Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,w...Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,we present a unipolar pulsed electrodeposition(UPED) strategy to induce strain in the Ni lattice by introducing trace amounts of Pt single atoms(SAs)(0.22 wt%).The overpotential decreased by 183 mV at 10 mA cm^(-2) in 1.0 M KOH after introducing trace amounts of Pt_(SAs).The industrial electrolyzer,assembled with Pt_(SAs)Ni cathode and a commercial NiFeO_(x) anode,requires a cell voltage of 1.90 V to attain 1 A cm^(-2) of current density and remains stable for 280 h,demonstrating significant potential for practical applications.Spherical aberration corrected scanning transmission electron microscopy(AC-STEM),X-ray absorption(XAS),and geometric phase analysis(GPA) indicate that the introduction of trace amounts of Pt SAs induces tensile strain in the Ni lattice,thereby altering the local electronic structure and coordination environment around cubic Ni for enhancing the water decomposition kinetics and fundamentally changing the reaction pathway.The doping-strain strategy showcases conformational relationships that could offer new ideas to construct efficient hydrogen evolution reaction(HER) electrocatalysts for industrial hydrogen production in the future.展开更多
A segmented basis set of quadruple zeta valence quality plus polarization functions(QZP)for H through Xe was developed to be used in conjunction with the ZORA Hamiltonian.This set was augmented with diffuse functions ...A segmented basis set of quadruple zeta valence quality plus polarization functions(QZP)for H through Xe was developed to be used in conjunction with the ZORA Hamiltonian.This set was augmented with diffuse functions to describe electrons farther away from the nuclei adequately.Using the ZORA-CCSD(T)/QZP-ZORA theoretical model,atomic ionization energies and bond lengths,harmonic vibrational frequencies,and atomization energies of some molecules were calculated.The addition of core-valence corrections has been shown to improve the agreement between theoretical and experimental results for molecular properties.For atomization energies,a similar observation emerges when considering spin-orbit couplings.With the augmented QZP-ZORA set,static mean dipole polarizabilities of a set of atoms were calculated and compared with previously published recommended and experimental values.Performance evaluations of the ZORA and Douglas–Kroll–Hess Hamiltonians were made for each property studied.展开更多
Collisions between hot H atoms and CO2 molecules were studied experimentally by time resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 k J/mol...Collisions between hot H atoms and CO2 molecules were studied experimentally by time resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 k J/mol respectively, were generated by UV laser photolysis to initiate a chemical reaction of H＋CO2→OH＋CO. Vibrationally excited CO （v≤2） was observed in the spectrum, where CO was the product of the reaction. The highly efficient T-V energy transfer fro,n the hot H atoms to the CO2 was verified too. The highest vibrational level of v=4 in CO2 （va） was found. Rate ratio of the chemical reaction to the energy transfer was estimated as 10.展开更多
The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(>...The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(> 400 ℃) conditions.Herein, a highly active catalytic conversion process of ethane at room temperature(25 ℃) is reported on single iron atoms confined in graphene via the porphyrin-like N4-coordination structures.Combining with the operando time of flight mass spectrometer and density functional theory calculations, the reaction is identified as a radical mechanism, in which the C–H bonds of the same C atom are preferentially and sequentially activated, generating the value-added C2 chemicals, simultaneously avoiding the over-oxidation of the products to CO2.The in-situ formed O–FeN4–O structure at the single iron atom serves as the active center for the reaction and facilitates the formation of ethyl radicals.This work deepens the understanding of alkane C–H activation on the FeN4 center and provides the reference in development of efficient catalyst for selective oxidation of light alkane.展开更多
Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2so, 3d＇0, 3po, 3p-1, 3...Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2so, 3d＇0, 3po, 3p-1, 3d_1, 4d-1, 3d-2, 4d-2, 4f-2 , and 5f-2 as a function of magnetic field strengths with a range from zero up to 2.35 × 10^6 T. The obtained results are compared with available high accuracy theoretical data reported in the literature and found to be in excellent agreement. The comparison also shows that the current method can produce energy levels with an accuracy higher than the existing high accuracy method [Phys. Rev. A 54 （1996） 287]. Here high accuracy energy levels are for the first time reported for the 3d＇0, 4d-1, 4d-2, 4f-2, and 5f-2 states.展开更多
