The adsorption and decomposition of H2S on the ZnO（0001） surface have been investigated with first-principles calculations.The results reveal that H2S is dissociatively adsorbed on the clean ZnO（0001） surface to g...The adsorption and decomposition of H2S on the ZnO（0001） surface have been investigated with first-principles calculations.The results reveal that H2S is dissociatively adsorbed on the clean ZnO（0001） surface to generate HS-and hydrogen species.To our interest,as indicated by Mulliken charge and density of states of the configuration calculation,the bonding mechanism of H2S on the ZnO（0001） surface can involve the donation of charge from the ＂s lone pairs＂ into the surface and the back donation of surface electrons to H2S.Therefore,the electrons should play an important role in decomposition.Furthermore,the reactivity of H2S adsorption and further thermal decomposition reactions on the ZnO（0001） surface have also been discussed by calculating the possible reaction pathways.As expected,H2 will be easily generated during the decomposition process.展开更多
Photocatalysis of CH3OH on the ZnO(0001) surface has been investigated by using temperature-programmed desorption (TPD) method with a 266 nm laser light. TPD results show that part of the CH3OH adsorbed on ZnO(0001) s...Photocatalysis of CH3OH on the ZnO(0001) surface has been investigated by using temperature-programmed desorption (TPD) method with a 266 nm laser light. TPD results show that part of the CH3OH adsorbed on ZnO(0001) surface are in molecular form, while others are dissociated. The thermal reaction products of H2, CH3·, H2O, CO, CH2O, CO2 and CH3OH have been detected. Experiments with the UV laser light indicate that the irradiation can promote the dissociation of CH3OH/CH3O· to form CH2O, which can be fu- ture converted to HCOO- during heating or illumination. The reaction between CH3OHZn and OHad can form the H2O molecule at the Zn site. Both temperature and illumination promote the desorption of CH3· from CH3O·. The research provides a new insight into the photocatalytic reaction mechanism of CH3OH on ZnO(0001).展开更多
The surface structures ofwurtzite ZnO（0001） and（0001） surfaces are investigated by using a first-principles calculation of plane wave ultra-soft pseudo-potential technology based on density functional theory（DFT...The surface structures ofwurtzite ZnO（0001） and（0001） surfaces are investigated by using a first-principles calculation of plane wave ultra-soft pseudo-potential technology based on density functional theory（DFT）.The calculated results reveal that the surface energy of ZnO-Zn is bigger than that of ZnO-O,and the ZnO-Zn surface is more unstable and active.These two surfaces are apt to relax inward,but the contractions of the ZnO-Zn surface are smaller than the ZnO-O surface.Due to the dispersed Zn4s states and the states of stronger hybridization between the Zn and O atoms,the ZnO-Zn surface shows n-type conduction,while the O2p dangling-bond bands in the upper part of the valence cause the ZnO-O surface to have p-type conduction.The above results are broadly consistent with the experimental results.展开更多
ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in th...ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in the first layer Al-O is reduced, even eliminated after the surface adsorption of ZnO, and the chemical bonding energy is 434.3(±38.6) kJ·mol?1. The chemical bond of ZnO (0.185 ± 0.01 nm) has a 30° angle away from the adjacent Al-O bond, and the stable chemical adsorption position of the Zn is deflected from the surface O-hexagonal symmetry with an angle of about 30°. The analysis of the atomic populations, density of state and bonding electronic density before and after the adsorption indicates that the chemical bond formed by the O2 of the ZnO ? and the surface Al3+ has a strong ionic bonding characteristic, while the chemical bond formed by the Zn2+ and the surface O2 has an obvious covalent characteristic, which ? comes mainly from the hybridization of the Zn 4s and the O 2p and partially from that of the Zn 3d and the O 2p.展开更多
基金supported by the Natural Science Foundation of Fujian Province (No. E0510004)
文摘The adsorption and decomposition of H2S on the ZnO（0001） surface have been investigated with first-principles calculations.The results reveal that H2S is dissociatively adsorbed on the clean ZnO（0001） surface to generate HS-and hydrogen species.To our interest,as indicated by Mulliken charge and density of states of the configuration calculation,the bonding mechanism of H2S on the ZnO（0001） surface can involve the donation of charge from the ＂s lone pairs＂ into the surface and the back donation of surface electrons to H2S.Therefore,the electrons should play an important role in decomposition.Furthermore,the reactivity of H2S adsorption and further thermal decomposition reactions on the ZnO（0001） surface have also been discussed by calculating the possible reaction pathways.As expected,H2 will be easily generated during the decomposition process.
