可见光驱动Ag@AgCl催化反应的原位微量热研究  

In situ microcalorimetric investigation on the photocatalysis with efficient visible-light-driven Ag@AgCl

作　　者：李星星[1] 范高超[1] 马昭[1] 谭学才[1] 黄在银[1,2,3] 

机构地区：[1]广西民族大学化学化工学院,南宁530006 [2]广西林产化学与工程重点实验室 [3]广西民族大学,南宁530006

出　　处：《中国科学：化学》2014年第10期1576-1584,共9页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金(20963001;21273050);广西研究生教育创新计划(YCSW2012065)资助

摘　　要：室温下用葡萄糖还原前驱体AgCl制备了可见光驱动的表面负载Ag纳米颗粒(NPs)催化剂Ag@AgCl,并采用X射线衍射(XRD)、场发射扫描电镜(FE-SEM)对其形貌、组成和结构进行了表征.首次运用自主设计的新型光化学-微量热系统,获取了三个功率光催化降解甲基橙的原位特征热谱曲线和原位热动力学精细信息,并与紫外-可见光谱获得的动力学信息关联,结合甲基橙逐步被氧化降解的特征,讨论了光催化降解机理.结果表明:光催化降解过程首先是偶氮双键在光的作用下迅速吸热断裂,再进入氧化降解中间产物的放热阶段,最后以恒定的速率长时间放热.光催化反应主要受光功率大小、粒子的传质以及活性氧化物种产生的速率等共同影响.随着光功率减小,光催化反应速率减缓,体系热效应的特征变化出现滞后现象,达到最大吸、放热峰及甲基橙完全降解所需时间延长.Visible-light-driven Ag@AgCl deposited Ag NPs on cubic AgCl was prepared via the reduction of precursor AgCl by glucose at room temperature, and it was characterized by X-ray diffraction（XRD） and field-emission scanning electron microscopy（FE-SEM）. In situ characteristic thermal spectrum and accurate thermokinetic information of three luminous power regarding the photocatalysis of methyl orange were obtained by first employing a novel photoreaction-microcalorimetric system designed by our laboratory. Associated with dynamic information acquired by UV spectrum, and rationally combined the fore three mentioned with the feature of step-wise photodegradation of methyl orange, the photocatalytic mechanism was discussed. The results showed that the initial destruction of azo double band via rapidly endothermic reaction under visible light and followed by a exothermic stage of the oxidation of intermediate products which finally kept a constant exothermic rate for at least 5 h. The procedure of this photocatalysis was influenced by the comprehensive factors of luminous power, mass transfer and diffusion, and the generation rate of reactive oxygen species. The variation of heat effect were lagged as the decrease of luminous power, simultaneously the photodegradation rate slowed down, which took much longer to reach the maximum endothermic peak, exothermic peak, and completely degrade methyl orange.

关 键 词：可见光催化 Ag@AgCl 原位热动力学 微量热法 降解机理 甲基橙 

分 类 号：O643.32[理学—物理化学]