Two-dimensional (2D) magnets with intrinsic ferromagnetic/antiferromagnetic (FM/AFM) ordering are highly desirable for future spintronic devices. However, the direct growth of their crystals is in its infancy. Here we report a chemical vapor deposition approach to controllably grow layered tetragonal and non-layered hexagonal FeTe nanoplates with their thicknesses down to 3.6 and 2.8 nm, respectively. Moreover, transport measurements reveal these obtained FeTe nanoflakes show a thickness-dependent magnetic transition. Antiferromagnetic tetragonal FeTe with the Néel temperature ( T N ) gradually decreases from 70 to 45 K as the thickness declines from 32 to 5 nm. And ferromagnetic hexagonal FeTe is accompanied by a drop of the Curie temperature ( T C ) from 220 K (30 nm) to 170 K (4 nm). Theoretical calculations indicate that the ferromagnetic order in hexagonal FeTe is originated from its concomitant lattice distortion and Stoner instability. This study highlights its potential applications in future spintronic devices.

Rational design of noble metal catalysts with the potential to leverage efficiency is vital for industrial applications. Such an ultimate atom-utilization efficiency can be achieved when all noble metal atoms exclusively contribute to catalysis. Here, we demonstrate the fabrication of wafer-size amorphous PtSex film on SiO2 substate via a low-temperature amorphizing strategy, which offers single-atom-layer Pt catalysts with high atom-utilization efficiency (~26 wt%). This amorphous PtSex (1.2

Alloying 2D transition metal dichalcogenides has opened up new opportunities for bandgap engineering and phase control. Developing a simple and scalable synthetic route is therefore essential to explore the full potential of these alloys with tunable optical and electrical properties. Here, the direct synthesis of monolayer WTe2xS2(1−x) alloys via one‐step chemical vapor deposition (CVD) is demonstrated. The WTe2xS2(1−x) alloys exhibit two distinct phases (1H semiconducting and 1T ′ metallic) under different chemical compositions, which can be controlled by the ratio of chalcogen precursors as well as the H2 flow rate. Atomic‐resolution scanning transmission electron microscopy–annular dark field (STEM‐ADF) imaging reveals the atomic structure of as‐formed 1H and 1T ′ alloys. Unlike the commonly observed displacement of metal atoms in the 1T ′ phase, local displacement of Te atoms from original 1H lattice sites is discovered by combined STEM‐ADF imaging and ab initio molecular dynamics calculations. The structure distortion provides new insights into the structure formation of alloys. This generic synthetic approach is also demonstrated for other telluride‐based ternary monolayers such as WTe2xSe2(1−x) single crystals.

Novel 2D semiconductors play an increasingly important role in modern nanoelectronics and optoelectronics. Herein, a novel topology designer based on component fusion is introduced, featured by the submolecular component integration and properties inheritance. As expected, a new air-stable 2D semiconductor PdPSe with a tailored puckered structure is successfully designed and synthesized via this method. Notably, the monolayer of PdPSe is constructed by two sublayers via PP bonds, different from 2D typical transition metal materials with sandwich-structured monolayers. With the expected orthorhombic symmetry and intralayer puckering, PdPSe displays a strong Raman anisotropy. The field-effect transistors and photodetectors based on few-layer PdPSe demonstrate good electronic properties with high carrier mobility of ≈35 cm 2 V −1 s −1 and a high on/off ratio of 10 6 , as well as excellent optoelectronic performance, including high photoresponsivity, photogain, and detectivity with values up to 1.06 × 10 5 A W −1 , 2.47 × 10 7 %, and 4.84 × 10 10 Jones, respectively. These results make PdPSe a promising air-stable 2D semiconductor for various electronic and optoelectronic applications. This work suggests that the component-fusion-based topology designer is a novel approach to tailor 2D materials with expected structures and interesting properties.

The 2D transitional metal oxides/transition-metal dichalcogenides vertical heterostructures of MoO3–MoS2 are successfully synthesized on SiO2/Si substrates via one-step chemical vapor deposition process. The vertical MoO3–MoS2 heterostructures exhibit the average size of ∼20 μm and the thickness down to ∼10 nm. Moreover, the phototransistor device based on MoO3–MoS2 heterostructures presents responsivity of 5.41 × 103 A W−1, detectivity of 0.89 × 1010 Jones and external quantum efficiency of 1263.4%, respectively, under a 532 nm wavelength light. This study affords a new path to simplify process of fabricating MoO3–MoS2 vertical heterostructures for electronic and optoelectronic applications.