Preparation of Titania Nanomaterials and Application to Gas Storage and Photoelectrochemical Cells
Date Issued
2014
Date
2014
Author(s)
Chen, Bai-Lin
Abstract
Titanate nanotubes (Tnts) were prepared by a hydrothermal method with Merck TiO2 powders immersed in concentrated NaOH solution. The white precipitate was washed with different times of 0.1 M HNO3(aq) in the preparation process. The prepared Tnts were denoted as Tnt-5, Tnt-7, Tnt-11, and Tnt-13 to signify the obtained pH values of the washing eluate at 5, 7, 11, and 13, respectively. The open-end and multi-layered feature of the Tnts with outer diameter in the range of 8-10 nm, inner diameter in the range of 3-5 nm, and up to several hundred nanometers in length can be observed by HRTEM. With increasing the cycles of acidic treatment, the sodium content decreased from 9.63 wt% in Tnt-13 to 4.30 wt% in Tnt-5, whereas the BET surface aera (SBET) increased from 168 m2/g in Tnt-13 to 291 m2/g in Tnt-5. In CO2 storage measurements, the CO2 storage capacity of Tnts, which based on the weight of adsorbent at 298 K and 32 atm, were 102.0 mg/g, 109.0 mg/g, 121.5 mg/g, and 136.2 mg/g for Tnt-5, Tnt-7, Tnt-11, and Tnt-13, respectively. The percentage of physisorption was mainly dependent on the SBET of the Tnts. Higher SBET corresponded to the higher amount of physisorption. The chemisorption proportion rised with increased the Na content. The Tnt-5 of the highest surface area was shown the best CO2 storage performance under 32 atm. In the H2 storage study, Pt/Tnt-13 and Pd/Tnt-13 with the noble metallic nanoparticles deposition on Tnt-13 was carried out by photochemical deposition method. The bare Tnt-13 presented 18.3 mg/g H2 storage capacity at 298 K and under 32 atm. The Pt/Tnt-13 and Pd/Tnt-13 sample shown the adsorption capacity were 68.0 mg/g and 87.5 mg/g, respectively.
In the photoelectrochemical cells study, we prepared the TiO2 nanoparticles (TNP) as an electron-conducting layer material from the transformations of titanate nanotube in acidic environment, and the TiO2 hollow microspheres (THMS) as scattering layer material by two-step solvothermal method. The TiO2 electrodes were prepared by coating TiO2 paste onto FTO glass by doctor-blade method. Successive ionic layer adsorption and reaction (SILAR) method were used to assemble the CdSe/CdS sensitized photoanodes. All of the prepared photoanodes were deposition of ZnS as a passivation layer. The photocurrent density (Jsc) and the solar energy conversion efficiency (η) of CdSe/CdS sensitized solar cells were increased from 8.6 mA/cm2 and 2.87 % of 5CdSe/7CdS/3TNP to 13.1 mA/cm2 and 3.99 % of 5CdSe/7CdS/THMS/3TNP, respectively. The η of 5CdSe/7CdS/THMS/3TNP was significantly enhanced by nearly 40 % as compared to 5CdSe/7CdS/3TNP which without THMS layer under AM 1.5 simulated solar irradiation (100 mW/cm2). The result indicated the light scattering layer can elongate the path length of incident light in photoanodes. For solar water splitting study, the photocurrent density of 7CdS/THMS/3TNP which only sensitization with CdS sensitizer was 8.8 mA/cm2. The photocurrent density of 4CdSe/7CdS/THMS/3TNP was increased to 12.2 mA/cm2. The results confirmed that adding CdSe as a co-sensitizer, the absorption of visible light can be effectively increased and the overall efficiency was improved.
Subjects
氧化鈦奈米管
二氧化鈦奈米顆粒
二氧化鈦空心微米球
二氧化碳儲存
氫氣儲存
硒化鎘/硫化鎘敏化太陽能電池
太陽光水分解
SDGs
Type
thesis
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