Transition metal dichalcogenides (TMDs) are a promising class of layered materials in the post-graphene era, with extensive research attention due to their diverse alternative elements and fascinating semiconductor behavior. Binary MX₂ layers with different metal and/or chalcogen elements have similar structural parameters but varied optoelectronic properties, providing opportunities for atomically substitutional engineering via partial alteration of metal or/and chalcogenide atoms to produce ternary or quaternary TMDs. The resulting multinary TMD layers still maintain structural integrity and homogeneity while achieving tunable (opto)electronic properties across a full range of composition with arbitrary ratios of introduced metal or chalcogen to original counterparts (0–100%). Atomic substitution in TMD layers offers new adjustable degrees of freedom for tailoring crystal phase, band alignment/structure, carrier density, and surface reactive activity, enabling novel and promising applications. This review comprehensively elaborates on atomically substitutional engineering in TMD layers, including theoretical foundations, synthetic strategies, tailored properties, and superior applications. The emerging type of ternary TMDs, Janus TMDs, is presented specifically to highlight their typical compounds, fabrication methods, and potential applications. Finally, opportunities and challenges for further development of multinary TMDs are envisioned to expedite the evolution of this pivotal field.

The impact of the size effect on the color and photoluminescence (PL) of quantum dots (QDs) has sparked a revolutionary field of research, culminating in the prestigious Nobel Prize in 2023. Prior to their widespread popularization and large-scale commercialization, it is of paramount importance to effectively manipulate and optimize their optical properties. In this review, we place specific emphasis on the striking correlation between the optical characteristics of QDs and their size, structure, composition, and interface environment. We commence by tracing the evolution of quantum dot technology and subsequently categorizing QDs while outlining their typical synthesis methods. This is followed by a deep dive into the pivotal roles of size, composition, structure, and interfacial ligands in fine-tuning, optimizing, and enhancing the optical properties of QDs. Additionally, we illustrate the luminescence enhancement and charge transfer phenomena stemming from the heterojunction between semiconductor QDs and metal nanomaterials, which contribute to improved performance. Lastly, we introduce the burgeoning field of chiral QDs and their innovative applications. Armed with this knowledge, QDs can be readily tailored to exhibit adjustable luminous characteristics across the entire spectrum, boasting high luminous efficiency through multifaceted regulation. These advancements render QDs even more enticing and promising for a wide array of applications.

Compositionally tuned hybridization of n-type Ag⁰ : Ag₂Se is achieved under ambient conditions via an aqueous synthetic approach in the absence of surfactants towards excellent thermoelectric properties at room temperature.