Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to...Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to CDs are atomically imprecise and their molecular weight distribution is broad.In this paper,a series of Pluronic-modified CDs were prepared and the structure of the CDs was briefly analyzed.Subsequently,a molecular weight measurement method based on colligative properties was developed,and the correction coefficient in the algorithm was briefly analyzed.The calculated molecular weight was applied to the determination of surface adsorption capacity.This work provided a method for averaging the molecular weight of atomically imprecise particulate materials,which is expected to provide new opportunities in related fields.展开更多
Surface adsorption plays a crucial role in various natural and industrial processes,particularly in the field of energy storage.The adsorption of sodium atoms on 2D layered materials can significantly impact their per...Surface adsorption plays a crucial role in various natural and industrial processes,particularly in the field of energy storage.The adsorption of sodium atoms on 2D layered materials can significantly impact their performance as carriers and electrodes in ion batteries.While it is commonly acknowledged that pristine graphene is not favorable for sodium ion adsorption,the suitability of other 2D materials with similar honeycomb symmetry remains unclear.In this study,we employ systematic first-principles calculations to explore interlayer interactions and electron transfer effects on sodium adsorption on 2D van der Waals(vdW)heterostructures(HTSs)surfaces.Our results demonstrate that sodium adsorption is energetically favorable on these substrates.Moreover,we find that the adsorption strength can be effectively tuned by manipulation of the electron accumulation or depletion of the layer directly interacting with the sodium atom.By stacking these layered materials with different electron abundancy to form vd W HTSs,the charge density of the substrate becomes tunable through interlayer charge transfer.In these vdW HTSs,the adsorption behavior of sodium is primarily controlled by the absorption layer and exhibits a linear correlation with its pz-band center.Additionally,we identify linear correlations between the sodium adsorption energies,the electron loss of the sodium atom,the interlayer charge transfer,and the heights of the adsorbed sodium atom.These discoveries underscore the impact of interlayer electron transfer and interactions on sodium ion adsorption on 2D vd W HTSs and providing new insights into material design for alkali atom adsorption.展开更多
The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable ad...The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.展开更多
Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by...Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by eutrophication. The co-existence of surface adsorbed and intracellular phosphorus pools indicate that phosphate uptake by phytoplankton is, to some extent, a two-stage kinetic process. However, almost all previous uptake models considered the internal uptake stage only and ignored the possible impact of surface adsorption. In this article, a two-stage kinetic uptake model considering both surface adsorption and P-stress on phosphate uptake by algae was constructed and compared to conventional one-stage models, based on experimental data on short-term uptake kinetics of a green algae S. quadricauda. Results indicated that with suitable parameters, the two-stage uptake model not only fit the experimental data better, but also gave more reasonable and realistic explanations to the phosphate uptake process. The results are meaningful as surface-adsorption of phosphate may affect the uptake process of phosphate and assist in understanding realistic phosphate uptake kinetics in phytoplankton.展开更多
There are a few studies on the use of ferro-nanofluids for enhanced oil recovery,despite their magnetic properties;hence,it is needed to study the adsorption of iron oxide(Fe2 O3 and Fe3 O4) nanoparticles(NPs) on rock...There are a few studies on the use of ferro-nanofluids for enhanced oil recovery,despite their magnetic properties;hence,it is needed to study the adsorption of iron oxide(Fe2 O3 and Fe3 O4) nanoparticles(NPs) on rock surfaces.This is important as the colloidal transport of NPs through the reservoir is subject to particle adsorption on the rock surface.Molecular dynamics simulation was used to determine the interfacial energy(strength) and adsorption of Fe2 O3 and Fe3 O4 nanofluids infused in reservoir sandstones.Fourier transform infrared spectroscopy and X-ray photon spectroscopy(XPS) were used to monitor interaction of silicate species with Fe2 O3 and Fe3 O4.The spectral changes show the variation of dominating silicate anions in the solution.Also,the XPS peaks for Si,C and Fe at 190,285 and 700 eV,respectively,are less distinct in the spectra of sandstone aged in the Fe3 O4 nanofluid,suggesting the intense adsorption of the Fe3 O4 with the crude oil.The measured IFT for brine/oil,Fe2 O3/oil and Fe3 O4/oil are 40,36.17 and 31 mN/m,respectively.Fe3 O4 infused with reservoir sandstone exhibits a higher silicate sorption capacity than Fe2 O3,due to their larger number of active surface sites and saturation magnetization,which accounts for the effectiveness of Fe3 O4 in reducing IFT.展开更多
