, Au, and Cu crystallites.
Sulfonated poly(ether ether ketone)/poly(vinyl alcohol) sensitizing system for solution photogeneration of small Ag, Au, and Cu crystallites.
复制标题
用于溶液光生小银、金和铜微晶的磺化聚（醚醚酮）/聚（乙烯醇）敏化系统。
DOI：
10.1021/jp045047b
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
G. Mills
中科院分区：
文献类型：
--
作者：
A. Korchev;Shulyak Ts;B. Slaten;W. Gale;G. Mills
用350 nm光照射含有磺化聚（醚醚酮）和聚（乙烯醇）的无空气水溶液，得到聚酮的二苯甲酮基自由基。聚合物自由基形成的量子产率为0.02，衰变的二阶速率常数比典型的α -羟基自由基低6个数量级。高分子二苯甲酮基自由基将Ag+、Cu2+和AuCl4-还原为纳米尺寸的金属颗粒。还原速率随着Ag(I)、Cu（II）和Au（III）浓度的增加而降低，这可以用一个动力学模型来解释，在这个模型中，金属离子会猝灭聚合二苯甲酮基团的激发态，从而形成大分子自由基。Ag+的猝灭速度最快，而Cu2+和AuCl4-的速率常数相似。随着减少金属离子所需的等价物数量的增加，粒子形成变得更加复杂；Au（III）体系是一个极端的例子，其中自由基反应与二次光激发和热还原通道并行进行。对于每种金属离子，聚合物引发的光反应产生具有不同性质的晶体，例如Ag的很强的等离子体激元或Au粒子表现出的窄尺寸分布。
Illumination of air-free aqueous solutions containing sulfonated poly(ether ether ketone) and poly(vinyl alcohol) with 350 nm light results in benzophenone ketyl radicals of the polyketone. The polymer radicals form with a quantum yield 0.02 and decay with a second-order rate constant 6 orders of magnitude lower than that of typical alpha-hydroxy radicals. Evidence is presented that the polymeric benzophenone ketyl radicals reduce Ag+, Cu2+, and AuCl4- to metal particles of nanometer dimensions. Decreases in the reduction rates with increasing Ag(I), Cu(II), and Au(III) concentrations are explained using a kinetic model in which the metal ions quench the excited state of the polymeric benzophenone groups, which forms the macromolecular radicals. Quenching is fastest for Ag+, whereas Cu2+ and AuCl4- exhibit similar rate constants. Particle formation becomes more complex as the number of equivalents needed to reduce the metal ions increases; the Au(III) system is an extreme case where the radical reactions operate in parallel with secondary light-initiated and thermal reduction channels. For each metal ion, the polymer-initiated photoreactions produce crystallites possessing distinct properties, such as a very strong plasmon in the Ag case or the narrow size distribution exhibited by Au particles.