Merga G, Milosavljevic B H, Meisel D
Radiation Laboratory, Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
J Phys Chem B. 2006 Mar 23;110(11):5403-8. doi: 10.1021/jp057231i.
The effect of high concentrations of large gold particles, in the hundreds of nanometer size regime, on the yields of molecular hydrogen, G(H(2)), produced in the radiolysis of several aqueous solutions was determined. In particular we look for direct effect of radiation absorbed by the solid particles on the yield of water products. These particles, however, are catalytically active in the conversion of reducing radicals to molecular hydrogen as well. A very small increase in G(H(2)) observed in bromide solutions upon addition of 50 wt % of gold particles indicates that the radiolysis of the solid particles does not affect the yields in the aqueous phase. Very little exchange of charge carriers or energy between the two phases occurs in these large particle suspensions. On the other hand, efficient catalytic conversion of (CH(3))(2)C(*)OH radicals to H(2) is shown to occur. The efficiency of the presently studied suspensions in the redox-catalytic process is similar to that of suspensions of small particles of similar total surface area. In the presence of radicals from hydrogen atom abstraction from tert-butyl alcohol the yield decreases significantly, again similar to the behavior in suspensions of small particles. We conclude that the redox catalysis does not depend on the size of the particles when their size exceeds a few nanometers.
测定了数百纳米尺寸范围内的高浓度大金颗粒对几种水溶液辐解产生的分子氢产额G(H₂)的影响。特别是，我们寻找固体颗粒吸收的辐射对水产品产额的直接影响。然而，这些颗粒在将还原自由基转化为分子氢的过程中也具有催化活性。在溴化物溶液中加入50 wt%的金颗粒后观察到G(H₂)有非常小的增加，这表明固体颗粒的辐解不会影响水相中的产额。在这些大颗粒悬浮液中，两相之间很少发生电荷载流子或能量的交换。另一方面，已表明(CH₃)₂C(*)OH自由基能有效地催化转化为H₂。目前研究的悬浮液在氧化还原催化过程中的效率与具有相似总表面积的小颗粒悬浮液的效率相似。在存在从叔丁醇中夺取氢原子产生的自由基的情况下，产额显著降低，这再次与小颗粒悬浮液中的行为相似。我们得出结论，当颗粒尺寸超过几纳米时，氧化还原催化不依赖于颗粒的大小。
