Room-temperature formation of alloy ZnxCd13-xSe13 magic-size clusters via cation exchange in diamine solution

Ion exchange in semiconductor magic-size clusters

As a crucial post-synthesis method, ion exchange allows for precise control over the composition, interface, and morphology of nanocrystals at the atomic scale, achieving material properties that are difficult to obtain with traditional synthesis techniques. In nanomaterial science, semiconductor magic-size clusters (MSCs), with their atomic-level precision and unique quantum confinement effects, serve as a bridge between molecules and nanocrystals. Despite this, research on ion exchange in MSCs is still in its infancy. This review introduces the principles of ion exchange and reactions in colloidal nanocrystals and MSCs, analyzing the importance and challenges of ion exchange in studying MSCs. This paper begins with a focus on the current research progress of cation and anion exchange in II-VI and III-V semiconductor MSCs. Then, the common methods for characterizing MSCs during the ion exchange process are discussed. Finally, the article envisions future research directions based on MSCs' ion exchange. Research on MSCs' ion exchange not only aids in designing MSCs with complex functionalities, but also plays an essential role in elucidating the ion exchange mechanisms in nanocrystals, providing new insights for the innovative design and synthesis of nanomaterials.

Synthesis and Modulation of Low-Dimensional Transition Metal Chalcogenide Materials via Atomic Substitution

In recent years, low-dimensional transition metal chalcogenide (TMC) materials have garnered growing research attention due to their superior electronic, optical, and catalytic properties compared to their bulk counterparts. The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications. In this context, the atomic substitution method has emerged as a favorable approach. It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely, crystal structures, and inherent properties of the resulting materials. In this review, we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional, one-dimensional and two-dimensional TMC materials. The effects of substituting elements, substitution ratios, and substitution positions on the structures and morphologies of resulting material are discussed. The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided, emphasizing the role of atomic substitution in achieving these advancements. Finally, challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.

CdTe magic-size cluster synthesis via a cation exchange method and conversion mechanism

The quasi-metallic nature of Te is not conducive to telluride formation and crystallization, which makes the synthesis of CdTe magic-size clusters (MSCs) in a single-ensemble form still challenging. CdTe MSCs are usually synthesized by direct synthesis, a method that must avoid the formation of quantum dots by selecting suitable active precursors and precisely controlling the reaction temperature. In addition, the organic Cd compounds and superhydrogenated precursors used are air-sensitive. Herein, CdTe MSC-448 in a single-ensemble form was synthesized for the first time via a cation exchange method using ZnTe MSC-389 as a template and Cd2+ as an exchange ion. In situ absorption spectroscopy characterization combined with the two-pathway model proposed by Yu's group reveals that the conversion of ZnTe MSC-389 into CdTe MSC-448 is assisted by their corresponding precursor compounds (PCs). After the addition of Cd precursors to ZnTe MSC-389 solution, ZnTe MSC-389 is transformed into ZnTe PC-389, which then undergoes a rapid cation exchange reaction with Cd2+ to yield CdTe PC-448, and CdTe PC-448 is finally converted into CdTe MSC-448. CdTe MSCs in single-ensemble form were obtained by cation exchange in air at room temperature, avoiding the formation of quantum dots (QDs) at high temperatures in the direct synthesis method conducted without the use of toxic and expensive active precursors, which provides a new route to the synthesis of CdTe MSCs.