Morphology management for tailoring the properties of monolayer transition-metal dichalcogenides (TMDCs), that is, molybdenum disulfide (MoS), has attracted great interest for promising applications such as in electrocatalysis and optoelectronics. Nevertheless, little progress has been made in engineering the shape of MoS. Herein, we introduce a modified chemical vapor deposition method to grow monolayer MoS dendrites by pretreating substrates with adhesive tapes. The as-grown MoS crystals are featured with hexagonal backbones with fractal shapes and tunable degrees. By characterizing the atomic structure, it is found that these morphologies are mainly initiated from the twin defect derived growth and controlled by the S:Mo vapor ratio. Due to the accumulated sulfur vacancies in the cyclic twin regions, strong enhancement of photoluminescence emission is localized, which determines the shape dependency of optical property. This work not only enriches the understanding of the twin defects derived crystal growth mechanism and extends its applications from nanomaterials to two-dimensional crystals, but also offers a robust and controllable protocol for shape-engineered monolayer TMDCs in electrochemical and optoelectronic applications.

This work reports an experimental study on an antiferromagnetic honeycomb lattice of MnPS that couples the valley degree of freedom to a macroscopic antiferromagnetic order. The crystal structure of MnPS is identified by high-resolution scanning transmission electron microscopy. Layer-dependent angle-resolved polarized Raman fingerprints of the MnPS crystal are obtained, and the Raman peak at 383 cm exhibits 100% polarity. Temperature dependences of anisotropic magnetic susceptibility of the MnPS crystal are measured in a superconducting quantum interference device. Anisotropic behaviors of the magnetic moment are explored on the basis of the mean field approximation model. Ambipolar electronic conducting channels in MnPS are realized by the liquid gating technique. The conducting channel of MnPS offers a platform for exploring the spin/valleytronics and magnetic orders in 2D limitation.

Actuators that convert other forms of energy to mechanical energy have attracted extensive interest for their critical applications in microelectromechanical systems and miniature robotics. Recently, it is discovered that vanadium dioxide (VO 2 )-based microscale bimorph actuators demonstrate comprehensive superiority of actuation performances, taking the good of the giant theoretical power density (7 J cm −3 ) and ultrafast response (∼picosecond) of crystalline VO 2 , while they still suffer from the intrinsic shortcomings of complex structures. Here, "single-crystalline VO 2 actuators" (SCVAs) that have unique self-bending behavior upon temperature change are reported. This is realized by facilely and precisely controlling the phase structures via lateral stoichiometry-engineering in VO 2 nanobeams at the nanoscale level. These SCVAs exhibit remarkable actuation performances and admirable stability, which are equivalent or even superior to the reported VO 2 -based conventional bimorph actuators. It is noteworthy that the gradual, reversible, and predictable bending of SCVAs enables a precise actuation control of related mechanics, such as the quantitative wind detector and thermal micromechanical claw. This work demonstrates the possibility of this strategy to enable single crystalline actuators excellent performance by internally lateral and gradual strain-engineering.