Structure modulation induced enhancement of microwave absorption in WS2 nanosheets

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.