Preparation And Photoelectrocatalytic Performance Characterization Of TiO₂ Nanomaterial On Weaveable Substrate

Semiconductor photocatalysis technology has a great potential to become one of the most promising solutions for energy shortages and environmental pollution, and a key for the photocatalysis technology is to develop semiconductor photocatalysts with excellent performances. Taking the macroscale shape of photocatalysts into account, three kinds of photocatalysts have been chiefly developed. The first kind is the nanosized semiconductors as powdery photocatalysts, Usually, nanosized photocatalysts exhibit relatively high photocatalytic activity, due to their small size and large specific surface area. Unfortunately, their small size and powdery appearance also result in some problems. For example, it is difficult to recycle them in practical application（such as degrading organic pollutants in lake and/or river）. The second kind is semiconductor films on flat substrates, these film-shaped photocatalysts can be easily recycled, and their photocatalytic activities can also be further improved by external electric field. However, there are also some limitations, such as relatively limited surface area and/or high cost. The last kind is semiconductor nonwoven cloth with nanostructure. It should be noted that these semiconductor nonwoven cloths are relatively easily fragile. In addition, they also have poor electrical conductivity and thus cannot be directly used as photoelectrodes for the enhanced photoelectrocatalytic degradation of pollutants in water. Therefore, it is quite necessary to develop efficient, easily recyclable and large-area photocatalysts with nanostructures and good conductivity.prerequisite for the photocatalytic application is to obtain efficient, easily recyclable and large-area photocatalysts with nanostructures. Therefore, in this paper, I have prepared TiO₂ nanomaterials on two kinds of weaveable substrate. These catalysts are possible to be prepared for large-scale, and they are also easy to recycle. The semiconductor is grown on the fibers, so the specific area is much larger than the one on flat substrates. We can also apply an external voltage on the catalysts to further improve the catalytic performance. The main works focus on the following aspects:（1） we have prepared TiO₂ nanorod bundles on carbon fibers as flexible and weaveable photocatalyst/photoelectrode. The growth of TiO₂ nanorod bundles are realized by using a dip-coating and hydrothermal growth method. TiO₂ nanorod-bundles exhibit square-column appearance with size of about 340-400 nm and length of 6 μm, and they are in fact composed of small nanorods with diameters of 30 nm. Subsequently, 16 bunches of CFs with TiO₂ nanorod bundles can be weaved to be a macroscale CFs/TiO₂ cloth（weight: 0.2 g, total area: 35 cm2） with excellent conductivity and flexibility. With CFs/TiO₂ cloth as the working electrode, photoelectrochemical measurements demonstrate that the separation of photo-induced charge carriers can be improved by increasing the applied voltage bias. Furthermore, under the illumination of simulated solar light, CFs/TiO₂ cloth can degrade 94.0% Rohdamine B（Rh B） in 100 min by photoelectrocatalytic degradation process（bias: 0.6V vs SCE）, which is higher than the efficiency from single photocatalysis（60.8% Rh B） or electrocatalysis（5.6% Rh B） process. In addition, CFs/TiO₂ cloth can be easily recycled with good performance stability.（2） We have prepared TiO₂ nanotube arrays on Ti wire by using anodization method. Then the Ti/TiO₂ wires were finally performed after annealing. This method is simpler than the dip-coating and hydrothermal growth method. So this photoelectrode has a good application perspective. The tube diameter and length of TiO₂ nanotube is about 85 nm and 10 μm, respectively. Subsequently, 16 Ti/TiO₂ wires can be weaved to be a macroscale Ti/TiO₂ net（weight: 0.25 g, total area: 36 cm2）. Moreover, under the illumination of simulated solar light, Ti/TiO₂ net can degrade 87.8% Rohdamine B（Rh B） in 100 min by photoelectrocatalytic degradation process（bias: 0.6V vs SCE）, which is higher than the efficiency from single photocatalysis（60.0% Rh B） or electrocatalysis（3.6% Rh B） process. Furthermore, The stability of Ti/TiO₂ net is excellent, the catalytic performance can be kept over 85% after 4 cycles.Therefore, CFs/TiO₂ cloth and Ti/TiO₂ net can be used as a promising, easily recyclable and large-area photocatalyst/photoelectrode in practical application（such as degrading organic pollutants in lake and/or river）. More importantly, this work provides some insights into the design of efficient and macroscale photocatalyst/photoelectrode with other nanosized semiconductor for enhancing visible-light-driven photocatalytic activity.