Metal Oxide Heteronanostructures Prepared by Electrospinning for the Humidity Detection: Fundamentals and Perspectives

Leão, Victor N. S.; Araújo, Evando S.

doi:10.4236/msce.2019.77006

Cited by 2 publications

(1 citation statement)

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“…In this research, relative humidity which is defined as the ratio of actual vapor pressure of water to its saturated vapor pressure at a specific temperature is the main commonly applied parameter for measuring the moisture [14].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and humidity sensing applications of calcium oxide nanoparticles synthesized by facile chemical precipitation method

Khan,

Din

2024

Preprint

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Calcium oxide nanoparticles were prepared by mixing aqueous calcium nitrate tetrahydrate solution with sodium hydroxide solution. After short time, a precipitate of white colour of calcium hydroxide was formed. This precipitate was then dried in an electric oven to form powder. The formed dried powder was then calcinated for 3 hours at about 600 oC by applying an electric furnace to form CaO nanoparticles. Characterization of the prepared nanomaterials was performed by applying various characterization methods. X-ray photoelectron spectroscopy (XPS) analysis was performed to study the surface chemical properties, UV-Visible spectroscopy was studied to examine the optical characteristics of the formed materials, thermogravimetric analysis (TGA) was done to study the thermal stability of the products and nitrogen adsorption-desorption was carried out to find out the porosity and surface area of the formed sample calcium oxide nanopartilcles. Humidity sensing performance was studied by measuring the variations in resistance of the sensor using LCR meter as a result of changes in humidity levels in a sealed chamber. From the results of XPS, it was proved that the sample mainly contains calcium and oxygen along with small amounts of impurities such as magnesium, sodium and chlorine. UV-Visible spectra showed two absorption bands at 230 nm and 267 nm. A broad absorption band was also found ranging from 300 nm to 350 nm. The band gap energy calculated from UV-Visible results was observed as 3.39 eV. TGA study confirmed that the weight loss occurred in two steps at two different temperatures. From nitrogen adsorption-desorption, BET surface area was calculated to be 129.49 m2/g and BJH surface area was observed to be 101.34. The average pore size estimated from BJH pore size distribution was 1.704 nm and the average pore volume was observed as 0.238 cc/g. The humidity sensing data showed a decrease in resistance of the sample with increase in the value of humidity, while sensitivity of the sample was increased linearly with increase in humidity levels. The response and recovery times of the sensor were 79 sec and 147 sec respectively. Humidity sensor stability evaluated for 90 days at 15 days intervals were noted and the results indicated that the formed sensor was 65 % stable for the above mentioned period. The results of the studied parameters concluded that the prepared calcium oxide nanoparticles can be effectively used for humidity sensing applications.

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Section: Introductionmentioning

confidence: 99%