基金National Key R&D Program of China (No.2016YFF0200500), the National Natural Science Foundation of China (No.21473173, No.21590802, and No.21403207), the Strategic Prior- ity Research Program of Chinese Academy of Sciences (No.XDB17000000), and the Fundamental Research Funds for the Central Universities. We thank Chen-biao Xu at Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Wen-shao Yang at Hangzhou Institute of Advanced Studies, Zhejiang Normal Uni- versity for their help during experiments.
文摘Photocatalysis of CH3OH on the ZnO(0001) surface has been investigated by using temperature-programmed desorption (TPD) method with a 266 nm laser light. TPD results show that part of the CH3OH adsorbed on ZnO(0001) surface are in molecular form, while others are dissociated. The thermal reaction products of H2, CH3·, H2O, CO, CH2O, CO2 and CH3OH have been detected. Experiments with the UV laser light indicate that the irradiation can promote the dissociation of CH3OH/CH3O· to form CH2O, which can be fu- ture converted to HCOO- during heating or illumination. The reaction between CH3OHZn and OHad can form the H2O molecule at the Zn site. Both temperature and illumination promote the desorption of CH3· from CH3O·. The research provides a new insight into the photocatalytic reaction mechanism of CH3OH on ZnO(0001).
基金Project supported by the National Natural Science Foundation of China(No.60877069)the Research Project of Science and Technology of Guangzhou,Guangdong Province,China(Nos.2007A010500011,2008B010200041).
文摘The surface structures ofwurtzite ZnO（0001） and（0001） surfaces are investigated by using a first-principles calculation of plane wave ultra-soft pseudo-potential technology based on density functional theory（DFT）.The calculated results reveal that the surface energy of ZnO-Zn is bigger than that of ZnO-O,and the ZnO-Zn surface is more unstable and active.These two surfaces are apt to relax inward,but the contractions of the ZnO-Zn surface are smaller than the ZnO-O surface.Due to the dispersed Zn4s states and the states of stronger hybridization between the Zn and O atoms,the ZnO-Zn surface shows n-type conduction,while the O2p dangling-bond bands in the upper part of the valence cause the ZnO-O surface to have p-type conduction.The above results are broadly consistent with the experimental results.
文摘ZnO adsorption on sapphire (0001) surface is theoretically calculated by using a plane wave ultrasoft pseudo-potential method based on ab initio molecular dynamics. The results reveal that the surface relaxation in the first layer Al-O is reduced, even eliminated after the surface adsorption of ZnO, and the chemical bonding energy is 434.3(±38.6) kJ·mol?1. The chemical bond of ZnO (0.185 ± 0.01 nm) has a 30° angle away from the adjacent Al-O bond, and the stable chemical adsorption position of the Zn is deflected from the surface O-hexagonal symmetry with an angle of about 30°. The analysis of the atomic populations, density of state and bonding electronic density before and after the adsorption indicates that the chemical bond formed by the O2 of the ZnO ? and the surface Al3+ has a strong ionic bonding characteristic, while the chemical bond formed by the Zn2+ and the surface O2 has an obvious covalent characteristic, which ? comes mainly from the hybridization of the Zn 4s and the O 2p and partially from that of the Zn 3d and the O 2p.
