FABRICATION AND CHARACTERIZATION OF Fe-DOPED TUNGSTEN TRIOXIDE PHOTOELECTRODES IN AQUEOUS MEDIUM USING TUNGSTIC ACID AND FERROCENE AS STARTING MATERIALS

Abstract

Different compositions of Fe-doped tungsten trioxide thin films were synthesized on fluorine-doped tin oxide (FTO) glass substrate by sol-gel method, with ferrocene and tungstic acid as starting materials. The synthesized thin films was characterized with X-ray diffraction (XRD), scanning electron microscope (SEM), UV/Vis spectrophotometer and photoelectrochemical (PEC) analysis. The results show that the surface morphology of the thin films became rough and the grain size increased along with the concentration of Fe. Monoclinic structure of tungsten trioxide was obtained for all doped and undoped WO 3 and red-shift can be observed from UV-vis spectrum. Band gap reduced from 2.74 eV of undoped WO 3 thin films to 2.60 eV of 20 % Fe-doped WO 3 thin films. Photoactivities of all Fe-doped WO 3 are higher than undoped thin films. The highest photoactivities contributed by 5 % Fe-doped WO 3 films with photocurrent densities measured was 0.148 mA/cm 2 , which is 3 times higher compared to undoped WO 3 .Keywords: Fe-doped WO 3 , direct water splitting, photoelectrochemical cell, photoanode Abstrak Filem nipis tungsten trioksida terdop Fe berbagai komposisi telah disediakan di atas kaca substrat FTO (fluorine-doped tin oxide) dengan kaedah sol-gel, dengan menggunakan ferosin dan asid tingstik sebagai bahan pemula. Filem nipis yang terhasil kemudiannya dicirikan dengan pembelauan sinar X (XRD), mikroskopi elektron pengimbasan (SEM), UV/Vis spektrofotometer dan analisis fotoelektrokimia. Keputusan menunjukkan bahawa morfologi permukaan filem nipis menjadi kasar dan saiz butiran bertambah dengan penambahan kepekatan Fe. Tungsten trioksida yang berstruktur monoklinik telah dihasilkan dan anjakan merah telah diperhatikan di dalam spectrum UV-vis. Jurang tenaga telah berkurang dari 2.74 eV (WO 3 tulen) kepada 2.60 eV (20 % Fe-dop WO 3 ). Fotoaktiviti WO 3 terdop Fe adalah lebih tinggi berbanding WO 3 tulen. Fotoaktiviti yang tertinggi dicatatkan oleh filem 5 % WO 3 terdop Fe dengan ketumpatan fotoarus 0.148 mA/cm 2 . Ia adalah 3 kali ganda lebih tinggi berbanding WO 3 tulen.Kata kunci: Fe-dop WO 3 , pembelahan air secara langsung, sel fotoelektrokimia, fotoanod