Department of Materials Science and Engineering, Chungnam National University, Daejeon, 305-764, Rep. of Korea.
Nanoscale. 2013 Jun 21;5(12):5530-8. doi: 10.1039/c3nr00889d.
The electrodes in photoelectrochemical cells responsible for the generation of hydrogen and oxygen by water splitting have been intensively studied because of their high photon-to-electron conversion efficiency. The morphology of nanostructures with these high-efficiency electrodes was systematically compared with the morphology of ZnO structures with vertically aligned nanorod arrays (NA), hollow hemisphere arrays (HA), urchin-like (UL) nanorod arrays, and thin films (TF). The UV-vis light absorption, photoresponse (current-voltage characteristics in the dark and under light), and photoelectrochemistry of the electrodes were measured. The highest photon-to-electron conversion efficiency of 65% at a specific UV wavelength for an electrode with a ZnO UL structure was derived from the UL morphology of high light-trapping efficiency and carrier collection efficiency. The UL morphology also produced a photon-to-electron conversion efficiency of 4.5% under a solar simulator by CdS-sensitization of the ZnO UL electrode. The value was the highest observed thus far among the ZnO-based electrodes. We demonstrated that photoresponse measurement is a practical and simple technique for the estimation of the photon-to-electron conversion efficiency of an electrode.
由于光电器件的光生电子转换效率高，负责通过水分解产生氢气和氧气的光电器件中的电极受到了广泛的研究。具有这些高效电极的纳米结构的形态与具有垂直取向纳米棒阵列（NA）、中空半球阵列（HA）、刺猬状（UL）纳米棒阵列和薄膜（TF）的 ZnO 结构的形态进行了系统比较。测量了电极的紫外-可见光吸收、光响应（暗电流-电压特性和光下电流-电压特性）和光电化学性能。具有 ZnO UL 结构的电极在特定紫外波长下的最高光生电子转换效率为 65%，这源于具有高光捕获效率和载流子收集效率的 UL 形态。通过 ZnO UL 电极的 CdS 敏化，UL 形态在太阳模拟器下也产生了 4.5%的光生电子转换效率。这是迄今为止在 ZnO 基电极中观察到的最高值。我们证明了光响应测量是一种用于估算电极的光生电子转换效率的实用且简单的技术。
