【作者】 魏凤玉；

【导师】 钱逸泰；

【作者基本信息】 合肥工业大学 ， 材料学， 2008， 博士

【摘要】 本文采用水热法制备了金属与非金属共掺杂、非金属共掺杂的纳米TiO₂和金属掺杂的TiO₂微球,并分别采用XRD、Uv-vis、XPS、FTIR和光催化降解甲基橙对其物相和光催化性能进行了研究。以TiCl₄和FeCl₃为原料、在表面活性剂Span—80存在时,180℃下水热反应48h可成功制得直径为3—10μm的金红石、锐钛矿和板钛矿混合相的微球TiO₂-Fe-Span。XPS表明掺杂的铁以Fe³⁺形式存在;Uv-vis结果表明,微球具有较高的可见光吸收性能,且吸收带边发生明显的红移。该微球在紫外光照射3h和太阳光照射6h时对甲基橙的降解率分别达100%和91%。特别地,光催化反应后微球可采用自然沉降的方法进行分离,这一特点为TiO₂光催化技术的实际应用提供了很好的基础。用TiCl₄、FeCl₃和硫脲为原料,制得了硫和铁共掺杂的金红石和锐钛矿混合相的纳米二氧化钛（TiO₂-S-Fe）。160℃下制得的TiO₂-Fe-S样品催化活性最优,紫外光照射60min和太阳光照射50min时对甲基橙的降解率分别达97%和99%。UV-vis表明该催化剂对可见光吸收增强,吸收带边明显红移。XPS表明,掺杂的硫取代TiO₂中的晶格氧形成Ti-S键,使得TiO₂的带隙能窄化引起对可见光的响应;同时部分掺杂的硫以S⁶⁺形式存在,从而增强了TiO₂-S-Fe的表面酸强度,提高了对氧和有机物的吸附;铁掺杂降低了电子和空穴的复合几率。阴阳离子的协同作用使得TiO₂-S-Fe具有很高的紫外和可见光催化活性。以Ti（SO₄）₄、硼酸和硫酸为原料,制得了B、S共掺杂的锐钛矿型纳米二氧化钛（TiO₂-B-S）。UV-vis表明该催化剂对可见光吸收增强,吸收带边明显红移。XPS显示B、S共掺杂改性使得TiO₂-B-S表面羟基氧含量提高,这对提高光活性是有益的。240℃下制得的TiO₂-B-S具有较高的催化活性,紫外光照射50min后对甲基橙几乎全部降解,太阳光照射230min后的降解率达92%。硼硫共掺杂TiO₂具有较高的紫外光和可见光活性的原因可能是掺杂的硼以B³⁺进入晶格中,导致TiO₂晶格畸变、带隙变窄,S掺杂提高了TiO₂的表面酸度;B、S共掺杂对提高TiO₂的光催化剂活性具有协同效应。以Ti（SO₄）₄为钛源、硫脲为掺杂剂时,得到了N、S共掺的锐钛矿型纳米二氧化钛（TiO₂-N-S）。UV-vis表明该催化剂对可见光吸收增强,吸收带边红移;EA和XPS分析表明催化剂表面的N含量高于体相的;光催化实验表明TiO₂-N-S催化活性高于纯TiO₂和单掺硫TiO₂,在紫外光照射90min和太阳光照射120min下对甲基橙的降解率分别达88.2%、41.4%。TiO₂-N-S光催化活性的提高与UV-vis光区的强吸收、吸收带边的红移、氧缺的产生以及表面酸度的提高等因素引起的协同效应有关。更多还原

