Adsorption of methanol and methoxy at four selected sites （top, bridge, hcp, fcc） on Cu（111） surface has been investigated by density functional theory method at the generalized gradient approximation （GGA） leve...Adsorption of methanol and methoxy at four selected sites （top, bridge, hcp, fcc） on Cu（111） surface has been investigated by density functional theory method at the generalized gradient approximation （GGA） level. The calculation on adsorption energies, geometry and electronic structures, Mulliken charges, and vibrational frequencies of CH3OH and CH3O on clean Cu（111） surface was performed with full-geometry optimization, and compared with the experimental data. The obtained results are in agreement with available experimental data. The most favorite adsorption site for methanol on Cu（111） surface is the top site, where C-O axis is tilted to the surface. Moreover, the preferred adsorption site for methoxy on Cu（111） surface is the fcc site, and it adsorbs in an upright geometry with pseudo-C2v local symmetry. Possible decomposition pathways also have been investigated by transition-state searching methods. Methoxy radical, CH3O, was found to be the decomposition intermediate. Methanol can be adsorbed on the surface with its oxygen atom directly on a Cu atom, and weakly chemisorbed on Cu（111） surface. In contrast to methanol, methoxy is strongly chemisorbed to the surface.展开更多
The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneli...The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneling microscopy. Anomalous moir6 superstructures composed of well-defined linear periodic modulations have been observed. We report here on comprehensive and detailed studies of these particular moir6 patterns present in the graphene topography revealing that, in certain conditions, the growth can occur on the oxygen-induced reconstructed copper surface and not directly on the oriented （111） copper film as expected.展开更多
Au-Cu双金属合金纳米颗粒对包括CO氧化和CO2还原等在内的多个反应有较好的催化活性,然而关于其表面性质的研究却相当匮乏。在此工作中,我们通过对低覆盖度的Au/Cu(111)和Cu/Au(111)双金属薄膜退火,制备出了单原子级分散的Au/Cu(111)和Cu...Au-Cu双金属合金纳米颗粒对包括CO氧化和CO2还原等在内的多个反应有较好的催化活性,然而关于其表面性质的研究却相当匮乏。在此工作中,我们通过对低覆盖度的Au/Cu(111)和Cu/Au(111)双金属薄膜退火,制备出了单原子级分散的Au/Cu(111)和Cu/Au(111)合金化表面,并利用高分辨扫描隧道显微镜(STM)和扫描隧道谱(STS)进一步研究了掺杂原子的电子性质及其对CO吸附行为的影响。研究发现,分散在Cu(111)表面的表层和次表层Au单原子在STM上表现出不同衬度。在-0.5 e V附近,前者表现出相较于Cu(111)明显增强的电子态密度,而后者则明显减弱。吸附实验表明表层Au单原子对CO的吸附能力并没有得到增强,甚至会减弱其周围Cu原子的吸附能力。与Au在Cu(111)表面较好的分散相反,Cu原子倾向于钻入Au(111)的次表层,并且形成多原子聚集体。且Cu原子受Au(111)衬底吸电子作用的影响,其对CO的吸附能力明显减弱。这个研究结果揭示了合金表面的微观结构与性质的关联,为进一步阐明Au-Cu双金属催化剂的表面反应机理提供参考。展开更多
基金National Key R&D Program of China(2021YFB3601600)National Natural Science Foundation of China(61827813,52002368,62121005,62074147,62022081,61974099)+1 种基金Natural Science Foundation of Jilin Province(20230101345JC,20230101107JC,20230508132RC)Youth Innovation Promotion Association of the Chinese Academy of Sciences(Y201945,2019222)。
基金supported by the National Natural Science Foundation of China(20903075,21273172)Program of Introducing Talents of Discipline to Universities,China(111 Project)(B08040)Northwestern Polytechnical University Foundation for Fundamental Research,China(JC20100226)~~
基金supported by the National Natural Science Foundation of China(10674042)Innovation Scientists and Technicians Troop Construction Projects of Henan Province,China(104200510014)~~
基金Project supported by the National Natural Science Foundation of China （No. 20273013）, the Fujian Provincial Department of Education （No JA03020） and Science and Technology Foundation of Fuzhou University （No. 2005-XQ-03）.
文摘Adsorption of methanol and methoxy at four selected sites （top, bridge, hcp, fcc） on Cu（111） surface has been investigated by density functional theory method at the generalized gradient approximation （GGA） level. The calculation on adsorption energies, geometry and electronic structures, Mulliken charges, and vibrational frequencies of CH3OH and CH3O on clean Cu（111） surface was performed with full-geometry optimization, and compared with the experimental data. The obtained results are in agreement with available experimental data. The most favorite adsorption site for methanol on Cu（111） surface is the top site, where C-O axis is tilted to the surface. Moreover, the preferred adsorption site for methoxy on Cu（111） surface is the fcc site, and it adsorbs in an upright geometry with pseudo-C2v local symmetry. Possible decomposition pathways also have been investigated by transition-state searching methods. Methoxy radical, CH3O, was found to be the decomposition intermediate. Methanol can be adsorbed on the surface with its oxygen atom directly on a Cu atom, and weakly chemisorbed on Cu（111） surface. In contrast to methanol, methoxy is strongly chemisorbed to the surface.
文摘The growth of graphene on oriented （111） copper films has been achieved by atmospheric pressure chemical vapor deposition. The structural properties of as-produced graphene have been investigated by scanning tunneling microscopy. Anomalous moir6 superstructures composed of well-defined linear periodic modulations have been observed. We report here on comprehensive and detailed studies of these particular moir6 patterns present in the graphene topography revealing that, in certain conditions, the growth can occur on the oxygen-induced reconstructed copper surface and not directly on the oriented （111） copper film as expected.
文摘Au-Cu双金属合金纳米颗粒对包括CO氧化和CO2还原等在内的多个反应有较好的催化活性,然而关于其表面性质的研究却相当匮乏。在此工作中,我们通过对低覆盖度的Au/Cu(111)和Cu/Au(111)双金属薄膜退火,制备出了单原子级分散的Au/Cu(111)和Cu/Au(111)合金化表面,并利用高分辨扫描隧道显微镜(STM)和扫描隧道谱(STS)进一步研究了掺杂原子的电子性质及其对CO吸附行为的影响。研究发现,分散在Cu(111)表面的表层和次表层Au单原子在STM上表现出不同衬度。在-0.5 e V附近,前者表现出相较于Cu(111)明显增强的电子态密度,而后者则明显减弱。吸附实验表明表层Au单原子对CO的吸附能力并没有得到增强,甚至会减弱其周围Cu原子的吸附能力。与Au在Cu(111)表面较好的分散相反,Cu原子倾向于钻入Au(111)的次表层,并且形成多原子聚集体。且Cu原子受Au(111)衬底吸电子作用的影响,其对CO的吸附能力明显减弱。这个研究结果揭示了合金表面的微观结构与性质的关联,为进一步阐明Au-Cu双金属催化剂的表面反应机理提供参考。
