酸处理对TiO₂薄膜光催化及亲水性能影响的研究

【作者】 陈永平；

【导师】 尹荔松；

【作者基本信息】 中南大学 ， 凝聚态物理， 2008， 硕士

【摘要】 本研究从提高TiO₂光催化活性和亲水性的角度对TiO₂进行表面改性，重点研究了用醋酸和硫酸对TiO₂薄膜进行表面改性处理，从机理的角度深入探讨了表面酸改性处理对TiO₂薄膜的亲水性和光催化性能的影响。本文采用三层薄膜在400℃第一次退火，制备未改性薄膜；然后将未改性薄膜在酸中浸泡24小时，再在不同温度下第二次退火处理，制备改性的薄膜。制备的薄膜采用XRD分析晶相结构、晶粒尺寸；用AFM分析表面形貌；用UV分析光学性能。研究了制备条件、改性酸的浓度等对TiO₂光催化活性和亲水性的影响，取得了一些显著创新性成果，对高效光催化剂和亲水性具有重要的指导意义。本论文主要研究结果如下：1．系统研究了醋酸和硫酸的处理浓度对TiO₂亲水性能影响。研究表明：改性后的薄膜的亲水性与酸的种类和酸的浓度有很大的关系。酸处理后，薄膜的热致亲水性和光致亲水性，比处理前明显提高。其中醋酸最佳浓度用1mol／L；硫酸最佳浓度为0．4 mol／L。在最佳浓度下，醋酸处理的薄膜有很好的超亲水性和光致响应速度，同时还能延长薄膜的亲水时间；紫外光照1．5h达到超亲水性，此后避光22h仍有强亲水性；硫酸处理后，光照1h达到超亲水性，此后避光12h失去亲水性。可见光照2．5h后，1mol／L醋酸处理的薄膜达到超亲水性；硫酸处理后，薄膜没有超亲水性。表明硫酸改性的薄膜光致响应速度优于醋酸改性，但从改善和延长薄膜的亲水时间的角度来看，醋酸优于硫酸改性。2．系统研究了醋酸与硫酸处理的浓度对对TiO₂光催化性能的影响。本实验结果表明，用醋酸与硫酸改性处理，能大幅度提高纳米TiO₂的光催化特性。其中用1mol／L醋酸和0．4mol／L硫酸处理的TiO₂薄膜光催化性能最好，用1mol／L醋酸改性后薄膜在紫外光照3h内对亚甲基兰和甲基橙溶液的降解率为66％、45％；用0．4mol／L硫酸处理的TiO₂薄膜在紫外光照3h内对亚甲基兰溶液的降解率为78％和62％；未改性的薄膜在相同条件下对亚甲基兰和甲基橙溶液的降解率仅为15％、10％。在可见光照3h内，用1mol／L醋酸改性后薄膜在紫外光照3h内对亚甲基兰和甲基橙溶液的降解率为30％、21％；用0．4mol／L硫酸处理的TiO₂薄膜在紫外光照3h内对亚甲基兰溶液的降解率为35％和27％；这说明用硫酸改性处理比醋酸改性处理相对好些。通过晶体结构分析，表明用硫酸处理薄膜能抑制晶粒生长，这主要是因为SO₄^2-依附，产生空间隔离效应；醋酸处理没有这种空间隔离效应，薄膜在相同条件下，晶粒尺寸相对较大。通过表面形貌分析，表明酸处理的薄膜，表面形貌发生了很大的变化。这种特殊的表面形貌增加了表面的活性中心和对紫外光的吸收，同时加速电子-空穴的分离，提高了量子产率。因此，酸处理能大幅度提高薄膜的光催化性能；同时对薄膜的亲水性能有很大的影响．本论文对于如何提高纳米TiO₂薄膜的亲水性和光催化性能具有重要意义，对纳米TiO₂的生产应用有直接指导意义。更多还原

【Abstract】 In this paper, TiO₂ was treated with acid to enhance photocatalytic activity and hydrophilicity. Point research of this thesis is that the TiO₂ thin film are treated with acetic acid and sulfuric acid. From the angle of mechanism, the effection of acid treatment is studied on photocatalyticty and hydrophilicity. They are researched from making condition, sour density of treatment etc. Some innovate result are obtained from these researches, which is instructive meaning. It has innovation and meaning -ful research result as follows:1 .We investigated systematically the effect of series density of acetic acid and sulfuric acid on activity of hydrophilicity TiO₂ thin film. It show that the activity of hydrophilicity of thin film is connection with density of acid and category, the hydrophilicity of thin films induced by heat and light is obviously improved after acidic treatment. Among all the samples treated, The acetic acid optimum concentration is 1mol/L, but sulfuric acid is 0.4 mol/L. In optimum concentration, the film treated with 1mol/L acetic acid is the best at hydrophilicity and optical response of speed, in the meantime hydrophilic time is prolonged.It reachs super hydrophilicity in 1.5h through UV; thereafter it is still hydrophilic lucifuging 22h. thin film treated with sulfuric acid reaches super hydrophilicity in In; but it is not hydrophilic lucifuging 12h. The films reaches super hydrophilicity in 2.5h through Vis with 1mol/L; Thin films with 0.4mol/L do not. These show that acetic acid processing is advantageous to improving hydrophilicityactivity of thin film. Treated with sulfuric acid, optical response of speed of the thin film is super to untreated film. But from hydrophilicit -y comprehensive treatment with acetic acid is better than sulfuric acid.2. We investigated systematically the effect of series density of acetic acid and sulfuric acid on activity of photocatalys of TiO₂ thin film. This article shows that activity of photocatalys of TiO₂ thin film treated with acid is greatly increased. Among all the samples treated, the thin films treated with 1mol/L acetic acid and 0.4 mol/L sulfuric acid are the best at active photocatalyst. The rate degration of MB and MOsolution which is treated with 1 mol/L acetic acid is 66% and 45% on UV thorogh 3h ,and film treated with 0.4 mol/L sulfuric acid is 78% and 62%,but film untreated is 15%. The rate degration of MB and MOsolution which is treated with 1 mol/L acetic acid is 30% and 21% on Vis thorogh 3h ,and film treated with 0.4 mol/L sulfuric acid is 35% and 27%,From comprehensive photocatalytic activity,treatment with sulfuric acid is better than acetic acid.The analysis of structure indicated that size of TiO₂ particle is suppressed because of treatment with sulfuric acid.The isolated effect of space is produced because SO₄^2- is adherenced.Treatment of acetic acid does not produce the effect.Under same condition ,the size of TiO₂ particle is bigger.The analysis of surface appearance indicated that treatment with acid have an effect on surface appearance of TiO₂ film. Special surface appearance can greatly improve the active centre of surface of TiO₂ film, absorption of UV , quantun efficiency accelerating electron-hole separation.So treatment with acid have obvious effects on the photocatalytic activity and hydrophilic activity of thin film. This result is very important to realize the essence of photocatalysis and hydrophilicity.更多还原