Kangying Shu

Fabrication of self-organized TiO2 nanotube arrays for photocatalytic reduction of CO2

The photocatalytic conversion of CO2 and H2O to alcohols was achieved using self-organized TiO2 nanotube arrays (TNAs), which were prepared by electrochemical anodization of Ti foils in 1xa0M (NH4)2SO4 electrolyte containing 0.5xa0wt% NH4F. Experimental results revealed that the morphology and structure of self-organized TNAs could be strongly influenced by the applied voltage and anodization temperature, and the optimized TNAs were prepared by electrochemical anodization of Ti foils under optimal conditions (i.e., at 20xa0V for 2xa0h at 30xa0°C). The as-prepared TNAs were amorphous and could be transformed to anatase phase during the thermal treatment at 450xa0°C in air for 3xa0h. By using the annealed TNAs as a photocatalyst, the photocatalytic reduction of CO2 to alcohol, predominately methanol and ethanol, was demonstrated under Xenon lamp illumination. Based on the photocatalytic measurements, the production rates of methanol and ethanol were calculated to be ∼10 and ∼9xa0nmolxa0cm−2xa0h−1, respectively. In addition, the formation mechanism of methanol and ethanol was also tentatively proposed.

Controllable synthesis of well-ordered TiO 2 nanotubes in a mixed organic electrolyte for high-efficiency photocatalysis

Well-ordered TiO2 nanotube arrays (TNAs) were fabricated by electrochemical anodization in a mixed organic electrolyte consisting of ethylene glycol and glycerol. The morphology, structure, crystalline phase, and photocatalytic properties of TNAs were characterized by using TEM, SEM, XRD and photodegradation of methylene blue. It was found that the morphology and structure of TNAs could be significantly influenced by the anodization time and applied voltage. The obtained tube length was found to be proportional to anodization time, and the calculated growth rate of nanotubes was 0.6 μm/h. The microstructure analysis demonstrated that the diameter and thickness of the nanotubes increased with the increase of anodization voltage. The growth mechanism of TNAs was also proposed according to the observed relationship between current density and time during anodization. As expected, the obtained TNAs showed a higher photocatalytic activity than the commercial TiO2 P25 nanoparticles.

Porous TiO2 nanowire microsphere constructed by spray drying and its electrochemical lithium storage properties

Porous TiO2 nanowire microspheres with greatly decreasing agglomeration were successfully prepared by spray drying of hydrothermal reaction suspension, followed by calcination at 350°C. The as‐obtained nanowire microspheres with TiO2‐B structure reach an initial discharge capacity 210 mAh g−1 with an irreversible capacity 25 mAh g−1 at a current density of 20 mA g−1. For the 450°C‐calcined one with anatase TiO2 crystal structure, the initial discharge capacity is 245 mAh g−1 but with a much higher irreversible capacity of 80 mAh g−1. The hierarchical porous structure in the 350°C‐calcined TiO2 nanowire microspheres collapsed at 450°C, annihilating the main benefit of nanostructuring. Microsc. Res. Tech. 77:170–175, 2014.