CoS₂ is considered to be a promising electrocatalyst for hydrogen evolution reaction (HER). However, its further widespread applications are hampered by the unsatisfactory activity due to relatively high chemisorption energy for hydrogen atom. Herein, theoretical predictions of first-principles calculations reveal that the introduction of a Cl-terminated MXenes-Ti₃CNCl₂ can significantly reduce the HER potential of CoS₂-based materials and the Ti₃CNCl₂@CoS₂ core–shell nanostructure has Gibbs free energy of hydrogen adsorption (|ΔG_H|) close to zero, much lower than that of the pristine CoS₂ and Ti₃CNCl₂. Inspired by the theoretical predictions, we have successfully fabricated a unique Ti₃CNCl₂@CoS₂ core–shell nanostructure by ingeniously coupling CoS₂ with a Cl-terminated MXenes-Ti₃CNCl₂. Interface-charge transfer between CoS₂ and Ti₃CNCl₂ results in a higher degree of electronic localization and a formation of chemical bonding. Thus, the Ti₃CNCl₂@CoS₂ core–shell nanostructure achieves a significant enhancement in HER activity compared to pristine CoS₂ and Ti₃CNCl₂. Theoretical calculations further confirm that the partial density of states of CoS₂ after hybridization becomes more non-localized, and easier to interact with hydrogen ions, thus boosting HER performance. In this work, the success of oriented experimental fabrication of high-efficiency Ti₃CNCl₂@CoS₂ electrocatalysts guided by theoretical predictions provides a powerful lead for the further strategic design and fabrication of efficient HER electrocatalysts.

Nowadays, realizing miniaturized nonlinear optical (NLO) device is crucial to meet the growing needs in on-chip nanophotonics as well as compact integrated devices. The strong optical nonlinearities, ultrafast photoexcitation dynamics, available exciton effects as well as without lattice matching make two-dimensional (2D) layered materials potential candidates for integrated and nano-scale NLO devices. Herein, a novel and inversion symmetry broken 2D layered SnP₂S₆ with strong second-harmonic and third-harmonic response has been reported for the first time. The second-order susceptibility (χ⁽²⁾) of SnP₂S₆ flakes can reach up to 4.06 × 10⁻⁹ m·V⁻¹ under 810 nm excitation wavelength, which is around 1–2 orders of magnitude higher than that of most reported 2D materials. In addition, the NLO response of 2D SnP₂S₆ can break through the limitation of odd/even layers and exhibit broadband spectral response. Moreover, since the second-harmonic signal is closely related to structure variation, the second-harmonic response in 2D SnP₂S₆ is extremely sensitive to polarization angle and temperature, which is beneficial to some specific applications. The excellent NLO response in 2D SnP₂S₆ provides a new arena for realizing miniaturized NLO devices in the future.

Searching for room temperature magnetic two-dimensional (2D) materials is a charming goal, but the number of satisfied materials is tiny. Strain can introduce considerable deformation into the lattice structure of 2D materials, and thus significantly modulate their intrinsic properties. In this work, we demonstrated a remarkable strain-modulated magnetic properties in the chemical vapor deposited Cr₂Te₃ nanoflakes grown on mica substrate. We found the Curie temperature of Cr₂Te₃ nanoflakes can be positively and negatively modulated under tensile and compressive strain respectively, with a maximum varied value of ~ 40 and −90 K, dependent on the thickness of samples. Besides, the coercive field of Cr₂Te₃ nanoflakes also showed a significant decrease under the applied strain, suggesting the decrease of exchange interaction or the change of the magnetization direction. This work suggests a promise to employ interfacial strain to accelerate the practical application of room temperature 2D magnetics.

Activating basal plane inert sites will endow MoTe₂ with prominent hydrogen evolution reaction (HER) catalytic capability and arouse a new family of HER catalysts. Herein, we fabricated single MoTe₂ sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies introducing. Through the extraction of electrical parameters of single MoTe₂ sheet, the in-plane and interlayer conductivities were optimized effectively by Te vacancies due to the defect levels. More deeply, Te vacancies can induce the delocalization of electrons around Mo atoms and shift the d-band center, as a consequence, facilitate the adsorption of H from the catalyst surface for HER catalysis. Benefiting by the coordinated regulation of band structure and local charge density, the overpotential at –10 mA∙cm⁻² was reduced to 0.32 V after Te vacancies compared to 0.41 V for the basal plane sites of same MoTe₂ nanosheet. Meanwhile, the insights gained from single nanosheet electrocatalytic microdevice can be applied to the improved HER of the commercial MoTe₂ power. That the in situ testing of the atomic structure-electrical behavior-electrochemical properties of a single nanosheet before/after vacancies introducing provides reliable insight to structure-activity relationships.

