Photocatalytic And Electrocatalytic Properties Of C₃N₄and Pt Supported On TiO₂Composite Materials

Due to the major problems of the global energy crisis and environmental pollution to be solved in the21st century, it is of great importance to develop new clean energy. Titanium dioxide (TiO2) brings the hope to resolve these issues because of its nontoxicity, low cost and high photocatalytic activity. Nevertheless, there still exist some defects with TiO2such as low utilization of sunlight and high electron-hole recombination rate, restricting its wide applications greatly. As is known, TiO2can be served as excellent catalyst support. However, the study on the influence of structure of support on catalytic activity is still scarce. In this thesis, on the one hand, TiO2nanotube arrays (TNTAs) and TiO2nanowire arrays (TNWAs) were prepared as the supports of Pt catalysts, the effect of different TiO2nanostructures on the performance of Pt catalysts was studied by taking electrocatalytic methanol oxidation as the probe reaction. On the other hand, C3N4/TiO2nanobelts (C3N4/TiO2-NBs) composite materials with different proportion of C3N4to TiO2-NBs were prepared to enhance the photocatalytic activity of TiO2and their photocatalytic mechanisms were also discussed. The main works are presented as follows:(1) TiO2nanomaterials with different structures were prepared by an electrochemical anodization method and a hydrothermal method. TNTAs and TNWAs were selected as the supports of Pt catalysts. Pt/TNTAs and Pt/TNWAs were prepared by a microwave heating method. The catalysts were characterized by XRD, SEM, and TEM. In addition, the performances of the two TiO2supported Pt catalysts for electrocatalytic methanol oxidation were investigated. The results demonstrated that Pt/TNTAs showed a superior performance to Pt/TNWAs for methanol oxidation. It can be speculated that the excellent activity of Pt/TNTAs is attributed to the confinement effects. The study reveals that the structure of supports plays an important role in determining the performances of Pt catalysts for methanol oxidation.(2) Using TiO2-NBs as the template, the C3N4/Ti02-NBs composite materials with different proportion(4:1,3:1,2:1,1:1) were successfully prepared, and then tested for the photocatalytic water splitting into H2and the photodegradation of organic dyes. Compared to the single C3N4or TiO2-NBs, the composite C3N4/TiO2-NBs showed the highest photocatalytic hydrogen production rate of46.9μmol·h-1when the proportion of C3N4to TiO2-NBs is3:1. In addition, the C3N4/TiO2NBs also exhibited the best performance in the photocatalytic decomposition of RhB when the proportion of C3N4to TiO2-NBs is1:1. It is believed that C3N4can act as a visible light sensitizer. The matched energy band of C3N4and TiO2-NBs suppresses the photogenerated electron-hole recombination, leading to the enhanced photocatalytic activity.