电子偶素在OMC/SBA-15,OMC@SBA-15及CuO@SBA-15催化剂中的化学猝灭  

Chemical quenching of positronium in OMC/SBA-15,OMC@SBA-15 and CuO@SBA-15 catalysts

作　　者：李重阳 赵宾 张俊伟 Li Chong-Yang;Zhao Bin;Zhang Jun-Wei(College of Electric Power,North China University of Water Resources and Electric Power,Zhengzhou 450045,China;School of Science,Zhongyuan University of Technology,Zhengzhou 450007,China)

机构地区：[1]华北水利水电大学电力学院,郑州450045 [2]中原工学院理学院,郑州450007

出　　处：《物理学报》2022年第6期343-353,共11页Acta Physica Sinica

基　　金：国家自然科学基金青年基金(批准号:11805295,11905063)资助的课题.

摘　　要：以P123为结构导向剂、TEOS为硅源制备了有序介孔二氧化硅SBA-15,并以此为模板制备了有序介孔碳(OMC).小角X射线衍射、高分辨透射电子显微镜和N_(2)吸附/脱附等测试结果均证实SBA-15与OMC具有高度有序的孔结构、相对较高的比表面积,且孔洞平均尺寸分别约为7.5 nm和3.3 nm.分别采用固相反应法和浸渍填充法制备了OMC/SBA-15复合材料和OMC@SBA-15及CuO@SBA-15复合材料.随着OMC和CuO质量分数的增大,3种复合材料中o-Ps寿命τ_(4)和其强度I_(4)均减小.o-Ps湮没率λ_(4)随OMC和CuO质量分数的变化可用一条或两条直线很好地拟合,OMC/SBA-15,OMC@SBA-15及CuO@SBA-15复合材料中反应速率常数k分别为(2.39±0.44)×10^(7) s^(-1)/(6.65±0.94)×10^(6) s^(-1),(2.28±0.19)×10^(7) s^(-1)和(8.76±0.47)×10^(6) s^(-1).因此,3种复合材料中τ_(4)及I_(4)降低是由于电子偶素与碳、铜元素在介孔内或孔表面发生了化学猝灭和禁止效应.同时,电子偶素也是一种检测多孔材料中孔隙结构的有效探针.Owing to highly ordered two-dimensional hexagonal structure,large surface area,variable pore size,high thermal stability and especially the electron delocalization energy determined by its frame structure,SBA-15 catalysts have received more and more researchers’attention.By using the structure-directing agent of P123 and the silicon source of TEOS,we synthesize ordered mesoporous silica SBA-15.At the same time,ordered mesoporous carbon OMC is succefully synthesized with the template of SBA-15.The small angle X-ray diffraction,high resolution transmission electron microscopy and N_(2) adsorption-desorption measurements are conducted to verify the highly ordered pore structure and relatively high specific surface area of SBA-15 and OMC,and their average pore radius are about 7.5 nm and 3.3 nm,respectively.Positron lifetime spectrum of SBA-15 catalyst is composed of two longer lifetimes and two shorter lifetimes:two longer lifetimes τ_(3) and τ_(4) are the annihilation in micropore and large pore of positronium(Ps),are 7.5 ns and 10^(6) ns.However,there is nearly no longer lifetime component in OMC,which indicates that there might exist the quenching or inhibiting of positronium by carbon material.To verify this guess,we synthesize the catalysts of OMC/SBA-15,OMC@SBA-15 and CuO@SBA-15 by the solid state reaction and the impregnation filling method.With the increasing of OMC and CuO content,both the o-Ps lifetime τ_(4) and its intensity I_(4) of these three compounds decrease.The annihilation rate of o-Ps lifetime varying with OMC and CuO content can be better fitted by one or two straight lines,The values of reaction rate constant K in OMC/SBA-15,OMC@SBA-15 and CuO@SBA-15 are(2.39±0.44)×10^(7)s^(-1)/(6.65±0.94)×10^(6)s^(-1),(2.28±0.19)×10^(7)s^(-1),and(8.76±0.47)×10^(6)s^(-1),Therefore,our results indicate that there are quenching effect and inhibition effect among the carbon,the CuO and the positronium,which lead τ_(4) and I_(4) to decrease,and positronium is also a probe for detecting the pore struct

关 键 词：正电子湮没谱学 有序介孔结构 电子偶素 化学猝灭 

分 类 号：O643.36[理学—物理化学]