A model for describing the adsorption process of hydrogen on surface of tungsten oxide was proposed based on the first-principle calculations. Multiple factors such as type of active surface, adsorption site and distr...A model for describing the adsorption process of hydrogen on surface of tungsten oxide was proposed based on the first-principle calculations. Multiple factors such as type of active surface, adsorption site and distribution of oxygen vacancies were considered to evaluate the hydrogen adsorption capability of tungsten oxide. The adsorption Gibbs free energies, electronic structures and bonding characteristics under various conditions were examined to reveal the influence of oxygen vacancies on the surface. It is found that the capability of hydrogen adsorption of tungsten oxide can be significantly enhanced by adjusting the oxygen vacancy on the outermost layer of certain active surfaces. The modeling predicts that the surface structure stability and gas adsorption ability of tungsten oxide can be simultaneously improved through the formation of W–H bonds. The proposed strategy for moderating surface provides a new approach to obtain excellent gas-sensitive metal oxide materials.展开更多
The 5-parameter Morse pntential（5-MP） of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe（211 ） high-index surfaces were invest...The 5-parameter Morse pntential（5-MP） of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe（211 ） high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe（100） surface with an eigenvibration at437 cm^-1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O-Fe（110） system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe（ 111 ） and Fe（211 ） surfaces, O atoms predominantly occupy the quasi-3-fold site.展开更多
The discrete variational Xα method (DV-Xα) within the framework of density-functional theory was applied to study O 2 molecule adsorption on NiTi (100) and (110) surfaces.The bond order and charge distribution betw...The discrete variational Xα method (DV-Xα) within the framework of density-functional theory was applied to study O 2 molecule adsorption on NiTi (100) and (110) surfaces.The bond order and charge distribution between Ti and O atoms for two possible O 2 molecule adsorption ways on NiTi(100) and (110) surfaces were calculated.It is found that the adsorption way for O-O bond perpendicular to NiTi surface is preferred to that for O-O bond parallel to NiTi surface,and O 2 molecule only interacted with one nearest surface titanium atom during the adsorption process.Mulliken population and the partial density of state analysis show that the interaction between Ti and O atoms is mainly donated by O 2p and Ti 4s electrons on NiTi(110) surface,O 2p and Ti 4s,4p electrons on NiTi(100) surface,respectively.The total density of state analysis shows that NiTi(100) surface is more favorable for O 2 molecule adsorption.展开更多
The crystal growth mechanism, kinetics, and microstructure development play a fundamental role in tailoring the materials with controllable size and morphology. In this study, by introducing the strong surface adsorpt...The crystal growth mechanism, kinetics, and microstructure development play a fundamental role in tailoring the materials with controllable size and morphology. In this study, by introducing the strong surface adsorption of the concentrated NaOH, two-stage crystal growth kinetics of ZnS nanoparficles was observed. In the first stage, the primary particles grow into a size over a hundred times of the original volume and the growth is controlled by the crystallographically specific oriented attachment. The first stage data were fitted by the ＂multistep OA kinetic model＂ built based on the molecular collision and reaction. In the second stage, following the dispersal of nanoparficles, an abrupt transition from asymptotic to parabola growth kinetics occurs, which can be fitted by a standard Ostwald ripening volume diffusion model. The presence of surface adsorption causes the two-stage growth kinetics and permits an almost exclusive OA-based growth to dominate in the first stage.展开更多
An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. ...An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.展开更多
