Low-Temperature Alloying Mechanism in Magic Size Clusters: A Pathway toward Alloy Nanocrystal Synthesis.

The non-classical nucleation process achieves controlled growth of nanomaterials at low temperatures by reducing energy barriers in stages. However, the synthesis of alloys remains challenging due to thermodynamic limitations and the unclear critical steps in the nonclassical nucleation process, often resulting in insufficient reaction driving forces and difficulties in compositional control. In this study, a covalent inorganic complex (CIC)-mediated alloying mechanism is proposed, which enables precise bonding control through ion-exchange reactions in the pre-nucleation stage at room temperature. The process involves the formation of CICs (Step 1), the regulation of alloy CICs (Step 2), and the directional assembly of alloyed CICs (Step 3). Step 2 plays a pivotal role as the composition-determining step, which results in the successful modulation of a series of binary-cation (ZnCdSe), binary-anion (CdSeS), and quaternary (ZnCdSeS) alloy CICs. Step 3 governs the size and morphology of the final alloy materials, facilitating the directed assembly of diverse alloy clusters (MSCs), quantum dots (QDs), and nanoplatelets (NPLs). This work not only advances the understanding of nonclassical nucleation processes but also offers a universal regulation strategy for alloy materials, providing a powerful tool for next-generation semiconductor design.