ABSTRACT Rationally designing broad-spectrum photocatalysts to harvest whole visible-light region photons and enhance solar energy conversion is a“holy grail”for researchers,but is still a challenging issue.Herein,b...ABSTRACT Rationally designing broad-spectrum photocatalysts to harvest whole visible-light region photons and enhance solar energy conversion is a“holy grail”for researchers,but is still a challenging issue.Herein,based on the common polymeric carbon nitride(PCN),a hybrid co-catalysts system comprising plasmonic Au nanoparticles(NPs)and atomically dispersed Pt single atoms(PtSAs)with different functions was constructed to address this challenge.For the dual co-catalysts decorated PCN(PtSAs–Au_(2.5)/PCN),the PCN is photoexcited to generate electrons under UV and short-wavelength visible light,and the synergetic Au NPs and PtSAs not only accelerate charge separation and transfer though Schottky junctions and metal-support bond but also act as the co-catalysts for H_(2) evolution.Furthermore,the Au NPs absorb long-wavelength visible light owing to its localized surface plasmon resonance,and the adjacent PtSAs trap the plasmonic hot-electrons for H_(2) evolution via direct electron transfer effect.Consequently,the PtSAs–Au_(2.5)/PCN exhibits excellent broad-spectrum photocatalytic H_(2) evolution activity with the H_(2) evolution rate of 8.8 mmol g^(−1) h^(−1) at 420 nm and 264μmol g^(−1) h^(−1) at 550 nm,much higher than that of Au_(2.5)/PCN and PtSAs–PCN,respectively.This work provides a new strategy to design broad-spectrum photocatalysts for energy conversion reaction.展开更多
6 Atomic fragment types of organic compound have been defined, and the multilevel atom-pair frequency matrix has been constructed according to the occurrence number in pairs of atomic fragments with different bond len...6 Atomic fragment types of organic compound have been defined, and the multilevel atom-pair frequency matrix has been constructed according to the occurrence number in pairs of atomic fragments with different bond lengths in the molecule. On the basis of them, a novel molecular coding technique： characteristic atom-pair holographic code （CAHC）, is obtained. To some extent, this method exhibits a large number of benefits at the same time. For example, it can calculate 2D molecular topological descriptor easily, operate without difficulty and possess definite physicochemical meaning of 3D molecular structural characterization methods, and may fetch the complicated information of molecule, etc. Therefore, it is appropriate for the study on quantitative structure-property/activity relationship （QSPR/QSAR） of medicines and biological molecules. We attempt in this paper to utilize the method of CAHC to the quantitative prediction of reversed-phase liquid chromatogram （RPLC） retention data of 33 purine derivatives and 24 steroids. The fitting multiple correlation coefficient R2, cross-validated multiple correlation coefficient Q2 and predicted ability Q^2 pred over test set＇s samples of obtained partial least-square （PLS） regression model are respectively 0.990, 0.893 and 0.977, 0.897, 0.941.展开更多
Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and...Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and W-Ta alloys. Only a single He atom favors a substitutional site in the presence of a nearby vacancy. However, in the coexistence of He and H atoms in the presence of the vacancy, the single H atom favors the tetrahedral interstitial site（TIS） closest to the vacancy, and the He atom takes the vacancy center. The addition of Ta can reduce the formation energy of TIS He or H defects. The substituted Ta affects the charge density distribution in the vicinity of the He atom and decreases the valence electron density of the H atoms. A strong hybridization of the H s states and the nearest W d state s exists in W（53）He1 H1 structure. The sequence of the He p projected DOS at the Fermi energy level is in agreement with the order of the formation energy of the He-H pair in the systems.展开更多
