Studies on Ni–SnO₂ Nanocomposites for Humidity Sensing Application

Abstract

We report a hydrothermal method for synthesis of nickel‐doped tin oxide (Ni–SnO2) nanoparticles. The samples are characterized by different analysis techniques to understand their structural, morphological, and optical properties. The synthesized nanomaterials are characterized by X‐ray diffraction, it is crystallized in a tetragonal rutile crystal structure and the crystallite size increases from ∼5 to ∼23 nm with the increasing nickel (Ni) doping concentration. The field emission electron microscopy demonstrates that in case of doping the addition of polyethylene glycol is responsible for the development of densely packed flower like bunches. Further, the synthesized n‐type SnO2 materials are systematically investigated for humidity sensing toward atmospheric moisture. The results indicate that nickel doping improves the performance of SnO2 sensor and is highly sensitive over a wide relative humidity (%RH) range from 10% to 100% at room temperature than pure SnO2. It is found that the resistance of the films decreases with increasing RH as the multilayer stacking of water molecules occurred on the surface of synthesized nanomaterials. Also, the fast response time of 15 s and recovery time of 4 s are observed for the 5% nickel‐doped SnO2 sensor. This improved sensing performance is attributed to nickel doping as doping developed the proportions of oxygen vacancy and improves the large surface to volume ratio as well as exhibited high conductivity. Thus, the doping of SnO2 nanoparticles with Ni should be a promising approach for designing and fabricating the high‐performance humidity sensor.

Synthesis and Characterization of Indium-Doped SnO2-Based Impedance Spectroscopy Sensor for Real-Time Humidity Sensing Applications

“…Thus, several effective strategies have been implemented to improve the sensing performance of SnO 2 -based sensors. For example, doping of sensing materials with other metal oxides or metal ions is predominant, resulting in increased surface areas/active sites and heterogeneous interfaces between the host and the dopant that facilitate an effective water adsorption/desorption process [48][49][50].…”

Role of polyaniline/molybdenum trioxide nanocomposites in tuning the characteristics of humidity sensors

“…capillary condensation, physisorption (at range 40 RH%<) and chemisorption (at range 20–40 RH%). When metal oxide materials are used for sensing, the collision of water molecules on material surface splits the molecule into protons (H + ) and hydroxide ions (OH − ) providing protonic conduction 19 . The sensing at lower humidity levels is due to chemisorption of single layer development of hydroxyl (OH − ) ions on the surface of the film.…”

“…In resistive-type humidity sensors, the materials show ionic sensing mechanism by changing resistance after water adsorption on the surface. As we move towards higher %RH, the resistance drops exponentially showing an increase in conductivity [18][19][20]. Humidity sensing can happen via three phenomena viz.…”