物理化学学报
物理化學學報
물이화학학보
ACTA PHYSICO-CHIMICA SINICA
2011年
4期
939-945
,共7页
苏雅玲%李轶%杜瑛珣%雷乐成
囌雅玲%李軼%杜瑛珣%雷樂成
소아령%리질%두영순%뢰악성
TiO2纳米管%氟掺杂%可见光%催化活性%电子结构
TiO2納米管%氟摻雜%可見光%催化活性%電子結構
TiO2납미관%불참잡%가견광%최화활성%전자결구
TiO2 nanotubes%Fluorine-doping%Visible-light%Catalytic property%Electronic structure
作为光催化技术的核心,提高TiO2的光催化活性和对可见光的利用率是当前光催化研究中最重要的研究课题.为了提高TiO2纳米管的可见光催化活性,采用化学气相沉积法对TiO2纳米管进行了氟掺杂.扫描电子显微镜(SEM)结果表明退火温度对于TiO2纳米管的形貌完整性有较大影响,当样品在550和700℃下退火,氟掺杂TiO2纳米管结构受损;X射线衍射(XRD)分析表明氟掺杂对TiO2由锐钛矿相转化为金红石相有阻碍作用;X射线光电子能谱(XPS)测试表明化学气相沉积能有效地对TiO2纳米管进行非金属掺杂,且该方法安全、操作简单.氟掺杂TiO2纳米管对甲基橙有较高的可见光催化降解活性.第一性原理计算结果表明氟掺杂对TiO2带隙无显著影响,费米能级附近的F2p轨道电子位于价带底部,与O2p交联作用较小,因此对TiO2光吸收带边影响不大.氟掺杂能促进表面氧空穴的产生,增加表面酸度与Ti3+,有利于减少电子-空穴复合率,从而提高其光催化活性.
作為光催化技術的覈心,提高TiO2的光催化活性和對可見光的利用率是噹前光催化研究中最重要的研究課題.為瞭提高TiO2納米管的可見光催化活性,採用化學氣相沉積法對TiO2納米管進行瞭氟摻雜.掃描電子顯微鏡(SEM)結果錶明退火溫度對于TiO2納米管的形貌完整性有較大影響,噹樣品在550和700℃下退火,氟摻雜TiO2納米管結構受損;X射線衍射(XRD)分析錶明氟摻雜對TiO2由銳鈦礦相轉化為金紅石相有阻礙作用;X射線光電子能譜(XPS)測試錶明化學氣相沉積能有效地對TiO2納米管進行非金屬摻雜,且該方法安全、操作簡單.氟摻雜TiO2納米管對甲基橙有較高的可見光催化降解活性.第一性原理計算結果錶明氟摻雜對TiO2帶隙無顯著影響,費米能級附近的F2p軌道電子位于價帶底部,與O2p交聯作用較小,因此對TiO2光吸收帶邊影響不大.氟摻雜能促進錶麵氧空穴的產生,增加錶麵痠度與Ti3+,有利于減少電子-空穴複閤率,從而提高其光催化活性.
작위광최화기술적핵심,제고TiO2적광최화활성화대가견광적이용솔시당전광최화연구중최중요적연구과제.위료제고TiO2납미관적가견광최화활성,채용화학기상침적법대TiO2납미관진행료불참잡.소묘전자현미경(SEM)결과표명퇴화온도대우TiO2납미관적형모완정성유교대영향,당양품재550화700℃하퇴화,불참잡TiO2납미관결구수손;X사선연사(XRD)분석표명불참잡대TiO2유예태광상전화위금홍석상유조애작용;X사선광전자능보(XPS)측시표명화학기상침적능유효지대TiO2납미관진행비금속참잡,차해방법안전、조작간단.불참잡TiO2납미관대갑기등유교고적가견광최화강해활성.제일성원리계산결과표명불참잡대TiO2대극무현저영향,비미능급부근적F2p궤도전자위우개대저부,여O2p교련작용교소,인차대TiO2광흡수대변영향불대.불참잡능촉진표면양공혈적산생,증가표면산도여Ti3+,유리우감소전자-공혈복합솔,종이제고기광최화활성.
Improving the photocatalytic activity and the utilization of visible light of TiO2 is the most important research topics in the photocatalytic field. To improve the photocatalytic activity of TiO2, we used chemical vapor deposition (CVD) to dope TiO2 nanotubes with fluorine. Scanning electron microscopy (SEM) images showed that the annealing temperature significantly affected the morphological integrity of TiO2 nanotubes. Upon annealing at 550 and 700 ℃, the structure of F-doped TiO2 nanotubes suffered from an observable disintegration of morphological integrity. X-ray diffraction (XRD) results indicated that the F impurity retarded the anatase-rutile phase transition. Fluorine was successfully doped into TiO2 by CVD, as indicated by the X-ray photoelectron spectroscopy (XPS) results. F-doped TiO2 nanotubes showed higher photocatalytic activity. First-principles calculations suggested that the F 2p states were located in the lower-energy range of valence band (VB) and less mixed with O 2p states. It thus contributed little to the reduction of the optical band gap. This is consistent with the finding that the band gap of F-doped TiO2 is very close to that of undoped TiO2. Therefore, the higher catalytic activity of F-doped TiO2 should be attributed to the creation of surface oxygen vacancies upon F-doping, which enhances surface acidity and increases the amount of Ti3+ ions.
