Monolayer and/or atomically thin transition metal dichalcogenides cover a wide range of two-dimensional (2D) materials, whose fascinating semiconducting and optical properties have made them promising candidate materials for optoelectronic devices. Controllable growth of these materials is critical for their device applications. By using MoCl and HS as precursors, monolayer and ultrathin molybdenum disulfide (MoS) films with controlled lamellar structure have been directly built layer by layer on SiO substrates without being followed by high-temperature annealing. Furthermore, the thickness of MoS films can be precisely regulated by applying different atomic layer deposition (ALD) cycles. Once an ALD cycle is applied, one molecular layer of MoS material will be 'added' on the substrate or original existing MoS films. At the initial stage (one to three ALD cycles), the density of MoS materials increases with an increase in ALD cycles, while a large area of continuous MoS film on the substrate can be obtained when four or more ALD cycles are applied. In this way, excellent triangular crystals of MoS with controlled atomic size in thickness and a highly oriented hexagonal crystal structures can be obtained by applying definite ALD cycles.
As a kind of specially modified chemical vapor deposition (CVD), atomic layer deposition (ALD) has long been used to fabricate thin films. The self-limiting reaction of ALD endows the films with excellent uniformity and precise controllability. The thickness of the films obtained by ALD can be controlled in an atomic scale (0.1 nm) on a large-area substrate even with complex structures. Therefore, it has recently been employed to produce the two-dimensional (2D) materials like MoS 2 . In this mini-review, the research progress in ALD MoS 2 is firstly summarized. Then the influences of precursors, substrates, temperature, and post-annealing treatment on the quality of ALD-MoS 2 are presented. Moreover, the applications of the obtained MoS 2 as an electrochemical catalysator are also described. Besides the perspective on the research of ALD of MoS 2 , the remaining challenges and promising potentials are also pointed out.
Cell penetrating peptides (CPPs) are commonly utilized for intracellular delivery of functional materials to circumvent biomembrane barrier. However, further application of CPPs is hindered by lacking selectivity toward targeted cells. The spider venom peptide, lycosin-I, is a CPP with potent cytotoxicity to cancer cells, which might enable lycosin-I to deliver functional materials into cancer cells selectively. In this study, we demonstrated that the lycosin-I-conjugated spherical gold nanoparticles (LGNPs) not only exhibited efficient cellular internalization efficiency toward cancer cells but also displayed unprecedented selectivity over noncancerous cells. Although LGNPs were removed from the living circulatory system via reticuloendothelial system-dominant clearance modes without noticeable adverse effects to animals, they actually displayed active tumor-targeting effects and efficient accumulation in tumors in vivo. Furthermore, the potential application of this platform for cancer therapy was explored by lycosin-I-conjugated gold nanorods (LGNRs). LGNRs exhibited selective intracellular translocation towards cancer cells and efficient photothermal effect under near infrared (NIR, 808 nm) irradiation, which consequently killed cancer cells in vitro and in vivo effectively. Therefore, the established LGNPs and LGNRs possessed great potential in cancer-targeting delivery and photothermal therapy.
Electrochemical water splitting into H 2 and O 2 has attracted wide attention owing to the urgent need for clean and renewable energy sources. However, the scarcity and high-cost limit the large-scale application of noble metal catalysts such as IrO 2 and RuO 2 . In this work, as a lowcost catalyst for the electrochemical O 2 evolution reaction (OER), MoS 2 nanoflakes were obtained by atomic layer deposition (ALD) using MoCl 5 and H 2 S on carbon fiber paper surface. According to the results of electrochemical measurements, the MoS 2 nanoflakes exhibit an excellent catalytic activity, and the activity can be modulated by controlling the density and the internal resistance of MoS 2 nanoflakes. Moreover, the plasma treatment can further improve the activity of MoS 2 nanoflakes, and the reason was discussed through the measurements of contact angle, electrochemical impedance spectroscopy, and electrochemically active surface area. The MoS 2 nanoflakes obtained by ALD possess huge values for electrochemical OER as a catalyst.
The sodium channels Na v 1.7, Na v 1.8 and Na v 1.9 are critical for pain perception in peripheral nociceptors. Loss of function of Na v 1.7 leads to congenital insensitivity to pain in humans. Here we show that the spider peptide toxin called HpTx1, first identified as an inhibitor of K v 4.2, restores nociception in Na v 1.7 knockout (Na v 1.7-KO) mice by enhancing the excitability of dorsal root ganglion neurons. HpTx1 inhibits Na v 1.7 and activates Na v 1.9 but does not affect Na v 1.8. This toxin produces pain in wild-type (WT) and Na v 1.7-KO mice, and attenuates nociception in Na v 1.9-KO mice, but has no effect in Na v 1.8-KO mice. These data indicate that HpTx1-induced hypersensitivity is mediated by Na v 1.9 activation and offers pharmacological insight into the relationship of the three Na v channels in pain signalling.
As a member of transition metal dichalcogenides, MoS2 is an ideal low-dimensional piezoelectric material, which makes it attract wide attention for potential usage in next generation piezoelectric devices. In this study, the size-dependent piezoelectricity of MoS2 films with different grain sizes obtained at different temperatures by atomic layer deposition (ALD) was determined, which indicates that the grain size is critical to the piezoelectric constant. When the grain size is less than 120 nm, the piezoelectric constant increases with the increase in the grain size. Moreover, the piezoelectric constant first increases and then decreases with the increase in the film thickness. Therefore, piezoelectric constants of these MoS2 films can be modulated by changing the growth temperature and applying different ALD cycles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.