Surface junctions between Bi OBr and BiVO4 were synthesized. The BiOBr/BiVO4 with 1 wt.%of Bi OBr exhibited the highest photocatalytic activity in the degradation of Rh B under visible-light irradiation. It was found ...Surface junctions between Bi OBr and BiVO4 were synthesized. The BiOBr/BiVO4 with 1 wt.%of Bi OBr exhibited the highest photocatalytic activity in the degradation of Rh B under visible-light irradiation. It was found that the highly efficient adsorption of Rh B molecules via the electrostatic attraction between Br-and cationic ／N（Et）2 group played a key role for the high photocatalytic activities of BiOBr/BiVO4. This efficient adsorption promoted the N-deethylation of Rh B and thus accelerated the photocatalytic degradation of Rh B.Moreover, the metal-to-metal charge transfer（MMCT） mechanism was proposed, which revealed the concrete path paved with Bi–O–Bi chains for the carrier migration in BiOBr/BiVO4. The interaction between photoexcited Rh B＊ and the Bi^（3＋） in BiVO4 provided the driving force for the migration of photo-generated carriers along the Bi–O–Bi chains. This work has not only demonstrated the important role of efficient adsorption in the photocatalytic degradation of organic contaminants, but also developed a facile strategy to improve the efficiency of photocatalysts.展开更多
The O-Ag（210） surface adsorption system was studied via the five-parameter Morse potential theory. Mean- while, the 20-Ag （ 210） system was investigated v/a the extended London-Eyring-Polanyi-Sato （LEPS） potenti...The O-Ag（210） surface adsorption system was studied via the five-parameter Morse potential theory. Mean- while, the 20-Ag （ 210） system was investigated v/a the extended London-Eyring-Polanyi-Sato （LEPS） potential theo- ry to learn the interaction between the adsorption states. Calculated results demonstrate that there are two stable on- surface adsorption sites（B and H） for 0 atoms on Ag（210） stepped surface. And the perpendicular vibrations are 30. 3 and 42.9 meV, which are close to that observed in high resolution electron energy loss spectroscopy （HREELS）. Also, there exists an octabedral subsurface adsorption state with a high vibrational frequency, and the interaction between the on-surface and subsurface 0 species is slight. The mode at 54.6 meV, which is close to that observed in HREELS（54-56 meV）, is because of the vibration of the 0 atom on B site under the influence of that on H site.展开更多
In this work,the nanostructures and phase diagrams of lamella-forming and cylinder-forming ABC linear triblock copolymers confined in spherical cavities are investigated on the basis of real-space self-consistent fiel...In this work,the nanostructures and phase diagrams of lamella-forming and cylinder-forming ABC linear triblock copolymers confined in spherical cavities are investigated on the basis of real-space self-consistent field theory.We designate specific monomer-monomer interactions and block composition and study morphology transformation under spherical confinement with a neutral surface.Various potentially valuable morphological structures,such as two-or three-colored spheres,rotational structures,and biconcave disklike structures,are identified in the phase diagrams constructed on confining diameters.Single confinement induces an obvious transformation of self-assembled structures,which still retain some of the conformational properties of bulk structures.We then focus on phase morphology under preferential surfaces.Absorption can smooth out differences in block ratios,and similar structures can be assembled from block copolymers with different proportions.We incorporate a non-centrosymmetric feature into our spherical confinement model and design a Janus adsorption field to explore unpredictable microphase behavior.Results show that the unbalance of the block ratio causes adsorption to exert a stable shaping effect on conformation.The influence of confinement on the degree of freedom of polymer chains disrupts the influence of adsorption on the complexity and transformation activity of self-assembled structures.The theoretical results correspond to recent experimental observations and contribute to the field functional material synthesis.展开更多
The 5-parameter Morse potential（5-MP） of the interactions between Cl atoms and Ni surfaces was constructed. The adsorption and diffusion of Cl atoms on Ni low index-surfaces were investigated with 5-MP in detail. Al...The 5-parameter Morse potential（5-MP） of the interactions between Cl atoms and Ni surfaces was constructed. The adsorption and diffusion of Cl atoms on Ni low index-surfaces were investigated with 5-MP in detail. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, eigenvalues for vibration, etc. were obtained. The calculated results show that chlorine atoms are likely to be adsorbed on the high symmetry- sites. Cl atoms locate on the four-fold hollow sites of the intact Ni（100） surface, while they tend to occupy threefold sites on the Ni（ 111 ） surface. The four-fold hollow sites are the most stable adsorption sites on the Ni （110） surface for Cl, although the three-fold sites and the long-bridge sites are stable adsorption sites on the Ni（110） surface for the atoms of the first and second periods. For the Cl-Ni surface adsorption system, the surface binding energy of a Cl atom is relevant to the coarse degree of the cluster surface, and the binding energies have an order of Ni （ 111 ） 〈 Ni（100） 〈Ni（100）.展开更多
