Activity and Adsorption Behavior of Oxygen on Rutile TiO_(2)(110)  

氧气在金红石型TiO_(2)(110)表面上的活性和吸附行为

作　　者：Rulin Sun Xinlu Liu Fangliang Li Li Che 孙如;刘馨璐;李方亮;车丽(大连海事大学环境科学与工程学院,大连116026;中国科学院大连化学物理研究所分子反应动力学国家重点实验室,大连116023;大连海事大学理学院,大连116026)

机构地区：[1]College of Environmental Sciences and Engineering,Dalian Maritime University,Dalian 116026,China [2]State Key Laboratory of Molecular Reaction Dynamics,Dalian Institute of Chemical Physics,Dalian 116023,China [3]School of Science,Dalian Maritime University,Dalian 116026,China

出　　处：《Chinese Journal of Chemical Physics》2024年第5期619-626,I0051-I0058,I0100,共17页化学物理学报（英文）

基　　金：This work was supported by the National Natural Science Foundation of China(No.21973010);Liaoning Revitalization Talents Program(No.XLYC1907032);The authors thank Qing Guo at Southern University of Science and Technolog for many insightful discussions。

摘　　要：The activity and adsorption behavior of oxygen on rutile TiO_(2)(110)(RTiO_(2)(110))were investigated using the temperature programmed desorption(TPD)method with methanol(CH_(3)OH)as the probe molecule.By controlling the coverage of molecular O_(2) on the surface via increasing or decreasing O_(2) exposure,two chemisorbed O_(2)species on the surface are confirmed,one at the bridging oxygen vacancy(Ov)site(O_(2)^(2-)/Ov)and the other at the five-fold coordinated titanium(Ti_(5c))site(O^(2-)/Ti_(5c)).At low O_(2)exposure,O^(2-)/Ov is the main species on the surface,which only leads to the O-H bond cleavage of CH_(3)OH,producing methoxy groups(CHgO).However,after the Ov sites are nearly filled by O_(2) at about 0.1 L O_(2) exposure,O_(2)/Tisc species begins to appear on R-TiO_(2)(110)surface,resulting in the formation of formaldehyde(CH_(2)O)via the reaction of O_(2)/Tisc species with CH_(3)OH or CH3O to break the C-H bond at low surface temperature.Moreover,the yield of CH_(2)O increases linearly with that of H_(2)O.In addition,when the 1 L O_(2)covered surface is irradiated with 355 nm UV irradiation to desorb and dissociate O_(2)/Ti_(5c) species,the yield of CH_(2)O decreases linearly with that of H_(2)O.Further analysis suggests that the charge state of O_(2)/Ti_(5c) may not change as the exposure of O_(2)changes on the R-TiO_(2)(110) surface,and O_(2) is most likely to adsorb on the Ti_(5c)sites in the form of O_(2)^(2-),not O_(2)^(-),The result not only advances our understanding on the adsorption state of O_(2) on TiO_(2),but also provides clues for low temperature C-H bond activation with O_(2) on TiO_(2).本文以CH_(3)OH为探针分子,使用程序升温脱附技术,研究了氧气在金红石型TiO_(2)(110)表面(R-TiO_(2)(110))上的活性和吸附行为.通过调节O_(2)的暴露量,控制O_(2)在表面的覆盖率,确认了表面上存在两种化学吸附的O_(2)物种:一种位于桥接氧空位(Ov),为O_(2)^(2-)/Ov;另一种位于五配位的钛位点(Ti_(5c)),为O_(2)^(2-)/Ti_(5c):在低O_(2)暴露条件下,O_(2)^(2-)/Ov是表面上的主要氧物种,这种氧物种只能导致CH_(3)OH的O-H键断裂,生成甲氧基(CH_(3)O).然而,当O_(2)的暴露量约0.1L,Ov位点几乎被填满时,O_(2)/Ti_(5c)物种开始出现.这一氧物种能够在低温下与CH_(3)OH或CH_(3)O反应,造成C-H键断裂,形成甲醛(CH_(2)O).而且,CH_(2)O产率随着H2O产率的增加而线性增加。此外,当采用355nm紫外光照射1LO_(2)覆盖的表面,导致O_(2)/Ti_(5c)发生脱附或解离时,CH_(2)O与H2O的产率呈线性下降的关系进一步分析表明,O_(2)/Ti_(5c)的电荷状态很可能不会因R-TiO_(2)(110)表面O_(2)的暴露量变化而发生改变,并且,O_(2)很可能以O_(2)^(2-)而非O_(2)^(-)的形式吸附在Ti_(5c)位点.本研究不仅加深了我们对O_(2)在TiO_(2)上吸附状态的理解,也为TiO_(2)上C-H键的低温活化研究提供了重要线索.

关 键 词：Rutile TiO_(2)(110) METHANOL OXYGEN Temperature programmed desorption 

分 类 号：O64[理学—物理化学]