Sains Malaysiana 41(7)(2012): 893–899

Fotoelektrod Tungsten Trioksida Terdop Nikel untuk Tindak Balas Pembelahan

Air Fotoelektrokimia

(Nickel-doped Tungsten Trioxide Photoelectrodes for Photoelectrochemical

Water Splitting Reaction)

Ng Kim Hang & Mohammad Bin Kassim

Pusat Pengajian Sains Kimia dan Teknologi Makanan, Fakulti Sains dan Teknologi,

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Lorna Jeffery Minggu*

Institut Sel Fuel, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Mohammad Hafizuddin Haji Jumali

Pusat Pengajian Fizik Gunaan, Fakulti Sains dan Teknologi, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor, Malaysia

Received: 19 October 2011 / Accepted: 30 January 2012

ABSTRAK

Tungsten trioksida (WO3) merupakan salah satu fotomangkin yang berpotensi dalam aplikasi penjanaan gas hidrogen daripada tindak balas pembelahan air. Dalam kajian ini, pelbagai komposisi filem nipis WO3 terdop nikel dihasilkan pada kaca stanum(IV) oksida terdop fluorin (FTO) dengan menggunakan asid tungstik dan nikel(II) asetat sebagai bahan pemula. Selepas disepuhlindap pada 500°C selama 30 min, sampel filem nipis ini dicirikan dengan menggunakan SEM, XRD, spektrofotometer UV-Vis serta analisis fotoelektrokimia (PEC). WO3 terdop nikel mempunyai saiz zarah yang lebih besar berbanding sampel WO3 tulen dan mempunyai struktur hablur monoklinik. Jurang tenaga WO3 terdop nikel yang dianggarkan daripada spektrum UV-Vis dengan menggunakan formula Tauc adalah lebih kecil berbanding jurang tenaga bagi WO3 tulen. Ujian aplikasi PEC di bawah sinaran lampu xenon menunjukkan kecekapan penghasilan gas hidrogen oleh filem WO3 terdop nikel yang digunakan sebagai fotoanod telah dipertingkatkan.

Kata kunci: Fotoanod; pembelahan air secara langsung; penjanaan hidrogen; sel fotoelektrokimia; tungsten trioksida terdop nikel

ABSTRACT

Tungsten trioxide (WO3) is one of the photocatalysts with a high potential for application in water splitting reaction to produce hydrogen gas. In this paper, different compositions of nickel-doped WO3 thin films on fluorine-doped tin oxide (FTO) glass were produced from tungstic acid and nickel(II) acetate. After annealing at 500°C for 30 min, the thin films were characterized using SEM, XRD, UV-Vis spectrophotometer and photoelectrochemical (PEC) test. Ni-doped WO3 exhibited an increased grain size compared to undoped WO3 and adopted a monoclinic structure. Optical band gaps calculated with Tauc formula from UV-Vis absorption data showed a reduction in band gap for Ni-doped WO3. Under the irradiation of xenon lamp, the efficiency of hydrogen production by nickel-doped WO3 thin films were improved.

Keywords: Direct water splitting; hydrogen production; nickel-doped tungsten trioxide; photoanode; photoelectrochemical cell

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*Corresponding author; email: lorna_jm@ukm.my