new coordination polymer {[Zn(CF3COO)2(C5H5ON)]·H2O}n was synthesized based on the reaction of zinc(Ⅱ) trifluoroacetate and 3-hydroxypyridine(C5H5ON) in methanol medium for the first time. The structure of the c...new coordination polymer {[Zn(CF3COO)2(C5H5ON)]·H2O}n was synthesized based on the reaction of zinc(Ⅱ) trifluoroacetate and 3-hydroxypyridine(C5H5ON) in methanol medium for the first time. The structure of the coordination polymer was confirmed by IR, 1H NMR, elemental analysis and thermal analysis. The crystal structure of the coordination polymer was also determined by X-ray single crystal diffraction. The crystal belongs to monoclinic system with space group P21/m, and crystallographic data of the coordination polymer are: a= 0.863 1(4) nm, b=0.717 7(3) nm, c=1.116 4(5) nm, α=γ=90°, β=107.542(6)°, V=0.659 4(5) nm3; Dc=2.037 g·cm-3; Z=2; F(000)=400; μ=1.969 mm-1. Zinc(Ⅱ) atom lies at the center of an octahedron formed by the coordination of zinc atom and six O atoms which come from four different trifluoroacetate ions and two different 3-hydroxypyridine molecules where each trifluoroacetate ion and 3-hydroxypyridine are coordinated to two different zinc ions to form coordination polymer. CCDC: 253909.展开更多
Diorganotin(Ⅳ) compound [(p-CNC6H4CH2)2Sn(C9H7N3O3)(H2O)]2 was synthesized by the reaction of tri-p-cyanobenzyltin chloride with Schiff base ligand pyruvic acid isonicotinyl hydrazone. The compound was characterized ...Diorganotin(Ⅳ) compound [(p-CNC6H4CH2)2Sn(C9H7N3O3)(H2O)]2 was synthesized by the reaction of tri-p-cyanobenzyltin chloride with Schiff base ligand pyruvic acid isonicotinyl hydrazone. The compound was characterized by elemental analysis, IR, 1H NMR. The crystal structure was determined by X-ray single crystal diffraction. The crystal belongs to monoclinic space group C2/c, with a=3.143 1(3) nm, b=0.989 99(10) nm, c=1.785 68(18) nm, β=114.908 0(13)°, V=5.039 6(9) nm3, Z=4, μ=1.054 mm-1, Dc=1.513 Mg·m-3, F(000)=2 304, R=0.042 8, wR=0.090 3, GOF=0.997. In this compound, the Sn atom exists in a distorted octahedral coordination environment in which one water molecule, one tridentate pyruvic acid isonicotinyl hydrazone ligand, and two trans p-cyanobenzyl groups coordinate to each Sn center, the angle of the axial C10-Sn1-C18 is 166.1(2)°. Two molecules form a weak-bridged dimmer with weak interactions of Sn...O bonding and hydrogen bonds. CCDC: 270796.展开更多
基金National Natural Science Foundation of China (grants U22A20418, 22075196, and 21878204)Research Project Supported by Shanxi Scholarship Council of China (2022-050)。
文摘Strategically designing the electrocatalytic system and cleverly inducing strain is an effective approach to balance the cost and activity of Pt-based electrocatalysts for industrial-scale hydrogen production.Herein,we present a unipolar pulsed electrodeposition(UPED) strategy to induce strain in the Ni lattice by introducing trace amounts of Pt single atoms(SAs)(0.22 wt%).The overpotential decreased by 183 mV at 10 mA cm^(-2) in 1.0 M KOH after introducing trace amounts of Pt_(SAs).The industrial electrolyzer,assembled with Pt_(SAs)Ni cathode and a commercial NiFeO_(x) anode,requires a cell voltage of 1.90 V to attain 1 A cm^(-2) of current density and remains stable for 280 h,demonstrating significant potential for practical applications.Spherical aberration corrected scanning transmission electron microscopy(AC-STEM),X-ray absorption(XAS),and geometric phase analysis(GPA) indicate that the introduction of trace amounts of Pt SAs induces tensile strain in the Ni lattice,thereby altering the local electronic structure and coordination environment around cubic Ni for enhancing the water decomposition kinetics and fundamentally changing the reaction pathway.The doping-strain strategy showcases conformational relationships that could offer new ideas to construct efficient hydrogen evolution reaction(HER) electrocatalysts for industrial hydrogen production in the future.
基金the financial support of Conselho Nacional de Desenvolvimento Científico e Tecnológico and Coordenacao de Aperfeic oamento de Pessoal de Nível Superior (Brazilian Agencies)。
文摘A segmented basis set of quadruple zeta valence quality plus polarization functions(QZP)for H through Xe was developed to be used in conjunction with the ZORA Hamiltonian.This set was augmented with diffuse functions to describe electrons farther away from the nuclei adequately.Using the ZORA-CCSD(T)/QZP-ZORA theoretical model,atomic ionization energies and bond lengths,harmonic vibrational frequencies,and atomization energies of some molecules were calculated.The addition of core-valence corrections has been shown to improve the agreement between theoretical and experimental results for molecular properties.For atomization energies,a similar observation emerges when considering spin-orbit couplings.With the augmented QZP-ZORA set,static mean dipole polarizabilities of a set of atoms were calculated and compared with previously published recommended and experimental values.Performance evaluations of the ZORA and Douglas–Kroll–Hess Hamiltonians were made for each property studied.
基金supported by the National Natural Science Foundation of China and the National Basic Research Program of China(973 Program).
