Electronic and surface structure engineering of oxygen vacancies-riched WO3 nanosheets toward highly efficient BTEX sensing

Abstract

Oxygen vacancies engineering is a promising strategy to develop high-performance benzene and its homologues chemiresistive gas sensors, however, the lack of insights into relationship between electronic and surface structure with sensing performance greatly hinder the design of materials with robust sensing behavior. Herein, the oxygen vacancies-riched WO3 nanosheets with individual defect coordination environment have been successfully synthesized by finely tuning the treating temperature. The electronic and surface structure engineering of WO3 can be systematically modulated, and the optimal d-band structure as well as surface oxygen species on H-WO3-500 NSs presents the superior BTEX sensing performance with ultrahigh response (Ra/Rg = 64.15, 50.54, 58.79 and 56.26 to 50 ppm ethylbenzene, benzene, toluene and xylene, respectively), outstanding reliability (σ = 0.1) and sensing stability (φ = 0.37%). The combination of experimental and theoretical results reveals that the surface oxygen vacancies of WO3 facilitate the activation of higher mobility surface O-(ad), O2-(ad) species and the upshift of d-band center of W compared with the bulk oxygen vacancies, endowing it with robust surface reaction and dramatically enhanced sensing performance. This work presents a new strategy for designing of highly efficient gas sensors for monitoring hazardous molecules.