Xia Chenghui, van Oversteeg Christina H M, Bogaards Veerle C L, Spanjersberg Tim H M, Visser Nienke L, Berends Anne C, Meeldijk Johannes D, de Jongh Petra E, de Mello Donega Celso
Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508 TA Utrecht, The Netherlands.
Materials Chemistry and Catalysis, Debye Institute for Nanomaterials Science, Utrecht University, 3508 TA Utrecht, The Netherlands.
ACS Nano. 2021 Jun 22;15(6):9987-9999. doi: 10.1021/acsnano.1c01488. Epub 2021 Jun 10.
Colloidal heteronanocrystals allow for the synergistic combination of properties of different materials. For example, spatial separation of the photogenerated electron and hole can be achieved by coupling different semiconductors with suitable band offsets in one single nanocrystal, which is beneficial for improving the efficiency of photocatalysts and photovoltaic devices. From this perspective, axially segmented semiconductor heteronanorods with a type-II band alignment are particularly attractive since they ensure the accessibility of both photogenerated charge carriers. Here, a two-step synthesis route to CuS/CuInS Janus-type heteronanorods is presented. The heteronanorods are formed by injection of a solution of preformed CuS seed nanocrystals in 1-dodecanethiol into a solution of indium oleate in oleic acid at 240 °C. By varying the reaction time, Janus-type heteronanocrystals with different sizes, shapes, and compositions are obtained. A mechanism for the formation of the heteronanocrystals is proposed. The first step of this mechanism consists of a thiolate-mediated topotactic, partial Cu for In cation exchange that converts one of the facets of the seed nanocrystals into CuInS. This is followed by homoepitaxial anisotropic growth of wurtzite CuInS. The CuS seed nanocrystals also act as sacrificial Cu sources, and therefore, single composition CuInS nanorods are eventually obtained if the reaction is allowed to proceed to completion. The two-stage seeded growth method developed in this work contributes to the rational synthesis of CuS/CuInS heteronanocrystals with targeted architectures by allowing one to exploit the size and faceting of premade CuS seed nanocrystals to direct the growth of the CuInS segment.
胶体异质纳米晶体能够实现不同材料性能的协同组合。例如，通过在单个纳米晶体中耦合具有合适带隙偏移的不同半导体，可以实现光生电子和空穴的空间分离，这有利于提高光催化剂和光伏器件的效率。从这个角度来看，具有II型能带排列的轴向分段半导体异质纳米棒特别有吸引力，因为它们确保了两种光生载流子都能被利用。在此，我们提出了一种两步合成路线来制备CuS/CuInS Janus型异质纳米棒。通过在240°C下将预先形成的CuS籽晶纳米晶体在1-十二烷硫醇中的溶液注入油酸铟溶液中，形成异质纳米棒。通过改变反应时间，可以获得具有不同尺寸、形状和组成的Janus型异质纳米晶体。我们提出了异质纳米晶体的形成机制。该机制的第一步包括硫醇盐介导的拓扑定向、部分Cu与In的阳离子交换，将籽晶纳米晶体的一个面转化为CuInS。随后是纤锌矿CuInS的同质外延各向异性生长。CuS籽晶纳米晶体也作为牺牲性Cu源，因此，如果让反应进行到底，最终会得到单一组成的CuInS纳米棒。这项工作中开发的两阶段籽晶生长方法有助于合理合成具有目标结构的CuS/CuInS异质纳米晶体，因为它允许人们利用预制CuS籽晶纳米晶体的尺寸和晶面来指导CuInS段的生长。
