Malaysian Journal of Analytical Sciences Vol 22 No 3 (2018): 435 - 440

PREPARATION AND CHARACTERIZATION OF Ag NANOPARTICLES DECORATED WITH ZnO MICROSTRUCTURES FOR THE CATALYTIC PHOTODEGRADATION OF METHYLENE BLUE DYE UNDER UV LIGHT IRRADIATION

(Penyediaan dan Pencirian Ag Berstruktur Nanopartikel Diubahsuai dengan ZnO Berstruktur Mikro untuk Penurunan Fotokatalisis Pewarna Metilena Biru di bawah Sinar UV)

Hartini Ahmad Rafaie¹*, Nur Azmina Mohemaed Safian², Roslan Md Nor², Yusof Mohd Amin²

¹Faculty of Applied Sciences,

Universiti Teknologi MARA Pahang, 26400 Bandar Tun Abdul Razak Jengka, Pahang,Malaysia

²Physics Department, Faculty of Science,

Universiti Malaya, 50603 Kuala Lumpur, Malaysia

*Corresponding author: hartinirafaie@pahang.uitm.edu.my

Received: 4 December 2016; Accepted: 1 December 2017

Abstract

Ag nanoparticles (AgNPs) decorated with ZnO microstructures was prepared by sol-gel method at different Ag concentration. The structures, composition and morphology of the samples were characterized by X-ray diffraction (XRD), electron dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscope (FESEM). FESEM images shows that the samples were composed of Ag and ZnO with the particles size ranging from 100 to 500 nm. EDS analysis confirmed that atomic % increases as higher molar concentration applied with value of 5.6 at.% and 16.1 at.% for sample 0.05M and 0.1M AgNPs decorated ZnO microstructures. Methylene blue (MB) dye was used as a representative of dye pollutant to conduct the catalytic photodegradation activity. The AgNPs decorated with ZnO particles exhibited a better photocatalytic activity than the pure ZnO particles. The results show that an increasing of photodegradation rate constant, k was obtained when higher concentration of Ag was applied to the ZnO with value of 0.016, 0.026 and 0.032 min^-1 for pure ZnO, 0.05M AgZnO and 0.1M AgZnO nanoparticles, respectively. The increased of k value in the presence of Ag was due to the prolonged lifetime of the photogenerated electron hole pairs in ZnO as a result of Ag nanoparticles acting as electron sink.

Keywords: Ag nanoparticles, zink oksida, sol-gel, photodegradation, methylene blue

Abstrak

Ag berstruktur nanopartikel (AgNPs) diubahsuai dengan ZnO berstruktur mikro pada kepekatan berbeza telah dibuat menggunakan teknik sol-gel. Sifat-sifat struktur, komposisi dan morfologi sampel diperincikan menggunakan pembelauan sinar-X (XRD), spektroskopi Sinar-X sebaran elektron (EDS) dan mikroskop elektron pancaran medan (FESEM). Analisis FESEM menunjukkan sampel terdiri daripada Ag dan ZnO yang mempunyai saiz partikel antara 100 – 500 nm. Analisis EDS pula membuktikan bahawa peratusan atomik meningkat apabila kepekatan Ag yang lebih tinggi digunakan dengan nilai 5.6 at.% dan 16.1 at.% bagi sampel 0.05 M dan 0.1 M ZnO berstruktur mikro diubahsuai dengan Ag berstruktur nanopartikel. Pewarna metilena biru (MB) digunakan sebagai contoh pencemaran warna untuk mengkaji aktiviti penurunan foto pemangkin. ZnO berstruktur mikro diubahsuai dengan Ag berstruktur nanopartikel menunjukkan aktiviti penurunan foto yang lebih baik daripada ZnO tulen. Keputusan menunjukkan bahawa peningkatan dalam pemalar kadar penurunan foto, k diperoleh apabila kepekatan Ag lebih tinggi digunakan pada ZnO dengan nilai 0.016, 0.026 dan 0.032 min^-1 untuk ZnO tulen, 0.05 M dan 0.01 M ZnO berstruktur mikro diubahsuai dengan Ag berstruktur nanopartikel. Peningkatan nilai k dengan kehadiran Ag disebabkan oleh jangka hayat berpanjangan penghasilan foto oleh pasangan lubang dan elektron di ZnO hasil daripada Ag nanopartikel yang bertindak sebagai penerima elektron.

Kata kunci: Ag berstruktur nanopartikel, zink oksida, sol-gel, penurunan foto, metilena biru

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