Mo_xW_x–1S₂ Nanotubes for Advanced Field Emission Application

Abstract

Transition metal dichalcogenide (TMDC) nanotubes complement the field of low‐dimensional materials with their quasi‐1D morphology and a wide set of intriguing properties. By introducing different transition metals into the crystal structure, their properties can be tailored for specific purpose and applications. Herein, the characterization and a subsequent preparation of single‐nanotube field emission devices of MoxWx‐1S2 nanotubes prepared via the chemical vapor transport reaction is presented. Energy‐dispersive X‐ray spectroscopy, Raman spectroscopy, and X‐ray diffraction indicate that the molybdenum and tungsten atoms are randomly distributed within the crystal structure and that the material is highly crystalline. High resolution transmission electron microscopy and electron diffraction (ED) patterns further corroborate these findings. A detailed analysis of the ED patterns from an eight‐layer nanotube reveal that the nanotubes grow in the 2H structure, with each shell consists of one bilayer. The work function of the nanotubes is comparable to that of pure MoS2 and lower of pure WS2 NTs, making them ideal candidates for field emission applications. Two devices with different geometrical setup are prepared and tested as field emitters, showing promising results for single nanotube field emission applications.

Synergistic Effect of Spark Plasma Sintering Driven Solid-Solution Phases on Scratch Resistance in Two-Dimensional Materials

“…Analogous to XRD results, peaks corresponding to new phases, namely B 4 C, BCN, and solid-solution (Mo, W)S 2 were apparent. The peaks for each of these phases, such as B 4 C, BCN, and (Mo, W)S 2 marked in Figure 5b, are in good agreement with those reported in the literature [55][56][57]. As a complementary approach for phase identification, Raman spectroscopy studies were performed on the received, BM and CM powders as well as the SPS-processed (see Figure 5).…”

Au Nanoparticles on Two-Dimensional MoWS2 as Highly Sensitive Surface-Enhanced Raman Spectroscopy Substrates for Adenine Detection

“…As shown in Figure c, the Raman peaks at 347.5 and 375.9 cm –1 of MoWS 2 correspond to in-plane vibrations of W and S atoms (WS 2 -like E 12g) and Mo and S atoms (MoS 2 -like E 12g), respectively . In addition, due to the D6h point group of the MoWS 2 alloy, only the out-of-plane vibration mode of A 1g at 407.7 cm –1 is observed . After decorating with AuNPs, two E 12g vibration modes of sample S 3:3 were blue-shifted by ∼5 cm –1 compared to sample S 0:0 without AuNPs, while the out-of-plane vibration mode of A 1g was only blue-shifted by ∼2 cm –1 .…”

Supersensitive and Broadband Photodetectors Based on High Concentration of Er3+/Yb3+ Co‐doped WS2 Monolayer

“…The peaks of in-plane vibration (E 2g ) and out-of-plane vibration (A 1g ) modes located at 350.8 cm −1 and 416.9 cm −1 are observed, respectively, which are consistent with the monolayer WS 2 . [35][36][37][38][39] It is to be noted that the A 1g peak is shifted from 416.9 (pristine WS 2 ) to 418.7 cm −1 (WS 2 (Er/Yb)), which could be attributed to the Er 3+ /Yb 3+ ions doping. [21] In addition, the Raman peak intensities of the WS 2 (Er/Yb) are approximately 2.5 times enhanced compared with those of the pristine WS 2 , implying the more active molecular vibration of WS 2 (Er/Yb).…”