S与Cr共掺杂TiO_2介孔材料的固相合成及其可见光降解中性红

Solid-phase Synthesis of S and Cr Co-doped TiO_2 Mesoporous Materials with Visible Light Degradation Property for Neutral Red

采用固相反应法分别合成了铬掺杂二氧化钛(Cr-TiO2)、硫掺杂二氧化钛(S-TiO2)及硫和铬共掺杂二氧化钛(S-Cr-TiO2)介孔材料,对其进行了物相织构表征,并研究了其对中性红的可见光降解性能.结果表明,在S-Cr-TiO2中,硫以阳离子S6+形式、铬以同晶取代方式进入TiO2晶格或晶格间隙;S-TiO2,Cr-TiO2及S-Cr-TiO2(摩尔比S/Cr=1:1)的比表面积分别为148.2,134.6,122.8m2/g,孔半径分布中心依次为2.4,2.6和3.06nm.S-Cr-TiO2则随S/Cr比增大比表面积逐渐降低,同时存在Ti—O—S和Cr—O—S键并出现微量Cr2O3与CrO3物相.S与Cr共掺杂能有效限制TiO2微晶的生长,其紫外-可见漫反射吸收光谱覆盖了可见光区并延伸到近红外区域.在25℃及pH=6.5条件下,S-Cr-TiO2(S/Cr=3:2)在60min内对中性红的降解率达91.8%,分别是纯TiO2(39.6%),S-TiO2(52.7%)及Cr-TiO2(43.4%)的2.32,1.74和2.11倍.Cr3+与Cr6+的相对含量及价态的转化控制中性红的降解率,Cr6+对中性红的降解起决定性作用.

S and Cr co-doped TiO2（S-Cr-TiO2） ,S-doped TiO2（S-TiO2） and Cr-doped TiO2（Cr-TiO2） mesoporous nanomaterials are synthesized by solid-state reaction. Their textural properties are characterized. And,the visible light degradation properties of neutral red（NR） on the materials are investigated. The results show that S atom as S^66＋ and Cr as Cr^3＋ and/or Cr^6＋ states are incorporated into the lattice of TiO2 or interstice of TiO2 lattice. The BET specific surface areas of 148.2,134.6 and 122.8 m2/g,as well as the pore distribution centres of 2.4,2.6 and 3.06 nm for S-TiO2,Cr-TiO2 and S-Cr-TiO2（S/Cr=1：1,molar ratio） materials are obtained,respectively. Moreover,the areas of S-Cr-TiO2 mesomaterials decrease with increasing of S/Cr molar ratio. The bonds of Ti—O—S and Cr—O—S and the trace of Cr2O3 and CrO3 exist in the S-Cr-TiO2 mesoporous materials. S and Cr co-doped TiO2 can effectively embarrass the crystal growth of TiO2. The UV-Vis spectra display that the adsorption region of S-Cr-TiO2 materials covers the visible light region and extends to near infrared light region. Moreover,at 25℃,pH=6.5,the high catalytic activity for NR is found on the S-Cr-TiO2（S/Cr=3：2） meso-material irradiated by the visible light. Within 60 min,the visible light degradation rate of NR on the S-Cr-TiO2 meso-material is 91.8%,which is 2.32,1.74 and 2.11 times corresponding to pure TiO2（39.6%） ,S-TiO2（52.7%） ,Cr-TiO2（43.4%） ,respectively. The atomic percentage and transformation between Cr^3＋ and Cr^6＋ in S-Cr-TiO2 meso-materials control the degradation rate of NR,and the Cr^6＋ ions act as a key role on S-Cr-TiO2 catalysts.