文摘Collisions between hot H atoms and CO2 molecules were studied experimentally by time resolved Fourier transform infrared emission spectroscopy. H atoms with three translational energies, 174.7, 241.0 and 306.2 k J/mol respectively, were generated by UV laser photolysis to initiate a chemical reaction of H＋CO2→OH＋CO. Vibrationally excited CO （v≤2） was observed in the spectrum, where CO was the product of the reaction. The highly efficient T-V energy transfer fro,n the hot H atoms to the CO2 was verified too. The highest vibrational level of v=4 in CO2 （va） was found. Rate ratio of the chemical reaction to the energy transfer was estimated as 10.
基金the financial support from the Ministry of Science and Technology of China (Nos.2016YFA0204100 and 2016YFA0200200)the National Natural Science Foundation of China (Nos.21890753, 21573220 and 21802124)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (No.QYZDB-SSW-JSC020)the DNL Cooperation Fund, CAS (No.DNL180201)the financial and technique supports from the Westlake Education Foundation, Supercomputing Systems in the Information Technology Center of Westlake University
文摘The catalytic conversion of ethane to high value-added chemicals is significantly important for utilization of hydrocarbon resources.However, it is a great challenge due to the typically required high temperature(> 400 ℃) conditions.Herein, a highly active catalytic conversion process of ethane at room temperature(25 ℃) is reported on single iron atoms confined in graphene via the porphyrin-like N4-coordination structures.Combining with the operando time of flight mass spectrometer and density functional theory calculations, the reaction is identified as a radical mechanism, in which the C–H bonds of the same C atom are preferentially and sequentially activated, generating the value-added C2 chemicals, simultaneously avoiding the over-oxidation of the products to CO2.The in-situ formed O–FeN4–O structure at the single iron atom serves as the active center for the reaction and facilitates the formation of ethyl radicals.This work deepens the understanding of alkane C–H activation on the FeN4 center and provides the reference in development of efficient catalyst for selective oxidation of light alkane.
文摘Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2so, 3d＇0, 3po, 3p-1, 3d_1, 4d-1, 3d-2, 4d-2, 4f-2 , and 5f-2 as a function of magnetic field strengths with a range from zero up to 2.35 × 10^6 T. The obtained results are compared with available high accuracy theoretical data reported in the literature and found to be in excellent agreement. The comparison also shows that the current method can produce energy levels with an accuracy higher than the existing high accuracy method [Phys. Rev. A 54 （1996） 287]. Here high accuracy energy levels are for the first time reported for the 3d＇0, 4d-1, 4d-2, 4f-2, and 5f-2 states.
基金supported by the National Natural Science Foundation of China(Grant No.51871078 and 52071119)Interdisciplinary Research Foundation of HIT(Grant No.IR2021208)+1 种基金State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology)(No.2022TS38)Heilongjiang Science Foundation(No.LH2020B006).
文摘ABSTRACT Rationally designing broad-spectrum photocatalysts to harvest whole visible-light region photons and enhance solar energy conversion is a“holy grail”for researchers,but is still a challenging issue.Herein,based on the common polymeric carbon nitride(PCN),a hybrid co-catalysts system comprising plasmonic Au nanoparticles(NPs)and atomically dispersed Pt single atoms(PtSAs)with different functions was constructed to address this challenge.For the dual co-catalysts decorated PCN(PtSAs–Au_(2.5)/PCN),the PCN is photoexcited to generate electrons under UV and short-wavelength visible light,and the synergetic Au NPs and PtSAs not only accelerate charge separation and transfer though Schottky junctions and metal-support bond but also act as the co-catalysts for H_(2) evolution.Furthermore,the Au NPs absorb long-wavelength visible light owing to its localized surface plasmon resonance,and the adjacent PtSAs trap the plasmonic hot-electrons for H_(2) evolution via direct electron transfer effect.Consequently,the PtSAs–Au_(2.5)/PCN exhibits excellent broad-spectrum photocatalytic H_(2) evolution activity with the H_(2) evolution rate of 8.8 mmol g^(−1) h^(−1) at 420 nm and 264μmol g^(−1) h^(−1) at 550 nm,much higher than that of Au_(2.5)/PCN and PtSAs–PCN,respectively.This work provides a new strategy to design broad-spectrum photocatalysts for energy conversion reaction.
