Photocurrent generation from semiconducting manganese oxide nanosheets in response to visible light
Photocurrent generation from semiconducting manganese oxide nanosheets in response to visible light
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DOI：
10.1021/jp0500485
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发表时间：
2005-05-19
影响因子：
3.3
通讯作者：
Sasaki, T
中科院分区：
文献类型：
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作者：
Sakai, N;Ebina, Y;Sasaki, T
在可见光照射下（1 < 500 nm），单层的氧化锰纳米片微晶产生阳极光电流，而纳米片本身是稳定的，这一点通过面内XRD和紫外-可见吸收光谱得到证实。根据光电流作用谱估算出带隙能量为2.23 eV。0.5nm的分子厚度可以促进激发的电子和空穴的电荷分离，这对于强局部化的d-d跃迁通常是非常困难的。MnO 2（纳米片）的单层膜响应于单色光照射（l = 400 nm）表现出0.16%的入射光子-电子转换效率，这与吸附在平坦单晶表面上的单层染料的敏化效率相当。随着MnO（2）纳米片层数的增加，光吸收增强，但效率下降。当载流子需要通过多层纳米片迁移比I层更长的距离时，激发的电子-空穴对的复合可能成为主导。
Unilamellar nanosheet crystallites of manganese oxide generated the anodic photocurrent under visible light irradiation (l < 500 nm), while the nanosheets themselves were stable as revealed by in-plane XRD and UV-visible absorption spectra. The band gap energy was estimated to be 2.23 eV on the basis of the photocurrent action spectrum. The molecular thickness of 0.5 nm may facilitate the charge separation of excited electrons and holes, which is generally very difficult for strongly localized d-d transitions. The monolayer film of MnO2 (nanosheets exhibited the incident photon-to-electron conversion efficiency of 0.16% in response to the monochromatic light irradiation (l = 400 nm), which is comparable to those for sensitization of monolayer dyes adsorbed on a flat single-crystal surface. The efficiency declined with increasing the layer number of MnO)(2) nanosheets, although the optical absorption was enhanced. The recombination of the excited electron-hole pairs may become dominant when the carriers need to migrate a longer distance than I layer through multilayered nanosheets.