氟、硼共掺杂对纳米TiO_2能带结构与可见光光催化性能的影响

Effect of Boron and Fluorine Co-doping on the Band Gap Structure of TiO_2 and Its Visible Light Photocatalytic Performance

以钛酸四丁酯、氟化铵、硼酸为原料,采取改进的溶胶-凝胶法制备了氟、硼共掺杂的纳米二氧化钛粉体。XRD结果显示氟、硼共掺杂不仅可以抑制晶粒生长,还可以阻止锐钛矿相向金红石相的转变。当氟、硼物质的量比为5∶20时,其表现出更好的可见光响应。XPS结果表明:氟和硼分别和钛形成了F-Ti键和B-Ti键,它们的形成可提高价带中光生空穴的氧化能力和拉窄二氧化钛的带隙,从而提高了其可见光照射下的光催化活性。可见光照射下降解4-氯苯酚,结果表明:经600℃煅烧2h的样品,氟、硼物质的量比为5∶20,其降解率分别是单掺杂和纯二氧化钛的1.5到3倍。总有机碳(TOC)分析结果表明4-氯苯酚在可见光照射下被光催化剂有效地矿化。

Boron and fluorine codoped TiO2 powders were prepared by hydrolysis of titanium tetra-n-butyl oxide in a mixed NH4F-H3BO3-H2O solution. The XRD results showed that the co-doping of boron and fluorine could not only efficiently inhibit the grain growth but also suppress the phase transition of anatase to rutile. When the molar ratios of B and F to Ti are 20∶100 and 5∶100 and calcined at 600 ℃,UV-vis spectroscopy of the sample showed better visible light responding. XPS results revealed that the Ti-B bonds and Ti-F bonds have formed which could extend the absorption spectra to visible light region and enhance visible light photocatalytic activity. When the molar ratios of B and F to Ti are 20∶100 and 5∶100 and calcined at 600 ℃,the degradation rate of 4-chlorophenol （4-CP） over the sample was about 1.5 to 3.0 times higher than that for other doped samples and undoped TiO2. The total organic carbon （TOC） removal rates of 4-CP showed that 4-CP has been mineralized efficiently with the sample under visible light illumination.