In order to carry out the preliminary cell test in Sessions 2.6 and 4.7, titanium oxide electrodes were prepared as follows. TiO2 colloidal dispersion was made employing commercial TiO2 powder (Aldrich, 99.7% anatase, particles size <25 nm). To 0.750 g of powder 1 mL of HNO3 0.1M was added. To this suspension 30 mg of PEG8000 and 2 drops of Triton-X100 were added. The solution was sonicated for 2h and stirred overnight. Films of nanocrystalline TiO2 colloidal on FTO glass (TEC 15, Solaronix) were prepared by sliding a glass rod over the conductive side of the glass. Sintering was carried out at 450°C for 30 minutes. The films were then dipped into a 0.3 mM dye solution in ethanol for 12h at 60°C. The dye coated TiO2 film, as working electrode, was placed on top of an FTO glass as counter electrode. The latter was made with solvent-assisted drop-casting technique, spreading a H2PtCl6 (5 mM) isopropanol solution onto FTO glass, and heating the resulting film at 500 °C for half an hour. The redox electrolyte was introduced into the inter-electrode space by capillary force.
Nanostructured NiO films used anchoring test in Session 3.6 were prepared as follows: 4.75 g (0.020 mol) NiCl2‚6H2O (Merck) was dissolved in 100 mL deionised water, and 45 mL of a 1.0M NaOH solution was added under strong stirring. A green Ni(OH)2 precipitate formed immediately. After settling overnight, the clear supernatant was removed and the precipitate (∼70 mL) was dialyzed against deionised water. Next, the suspension was concentrated using a rotary evaporator until it was visibly viscous. A small amount of acetic acid (10 drops of 1.75M acetic acid) and up to 30% ethanol were added to improve spreading and drying characteristics. The sol was spread using a glass rod on conducting FTO glass (TEC 15, Solaronix), which was masked by adhesive tape (Scotch Magic, 40 µm thickness). The film was dried in air and fired at
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300-320 °C for 15 min in a hot air stream. 223 Pt-electrodes were made as described above.For the measurements at University of Nottingham (Chapter 2), FTO glass was used as current collector (T CO 3 0 - 8 , 3 mm thick glass substrate with a 8 Ω/sq fluorine doped tin oxide coating on one face), which was cut into 1.5x1.5 cm size by using a diamond glasscutter. To prepare the DSSC working electrodes, the FTO glass was first cleaned with ethanol. After drying, they were immersed into a 40 mM aqueous TiCl4 (877 µL in 200 mL of water) solution at 70° C for 30 minutes and washed with pure water and ethanol and dried. Then the plates were cleaned in a boiling acetone bath for 15 minutes, followed by a bath of 0.1M HCl in ethanol for 10 minutes and again in a boiling acetone bath. A layer of nanocrystalline TiO2 paste (Solaronix Ti-Nanoxide D) was coated on the FTO glass plates by doctor blade technique, using a round mask (5 mm diameter, 0.2 cm2 area) made by adhesive tape (3M Magic). The film was dried for 5 minutes on a hotplate and a second layer of TiO2 was deposited as before. The films were sintered at 450° C for 30 minutes. After cooling to 80 °C, the TiO2 electrodes were immersed into a 0.5 mM dye solution in a mixture of ethanol/tert-buthanol 4:1 and kept at 45 °C overnight in the dark. To prepare the counter electrode, a hole was drilled in the FTO glass (T CO 3 0 - 8 , 3 mm thick glass substrate with an 8 Ω/sq fluorine doped tin oxide coating on one side). The perforated plate was washed with water and cleaned by a boiling acetone bath for 15 minutes. After drying, the Pt catalyst was deposited on the FTO glass by doctor blade coating with 10µL/cm2 of H2PtCl6 solution (5 mM isopropanol solution), air dried and heated at 400°C for 15 minutes. The dye- covered TiO2 electrodes, previously washed with acetonitrile, and Pt-counter electrodes were assembled into a sandwich-type cell and sealed with a hot-melt gasket of 60 µm thickness made of Surlyn on a heating stage. Then, the hole in the back of the counter electrode was covered with a hot-melt ionomer film. A hole was made in the hot-melt ionomer film with a needle. A drop of the electrolyte, a solution of 0.4 M 1- butyl-3-methyl-imidazolium iodide, 0.03 M I2 and 0.3 M LiI in acetonitrile:valeronitrile 9:1, was introduced through the predrilled hole in the counter electrode, which was sealed afterward. The edge of the FTO was painted with a silver conductive painting. NiO electrodes (Chapter 3 and 5) were made by applying the precursor solution described in previous literature224 onto conducting glass substrates (Pilkington TEC15, sheet resistance 15 Ω/sq) by doctor blade using Scotch tape as a spacer (0.25 cm2 active area), followed by sintering in a NaberthermB150 oven at 450 °C for 30 min. The NiO electrodes were soaked in an acetonitrile solution of the dye (0.3 mM) for 16 h at room temperature. The dyed NiO electrode was assembled face-to-face with a
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platinized counter electrode (Pilkington TEC8, sheet resistance 8 Ω/sq) using a 30 μm thick thermoplastic frame (Surlyn 1702). The electrolyte, containing LiI (1.0 M) and I2 (0.1 M) in acetonitrile, was introduced through the predrilled hole in the counter electrode, which was sealed afterward.For the measurements at Newcastle University (Chapter 4 and 5), FTO glass was used as current collector (T CO 3 0 - 1 0 , 3 mm thick glass substrate with a 10 Ω/sq fluorine doped tin oxide coating on one side), which was cut into 1.5x1.5 cm size by using a diamond glasscutter. To prepare the DSSC working electrodes, the FTO glass was first cleaned with ethanol. After dried they were immersed into a 40 mM aqueous TiCl4 (877 µL in 200 mL of water) solution at 70 °C for 30 minutes and washed with pure water and ethanol and dried. A layer of nanocrystalline TiO2 paste (Solaronix Ti-Nanoxide SP-T) was coated on the FTO glass plates by doctor blade technique, using a round mask (5 mm diameter, 0.25 cm2 area) made by adhesive tape (3M Magic). The film was dried for 5 minutes on a hotplate and a second layer of TiO2 was deposited as before. The films were sintered at 450° C for 30 minutes. After cooling to 80 °C, the TiO2 electrodes were immersed into a 0.5 mM acetonitrile dye solution overnight. To prepare the counter electrode, a hole was drilled in the FTO glass (T CO3 0 - 8 , 3 mm thick glass substrate with an 8 Ω/sq fluorine doped tin oxide coating on one side). The perforated plate was washed with water and cleaned by a boiling acetone bath for 15 minutes. After drying, the Pt catalyst was deposited on the FTO glass by doctor blade coating with 10µL/cm2 of H2PtCl6 solution (5 mM isopropanol solution), air dried and heated at 400°C for 15 minutes. The dye-covered TiO2 electrodes, previously washed with ethanol, and Pt-counter electrodes were assembled into a sandwich-type cell and sealed with a hot-melt gasket of 60 µm thickness made of Surlyn on a heating stage. Then, the hole in the back of the counter electrode was covered with a hot-melt ionomer film. A hole was made in the hot-melt ionomer film with a needle. A drop of the electrolyte, 0.5 M TBP, 0.015 M I2, 0.6 M TBAI and 0.1 M GuSCN in acetonitrile, was introduced through the predrilled hole in the counter electrode, which was sealed afterwards.