A facile nanocasting synthesis of mesoporous Ag-doped SnO2 nanostructures with enhanced humidity sensing performance

A class of fast response and highly sensitive relative humidity (RH) sensors were developed based on ordered mesoporous SnO2 and Ag/SnO2, which were synthesized via the nanocasting route by directly using mesoporous silica, SBA-15, as hard template. The negative replicated structure of mesoporous SnO2 could provide more channels for transmission of water molecules and charge carriers. Therefore, the nanocasted SnO2 exhibited high humidity sensing performance. The sensitivity of nanocasted mesoporous SnO2 increases 7.5 times than SnO2 synthesized using sodium dodecyl sulfate (SDS), an anionic surfactant. The sensitivity to humidity increased by 5.5 times after adding Ag nanoparticles to nanocasted SnO2. Additionally, the RH sensors show excellent performance with ultra-high sensitivity, fast response/recovery speed, a wide range of RH response, high stability, reversibility and selectivity towards a variety of volatile organic compounds (VOCs) at room temperature. This work could stimulate a right approach to the design of practical humidity sensors with high sensitivity, long stability and fast response. (C) 2015 Elsevier B.V. All rights reserved.