High precision and long-lasting Kepler data enabled us to estimate stellar properties with asteroseismology as an accurate tool. We performed asteroseismic analysis on six solar-like stars observed by the Kepler miss...High precision and long-lasting Kepler data enabled us to estimate stellar properties with asteroseismology as an accurate tool. We performed asteroseismic analysis on six solar-like stars observed by the Kepler mission: KIC 6064910, KIC 6766513, KIC 7107778, KIC 10079226, KIC 10147635 and KIC 12069127. The extraction of seismic information includes two parts. First, we obtained two global asteroseismic parameters, mean large separation ?_ν and frequency of maximum power ν_(max),with autocorrelation function and collapsed autocorrelation function. Second, we extracted individual oscillation modes ν_(nl) with low-l degree using a least-squares fit. Stellar grid models were built with Yale Rotating Stellar Evolution Code(YREC) to analyze stellar properties. They covered the range of M = 0.8 ~ 1.8 M_⊙with a step of 0.02 M_⊙ and [Fe/H] =-0.3 ~ 0.4 dex with a step of 0.1 dex.We used a Bayesian approach to estimate stellar fundamental parameters of the six stars, under the constraints of asteroseismic parameters(?_ν, ν_(max)) and non-asteroseismic parameters(Teff, [Fe/H]). We discover that the six targets include five sub-giant stars with 1.2 ~1.5 M_⊙ and one main-sequence star with 1.08 M_⊙, and with ages in the range of 3 ~5 Gyr.展开更多
Molecular solid solutions of metal clusters containing different metal centers with well-defined structures can accurately regulate the HOMO-LUMO gap,but are rarely available.Herein,a series of colorless lanthanide-ti...Molecular solid solutions of metal clusters containing different metal centers with well-defined structures can accurately regulate the HOMO-LUMO gap,but are rarely available.Herein,a series of colorless lanthanide-titanium-oxo clusters Ln_(2)Ti_4(μ_(2)-O)_(2)(μ_(3)-O)_4(Piv)_(10)(THF)_(2)(Ln_(2)Ti_4,Ln = Eu,Gd,Tb,and Ce,HPiv = pivalic acid) were synthesized by the reaction of pivalic acid with Ln(Ac)_(3) and titanium isopropoxide.The light yellow crystal of cluster solid solutions Eu_(2)Ti_(4-x)Cd_(x),containing a mixture of Eu_(2)Ti_4 and Eu_(2)Ti_(3)Cd,was obtained by in situ doping Cd^(2+) and S^(2–).Eu_(2)Ti_(3.92)Cd_(0.08) displays efficient photocatalytic hydrogen evolution activity without a co-catalyst,which is up to 2.6 times that of Eu_(2)Ti_4.Femtosecond time-resolved transient absorption spectroscopy and spin-polarized density functional calculations showed that the enhanced photocatalytic performance of Eu_(2)Ti_(4-x)Cd_(x) can be attributed to the narrower HOMO-LUMO gap and lower LUMO position than that of Eu_(2)Ti_4.This studyprovides an in situ doping method to realize the simple preparation of cluster solid solution.展开更多
Photocatalytic reduction of CO2 to CO is a promising strategy for reducing atmospheric CO2 levels and storing solar radiation as chemical energy.Here,we demonstrate that a molecular catalyst[NiⅡ(bpet)(H2O)2]successfu...Photocatalytic reduction of CO2 to CO is a promising strategy for reducing atmospheric CO2 levels and storing solar radiation as chemical energy.Here,we demonstrate that a molecular catalyst[NiⅡ(bpet)(H2O)2]successfully encapsulated into a highly robust and visible-light responsive metal–organic framework(Ru-UiO-67)to fabricate composite catalysts for photocatalytic CO2 reduction.The composite Ni@Ru-UiO-67 photocatalysts show efficient visible-light-driven CO2 reduction to CO with a TON of 581 and a selectivity of 99% after 20-h illumination,because of the facile electron transfer from Ru-photosensitizer to Ni(Ⅱ)active sites in Ni@Ru-UiO-67 system.The mechanistic insights into photoreduction of CO2 have been studied based on thermodynamical,electrochemical,and spectroscopic investigation,together with density functional theory(DFT)calculations.This work shows that encapsulating molecular catalyst into photoactive MOF highlights opportunities for designing efficient,stable and recyclable photocatalysts.展开更多
