Regulating the electronic status on open WO2.83 surfaces for ultrasensitive H2S sensors

Abstract

Engineering open nanostructures with regulable surface electron status possess great potential to increase gas-sensing performance of metal oxide semiconductor. Here, we develop a mesoporous tungsten oxide with special non-stoichiometric nature and double-activated surface electron status to realize ultralow-concentration detection of hydrogen sulfide. We found that the ordered mesoporous framework plays a crucial role in inducing the kinetic evolution to selectively form fixed non-stoichiometric meso-WO2.83 crystal, while the bulk-WO3 trends to lead the formation of bulk-WO2.9 or bulk-WO2.72 crystal. Impressively, the meso-WO2.83 crystal and co-existing oxygen defects exhibit obviously enhanced surface electron resonance and delocalization, thus leading a marked localized surface plasmon resonance (LSPR) effect. Further theoretical and experimental results confirm that the LSPR effect and oxygen defects endow special surface electron status to markedly improve the adsorption and electron transfer process of H2S molecules. The as-obtained meso-WO2.83 based MEMS sensors exhibit superior sensitivity, rapid response (<7 s), and ultralow detection limit of 5 ppb H2S. Our proposed strategy of open nanostructures with regulable surface electron status may create a new path to design fast and highly-effective H2S detection.