High-entropy structure design of transition metal dichalcogenides for improved electromagnetic wave absorption performance†

Abstract

Transition metal dichalcogenides (TMDs) have attracted great attention owing to their unique properties and wide range of applications. The versatile composition and tunable phase structure provide a larger potential to explore TMDs with unprecedented properties. In this work, a simple model based on the Hume-Rothery rules was proposed to predict the formation possibility of TMDs containing multiple transition metal elements. Several predicted high-entropy TMDs, e.g. (Ti_0.25V_0.25Cr_0.25Nb_0.25)S₂ and (Ti_0.2V_0.2Cr_0.2Nb_0.2Ta_0.2)S₂, were synthesized through a solid-phase reaction route. The high-entropy solid solution of the M-site element resulted in an atomic-scale ordered/disordered stacking structure of the TMD crystals, which enhanced the dipole polarization. The multiple M-site elements induced 1T/2H phase transition within the TMDs sheets, which enhanced the interfacial polarization. These two factors significantly enhanced the dielectric loss of the high-entropy TMDs, particularly endowing (Ti_0.25V_0.25Cr_0.25Nb_0.25)S₂ with exceptional electromagnetic wave absorption capabilities. The maximum reflection loss of (Ti_0.25V_0.25Cr_0.25Nb_0.25)S₂ reached −60.31 dB, and the effective absorption bandwidth was 2.31 GHz at the 8.2–12.4 GHz band. Thus, this study demonstrates great potential for tuning the properties and broadening the applications of TMDs through high-entropy structure design.