The surface tension and cenductivity of tetracthylarnmomum perfluorooctanesulfonate (TEPFOS) solu-tions in mixed solvents were determined The criticsl micelle concentrations (cmc) and surface adsorption of TEPFOS in v...The surface tension and cenductivity of tetracthylarnmomum perfluorooctanesulfonate (TEPFOS) solu-tions in mixed solvents were determined The criticsl micelle concentrations (cmc) and surface adsorption of TEPFOS in various solvents (Dimetbylsulfoxlde and DMSO, formamide and FA, and DMSO-H2O and FA H2O mixtures) were calculated from the above experimental date. The results show that the surface activity of TEPFOS is much higher than that of typical hydrocarbon surfactant, sodium dodecylsulfate (SDS); the melecalar interaction (in terms of colubility araneter or surface tension) of solvent is the decisive factor in sffecting the cmc of TEPFOS , in the apretic solvent DMSO, the value of entropy change during micelliza-tion of TEPFOS may beecme subsantially negative; the surfaof adsorption amount of TEPFOS is the largest in H2O, smaller in FA , and the smallest in DMSO.展开更多
Aqueous zinc-ion batteries(ZIBs) are considered promising power sources for grid storage,but they face several issues,including dendrite growth,corrosion,hydrogen evolution,etc.,which are related to the Zn metal/liqui...Aqueous zinc-ion batteries(ZIBs) are considered promising power sources for grid storage,but they face several issues,including dendrite growth,corrosion,hydrogen evolution,etc.,which are related to the Zn metal/liquid electrolyte interface.To address these challenges,many researchers have focused on modifying the Zn anode with surface adsorption.However,the underlying mechanism between the Zn surface and adsorbed/protective molecules has not been thoroughly explored.In this study,we built a multiscale simulation platform that integrates state-of-art simulation methods to comprehensively investigate the adsorption process of amino acids on the Zn metal surface.Our major finding is that adsorption sites,adsorbate–surface angle,and average distance are critical parameters for the stability and strength of surface adsorption.Additionally,ab initio molecular dynamics reveal the kinetics of the surface adsorption and molecule reorientation processes.Specifically,it can be discovered that the amino acids prefer to align parallel to the Zn metal surface,leading to better surface protection against corrosion and preventing dendrite growth.These findings pave the way for an in-depth understanding of the surface adsorption process,as well as providing concrete design principles for stable Zn metal anodes.展开更多
A general expression of the dynamic surface adsorption [Г（t）] on the expanding spherical surface was derived by solving the corresponding diffusion equation under different initial and boundary conditions. Differen...A general expression of the dynamic surface adsorption [Г（t）] on the expanding spherical surface was derived by solving the corresponding diffusion equation under different initial and boundary conditions. Different from the result of the still spherical surface, two factors （smaller than 1） appeared in the equation for the short time adsorption. Using the derived results, the adsorption kinetics of aqueous decanoyl-N-methylglucamine （Mega-10） solution was studied. In the short time region （t→0）, a good agreement of experimental results with the theory was reached and the adsorption was controlled by diffusion.展开更多
The adsorptions of nitrogen atoms on Ru（0001）, （1010） low index surfaces and （1120）, （1121） stepped surfaces were investigated by the five-parameter Morse potential（5-MP） method in details, Calculated result...The adsorptions of nitrogen atoms on Ru（0001）, （1010） low index surfaces and （1120）, （1121） stepped surfaces were investigated by the five-parameter Morse potential（5-MP） method in details, Calculated results demonstrate that N atoms show a tendency to be adsorbed at threefold sites. No subsurface state was found for N atoms on Ru（1010） surface. There exist 6 stable adsorption sites for N atoms on Ru（1121） stepped surface which can be classified into 3 types： the on-surface adsorption state, the facet adsorption state and the subsurface state. Moreover, two new perpendicular vibrations at 97 and 98 meV are predicted. All calculated results are in good accord with HR-EELS experiments.展开更多
We carry out the first time-resolved measurement of Rb atoms desorbing from octadecyltrichlorosilane coated sur- faces by polarizing the atoms near the surface using an evanescent wave pump pulse and watching the subs...We carry out the first time-resolved measurement of Rb atoms desorbing from octadecyltrichlorosilane coated sur- faces by polarizing the atoms near the surface using an evanescent wave pump pulse and watching the subsequent intensity change of another evanescent wave probe beam, and find the mean adsorption （dwell） time to be about 400ns at a cell body temperature of 112℃. The adsorption energy is found to be 0.19eV from the surface tem- perature dependence of the adsorption time. This method can be extended to study the adsorption/desorption process of other alkali atoms on other surfaces of transparent substrates with an ultimate time resolution limited by the flight time of atoms in the evanescent wave which is of the order of nanoseconds.展开更多
