Photoinduced charge separation in a colloidal system of exfoliated layered semiconductor controlled by coexisting aluminosilicate clay.
Photoinduced charge separation in a colloidal system of exfoliated layered semiconductor controlled by coexisting aluminosilicate clay.
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DOI：
10.1021/jp807214w
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
T. Nakato;Yoshimi Yamada;N. Miyamoto
中科院分区：
文献类型：
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作者：
T. Nakato;Yoshimi Yamada;N. Miyamoto
我们研究了发生在多组分胶体体系中的光诱导电荷分离，所述多组分胶体体系由具有光催化活性的氧化物纳米片和光化学惰性粘土以及电子接受甲基紫精指示剂（MV 2+）组成。通过层状六铌酸盐和锂蒙脱石粘土的剥离获得无机纳米片。在胶体分散状态下，蒙脱土和粘土纳米片在空间上分离，MV2+分子选择性地吸附在粘土片晶上。紫外线照射的胶体导致电子转移的吸附在粘土上的MV2+分子的纳米片。光诱导电子转移产生甲基紫精自由基阳离子（MV*+），其特征在于高产率和长寿命。发现MV*+物种的产率和稳定性强烈依赖于胶体的粘土含量：从几摩尔%到约70摩尔%的产率和几十分钟到超过40小时的寿命。纳米片和MV2+分子的含量以及胶体的老化也影响光诱导电荷分离。在胶体中不存在MV2+分子的情况下，UV照射诱导电子在纳米片中积累。电子积累态的稳定性也依赖于粘土含量。在光化学行为的变化进行了讨论有关的胶体的粘度。
We investigated photoinduced charge separation occurring in a multicomponent colloidal system composed of oxide nanosheets of photocatalytically active niobate and photochemically inert clay and electron accepting methylviologen dications (MV2+). The inorganic nanosheets were obtained by exfoliation of layered hexaniobate and hectorite clay. The niobate and clay nanosheets were spatially separated in the colloidally dispersed state, and the MV2+ molecules were selectively adsorbed on the clay platelets. UV irradiation of the colloids led to electron transfer from the niobate nanosheets to the MV2+ molecules adsorbed on clay. The photoinduced electron transfer produced methylviologen radical cations (MV*+), which was characterized by high yield and long lifetime. The yield and stability of the MV*+ species were found to depend strongly on the clay content of the colloid: from a few mol % to approximately 70 mol % of the yield and several tens of minutes to more than 40 h of the lifetime. The contents of the niobate nanosheets and MV2+ molecules and the aging of the colloid also affected the photoinduced charge separation. In the absence of MV2+ molecules in the colloid, UV irradiation induced electron accumulation in the niobate nanosheets. The stability of the electron-accumulated state also depended on the clay content. The variation in the photochemical behavior is discussed in relation to the viscosity of the colloid.