Sains Malaysiana 40(3)(2011): 203–208

Influence of PANI Additions on Methanol Sensing Properties of ZnO Thin Films

(Pengaruh Penambahan PANI ke atas Sifat Pengesanan Wap Metanol oleh Filem Nipis ZnO)

Mohammad Hafizuddin Haji Jumali*, Norhashimah Ramli, Izura Izzuddin & Muhammad Yahaya

School of Applied Physics, Faculty of Science & Technology

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia

Muhamad Mat Salleh

Institute of Microengineering and Nanoelectronic (IMEN)

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E., Malaysia

Received: 15 May 2010 / Accepted: 3 September 2010

ABSTRACT

The influence of PANI additions on methanol sensing properties of ZnO thin films at room temperature had been investigated. Commercial polyaniline powder (PANI) was mixed into 3 mL ZnO solution in five different weight percentages namely 1.25, 2.50, 3.75, 5.00 and 6.25% to obtain ZnO/PANI composite solutions. These solutions were spin coated onto glass substrate to form thin films. Microstructural studies by FESEM indicated that ZnO/PANI films showed porous structures with nanosize grains. The thickness of the film increased from 55 to 256 nm, proportionate to increment of PANI. The presence of 2 adsorption peaks at ~310 and ~610 nm in UV-Vis spectrum proved that addition of PANI has modified the adsorption peak of ZnO film. Methanol vapour detection showed that addition of PANI into ZnO dramatically improved the sensing properties of the sensor. The sensors also exhibited good repeatability and reversibility. Sensor with the amount of PANI of 3.75 wt% exhibited the highest sensitivity with response and recovery time was about 10 and 80 s, respectively. The possible sensing mechanism of the sensor was also discussed in this article.

Keywords: Gas sensor; methanol vapour; microstructure; UV-Vis analysis; ZnO/PANI thin film

ABSTRAK

Pengaruh penambahan PANI ke atas sifat pengesanan wap metanol oleh filem nipis ZnO telah dikaji pada suhu bilik. Lima amaun serbuk polianilina (PANI) dengan peratusan berat 1.25, 2.50, 3.75, 5.00 dan 6.25% dicampurkan ke dalam 3 mL larutan ZnO untuk menghasilkan larutan komposit ZnO/PANI. Larutan ini kemudiannya dimendapkan ke atas substrat kaca menggunakan teknik salutan berputar untuk membentuk filem nipis. Analisis mikrostruktur melalui FESEM menunjukkan filem nipis komposit ZnO/PANI adalah poros dengan saiz butiran yang terhasil berskala nanometer. Nilai ketebalan filem yang diperolehi meningkat daripada 55 sehingga 256 nm setara dengan penambahan amaun PANI. Analisis UV-Vis mengesahkan kehadiran PANI yang mengubah puncak penyerapan filem ZnO dengan penghasilan 2 puncak penyerapan pada panjang gelombang ~310 dan ~610 nm. Ujian pengesanan sensor terhadap wap metanol menunjukkan kehadiran PANI telah meningkat sifat pengesanan sensor secara mendadak dengan menonjolkan sifat kebolehulangan dan kebolehbalikan yang baik. Diperoleh, sensor dengan amaun PANI sebanyak 3.75 wt% mempamerkan kepekaan tertinggi dengan masa tindak balas dan pemulihan masing-masing adalah 10 dan 80 s. Andaian mekanisme pengesanan sensor dibincangkan dalam artikel ini.

Kata kunci: Analisis UV-Vis; filem nipis ZnO/PANI; mikrostruktur; sensor gas; wap methanol

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*Corresponding author; e-mail: hafizhj@ukm.my