As a powerful non-destructive and label-free detection technology,surface-enhanced Raman scattering(SERS)has been widely used in environmental-pollutant detection,biological-tissue sensing,molecular fingerprint analys...As a powerful non-destructive and label-free detection technology,surface-enhanced Raman scattering(SERS)has been widely used in environmental-pollutant detection,biological-tissue sensing,molecular fingerprint analysis and so on.Different from the traditional SERS substrates represented by noble metals and semiconductors,herein,we report a new highly sensitive SERS substrate material with high stability,biocompatibility,and low cost,namely nucleusfree two-dimensional electron gas(2DEG)Ti3C2 monolayer nanosheets.The highly crystalline monolayer Ti3C2 nanosheets with clean surface are synthesized by an improved chemical exfoliation and microwave heating method.The unique structure of nucleus-free-2DEG in Ti3C2 monolayer provides an ideal transport channel without nuclear scattering,which makes the highly crystalline monolayer Ti3C2 nanosheets achieve a Raman enhanced factor of 3.82×108 and a 10-11 level detection limit for typical environmental pollutants such as azo dyes,trichlorophenol,and bisphenol A.Singlemolecule imaging is also realized on the surface of the Ti3C2 monolayers,which may be the first time that approximate single-molecule imaging has been achieved on a non-noblemetal SERS substrates.Preliminary toxicological experiments show that the cytotoxicity of this material is very low.Considering the facile synthesis,high biocompatibility,low cost and high chemical stability of carbide nanosheets,these Ti3C2 monolayer nanosheets show significant promise for the design and fabrication of flexible SERS substrates for the sensing of trace substances with ultrahigh sensitivity.展开更多
A magnetic ground state is revealed for the first time in zigzag-edged carbon nanoscrolls(ZCNSs)from spin-unrestricted density functional theory calculations.Unlike their flat counterpart-zigzag-edged carbon nanoribbo...A magnetic ground state is revealed for the first time in zigzag-edged carbon nanoscrolls(ZCNSs)from spin-unrestricted density functional theory calculations.Unlike their flat counterpart-zigzag-edged carbon nanoribbons,which are semiconductors with spin-degenerate electronic structure-ZCNSs show a variety of magnetic configurations,namely spin-selective semiconductors,metals,semimetals,quasi-half-metals,and half-metals.To the best of our knowledge,this is the first discovery of quasi-half-metals and half-metals in a pure hydrocarbon without resort to an external electric field.In addition,we calculated the spin-dependent transportation of the semiconducting ZCNSs with 12 and 20 zigzag chains,and found that they are 13% and 17% at the Fermi level,respectively,suggesting that ZCNS can be an effective spin filter.展开更多
The electrophilic substitution reaction occurring to the chelate ring of the complexes could be regarded as an indication of quasi-aromaticity of the ring systems, no catalyst was used and only triethylamine was emplo...The electrophilic substitution reaction occurring to the chelate ring of the complexes could be regarded as an indication of quasi-aromaticity of the ring systems, no catalyst was used and only triethylamine was employed, implying that the aroylating agents with different p-substituents are polarized enough to be effective electrophiles to attack the methine carbon of the electron-rich substrate 1. This property is probably the clue to polarization of the ligand electrons by the nickel( Ⅱ ) ion and to the participation of the nickel( Ⅱ ) in the π-bond systems of the two coordinated conjugated rings. The linearity relationship between vd-d maxima, E1/2OX(1) and σp are obtained, respectively. The electronic environment of central metal ion as well as the aromaticity of the ring system are affected by the electronic properties of the p-substituents. A comparison of the electrochemical results with each other showed .that when the electronegativity of the substituent was higher, the oxidation(Ni2+/Ni3+) becomes more difficult.展开更多
基金support from the Science Foundation of Chinese Academy of Inspection and Quarantine(2019JK004)the National Key Research and Development Program of China(2017YFF0210003)the high performance computing center of Qufu Normal University。
文摘As a powerful non-destructive and label-free detection technology,surface-enhanced Raman scattering(SERS)has been widely used in environmental-pollutant detection,biological-tissue sensing,molecular fingerprint analysis and so on.Different from the traditional SERS substrates represented by noble metals and semiconductors,herein,we report a new highly sensitive SERS substrate material with high stability,biocompatibility,and low cost,namely nucleusfree two-dimensional electron gas(2DEG)Ti3C2 monolayer nanosheets.The highly crystalline monolayer Ti3C2 nanosheets with clean surface are synthesized by an improved chemical exfoliation and microwave heating method.The unique structure of nucleus-free-2DEG in Ti3C2 monolayer provides an ideal transport channel without nuclear scattering,which makes the highly crystalline monolayer Ti3C2 nanosheets achieve a Raman enhanced factor of 3.82×108 and a 10-11 level detection limit for typical environmental pollutants such as azo dyes,trichlorophenol,and bisphenol A.Singlemolecule imaging is also realized on the surface of the Ti3C2 monolayers,which may be the first time that approximate single-molecule imaging has been achieved on a non-noblemetal SERS substrates.Preliminary toxicological experiments show that the cytotoxicity of this material is very low.Considering the facile synthesis,high biocompatibility,low cost and high chemical stability of carbide nanosheets,these Ti3C2 monolayer nanosheets show significant promise for the design and fabrication of flexible SERS substrates for the sensing of trace substances with ultrahigh sensitivity.
基金the National Natural Science Foundation of China(NSFC)(Grant Nos.10774003,10474123,10434010,90606023,and 20731160012)National 973 Projects(No.2007CB936200,Ministry of Science and Technology(MOST)of China)Program for New Century Excellent Talents in University of Ministry of Education(MOE)of China,the Grant-in-Aid for National Research Grid Initiative(NAREGI)Nanoscience Project from the Ministry of Education,Sports,Culture,Science and Technology(MEXT)of Japan,the Kurata Memorial Hitachi Science and Technology Foundation,and Nebraska Research Initiative(No.4132050400)of USA.
文摘A magnetic ground state is revealed for the first time in zigzag-edged carbon nanoscrolls(ZCNSs)from spin-unrestricted density functional theory calculations.Unlike their flat counterpart-zigzag-edged carbon nanoribbons,which are semiconductors with spin-degenerate electronic structure-ZCNSs show a variety of magnetic configurations,namely spin-selective semiconductors,metals,semimetals,quasi-half-metals,and half-metals.To the best of our knowledge,this is the first discovery of quasi-half-metals and half-metals in a pure hydrocarbon without resort to an external electric field.In addition,we calculated the spin-dependent transportation of the semiconducting ZCNSs with 12 and 20 zigzag chains,and found that they are 13% and 17% at the Fermi level,respectively,suggesting that ZCNS can be an effective spin filter.
基金Supported by the National Natural Science Foundation of China
文摘The electrophilic substitution reaction occurring to the chelate ring of the complexes could be regarded as an indication of quasi-aromaticity of the ring systems, no catalyst was used and only triethylamine was employed, implying that the aroylating agents with different p-substituents are polarized enough to be effective electrophiles to attack the methine carbon of the electron-rich substrate 1. This property is probably the clue to polarization of the ligand electrons by the nickel( Ⅱ ) ion and to the participation of the nickel( Ⅱ ) in the π-bond systems of the two coordinated conjugated rings. The linearity relationship between vd-d maxima, E1/2OX(1) and σp are obtained, respectively. The electronic environment of central metal ion as well as the aromaticity of the ring system are affected by the electronic properties of the p-substituents. A comparison of the electrochemical results with each other showed .that when the electronegativity of the substituent was higher, the oxidation(Ni2+/Ni3+) becomes more difficult.
