**2. Experimental**

#### **2.1. Procedure to prepare Fe/TiO2 film**

Sol-gel and dip-coating process, which is a general procedure, was selected to prepare Fe/TiO<sup>2</sup> film. TiO<sup>2</sup> sol solution consists of [(CH<sup>3</sup> )2 CHO4 ] Ti (purity of 95 wt%, produced by Nacalai Tesque Co.) of 0.3 mol, anhydrous C<sup>2</sup> H5 OH (purity of 99.5 wt%, produced by Nacalai Tesque Co.) of 2.4 mol, distilled water of 0.3 mol and HCl (purity of 35 wt%, produced by Nacalai Tesque Co.) of 0.07 mol. Fe particles (produced by Merck KGaA, particle size below 10 μm) were added to TiO<sup>2</sup> sol solution. Netlike glass fiber was cut to disc, and its diameter and thickness were 50 and 1 mm, respectively. The Cu disc used has diameter and thickness of 50 and 1 mm, respectively. The base material was dipped into Fe/TiO<sup>2</sup> sol solution at the speed of 1.5 mm/s and pulled up at the fixed speed of 0.22 mm/s. Then, it was dried out and fired under the controlled firing temperature (FT) and firing duration time (FD), with Fe/TiO<sup>2</sup> film fastened on the base material. FT and FD were set at 623 K and 180 s, respectively. The ratio of amount of added Fe to amount of TiO<sup>2</sup> sol solution (R) was set at 10 wt%.

(D) × 10 mm (t)), a sharp cut filter cutting off the light whose wavelength is below 400 nm (SCF-49.5C-42 L, produced by SIGMA KOKI Co. Ltd.), Xe lamp (L2175, produced by Hamamatsu

the sharp cut filter and the quartz glass disc that are at the top of the stainless pipe. The Xe lamp illuminates the light whose wavelength ranged from 185 to 2000 nm. A sharp cut filter can remove UV components of the light, resulting in the wavelength of light from Xe lamp ranging from 401 to 2000 nm. **Figure 3** indicates that the sharp cut filter can remove the light whose wavelength ranged below 400 nm. During the experiment, the light intensity of Xe lamp illuminating the photocatalyst without and with setting the sharp cut filter is estimated

flowed through the reactor as a purged gas for approximately 15 min. The valves at the inlet

ture in the reactor were set at 0.1 MPa and 298 K, respectively, the distilled water of 100 μL was injected into the reactor through a gas pipe and Xe lamp was started to illuminate at the same time. The water injected vaporized completely in the reactor. Since Xe lamp emits the heat, the gas temperature in reactor was attained at 343 K within an hour and maintained at

were in the reactor. The gas in the reactor was sampled by a gas syringe every 24 h during the experiment, which was analyzed by FID gas chromatograph (GC353B, produced by GL Science) and methanizer (MT221, produced by GL Science). FID gas chromatograph and

approximately 343 K during the experiment. The water of 5.56 mmol and CO<sup>2</sup>

methanizer can detect a gas whose concentration is 1 ppmV order level.

. The Xe lamp illuminates the netlike glass

http://dx.doi.org/10.5772/intechopen.70389

67

gas whose purity was 99.995 vol% was

. The gas pressure and gas tempera-

of 576 mmol

film, which is located inside the stainless pipe, through

Effect of Overlapping Fe/TiO2 Coated on Netlike Glass Disc and Cu Disc on CO2 Reduction

gas cylinder (purity of 99.995 vol%).

is 1.25 × 10−4 m<sup>3</sup>

, respectively.

and the outlet of reactor were closed after charging CO<sup>2</sup>

**Figure 3.** Light transmittance data of sharp cut filter.

reduction experiment in this study, CO<sup>2</sup>

Photonics K. K.) and CO<sup>2</sup>

at 81.9 and 60.7 mW/cm<sup>2</sup>

To start CO<sup>2</sup>

The size of reactor for charging CO<sup>2</sup>

disc or Cu disc coated with Fe/TiO<sup>2</sup>

#### **2.2. Characterization of Fe/TiO2 film**

The surface structure and crystallization characteristics of Fe/TiO<sup>2</sup> film were evaluated by SEM (JXA-8530F, produced by JEOL Ltd.) and EPMA (JXA-8530F, produced by JEOL Ltd.). Since these two measuring instruments use electron for analysis, the sample should be an electron conductor. Though Cu disc is a good electron conductor, netlike glass disc is not an electron conductor. In this study, the carbon vapor deposition was conducted by the dedicated device (JEE-420, produced by JEOL Lt.) for Fe/TiO<sup>2</sup> coated on netlike glass disc before analysis by SEM and EPMA. The thickness of carbon deposited on sample was approximately 20–30 nm. The electron probe emits the electron to the sample under an acceleration voltage of 15 kV and a current of 3.0 × 10−8 A; the surface structure of sample is analyzed by SEM. The characteristics of X-ray are detected by EPMA at the same time, resulting in the concentration of chemical element analyzed according to the relationship between the characteristics of X-ray energy and the atomic number. The spatial resolution of SEM and EPMA is 10 μm. The EPMA analysis helps not only to understand the coating state of prepared photocatalyst but also to measure the amount of doped metal within TiO<sup>2</sup> film on the base material.