Infrared (IR) light photodetection based on two dimensional (2D) materials of proper bandgap has attracted increasing attention. However, the weak IR absorption in 2D materials, due to their ultrathin attribute and indirect bandgap in multilayer structures, degrades their performance when used as IR photodetectors. In this work, we utilize the fact that few-layer MoTe₂ flake has a near-IR (NIR) bandgap and demonstrate a ~ 60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface. Such gold hollow nanorods have distinct absorption peak located also at the NIR regime, therefore induces strong resonance, benefitting NIR absorption in MoTe₂, resulting in strong near-field enhancement. With the evidence from steady and transient state optical spectra, we confirm that the enhancement of NIR response originates only photon absorption, rather than electron transport at interfaces as observed in other heterostructures, therefore, precluding the requirement of high-quality interfaces for commercial applications.

Two dimensional (2D) nanomaterials are promising fundamental building blocks for use in the next-generation semiconductor industry due to their unique geometry and excellent (opto)-electronic properties. However, large scale high quality fabrication of 2D nanomaterials remains challenging. Thus, the development of controllable fabrication methods for 2D materials is essential for their future practical application. In this review, we will discuss the importance of the space-confined vapor deposition strategy in the controllable fabrication of 2D materials and summarize recent progress in the utilization of this strategy for the synthesis of novel materials or structures. Using this method, various high quality ultrathin 2D materials, including large-area graphene and boron nitride, ReS₂/ReSe₂, HfS₂, pyramid-structured multilayer MoS₂, and the topological insulators Bi₂Se₃ and Bi₂Te₃, have been successfully obtained. Additionally, by utilizing van der Waals epitaxy growth substrates such as mica or other 2D materials, patterned growth of 2D nanomaterials can be easily achieved via a surface-induced growth mechanism. Finally, we provide a short prospect for future development of this strategy.

Nickel cobalt sulfides (Ni-Co-S) have attracted extensive attention for application in electronic devices owing to their excellent conductivity and high electrochemical capacitance. To facilitate the large-scale practical application of Ni-Co-S, the excellent rate capability and cyclic stability of these compounds must be fully exploited. Thus, hierarchical Ni-Co-S@Ni-W-O (Ni-Co-S-W) core/shell hybrid nanosheet arrays on nickel foam were designed and synthesized herein via a facile three-step hydrothermal method, followed by annealing in a tubular furnace under argon atmosphere. The hybrid structure was directly assembled as a free-standing electrode, which exhibited a high specific capacitance of 1, 988 F·g^-1 at 2 A·g^-1 and retained an excellent capacitance of approximately 1, 500 F·g^-1 at 30 A·g^-1, which is superior to the performance of the pristine Ni-Co-S nanosheet electrode. The assembled asymmetric supercapacitors achieved high specific capacitance (155 F·g^-1 at 1 A·g^-1), electrochemical stability, and a high energy density of 55.1 W·h·kg^-1 at a power density of 799.8 W·kg^-1 with the optimized Ni-Co-S-W core/shell nanosheets as the positive electrode, activated carbon as the negative electrode, and 6 M KOH as the electrolyte.

High quality In₂S₃ kinks were synthesized via a kinetically controlled thermal deposition process and their optoelectronic characteristics were systematically explored. The growth mechanism was attributed to the combination of kinetic dynamic, crystal facial energy, and surface roughness. Two trap induced emission bands were evidenced via a low temperature cathodoluminescence (CL) study. Furthermore, the nanowire junctions demonstrated a degenerative photodetection performance, as compared to the straight arms, attributed to a stress-induced extra series resistance measured from the kinked area. The well-controllable shape of the inorganic nanostructures and the detailed exploration of their optoelectronic properties are particularly valuable for their further practical applications.