No abstract

No abstract

The materials with high electrical conductivity σ and low thermal conductivity κ are the driving force for an efficient thermoelectric device. In general, electrical and thermal conductivity cannot be controlled independently as both electron and phonon participate in transport processes. Two dimensional layered materials are one such kind where van der Waals inter-layer interaction and covalent intra-layer bond favours strong phonon mediated electronic interaction. Here, we report that the substitutional p-type doping of WSe2 demonstrate negative correlation between σ and κ at wide temperature range from 5–300 K. Nominal 0.5% Nb doping of WSe2 (WSe2:Nb) increases the electrical conductivity by an order of magnitude and suppresses the thermal conductivity by the same magnitude. The formation of impurity band at close proximity (0.2 meV) of valance band display large delocalized carrier density and temperature independent mobility as compared to the undoped sample. Simultaneously, the strong delocalization of degenerate band impurity is also found to lower the thermal conductivity to 6 W m−1 K−1 at 300 K.

No abstract

Transition metal oxide has emerged as one of the most potential candidates for environment remediation by utilizing solar energy through photocatalysis. This study compares the optical characteristics of zinc oxide (ZnO) and ceria‐doped zinc oxide (CeZnO) nanoparticles synthesized through a facile chemical precipitation method without using any assistant catalyst. The present work investigates the consequences of ceria (cerium dioxide, CeO2) intrusion on the photocatalytic activity of ZnO nanoparticles using methylene blue (MB) as a probe pollutant. The CeZnO showed an increase in photoactivity when compared to ZnO nanoparticles for degradation of MB in an aqueous solution under ultraviolet (UV) irradiance. The resulting heterojunction between ZnO and that of ceria enhances the charge separation efficiency showing a strong correlation between ZnO and CeO2 heterojunction on the charge transfer mechanism across the interface.