Enhanced gas sensing properties of In2O3:Ag composite nanoparticle layers; electronic interaction, size and surface induced effects

For investigating the role of metal additives in enhancing the gas sensing response of an oxide semiconductor material, In2O3:Ag composite nanoparticle layers having well-defined individual (In2O3 and Ag) nanoparticle sizes and composition have been grown by a dip coating method using chemically grown nanoparticles as precursors. X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) have been used to characterize the composite nanoparticle layers. Gas sensing properties of the In2O3:Ag layers have been investigated as a function of Ag composition and ethanol concentration. The In2O3:Ag composite nanoparticle layer with 15% silver shows a higher sensor response of 436 and a short response time of 6 s to 1000 ppm ethanol at 400 °C, in comparison to an In2O3 nanoparticle layer. The proposed energy level diagram for the In2O3:Ag2O and In2O3:Ag interface explains the enhanced gas sensing response of the composite nanoparticle samples.