官能团修饰缺陷型二氧化钛水凝胶低温常压合成及其用于降解涂料中挥发甲醛的研究

Synthesis of functional group modified defective titania hydrogel at low temperature and normal pressure and its application in degradation of formaldehyde released from coatings

[目的]涂料中挥发的甲醛是一种常见的空气污染物,具有刺激性气味和潜在的健康危害。TiO_(2)光催化降解技术作为一种环境友好的甲醛治理方法被广泛使用。[方法]本研究以缺陷型TiO_(2)水溶胶(PTC)为原料,羟胺溶液、甲胺溶液、水合肼、甲醇和过氧化氢溶液分别作为修饰剂,制备了不同官能团修饰的TiO_(2)光催化剂,并考察了它们对光催化降解甲醛的性能。利用X射线衍射(XRD)、氮气物理吸脱附、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis)、荧光光谱(PL)、电化学测量等技术对光催化剂的组成、结构和光电化学性质进行表征。[结果]以羟胺为修饰剂所得到的TiO_(2)光催化剂性能最佳,在紫外光照射下2h内降解甲醛的效率达到73.3%,是未使用催化剂时的36倍和改性前PTC的3.6倍。[结论]由于官能团的修饰,TiO_(2)的低能价带(VB)和高能导带(CB)之间形成了缺陷能级。当光辐照TiO_(2)时,这些缺陷能够作为陷阱捕捉光生载流子,提升光吸收能力和光生载流子分离效率,快速生成氧化性很强的活性氧物质,促进光催化降解反应的进行。

[Introduction]Formaldehyde released from coatings is a common air pollutant,known for its pungent odor and potential health hazards.TiO_(2) photocatalytic degradation technology is widely adopted as an environmentally friendly method for formaldehyde removal.[Method]Functional group-modified TiO_(2) photocatalysts were prepared based on defective TiO_(2) hydrosol(PTC)with hydroxylamine solution,methylamine solution,hydrazine hydrate,methanol,or hydrogen peroxide solution as modifier.Their photocatalytic performance for formaldehyde degradation was then studied.The composition,structure,and photoelectrochemical properties of the photocatalysts were characterized by using X-ray diffraction(XRD),nitrogen adsorption/desorption,transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),ultraviolet-visible diffuse reflectance spectroscopy(UV-Vis),fluorescence spectroscopy,and electrochemical measurements.[Result]The TiO_(2) photocatalyst modified with hydroxylamine exhibited the best performance.Under ultraviolet irradiation,it achieved a formaldehyde degradation efficiency of 73.3%within 2 hours,which was 36 times higher than that without any catalyst and 3.6 times higher than that of unmodified PTC.[Conclusion]Due to the modification of functional groups,defect energy levels are formed between the low-energy valence band(VB)and the high-energy conduction band(CB)of TiO_(2).When TiO_(2) is irradiated by light,these defects can act as traps to capture photogenerated carriers,enhancing the light absorption capacity and the separation efficiency of photogenerated carriers.This rapidly generates highly oxidative reactive oxygen species,thereby facilitating the photocatalytic degradation reaction.