Reduction of nitric oxide by acetylene on Ir surfaces with different morphologies: comparison with reduction of NO by CO.
Reduction of nitric oxide by acetylene on Ir surfaces with different morphologies: comparison with reduction of NO by CO.
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DOI：
10.1021/la3043878
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发表时间：
2013-01
期刊：
影响因子：
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通讯作者：
Wenhua Chen;Q. Shen;R. Bartynski;P. Kaghazchi;T. Jacob
中科院分区：
文献类型：
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作者：
Wenhua Chen;Q. Shen;R. Bartynski;P. Kaghazchi;T. Jacob
通过程序升温脱附（TPD）研究了乙炔（C（2）H（2））对一氧化氮（NO）的还原作用，所述程序升温脱附作用在平面Ir（210）和多面Ir（210）上进行，所述多面Ir（210）具有暴露（311）、（311[上划线]）和（110）面的可调尺寸的三面纳米角锥体。吸附后，C（2）H（2）解离，形成乙炔化物（CCH）和H物种的Ir表面在低C（2）H（2）precoverage。对于NO在C（2）H（2）覆盖的Ir上的吸附，平面和刻面Ir（210）在低C（2）H（2）预覆盖下表现出高的还原NO的反应性和高的N（2）选择性，尽管反应在高C（2）H（2）预覆盖下被完全抑制。共吸附的C（2）H（2）显著影响NO的解离。含N、H和C的TPD产物主要由N（2）、H（2）、CO和CO（2）以及少量的H（2）O组成。对于NO在C覆盖的Ir（210）上的吸附，在部分C预覆盖下，促进CO（2）的形成，而减少CO的产生。与平面Ir（210）相比，C（2）H（2）还原NO在小面Ir（210）上具有结构敏感性，但对于平均小面尺寸为5 nm和14 nm的小面Ir（210），没有发现C（2）H（2）还原NO的尺寸效应。的结果进行了比较，减少NO由CO在相同的Ir表面。对于NO+C（2）H（2），Ir表面对CO还原NO反应具有很高的活性，对N（2）具有很高的选择性，反应是结构敏感的，但在纳米尺度上发现了CO还原NO反应的尺寸效应.此外，共吸附CO不影响NO的解离在低CO precoverage，而共吸附CO显着影响NO的解离在高CO precoverage。用密度泛函理论研究了CCH+H在Ir上的吸附位。
Reduction of nitric oxide (NO) by acetylene (C(2)H(2)) has been investigated by temperature-programmed desorption (TPD) on planar Ir(210) and faceted Ir(210) with tunable sizes of three-sided nanopyramids exposing (311), (311[overline]), and (110) faces. Upon adsorption, C(2)H(2) dissociates to form acetylide (CCH) and H species on the Ir surfaces at low C(2)H(2) precoverage. For adsorption of NO on C(2)H(2)-covered Ir, both planar and faceted Ir(210) exhibit high reactivity for reduction of NO with high selectivity to N(2) at low C(2)H(2) precoverage, although the reaction is completely inhibited at high C(2)H(2) precoverage. Coadsorbed C(2)H(2) significantly influences dissociation of NO. The N-, H-, and C-containing TPD products are dominated by N(2), H(2), CO, and CO(2) together with small amounts of H(2)O. For adsorption of NO on C-covered Ir(210) at fractional C precoverage, formation of CO(2) is promoted while production of CO is reduced. Reduction of NO by C(2)H(2) is structure sensitive on faceted Ir(210) versus planar Ir(210), but no evidence is found for size effects in the reduction of NO by C(2)H(2) on faceted Ir(210) for average facet sizes of 5 nm and 14 nm. The results are compared with reduction of NO by CO on the same Ir surfaces. As for NO+C(2)H(2), the Ir surfaces are very active for reduction of NO by CO with high selectivity to N(2) and the reaction is structure sensitive, but clear evidence is found for size effects in the reduction of NO by CO on the nanometer scale. Furthermore, coadsorbed CO does not affect dissociation of NO at low CO precoverage whereas coadsorbed CO considerably influences dissociation of NO at high CO precoverage. The adsorption sites of CCH+H on Ir are characterized by density functional theory.