#### **2.3. CO2 reduction experiment**

**Figure 2** shows that experimental setup of the reactor consisting of stainless pipe (100 mm (H) × 50 mm (ID)), a netlike glass or Cu that is disc shaped (50 mm (D) × 1 mm (t)) with Fe/ TiO2 film placed on the Teflon cylinder (50 mm (H) × 50 mm (D)), a quartz glass disc (84 mm

**Figure 2.** Schematic drawing of CO<sup>2</sup> reduction experimental setup.

(D) × 10 mm (t)), a sharp cut filter cutting off the light whose wavelength is below 400 nm (SCF-49.5C-42 L, produced by SIGMA KOKI Co. Ltd.), Xe lamp (L2175, produced by Hamamatsu Photonics K. K.) and CO<sup>2</sup> gas cylinder (purity of 99.995 vol%).

The size of reactor for charging CO<sup>2</sup> is 1.25 × 10−4 m<sup>3</sup> . The Xe lamp illuminates the netlike glass disc or Cu disc coated with Fe/TiO<sup>2</sup> film, which is located inside the stainless pipe, through the sharp cut filter and the quartz glass disc that are at the top of the stainless pipe. The Xe lamp illuminates the light whose wavelength ranged from 185 to 2000 nm. A sharp cut filter can remove UV components of the light, resulting in the wavelength of light from Xe lamp ranging from 401 to 2000 nm. **Figure 3** indicates that the sharp cut filter can remove the light whose wavelength ranged below 400 nm. During the experiment, the light intensity of Xe lamp illuminating the photocatalyst without and with setting the sharp cut filter is estimated at 81.9 and 60.7 mW/cm<sup>2</sup> , respectively.

To start CO<sup>2</sup> reduction experiment in this study, CO<sup>2</sup> gas whose purity was 99.995 vol% was flowed through the reactor as a purged gas for approximately 15 min. The valves at the inlet and the outlet of reactor were closed after charging CO<sup>2</sup> . The gas pressure and gas temperature in the reactor were set at 0.1 MPa and 298 K, respectively, the distilled water of 100 μL was injected into the reactor through a gas pipe and Xe lamp was started to illuminate at the same time. The water injected vaporized completely in the reactor. Since Xe lamp emits the heat, the gas temperature in reactor was attained at 343 K within an hour and maintained at approximately 343 K during the experiment. The water of 5.56 mmol and CO<sup>2</sup> of 576 mmol were in the reactor. The gas in the reactor was sampled by a gas syringe every 24 h during the experiment, which was analyzed by FID gas chromatograph (GC353B, produced by GL Science) and methanizer (MT221, produced by GL Science). FID gas chromatograph and methanizer can detect a gas whose concentration is 1 ppmV order level.

**Figure 3.** Light transmittance data of sharp cut filter.

fastened on the base material. FT and FD were set at 623 K and 180 s, respectively. The ratio of

SEM (JXA-8530F, produced by JEOL Ltd.) and EPMA (JXA-8530F, produced by JEOL Ltd.). Since these two measuring instruments use electron for analysis, the sample should be an electron conductor. Though Cu disc is a good electron conductor, netlike glass disc is not an electron conductor. In this study, the carbon vapor deposition was conducted by the dedi-

analysis by SEM and EPMA. The thickness of carbon deposited on sample was approximately 20–30 nm. The electron probe emits the electron to the sample under an acceleration voltage of 15 kV and a current of 3.0 × 10−8 A; the surface structure of sample is analyzed by SEM. The characteristics of X-ray are detected by EPMA at the same time, resulting in the concentration of chemical element analyzed according to the relationship between the characteristics of X-ray energy and the atomic number. The spatial resolution of SEM and EPMA is 10 μm. The EPMA analysis helps not only to understand the coating state of prepared photocatalyst but

**Figure 2** shows that experimental setup of the reactor consisting of stainless pipe (100 mm (H) × 50 mm (ID)), a netlike glass or Cu that is disc shaped (50 mm (D) × 1 mm (t)) with Fe/

reduction experimental setup.

film placed on the Teflon cylinder (50 mm (H) × 50 mm (D)), a quartz glass disc (84 mm

 **film**

The surface structure and crystallization characteristics of Fe/TiO<sup>2</sup>

cated device (JEE-420, produced by JEOL Lt.) for Fe/TiO<sup>2</sup>

also to measure the amount of doped metal within TiO<sup>2</sup>

 **reduction experiment**

**Figure 2.** Schematic drawing of CO<sup>2</sup>

sol solution (R) was set at 10 wt%.

film were evaluated by

coated on netlike glass disc before

film on the base material.

amount of added Fe to amount of TiO<sup>2</sup>

66 Carbon Dioxide Chemistry, Capture and Oil Recovery

**2.2. Characterization of Fe/TiO2**

**2.3. CO2**

TiO2