基金provided by National College Students Innovation Training Programsupported by the National Natural Science Foundation of China (NSFC, Grant Nos. 11273007 and 10933002)+1 种基金the Joint Research Fund in Astronomy (U1631236) under cooperative agreement between the NSFC and Chinese Academy of Sciences (CAS)the Fundamental Research Funds for the Central Universities
文摘High precision and long-lasting Kepler data enabled us to estimate stellar properties with asteroseismology as an accurate tool. We performed asteroseismic analysis on six solar-like stars observed by the Kepler mission: KIC 6064910, KIC 6766513, KIC 7107778, KIC 10079226, KIC 10147635 and KIC 12069127. The extraction of seismic information includes two parts. First, we obtained two global asteroseismic parameters, mean large separation ?_ν and frequency of maximum power ν_(max),with autocorrelation function and collapsed autocorrelation function. Second, we extracted individual oscillation modes ν_(nl) with low-l degree using a least-squares fit. Stellar grid models were built with Yale Rotating Stellar Evolution Code(YREC) to analyze stellar properties. They covered the range of M = 0.8 ~ 1.8 M_⊙with a step of 0.02 M_⊙ and [Fe/H] =-0.3 ~ 0.4 dex with a step of 0.1 dex.We used a Bayesian approach to estimate stellar fundamental parameters of the six stars, under the constraints of asteroseismic parameters(?_ν, ν_(max)) and non-asteroseismic parameters(Teff, [Fe/H]). We discover that the six targets include five sub-giant stars with 1.2 ~1.5 M_⊙ and one main-sequence star with 1.08 M_⊙, and with ages in the range of 3 ~5 Gyr.
基金supported by the National Natural Science Foundation of China (21871224,92161104,92161203,21721001)。
文摘Molecular solid solutions of metal clusters containing different metal centers with well-defined structures can accurately regulate the HOMO-LUMO gap,but are rarely available.Herein,a series of colorless lanthanide-titanium-oxo clusters Ln_(2)Ti_4(μ_(2)-O)_(2)(μ_(3)-O)_4(Piv)_(10)(THF)_(2)(Ln_(2)Ti_4,Ln = Eu,Gd,Tb,and Ce,HPiv = pivalic acid) were synthesized by the reaction of pivalic acid with Ln(Ac)_(3) and titanium isopropoxide.The light yellow crystal of cluster solid solutions Eu_(2)Ti_(4-x)Cd_(x),containing a mixture of Eu_(2)Ti_4 and Eu_(2)Ti_(3)Cd,was obtained by in situ doping Cd^(2+) and S^(2–).Eu_(2)Ti_(3.92)Cd_(0.08) displays efficient photocatalytic hydrogen evolution activity without a co-catalyst,which is up to 2.6 times that of Eu_(2)Ti_4.Femtosecond time-resolved transient absorption spectroscopy and spin-polarized density functional calculations showed that the enhanced photocatalytic performance of Eu_(2)Ti_(4-x)Cd_(x) can be attributed to the narrower HOMO-LUMO gap and lower LUMO position than that of Eu_(2)Ti_4.This studyprovides an in situ doping method to realize the simple preparation of cluster solid solution.
基金supported by the National Natural Science Foundation of China (21871224, 21673184, 21431005, and 21390391)the Fok Ying Tong Education Foundation (151013)the Fundamental Research Funds for the Central Universities (20720180032)
文摘Photocatalytic reduction of CO2 to CO is a promising strategy for reducing atmospheric CO2 levels and storing solar radiation as chemical energy.Here,we demonstrate that a molecular catalyst[NiⅡ(bpet)(H2O)2]successfully encapsulated into a highly robust and visible-light responsive metal–organic framework(Ru-UiO-67)to fabricate composite catalysts for photocatalytic CO2 reduction.The composite Ni@Ru-UiO-67 photocatalysts show efficient visible-light-driven CO2 reduction to CO with a TON of 581 and a selectivity of 99% after 20-h illumination,because of the facile electron transfer from Ru-photosensitizer to Ni(Ⅱ)active sites in Ni@Ru-UiO-67 system.The mechanistic insights into photoreduction of CO2 have been studied based on thermodynamical,electrochemical,and spectroscopic investigation,together with density functional theory(DFT)calculations.This work shows that encapsulating molecular catalyst into photoactive MOF highlights opportunities for designing efficient,stable and recyclable photocatalysts.