The gas sensing characteristics of pure and 0.4-2.0 at% Ni-loaded SnO 2 nanoparticles have been measured in dry and humid atmospheres. Approximately the same response to 50 ppm CO, response/recovery kinetics, and resistance in air regardless of wide range of humidity variation from dry to 80% r.h. have been accomplished by loading 1.0 and 2.0 at% Ni to SnO2. The role of Ni related surface species in the decrease of humidity dependence of gas sensing characteristics has been elucidated by diffuse-reflectance Fourier transform IR spectroscopy. The work function values determined from the transient of sensor resistance and contact potential difference revealed that Ni loading to SnO2 determines the appearance of surface electron acceptors responsible for a significant upward energy bands bending even in N2 atmosphere (>0.5 eV), and, ultimately, explains the significant increase of the sensors baseline resistance and the decrease of the sensor signals. In this way, the origins of the ambivalent effect of Ni loading are clarified and the way towards a rational optimization of the sensor performance opened.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) ( No. R0A-2008-000-20032-0 ).
Copyright 2013 Elsevier B.V., All rights reserved.
- Gas sensors
- Humidity dependence
- Ni-loaded SnO
- Recovery speed
- Work function
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Metals and Alloys
- Electrical and Electronic Engineering
- Materials Chemistry