Study Of The Nanocatalyst Supported By Polymer Single Crystal

In recent years, nanocatalysts have attracted more and more attention due to its high catalytic activity. The high catalytic activity mainly comes from the high surface area to volume ratio of the nanocatalysts. However, there are still challenges during the utilization of the nanocatalysts. First, nanocatalysts tend to form aggregates in the solution, which greatly reduce their surface area, resulting in the decrease of their catalytic activity. Second, because of the small sizes of the nanoparticles, it is difficult to recover them from the solution after the reaction, resulting in the loss of the nanocatalysts. In order to overcome the above problems, we have utilized the two dimensional polymer single crystal lamella as the support for the nanocatalyst. The polymer single crystals not only haves very high surface area to volume ratio but also possess abundant surface functional groups through surface reactions. As a consequence,a high load rate of the nanocatalyst can be achieved. In addition, the recycling of the polymer single crystal supported nanocatalyst can be easily realized through simple centrifugation or magnetic methods. Detailed as follows:(a) Unprotected silver nanoparticles were immobilized onto the functional carboxylic acid groups on the surface of the polymer single crystal with controllable size through photogenerated chemical reduction reaction. The resulting hybrid structures were characterized by transmission electron microscopy, UV-Vis spectroscopy, and atomic force microscopy. The polymer single crystal supported nanocatalysts are utilized in the 4-nitrophenol reduction reaction. Its catalytic performance is evaluated in the presence of NaBH4. As compared to surface ligand protected silver nanoparticles, silver nanoparticles modified on the surface of the polymer single crystals not only exhibit high catalytic activity, but also showsize-dependent catalytic activity. Smaller sized silver nanoparticles(~ 1.5 nm) exhibit the highest cativity. The obtained catalyst system can be magnetically recovered and reused through the introduction of the iron oxide magnetic nanoparticles on the surface of the polymer single crystal. The high nanocatalyst loading on the polymer single crystal surface due to its high surface area to volume ratio makes the current catalyst system attractive for practical applications.(b) The polymer single crystal was treated with alkali, resulting in carboxyl acid functional groups on its surface. TiO2 nanoparticles were then successfully immobilized onto the surface carboxyl acid groups of the polymer single crystal. In addition, we have realized the photocatalytic degradation process of methyl orange based on the polymer single crystal supported TiO2. UV-Vis spectroscopy was utilized to study the photocatalytic degradation process. The results show that the catalytic system has high catalytic activity which can effectively degrade methyl orange. In addition, we found out the recycling of the polymer single crystal supported TiO2 nanocatalyst can be achieved simple centrifugation method. Furthermore, we have prepared four catalyst systems, including poly(epsilon-caprolactone) single crystal loaded with TiO2 nanoparticles and silver nanoparticles, poly(epsilon-caprolactone) single crystals loaded with TiO2 nanoparticles and gold nanoparticles, poly(epsilon-caprolactone) single crystals loaded with poly(acrylic acid) and TiO2 nanoparticles,poly(epsilon-caprolactone) single crystal loaded with titanium nanoparticle, polypyrrole polymer, poly(acrylic acid) and TiO2 nanoparticles. We have studed their photocatalytic degradation of methyl orange dyes.(c) We have synthesized poly(ethylene oxide) single crystal and poly(epsilon-caprolactone) single crystals. The size of these two single crystals can be controlled by controlling the seeding temperature. CdSe quantum dots and gold nanoparticles can be immobilized on the surface of the polymer single crystal through the thiol groups on the polymer crystal surface. After sodium hydroxide treatment, the surface of poly(epsilon-caprolactone) single crystal is rich of carboxyl acid groups. TiO2 nanoparticles, catalase, glucose oxidase and horseradish peroxidase can thus beimmobilized on the surface of the polymer single crystal. Furthermore, we have studied the properties of these functionalized polymer single crystals.