【Abstract】 S-Fe,B-S,N-S-codoped TiO₂ nanoparticle and Fe doped microspheres had been prepared by hydrothermal method.Their characteristics were investigated by XRD,UV-vis,XPS,FTIR and photocatalytic degradation for methyl orange（MO）.Fe doped titania microspheres with a diameter of about 5-7μm have been synthesized using TiCl₄ and FeCl₃ as the precursor in the presence of Span-80 at 180℃for 48h.XRD indicated that the microspheres were a mixture of rutile,brookite and anatase.XPS showed that the oxidation state of iron in the lattices was probably Fe₂O₃.The UV-Vis DRS revealed that the absorption edge of microspheres had a remarkable shift to the visible light region,its absorption in the visible region was increased.The photocatalytic experiments revealed that the microspheres exhibited high photocatalytic activities under UV-light and solar irradiation.The degradation rate of MO were 100%under UV light irradiation for 3h and 91%under solar irradiation for 6h.In particular, the microspheres could be readily separated by sedimentation after the photocatalytic reaction.It is expected that the TiO₂ microspheres could be one of the ideal photocatalysts for the water purification.S and Fe co-doped TiO₂ nanoparticles（TiO₂-S-Fe） were prepared by in situ hydrothermal method using TiCl₄,FeCl₃ and thiurea as the precursor.The results of photocatalytic degradation MO demonstrated that the TiO₂-S-Fe catalyst obtained at 160℃for 2 h exhibited the highest photocatalytic activity,the degradation ratio of MO were 99%and 97%under sunlight irradiation for 50 min and UV light irradiation for 60 min,respectively.XRD indicated that the TiO₂-S-Fe is in conformity with anatase and rutile mixed phase TiO₂ form.UV-vis DRS showed that its absorption in the visible light district was strengthened and the band edge moved to longer wave obviously.XPS indicated that the partial S atoms occupied O-atom sites in the TiO₂ to form Ti-S bond,lowered the band gap and caused the absorption edge of TiO₂ to be shifted into the lower-energy region.The partial sulfur atoms existed in a six-oxidation state(S⁶⁺) and then enhanced the surface acidity that favored to the adsorption of both oxygen and organic molecules. Doping of Fe³⁺ reduced the recombination of electrons and holes.Both of the above doped effects are beneficial for improving the photocatalysis of TiO₂-S-Fe under UV-light and sun-light irradiation.B-S-codoped anatase TiO₂ nanoparticles（TiO₂-B-S） was prepared using Ti（SO₄）₂,H₂SO₄ and H₃BO₃ as starting materials.UV-vis DRS showed that its absorption in the visible light district was strengthened and the band edge moved to longer wave obviously.XPS showed that the content of hydroxyl group on its surface increased,compared with that of B or S-doped TiO₂, which favored its photocatalysis.The photocatalytic experimental results indicated that TiO₂-B-S prepared at 240℃for 12 hours exhibited the highest photocatalytic activity,the degradation ratio prepared at 240℃for 12 hours exhibited the highest photocatalytic activity,the degradation ratio of methyl orange were 99.8%and 92.0%under UV light irradiation for 50 min and sunlight irradiation for 230 min,respectively.The higher visible light photocatalytic activity of B-S co-doped TiO₂ was attributed to the doped boron that lowered the band gap,resulted in the localized crystal deformation and the doped sulfur which enhanced the surface acidity of TiO₂. Doping of B and S possessed the synergistic effects on enhancement of TiO₂ photocatalytic activity.N-S-codoped anatase TiO₂ nanoparticles（TiO₂-N-S） was prepared using Ti（SO₄）₂ with thiourea as N,S sources.A red shift of the absorption edge was brought out owing to N and S codoping, and the extension for photoabsorption range of it occurred.XPS and EA studies showed that N concentration decreased from the surface to the center.Especially,the photocatalytic tests indicated that it demonstrated a high photocatalytic activity for decomposition of methyl orange, comparing to S doped TiO₂ and undoped TiO₂.The degradation ratio of methyl orange were 88.2 %and 41.4%under UV light irradiation 90 min and sunlight irradiation for 120 min,respectively. The high activity of it can be related to the results of the synergetic effects of strong absorption in the UV-vis light region,red shift in adsorption edge,oxygen vacancies and the enhancement of surface acidity induced by N and S codoping.更多还原