Enhanced Thermoelectric Figure-Of-Merit Of Mos2/Alpha-Moo3 Nanosheets Via Tuning Of Sulphur Vacancies

As a consequence of high thermoelectric (TE) properties, low cost, and environmental friendliness, molybdenum disulphide (MoS2) has emerged as the material of choice for TE generator for room temperature to mid temperature (800 K) applications. The compound has high figure-of-merit (zT) value due to the combination of anharmonicity, valley degeneracy and ultralow thermal conductivity (at low-dimension). In this work, MoS2/ MoO3 hierarchical structures are prepared by hydrothermal method and it exhibits improved TE performance. The enhanced phonon scattering is observed in thin layered nanosheets and improved electrical conductivity by zero-barrier charge injection at MoS2/MoO3 interface. While MoO3 supports in optimizing the electrical transport properties, low-dimension layered MoS2 nanosheets and interfaces of MoS2/MoO3 results in phonon scattering. High resolution transmission electron microscopy (HRTEM) indicates enriched interface of nanocrystals and nanosheets. This results in -97% increased electrical conductivity compared to the pristine MoS2 at 600 K while retaining -44% reduction in thermal conductivity at 550 K. More importantly, the phonon scattering and carrier optimization have been tailored strategically, and a relatively high power factor (PF) of 411.43 ?W m- 1 K-2 at 600 K with a significantly lowered thermal conductivity of 0.16 W m-1 K-1 at 550 K have been achieved. The maximum zT of 1.18 at 600 K is achieved for hierarchical MoS2 nanosheets/MoO3 nanocrystal?s optimized effective interface.