Kristal tin dioksida (SnO2) bersaiz nano telah berjaya disintesis melalui
pemendakan kimia antara tin (IV) klorida dengan ammonia untuk digunakan
sebagai bahan pengesan ethanol. Serbuk SnO2 yang berjaya dihasilkan ini telah
dicirikan dengan mengunakan Pembelau X-ray (XRD), Mikroskop Elekton
Mengimbas (SEM), Serakkan Sinar-X (EDX) dan Penganalisa Luas Permuakaan
(BET). Berdasarkan keputusan analisis XRD, peningkatan suhu pengkalsinan
dari 400 oC kepada 500 oC akan meningkatkan saiz kristalit dari 3.08 nm kepada
6.16 nm. Hasil analisis SEM pula menunjukkan permukaan tin dioksida adalah
berkeliangan manakala, EDX telah mengesahkan komposisi serbuk yang
dihasilkan adalah SnO2. BET telah mengesahkan bahawa serbuk SnO2 berliangmeso
yang mempunyai luas permukaan yang tinggi telah berjaya diperolehi.
Seterusnya, serbuk SnO2 yang disintesis telah disalutkan di atas substrat alumina
menggunakan kaedah salutan jatuhan dan kesan perbezaan lapisan drop (3, 5 dan
7) telah dikaji. Selain itu, tindakbalas sensor terhadap suhu yang berbeza (150 –
400 °C) dan kepekatan wap etanol yang berbeza (200 – 1000 ppm) telah dikaji.
Suhu operasi yang optimum bagi sensor SnO2 yang telah disintesis telah dikenal
pasti pada 300 oC. Tambahan pula, kepekaan sensor gas yang telah dibangunkan
didapati berkadar terus dengan kepekatan wap etanol. Pada kesuluruhannya,
sensor yang mempunyai sensitiviti yang paling tinggi telah dihasilkan dengan
memenggunakan serbuk SnO2 yang dikalsin pada 500 oC dengan 5 lapisan
jatuhan. Hasil kajian ini telah membuktikan sensor gas SnO2 yang mempunyai
kepekaan yang lebih tinggi berbanding dengan sensor komersial dalam
pengesanan wap etanol telah berjaya disintesis. Penemuan ini telah dianalisa
dengan menghubungkaitkan dengan ciri-ciri SnO2.
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Tin dioxide (SnO2) nanocrystalline were successfully synthesised via chemical
precipitation by adding ammonia solution to a solution containing tin chloride
pentahydrate to be used as ethanol sensing material. The obtained sensing
materials have been characterized by X-Ray Diffraction (XRD), Scanning
Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) and Brunauer–
Emmett–Teller (BET) surface area analyser. The XRD result indicates that the
crystallite size increases from 3.08 nm to 6.16 nm as the calcinations temperature
rises from 400 oC to 500 oC. The SEM characterization shows the presence of
porosity for the SnO2 particles while EDX confirms the chemical composition of
SnOx to be SnO2. The BET results prove that mesoporous SnO2 powders with
high surface area were successfully being synthesised. Then, the synthesised
SnO2 powders were drop coated on alumina substrates. Different drop layers (3,
5 and 7) have been used to study the effect of film thickness towards the
sensitivity. The fabricated gas sensors were also used to test their responses to
different operating temperatures (150 – 400 °C) and different concentrations of
ethanol gas (200 – 1000 ppm). The results showed that the optimum operating
temperature for the synthesised gas sensor is at 300 oC. Moreover, the sensitivity
of the synthesised SnO2 sensor exhibits an almost linear dependency on the
concentration of ethanol gas. Overall, the sensor fabricated by using the SnO2
calcinated at 500 oC and 5 drop layer illustrates the best sensing performance
with the highest sensitivity. This sensor also shows a better performance as
compared to the commercial sensor by having a lower optimum operating
temperature and smaller particle size. These findings were analyzed and
discussed by correlating the experimental results with the characterization
analysis which were closely related to the properties of the sensing materials.
Synthesis and characterization of ethanol sensing material via chemical precipitation / Wong Win Yee