Ligand evolution in cadmium sulfide nanoclusters: tailoring surface coordination for atomic precision

Cadmium sulfide (CdS) nanoclusters, as an important member of the II-VI group of semiconductor nanomaterials, have a wide range of applications in the fields of optoelectronic devices, luminescence, sensing and self-assembly. The surface coordination chemistry of CdS nanoclusters plays a pivotal role in dictating their synthesis, stability, and properties. In this paper, we summarize the research progress in CdS nanoclusters in terms of both surface coordination chemistry and synthesis strategies. At the level of surface coordination chemistry, comprehensive and systematic research on carboxylate ligands has thoroughly elucidated their coordination modes, types, and dynamic behavior on the surfaces of CdS/CdSe nanocrystals. In contrast, for CdS nanoclusters driven by ligands such as carboxylates, thiols, iodines and phosphines, the research focuses on their core structure, and the interaction mechanism between the core and the ligand of CdS clusters has been elucidated. These studies indicate that the final structure of CdS nanoclusters is determined not only by the arrangement of their core atoms but also by the type of surface ligand and coordination mode. In terms of synthesis strategies, this review systematically analyzes solvothermal, high-temperature, ion-exchange, and two-step synthesis schemes from two major types of thiol and non-thiol ligands. The importance of ligand selection and fine-tuning of experimental conditions in achieving structurally precise CdS nanocluster preparation is highlighted. Finally, the paper looks at the core challenges and opportunities for future development in this field, aiming to provide guidance for the in-depth exploration and functionalization of CdS nanoclusters.