Agx@WO3 core-shell nanostructure for LSP enhanced chemical sensors

Abstract

Exceptional properties of graphene have triggered intensive research on other 2D materials. Surface plasmon is another subject being actively explored for many applications. Herein we report a new class of core-shell nanostructure in which the shell is made of a 2Dmaterial for effective plasmonic propagation. We have designed a much enhanced chemical sensor made of plasmonic AgxAT(2D-WO3) that combines above advantages. Specifically, the sensor response increases from 38 for Agx-WO3 mixture to 217 for the AgxAT(2D-WO3) core-shell structure; response and recovery time are shortened considerably to 2 and 5 seconds; and optimum sensor working temperature is lowered from 370°C to 340°C. Light irradiation is found to increase the AgxAT(2D-WO3) sensor response, particularly at blue wavelength where it resonates with the absorption of Ag nanoparticles. Raman scattering shows significantly enhanced intensity for both the 2D-WO3 shell and surface adsorbates. Both the resonance sensor enhancement and the Raman suggest that the improved sensor performance is due to nanoplasmonic mechanism. It is demonstrated that (1) 2D material can be used as the shell component of a core-shell nanostructure, and (2) surface plasmon can effectively boost sensor performance.