| Under the background of energy crisis, hydrogen is widely concerned as a kind of green energy. The transformation from unstable solar energy into convenient and clean hydrogen via photocatalytic reaction is an important part in the field of green energy technology. To accomplish this transformation, efficient and stable photocatalyst is indispensable. Around the studies on this kind of catalysts, TiO2 is one of which show a very superior photocatalytic hydrogen evolution performance. Thus, research on TiO2 is the most widespread.Although TiO2 is a promising photocatalyst with many notable characteristics, it’s not perfect because it only responds to UV light. Also the combination rate of photo-generated electronic-hole pairs is comparatively high. Therefore, TiO2 is not very satisfactory as a catalyst for photocatalytic hydrogen evolution. In order to improve the performance of TiO2, a lot of studies have been conducted, and many new TiO2 photocatalyst was developed. Around these catalysts, TiO2 nanotubes arrays, especially those fabricated on 3D mesh substrate, present considerable potentials. At present, TiO2 nanotube arrays loaded precious metals were applied widely in photocatalytic hydrogen evolution from water, and showed good catalytic performance. But researches on the morphology of cocatalysts in the 3D nanoarrays and the fabrication of the coaxial nano structure are not comprehensive yet. Moreover, the exploration of their application is relatively slow. Based above, we completed a series of in-depth studies on novel TiO2 nanoarrays and its photocatalytic hydrogen evolution behavior. Meantime, we also developed the photocatalytic reactor according to the researches. The main results obtained are as follows:1) Developed a novel continuous photocatalytic hydrogen evolution sysytem, including four parts:photocatalytic reactor, circulating tank, piping and power. Gas-liquid separation, online sampling and continuous production can be achieved in the fixed bed reactor. The reactor has many characteristics such as normal pressure operation, convenient detection, the experiment data precision, good repeatability, and less dosage of catalyst etc. It is quite suitable for using in the evaluation of the photocatalytic hydrogen evolution over new photocatalysis in laboratory sacale. In addition, this system has a certain potential of large-scale application, and the experimental data can be used in scale up design of the reactor.2) 3D TiO2 nanotube arrays were buided on the titanium mesh. The arrays loaded Pt present a strong activity in photocatalytic hydrogen evolution. The highest hydrogen evolution rate can be up to 4.6 L m-2 h-1. To fabricated TiO2 nanotube arrays on the titanium mesh is a quite promising immobilization method for TiO2 nanomaterials. The problems caused by immobilization of nano TiO2, such as decline of the specific surface area, ability to capture light and photocatalytic activity etc., all can be effectively solved in this way.3) Coaxial TiO2-Ag nanowire arrays were preparation on the titanium meshes by a combination of anodic oxidation method and electrodeposition method. The array composed of TiO2-Ag coaxial nanowires.The introduction of Ag seed is critical for the formation of TiO2-Ag coaxial nanowires arrays during the process. Without this step, most Ag will be deposited outside the openings of the TiO2 nanotubes. In addition, the arrays have a good optical absorption capacity, ranging across ultraviolet-visible absorption area until 800 nm. It indicates that these arrays may have a higher efficiency in the solar light, and are potential photocatalytic hydrogen evolution catalysts. |
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