Impact of Overlapping Fe/TiO₂Prepared by Sol-Gel and Dip-Coating Process on CO₂Reduction

Abstract

Fe-doped TiO2(Fe/TiO2) film photocatalyst was prepared by sol-gel and dip-coating process to extend its photoresponsivity to the visible spectrum. To promote the CO2reduction performance with the photocatalyst, some types of base materials used for coating Fe/TiO2, which were netlike glass fiber and Cu disc, were investigated. The characterization of prepared Fe/TiO2film coated on netlike glass fiber and Cu disc was analyzed by SEM and EPMA. In addition, the CO2reduction performance of Fe/TiO2film coated on netlike glass disc, Cu disc, and their overlap was tested under a Xe lamp with or without ultraviolet (UV) light, respectively. The results show that the concentration of produced CO increases by Fe doping irrespective of base material used under the illumination condition with UV light as well as that without UV light. Since the electron transfer between two overlapped photocatalysts is promoted, the peak concentration of CO for the Fe/TiO2double overlapping is approximately 1.5 times as large as the Fe/TiO2single overlapping under the illumination condition with UV light, while the promotion ratio is approximately 1.1 times under that without UV light.

Effect of Concentration Variation on Optical and Structural Properties of TiO2 Thin Films

“…TiO2 as N-type semiconducting material has wide band gap with indirect energy band gap of 3.2 eV (anatase) and 3.02 eV (rutile) [6]. Several methods employed in preparation of TiO2 films include electron-beam evaporation [7,8], sputtering [9], sol-gel and dip coating, chemical vapour deposition [10] and spin-coating process [11][12][13]. Among the methods used, spin-coating offers advantages of low temperature processing, low cost, ease of coating large area and suitable for porous film preparation.…”

Effect of Fe Loading Condition and Reductants on CO2 Reduction Performance with Fe/TiO2 Photocatalyst

“…From these figures, it can be observed that the TiO 2 film with teeth-like shape was coated on a netlike glass fiber. It is also seen that TiO 2 film builds a bridge among several glass fibers like reported also in [38]. During firing process, the temperature profile of TiO 2 solution adhered on the [39].…”

“…The Xe lamp can be fitted with a sharp cut filter to remove UV components of the light. With the filter, the wavelengths of light from the Xe lamp are ranged from 401 nm to 2000 nm [38]. The average light intensity of the Xe lamp on the photocatalyst without and with setting the sharp cut filter is 57.5 mW/cm 2 and 43.7 mW/cm 2 , respectively.…”

“…The authors have already reported that the double overlapping arrangement of Fe/TiO 2 coated on netlike glass disc was effective to improve CO 2 reduction performance of Fe/TiO 2 under H 2 O/CO 2 condition since the electron transfer between two overlapped photocatalysts was promoted by overlapping [38]. In addition, the other dopants like Cu, which can absorb the longer wavelength light than Fe [19], should be used at lower positioned layers since the wavelength of penetrating light becomes long through higher positioned photocatalyst by losing energy [38]. This idea is similar to the concept of the hybrid photocatalyst using two photocatalysts having different band gaps [43][44][45].…”

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“…The present study has investigated overlapping two Fe/TiO 2 coated on netlike glass fiber in order to utilize the light more effectively as well as increase the amount of photocatalyst for CO 2 reduction. Though the effect of overlapping two Fe/TiO 2 coated on netlike glass fiber on CO 2 reduction performance with H 2 O was reported by Nishimura et al, 30 it was not investigated for CO 2 /H 2 /H 2 O. In addition, Nishimura et al 30 prepared Fe/TiO 2 by sol-gel dip-coating process only.…”