It is appealing to fill up TiO₂ nanotube arrays with other semiconductors to form three‐dimensional heterojunctions of interdigitated feature. This benefits from the large interfacial area for rapid charge separation and the ordered vertical channels for oriented charge transport. However, it remains a great challenge to fill the nanotubes with dense films and more importantly in a conformal manner. In this study, the TiO₂ nanotubes are conformally filled with ZnS by successive ionic layer adsorption and reaction. The ZnS exists in the form of either discrete nanoparticles or dense films when using nitrate or acetate precursor solutions, respectively. This is attributed to the hydrolysis process of the acetates in aqueous solutions, which releases extra hydroxyl ions beneficial to film formation. The CuS/TiO₂ heterojunctions, resulted from ZnS dense films, show better rectifying behaviors in view of the interdigitated structure. Such a conformal filling process with dense films can also be used to form other M_xS_y/TiO₂ bulk heterojunctions toward applications in optoelectronics, photovoltaics, photocatalysis, and so on.

中文翻译：

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用稠密的MxSy膜共形填充TiO2纳米管用于3D异质结：阴离子效应

用其他半导体填充TiO ₂纳米管阵列以形成具有叉指特征的三维异质结是很吸引人的。这得益于较大的界面区域，可快速进行电荷分离，并使用有序的垂直通道进行定向电荷传输。然而，用致密的膜填充纳米管仍然是一个巨大的挑战，更重要的是以保形的方式填充。在这项研究中，TiO ₂通过连续的离子层吸附和反应，纳米管被ZnS共形填充。当分别使用硝酸盐或乙酸盐前体溶液时，ZnS以离散的纳米颗粒或致密膜的形式存在。这归因于乙酸盐在水溶液中的水解过程，该过程释放出有利于成膜的额外羟基离子。ZnS致密膜产生的CuS / TiO ₂异质结，由于具有叉指结构，因此具有更好的整流性能。这种具有致密膜的保形填充工艺还可以用于形成其他M _x S _y / TiO ₂本体异质结，以用于光电，光伏，光催化等领域。