Meng Ming, Wu Xinglong, Zhu Xiaobin, Zhu Xiaoshu, Chu Paul K
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University , Nanjing 210093, P. R. China.
ACS Appl Mater Interfaces. 2014 Mar 26;6(6):4081-8. doi: 10.1021/am4056358. Epub 2014 Mar 6.
Semiconductor nanowires (NWs) are useful building blocks in optoelectronic, sensing, and energy devices and one-dimensional NWs have been used in photoelectrochemical (PEC) water splitting because of the enhanced light absorption and charge transport. It has been theoretically predicted that the {001} facets of body center cubic (bcc) In2O3 nanocrystals can effectively accumulate photogenerated holes under illumination, but it is unclear whether facet cutting of NWs can enhance the efficiency of PEC water splitting. In this work, the photocurrent of square In2O3 NWs with four {001} facets is observed to be an order of magnitude larger than that of cylindrical In2O3 NWs under the same conditions and subsequent hydrogen treatment further promotes the PEC water splitting performance of the NWs. The optimized hydrogenated In2O3 NWs yield a photocurrent density of 1.2 mA/cm(2) at 0.22 V versus Ag/AgCl with a Faradaic efficiency of about 84.4%. The enhanced PEC properties can be attributed to the reduced band gap due to merging of the disordered layer-induced band tail states with the valence band as well as improved separation of the photogenerated electrons/holes between the In2O3 crystal core and disordered layer interface. The results provide experimental evidence of the important role of facet cutting, which is promising in the design and fabrication of NW-based photoelectric devices.
半导体纳米线（NWs）是光电子、传感和能量器件中有用的构建块，一维NWs由于增强的光吸收和电荷传输已被用于光电化学（PEC）水分解。理论预测体心立方（bcc）In2O3纳米晶体的{001}面在光照下可有效积累光生空穴，但尚不清楚NWs的刻面切割是否能提高PEC水分解效率。在这项工作中，观察到具有四个{001}面的方形In2O3 NWs的光电流在相同条件下比圆柱形In2O3 NWs大一个数量级，随后的氢处理进一步提高了NWs的PEC水分解性能。优化后的氢化In2O3 NWs在相对于Ag/AgCl为0.22 V时产生的光电流密度为1.2 mA/cm²，法拉第效率约为84.4%。增强的PEC性能可归因于无序层诱导的带尾态与价带合并导致的带隙减小，以及In2O3晶体核与无序层界面之间光生电子/空穴分离的改善。这些结果为刻面切割的重要作用提供了实验证据，这在基于NWs的光电器件的设计和制造中具有广阔前景。
