Structure modulation induced enhancement of microwave absorption in WS2 nanosheets

Abstract

This work reports the structural phase manipulation and the enhancement of microwave absorption in WS2 nanosheets. Large-scale WS2 nanosheets (1T@2H WS2) containing mixed 2H and 1T phases were synthesized by a simple hydrothermal process. The structural characteristics and concentration (∼60%) of the 1T phase in 1T@2H WS2 nanosheets were identified by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. With the emergence of the 1T phase, the permittivity of 1T@2H WS2 is more than three times higher than that of WS2 with a pure 2H phase (2H WS2). Moreover, the microwave absorption properties were remarkably enhanced due to the emergence of the 1T phase. Contrary to 2H WS2, in which microwave reflection loss (RL) is close to zero, the RL for 1T@2H WS2 can reach −47 dB with an effective bandwidth (<−10 dB) of 5.2 GHz. In addition, with the adjustment of the thickness of the absorber layer from 1.5 to 5 mm, 1T@2H WS2 can achieve strong absorption in a wide band from 4 to 18 GHz. This finding provides an effective strategy for designing and synthesizing the microwave absorption materials.

Work Function Tunability of Graphene with Thermally Evaporated Rhenium Heptoxide for Transparent Electrode Applications

“…Innovative solutions in modern electronics are mostly based on applications of new types of materials. [1][2][3][4][5][6][7] Graphene, a monolayer thick allotrope of carbon, is a 2D material, which shows mechanical flexibility and very high mobility of charge carriers complemented by unusual optical transparency in the range of visible light. [8][9][10][11][12] It is believed that graphene can serve as a conducting transparent electrode in organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs) [13][14][15][16][17][18][19][20][21][22] due to its low resistance below 50 Ω □ À1 and optical transmittance of at least 90%.…”

“…Innovative solutions in modern electronics are mostly based on applications of new types of materials . Graphene, a monolayer thick allotrope of carbon, is a 2D material, which shows mechanical flexibility and very high mobility of charge carriers complemented by unusual optical transparency in the range of visible light .…”

Phase Manipulating toward Molybdenum Disulfide for Optimizing Electromagnetic Wave Absorbing in Gigahertz

“…[ 11a,e 4c,12 ] Several studies have provided evidences that the 1T phase has a beneficial effect for achieving better EMW attenuation of TMDs compared to its semiconducting counterpart (2H‐MoS 2 ). [ 5,9b,13 ] The recent work reported by Che et al. found that the unique crystalline phase switch between 2H and 1T phase in rose‐like 1T@2H‐MoS 2 /rGO composites was considered to ameliorate the related EMW absorbing performance.…”

“…[ 9b ] Our previous work also verified that the MoS 2 and WS 2 with moderate content of metallic 1T phase endow the advantages of boosting the EMW absorbing performance over that of pure 2H‐MoS 2 . [ 5,13 ] In view of the superior properties of 1T phase of TMDs, one can expect that the phase manipulating toward MoS 2 (i.e., tuning the 2H/1T phase ratio inside) would be an effective strategy to boost the EMW absorbing performance by the synergistic effect of phase interfaces manipulation and large 2D specific surface area. [ 11b,14 ] Nevertheless, three major challenges standing in front of the researchers: i) how to obtain the stable 1T phase regardless of its intrinsic metastable properties; ii) the MoS 2 with 2H and 1T phases should be synthesized in a manner that results in high interface defect density; and iii) the phase ratio should be easily manipulated for the purpose of tuning the dielectric and related EMW attenuation performance.…”

“…[ 11b,14 ] Nevertheless, three major challenges standing in front of the researchers: i) how to obtain the stable 1T phase regardless of its intrinsic metastable properties; ii) the MoS 2 with 2H and 1T phases should be synthesized in a manner that results in high interface defect density; and iii) the phase ratio should be easily manipulated for the purpose of tuning the dielectric and related EMW attenuation performance. [ 13,14 ] Unfortunately, to the best of our knowledge, the research on the relation between the gradually tuned phase composition and the corresponding EMW absorbing performance of TMDs are rarely reported and little has been done to explicitly unravel the underlying EMW attenuation mechanisms involved.…”