Abstract
TiO2 nanotubes attract much attention because of their high photoelectron-chemical and photocatalytic efficiency. But their large band gap leads to a low absorption of the solar light and limits the practical application. How to obtain TiO2 nanotubes without any dopant and possessing visible light response is a big challenge nowadays. Orthorhombic titanic acid nanotubes (TAN) are a special precursor of TiO2, which possess large Brunauer-Emmett-Teller (BET) surface areas and strong ion exchange and adsorption capacity. TAN can transform to a novel TiO2 with a large amount of single-electron-trapped oxygen vacancies (SETOV) during calcination, while their nanotubular structure would be destroyed, and a BET surface area would decrease remarkably. And interestingly, SETOV can lead to a visible light response for this kind of TiO2. Herein, glucose was penetrated into TAN by the vacuum inhalation method, and TAN would dehydrate to anatase TiO2, and glucose would undergo thermolysis completely in the calcination process. As a result, the pure TiO2 nanotubes with visible light response and large BET surface areas were obtained. For further improving the photocatalytic activity, Pd nanoparticles were loaded as the foreign electron traps on TiO2 nanotubes and the photocatalytic oxidation efficiency of propylene was as high as 71 % under visible light irradiation, and the photostability of the catalyst kept over 90 % after 4 cyclic tests.
Highlights
The last decades have witnessed the flying advance of our society; at the same time, many problems appear
These pure anatase TiO2 nanotubes with a small diameter, large BET surface areas, and visible light response would have a large potential in the field of visible light photocatalysis and solar cell
In our previous researches [28, 29], we found that when titanic acid nanotubes (TAN) were dehydrated at 400 °C or above, a novel anatase TiO2 containing a large amount of single-electron-trapped oxygen vacancies (SETOV) was obtained
Summary
The last decades have witnessed the flying advance of our society; at the same time, many problems appear. One of the top problems is environmental concern. It has effects on ecological balance, human health, and sustainable development. Photocatalytic elimination of the organic pollutants is one of the efficient ways to alleviate the pollution of the environment and which has been widely studied in the past decades [1,2,3,4,5]. A TiO2 photocatalyst has attracted much attention and has been widely used in degradation of organic pollutants, CO2 reduction, and so on [7,8,9,10,11,12]. To increase the light response region and enhance the efficiency, many approaches have been tried, such as modifying with metal or nonmetal ions [12,13,14,15,16], coupling with other narrow band gap semiconductors [17,18,19], or sensitizing by various dyes [20,21,22,23]
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