基金This work was supported by the State Key Laboratory of Chemo/Biosensing and Chemometrics Foundation (No. 05-12-1), Fok-Yingtung Educational Foundation (No. 98-7-6) and Chongqing University Innovation Foundation of Science and Technology ( No. 06-1-1)
文摘6 Atomic fragment types of organic compound have been defined, and the multilevel atom-pair frequency matrix has been constructed according to the occurrence number in pairs of atomic fragments with different bond lengths in the molecule. On the basis of them, a novel molecular coding technique： characteristic atom-pair holographic code （CAHC）, is obtained. To some extent, this method exhibits a large number of benefits at the same time. For example, it can calculate 2D molecular topological descriptor easily, operate without difficulty and possess definite physicochemical meaning of 3D molecular structural characterization methods, and may fetch the complicated information of molecule, etc. Therefore, it is appropriate for the study on quantitative structure-property/activity relationship （QSPR/QSAR） of medicines and biological molecules. We attempt in this paper to utilize the method of CAHC to the quantitative prediction of reversed-phase liquid chromatogram （RPLC） retention data of 33 purine derivatives and 24 steroids. The fitting multiple correlation coefficient R2, cross-validated multiple correlation coefficient Q2 and predicted ability Q^2 pred over test set＇s samples of obtained partial least-square （PLS） regression model are respectively 0.990, 0.893 and 0.977, 0.897, 0.941.
基金Supported by the National Natural Science Foundation of China under Grant No 11605007the Funding from the China Scholarship Council under Grant No 201506465019
文摘Properties of various defects of He and H atoms in W-Ta alloys are investigated based on density functional theory. The tetrahedral interstitial site is the most configured site for self-interstitial He and H in W and W-Ta alloys. Only a single He atom favors a substitutional site in the presence of a nearby vacancy. However, in the coexistence of He and H atoms in the presence of the vacancy, the single H atom favors the tetrahedral interstitial site（TIS） closest to the vacancy, and the He atom takes the vacancy center. The addition of Ta can reduce the formation energy of TIS He or H defects. The substituted Ta affects the charge density distribution in the vicinity of the He atom and decreases the valence electron density of the H atoms. A strong hybridization of the H s states and the nearest W d state s exists in W（53）He1 H1 structure. The sequence of the He p projected DOS at the Fermi energy level is in agreement with the order of the formation energy of the He-H pair in the systems.
文摘new coordination polymer {[Zn(CF3COO)2(C5H5ON)]·H2O}n was synthesized based on the reaction of zinc(Ⅱ) trifluoroacetate and 3-hydroxypyridine(C5H5ON) in methanol medium for the first time. The structure of the coordination polymer was confirmed by IR, 1H NMR, elemental analysis and thermal analysis. The crystal structure of the coordination polymer was also determined by X-ray single crystal diffraction. The crystal belongs to monoclinic system with space group P21/m, and crystallographic data of the coordination polymer are: a= 0.863 1(4) nm, b=0.717 7(3) nm, c=1.116 4(5) nm, α=γ=90°, β=107.542(6)°, V=0.659 4(5) nm3; Dc=2.037 g·cm-3; Z=2; F(000)=400; μ=1.969 mm-1. Zinc(Ⅱ) atom lies at the center of an octahedron formed by the coordination of zinc atom and six O atoms which come from four different trifluoroacetate ions and two different 3-hydroxypyridine molecules where each trifluoroacetate ion and 3-hydroxypyridine are coordinated to two different zinc ions to form coordination polymer. CCDC: 253909.
文摘Diorganotin(Ⅳ) compound [(p-CNC6H4CH2)2Sn(C9H7N3O3)(H2O)]2 was synthesized by the reaction of tri-p-cyanobenzyltin chloride with Schiff base ligand pyruvic acid isonicotinyl hydrazone. The compound was characterized by elemental analysis, IR, 1H NMR. The crystal structure was determined by X-ray single crystal diffraction. The crystal belongs to monoclinic space group C2/c, with a=3.143 1(3) nm, b=0.989 99(10) nm, c=1.785 68(18) nm, β=114.908 0(13)°, V=5.039 6(9) nm3, Z=4, μ=1.054 mm-1, Dc=1.513 Mg·m-3, F(000)=2 304, R=0.042 8, wR=0.090 3, GOF=0.997. In this compound, the Sn atom exists in a distorted octahedral coordination environment in which one water molecule, one tridentate pyruvic acid isonicotinyl hydrazone ligand, and two trans p-cyanobenzyl groups coordinate to each Sn center, the angle of the axial C10-Sn1-C18 is 166.1(2)°. Two molecules form a weak-bridged dimmer with weak interactions of Sn...O bonding and hydrogen bonds. CCDC: 270796.
