In-situ preparation of Ag and TiOz multi-phase nanometer crystal composite thin-membrane light catalyst

A composite film, photocatalyst technology, applied in catalyst activation/preparation, chemical instruments and methods, physical/chemical process catalysts, etc., can solve the problems of difficult separation and recovery of powder, secondary pollution, etc.

Inactive Publication Date: 2005-05-11
WUHAN UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In practical application TiO 2 The powder photocatalyst also has the following defects: After the photocatalytic reaction, TiO 2 The powder is difficult to separate and recover from the aqueous solution, and there is a problem of secondary pollution, so it is necessary to treat TiO 2 The powder photocatalyst is immobilized, that is, TiO 2 Particles adhere to substrates such as quartz glass, boron glass, stainless steel and ceramics, or directly prepare TiO on the surface of various substrates 2 thin film photocatalyst
But all these methods have many disadvantages in industrial applications
For example, the sol-gel method requires repeated coatings to obtain the required thickness; magnetron sputtering and chemical vapor deposition require special and expensive equipment

Method used

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  • In-situ preparation of Ag and TiOz multi-phase nanometer crystal composite thin-membrane light catalyst
  • In-situ preparation of Ag and TiOz multi-phase nanometer crystal composite thin-membrane light catalyst
  • In-situ preparation of Ag and TiOz multi-phase nanometer crystal composite thin-membrane light catalyst

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Ammonium hexafluorotitanate, silver nitrate and boric acid are used as raw materials to prepare aqueous solutions of ammonium hexafluorotitanate, silver nitrate and boric acid respectively, and then the three aqueous solutions are mixed according to a set ratio, and the precursor solution is prepared after stirring evenly. The molar concentrations of ammonium hexafluorotitanate, silver nitrate and boric acid in the resulting final solution were 0.1, 0.03 and 0.3 M, respectively. At room temperature (25°C), immerse a clean quartz glass sheet in the prepared precursor solution and hang it vertically for 48 hours, then take it out and rinse it with distilled water, dry it, and then heat treat it at 500°C for 1 hour to obtain Ag / TiO 2 Nanocrystalline composite thin film photocatalyst, the photocatalytic test results show that the prepared Ag / TiO 2 Nanocrystalline composite films have good photocatalytic activity. Its apparent rate constant is 15.4×10 -3 (min -1 ).

Embodiment 2

[0042] In order to examine the effect of precursor concentration on film quality and photocatalytic activity, other experimental conditions such as reaction temperature and time, heat treatment temperature and time, etc. are exactly the same as in Example 1 except that the concentration of precursors is different. It was found that: when the molar concentrations of ammonium hexafluorotitanate and boric acid were too high, greater than 3.0 and 6.0 M, respectively, due to the high degree of supersaturation, homogeneous nucleation was the main form in the solution to form TiO 2 Precipitate, but can not form good TiO 2 film, when the film is heat-treated, TiO 2 It is easy to fall off from the surface of the substrate; on the contrary, if the molar concentration of ammonium hexafluorotitanate and boric acid is too low, lower than 0.01 and 0.03M, respectively, the solution is in a metastable state due to too small supersaturation and cannot form TiO 2 Precipitation or film. When t...

Embodiment 3

[0044] In order to test the influence of the ratio of molar concentration between boric acid and ammonium hexafluorotitanate on film quality and photocatalytic activity, except that the ratio of molar concentration between boric acid and ammonium hexafluorotitanate is different, other experimental conditions such as reaction temperature and Time, heat treatment temperature and time etc. are all identical with embodiment 1. It was found that when the ratio of the molar concentration between boric acid and ammonium hexafluorotitanate is less than 1, because the fluoride ions in the precursor solution cannot be effectively complexed, the film formation rate is slow, and the obtained film is very thin, and the film shows low photocatalytic activity. On the contrary, if the ratio of the molar concentration between boric acid and ammonium hexafluorotitanate is too high (when greater than 6), because the reaction rate is too fast, the formed film is easy to fall off after heat treatm...

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Abstract

An in-situ preparing process for the composite film photocatalyst of Ag / TiO2 nanocrystals includes such steps as preparing the saturated aqueous solutions of ammonium fluorotitanate, boric acid and silver ntirate, proportional mixing, immersing quartz glass plate in it at 5-80 deg.C for 4-60 hr, flushing with distilled water, baking and heat treating at 400-800 deg.C. Its advantage is high photocatalytical activity.

Description

technical field [0001] The invention relates to the technology for preparing metal and semiconductor oxide composite thin film materials, in particular to Ag and TiO with high photoactivity 2 The invention relates to a method for preparing nanocrystal composite thin film semiconductor photocatalyst with multiple phases, that is, three phases of Ag and anatase, brookite phase or four phases of Ag, anatase, brookite and rutile phase. technical background [0002] In recent years, in order to solve the increasingly serious problem of environmental pollution, the research and development of highly active heterogeneous semiconductor photocatalytic materials has received extensive attention from governments and researchers all over the world. There are more and more research papers and patents in this area, and every year Thousands of research papers have been published, because this kind of photocatalytic materials can be widely used in the degradation of organic pollutants, wate...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J21/06B01J23/50B01J37/03
Inventor 余家国程蓓熊建锋
Owner WUHAN UNIV OF TECH
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