Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
Science. 2012 Sep 7;337(6099):1200-3. doi: 10.1126/science.1223598.
Electron mobility within iron (oxyhydr)oxides enables charge transfer between widely separated surface sites. There is increasing evidence that this internal conduction influences the rates of interfacial reactions and the outcomes of redox-driven phase transformations of environmental interest. To determine the links between crystal structure and charge-transport efficiency, we used pump-probe spectroscopy to study the dynamics of electrons introduced into iron(III) (oxyhydr)oxide nanoparticles via ultrafast interfacial electron transfer. Using time-resolved x-ray spectroscopy and ab initio calculations, we observed the formation of reduced and structurally distorted metal sites consistent with small polarons. Comparisons between different phases (hematite, maghemite, and ferrihydrite) revealed that short-range structural topology, not long-range order, dominates the electron-hopping rate.
铁（氧）氢氧化物中的电子迁移率使电荷能够在相隔很远的表面位置之间转移。越来越多的证据表明，这种内部传导会影响界面反应的速率以及环境感兴趣的氧化还原驱动的相变的结果。为了确定晶体结构和电荷传输效率之间的联系，我们使用泵浦探针光谱法研究了通过超快界面电子转移引入铁（III）（氧）氢氧化物纳米粒子的电子的动力学。使用时间分辨 X 射线光谱和从头算计算，我们观察到与小极化子一致的还原和结构变形金属位点的形成。不同相（赤铁矿、磁铁矿和水铁矿）之间的比较表明，短程结构拓扑结构而非长程有序控制着电子跳跃率。
