The electrochemical reduction of CO_(2) towards hydrocarbons is a promising technology that can utilize CO_(2) and prevent its atmospheric accumulation while simultaneously storing renewable en‐ergy.However,current C...The electrochemical reduction of CO_(2) towards hydrocarbons is a promising technology that can utilize CO_(2) and prevent its atmospheric accumulation while simultaneously storing renewable en‐ergy.However,current CO_(2) electrolyzers remain impractical on a large scale due to the low current densities and faradaic efficiencies(FE)on various electrocatalysts.In this study,hybrid HKUST‐1 metal‐organic framework‒fluorinated imidazolium‐based room temperature ionic liquid(RTIL)electrocatalysts are designed to selectively reduce CO_(2) to CH_(4).An impressive FE of 65.5%towards CH_(4) at-1.13 V is achieved for the HKUST‐1/[BMIM][PF_(6)]hybrid,with a stable FE greater than 50%maintained for at least 9 h in an H‐cell.The observed improvements are attributed to the increased local CO_(2) concentration and the improved CO_(2)‐to‐CH_(4) thermodynamics in the presence of the RTIL molecules adsorbed on the HKUST‐1‐derived Cu clusters.These findings offer a novel approach of immobilizing RTIL co‐catalysts within porous frameworks for CO_(2) electroreduction applications.展开更多
A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^＊ level. Based on the optimized geometries, the electronic, fluorescent and ...A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^＊ level. Based on the optimized geometries, the electronic, fluorescent and 13C NMR spectra are calculated with INDO/CIS, CIS-ZINDO TD, and B3LYP/6-31G^＊ methods, respectively. Starting with the first of the series, the LUMO-HOMO energy gaps of the derivatives become wider and the fluorescent wavelengths and the main peaks in the electronic spectra are blue-shifted owing to the large steric effect of naphthyl rings. On the contrary, the energy gaps of the derivatives turn narrow, and the fluorescent wavelengths and the main peaks in the electronic spectra are red-shifted since hydroxyl groups improve the symmetry and extend the conjugation system. The chemical shifts of sp^2-C on the phenyl rings are moved upfield, while chemical shifts of carbon atoms on the cyano groups and those connected with the cyano groups are changed downfield in the presence of hydroxyl groups.展开更多
Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from expe...Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from experimental in- vestigation. Binding energy calculations suggest that the boron structure designed from theory is more stable than that made by experiment. Elastic constants calculations show that both structures are mechanically stable. The electronic structure results show that the theoretical designed structure exhibits semi-metal behavior, while the other structure exhibits metMlic character. No magnetic phenomenal is discovered from them. All the calculations are carried out by the first principles calculation through the MatC1oud platform, which is developed by our research group.展开更多
The insensitive property of explosives containing pyfidine is combined with the high energy of nitramine explosives, and the concept of new nitramine explosives containing pyridine is proposed, into which nitramine gr...The insensitive property of explosives containing pyfidine is combined with the high energy of nitramine explosives, and the concept of new nitramine explosives containing pyridine is proposed, into which nitramine group with N-N bonds is intro- duced as much as possible. Based on molecular structures of nitramine compounds containing pyridine, density functional the- ory （DFT） calculation method was applied to study designed molecules at B3LYP/6-31＋G（d） level. The geometric and elec- tronic structures, density, heats of formation （HOF）, detonation performance and bond dissociation energies （BDE） were investigated and comparable to 1,3,5-trinitro-l,3,5-triazinane （RDX） and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane （HMX）. The simulation results reveal that molecules B and D perform similarly to traditionally used RDX. Molecule E outperform RDX, with performance that approach that of HMX and may be considered as potential candidate of high energy density compound （HEDC）. These results provide basic information for molecular design of novel high energetic density compounds.展开更多
文摘The electrochemical reduction of CO_(2) towards hydrocarbons is a promising technology that can utilize CO_(2) and prevent its atmospheric accumulation while simultaneously storing renewable en‐ergy.However,current CO_(2) electrolyzers remain impractical on a large scale due to the low current densities and faradaic efficiencies(FE)on various electrocatalysts.In this study,hybrid HKUST‐1 metal‐organic framework‒fluorinated imidazolium‐based room temperature ionic liquid(RTIL)electrocatalysts are designed to selectively reduce CO_(2) to CH_(4).An impressive FE of 65.5%towards CH_(4) at-1.13 V is achieved for the HKUST‐1/[BMIM][PF_(6)]hybrid,with a stable FE greater than 50%maintained for at least 9 h in an H‐cell.The observed improvements are attributed to the increased local CO_(2) concentration and the improved CO_(2)‐to‐CH_(4) thermodynamics in the presence of the RTIL molecules adsorbed on the HKUST‐1‐derived Cu clusters.These findings offer a novel approach of immobilizing RTIL co‐catalysts within porous frameworks for CO_(2) electroreduction applications.
文摘A new series of fluorescent arylamino fumarinitrile derivatives was designed and optimized using density function theory at the B3LYP/6-31G^＊ level. Based on the optimized geometries, the electronic, fluorescent and 13C NMR spectra are calculated with INDO/CIS, CIS-ZINDO TD, and B3LYP/6-31G^＊ methods, respectively. Starting with the first of the series, the LUMO-HOMO energy gaps of the derivatives become wider and the fluorescent wavelengths and the main peaks in the electronic spectra are blue-shifted owing to the large steric effect of naphthyl rings. On the contrary, the energy gaps of the derivatives turn narrow, and the fluorescent wavelengths and the main peaks in the electronic spectra are red-shifted since hydroxyl groups improve the symmetry and extend the conjugation system. The chemical shifts of sp^2-C on the phenyl rings are moved upfield, while chemical shifts of carbon atoms on the cyano groups and those connected with the cyano groups are changed downfield in the presence of hydroxyl groups.
基金Supported by National Natural Science Foundation of China under Grant No.11547177
文摘Electronic structures in two kinds of boron structures are investigated by the first-principle density func- tional theory （DFT） calculations. One structure is from theoretical prediction, and the other is from experimental in- vestigation. Binding energy calculations suggest that the boron structure designed from theory is more stable than that made by experiment. Elastic constants calculations show that both structures are mechanically stable. The electronic structure results show that the theoretical designed structure exhibits semi-metal behavior, while the other structure exhibits metMlic character. No magnetic phenomenal is discovered from them. All the calculations are carried out by the first principles calculation through the MatC1oud platform, which is developed by our research group.
基金supported by the NSAF Foundation of National Natural Science Foundation of China and China Academy of Engineering Physics(11076017)
文摘The insensitive property of explosives containing pyfidine is combined with the high energy of nitramine explosives, and the concept of new nitramine explosives containing pyridine is proposed, into which nitramine group with N-N bonds is intro- duced as much as possible. Based on molecular structures of nitramine compounds containing pyridine, density functional the- ory （DFT） calculation method was applied to study designed molecules at B3LYP/6-31＋G（d） level. The geometric and elec- tronic structures, density, heats of formation （HOF）, detonation performance and bond dissociation energies （BDE） were investigated and comparable to 1,3,5-trinitro-l,3,5-triazinane （RDX） and 1,3,5,7-tetranitro-1,3,5,7-tetrazocane （HMX）. The simulation results reveal that molecules B and D perform similarly to traditionally used RDX. Molecule E outperform RDX, with performance that approach that of HMX and may be considered as potential candidate of high energy density compound （HEDC）. These results provide basic information for molecular design of novel high energetic density compounds.
