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Mono‐ to few‐layers of 2D semiconducting materials have uniquely inherent optical, electronic, and magnetic properties that make them ideal for probing fundamental scientific phenomena up to the 2D quantum limit and exploring their emerging technological applications. This Review focuses on the fundamental optoelectronic studies and potential applications of in‐plane isotropic/anisotropic 2D semiconducting heterostructures. Strong light–matter interaction, reduced dimensionality, and dielectric screening in mono‐ to few‐layers of 2D semiconducting materials result in strong many‐body interactions, leading to the formation of robust quasiparticles such as excitons, trions, and biexcitons. An in‐plane isotropic nature leads to the quasi‐2D particles, whereas, an anisotropic nature leads to quasi‐1D particles. Hence, in‐plane isotropic/anisotropic 2D heterostructures lead to the formation of quasi‐1D/2D particle systems allowing for the manipulation of high binding energy quasi‐1D particle populations for use in a wide variety of applications. This Review emphasizes an exciting 1D–2D particles dynamic in such heterostructures and their potential for high‐performance photoemitters and exciton–polariton lasers. Moreover, their scopes are also broadened in thermoelectricity, piezoelectricity, photostriction, energy storage, hydrogen evolution reactions, and chemical sensor fields. The unique in‐plane isotropic/anisotropic 2D heterostructures may open the possibility of engineering smart devices in the nanodomain with complex opto‐electromechanical functions.

By one-step assembly with mesoporous silica, different amounts of EmimBr were dispersed and confined for boosting CO2 conversion into cyclic carbonates.

Different from layered two-dimensional (2D) transition metal dichalcogenides (TMDs), iron dichalcogenides crystallize in the most common three-dimensional pyrite or marcasite structures. Layered iron dichalcogenides are rarely reported and little is known about their structures and properties. Here, layered hexagonal phase iron ditelluride FeTe2 (h-FeTe2) nanocrystals are grown on mica by atmospheric pressure chemical vapor deposition (APCVD) method and are fully characterized by various methods. Like other 2D layered TMD materials, the FeTe2 nanoflakes exhibit regular hexagon, half hexagon, or triangle shapes with a controllable thickness of 6–95 nm and lateral length from a few to tens of micrometers. A simple and effective method is used to transfer the FeTe2 nanoflakes from the mica substrate onto any other substrates without quality deterioration by using polystyrene (PS) as a support polymer, which can also be operated in ethanol or ethylene glycol in a glovebox to avoid contact with water and air. Temperature-dependent electrical transport demonstrates that the FeTe2 nanoflake is a semiconductor with a variable range hopping (VRH) conduction, and its nonsaturated linear magnetoresistance (MR) reaches up to 10.4% under magnetic field of 9 T at 2 K, both probably due to its structure disorders. No signature of magnetic ordering is observed down to 2 K. The CVD growth of this layered FeTe2 represents an addition to the extensive library of 2D materials, particularly iron chalcogenides or alloys. Synthesis, properties, and even doping of phase pure h-FeTe2 call for further study in the future.

Recently, ferromagnetism observed in monolayer two-dimensional (2D) materials has attracted attention due to the promise of its application in next-generation spintronics. Here, we predict a symmetry-breaking phase in 2D FeTe2 that differs from conventional transition metal ditellurides shows superior stability and room-temperature ferromagnetism. Through density functional theory calculations, we find the exchange interactions in FeTe2 consist of short-range superexchange and long-range oscillatory exchanges mediated by itinerant electrons. For six nearest neighbors, the exchange constants are calculated to be 50.95, 33.41, 2.70, 11.02, 14.46, and −4.12 meV. Furthermore, the strong relativistic effects on Te2+ induce giant out-of-plane exchange anisotropy and open up a significantly large spin wave gap (ΔSW) of 1.22 meV. All of this leads to robust ferromagnetism with the T c surpassing 423 K, which is predicted by the renormalization group Monte Carlo method, sufficiently higher than room temperature. Our findings shed light on the promising future of FeTe2 in 2D magnetic research and spintronic applications.

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