Regulable switching from p- to n-type behavior of ordered nanoporous Pt-SnO2 thin films with enhanced room temperature toluene sensing performance

Abstract

Gas sensing with ordered nanoporous materials is achieving much attention because of its promising capability of detecting toxic gases at room temperature. In this work, an ordered nanoporous Pt-SnO₂ sensing film is fabricated in situ on a sensing device using a block polymer template and is applied as a chemiresistive toluene gas sensor. Post synthetic hydrothermal treatment was developed for the synthesis of the ordered Pt-SnO₂ sensing films with homogeneous and controlled film thickness and controllable pore size. The structure, crystallinity and composition of the ordered nanoporous Pt-SnO₂ thin films are characterized by HRTEM, FESEM, SAED, and STEM. Interestingly, the Pt-SnO₂ nanoporous film, an n-type material, presents tunable sensing behaviour with switching from p- to n-type toluene sensing performance as a function of the platinum content and calcination temperature. The ordered nanoporous sensing film is capable of detecting low levels of toluene, as low as 10 ppm, at room temperature, and shows good stability. Furthermore, a transition diagram has been created on the basis of the toluene sensing response, which can be used to design the p–n transitions.