First-principles calculations are carried out to study the relaxation of 6H-SiC （0001） surface and chemisorption models of Si adatoms on four high-symmetry adsorption sites. The surface results show that Si-terminat...First-principles calculations are carried out to study the relaxation of 6H-SiC （0001） surface and chemisorption models of Si adatoms on four high-symmetry adsorption sites. The surface results show that Si-termination is the preferred termination of the 6H-SiC（0001） polar surface and is more stable than the C-terminated 61-1- SiC（0001） polar surface over a wide range of allowed chemical potentials. Four stable atomic configurations （top, bridge, hcp and fcc） are considered, and the adsorption energies and geometries, Mulliken charge population, and partial density of state （PDOS） properties are analyzed. Adsorption energy results show that the top site is the most stable site. The structural properties of Si adsorption on the SiC （0001） surface shows that increasing stability means decreasing bond lengths. Charge populations analysis and PDOS results imply that there is strong interaction between Si adatoms and 6H-SiC （0001） surface.展开更多
文摘Since the discovery of carbon dots(CDs)in 2004,the unique photoluminescence phenomenon of CDs has attracted widespread attention.However,the molecular weight of CDs has not been adequately quantified at present,due to CDs are atomically imprecise and their molecular weight distribution is broad.In this paper,a series of Pluronic-modified CDs were prepared and the structure of the CDs was briefly analyzed.Subsequently,a molecular weight measurement method based on colligative properties was developed,and the correction coefficient in the algorithm was briefly analyzed.The calculated molecular weight was applied to the determination of surface adsorption capacity.This work provided a method for averaging the molecular weight of atomically imprecise particulate materials,which is expected to provide new opportunities in related fields.
基金the financial support by the National Key Research and Development Program of China(No.2019YFA0708700)the National Natural Science Foundation of China(Nos.62305196,U23B2087 and 62375158)+4 种基金the China Postdoctoral Science Foundation(No.GZC20231498)the Qingdao Postdoctoral Innovation Project(No.QDBSH20240102078)the Postdoctoral Innovation Program of Shandong Province(No.SDCX-ZG-202400318)Science and Technology Research Project of Hubei Provincial Department of Education(No.D20212603)Hubei University of Arts and Science(No.2020kypytd002)。
文摘Surface adsorption plays a crucial role in various natural and industrial processes,particularly in the field of energy storage.The adsorption of sodium atoms on 2D layered materials can significantly impact their performance as carriers and electrodes in ion batteries.While it is commonly acknowledged that pristine graphene is not favorable for sodium ion adsorption,the suitability of other 2D materials with similar honeycomb symmetry remains unclear.In this study,we employ systematic first-principles calculations to explore interlayer interactions and electron transfer effects on sodium adsorption on 2D van der Waals(vdW)heterostructures(HTSs)surfaces.Our results demonstrate that sodium adsorption is energetically favorable on these substrates.Moreover,we find that the adsorption strength can be effectively tuned by manipulation of the electron accumulation or depletion of the layer directly interacting with the sodium atom.By stacking these layered materials with different electron abundancy to form vd W HTSs,the charge density of the substrate becomes tunable through interlayer charge transfer.In these vdW HTSs,the adsorption behavior of sodium is primarily controlled by the absorption layer and exhibits a linear correlation with its pz-band center.Additionally,we identify linear correlations between the sodium adsorption energies,the electron loss of the sodium atom,the interlayer charge transfer,and the heights of the adsorbed sodium atom.These discoveries underscore the impact of interlayer electron transfer and interactions on sodium ion adsorption on 2D vd W HTSs and providing new insights into material design for alkali atom adsorption.
基金supported by the National Natural Science Foundation of China(No.22373084,No.62201494)Hebei Natural Science Foundation(B2022203007)the Cultivation Project for Basic Research and Innovation of Yanshan University(2024LGZD002).
文摘The adsorption properties of a magnesium porphyrin(MgP)molecule on Au(111)surface covered with up to three lay-ers of sodium chloride(NaCl)were investigated by means of first-principles calculations.The most stable adsorption configuration of MgP on the NaCl/Au(111)heterosurfaces was found to be at the Cl-top site with a 20°angle between the[110]lattice direction of NaCl and the Mg–N bond of the molecule.Compared with MgP molecule adsorbed on bare Au(111),the inclusion of NaCl lay-ers can lead to a significant decrease in the adsorption energy of the MgP molecule.The exis-tence of NaCl layers also reduced the charge transfer between the molecule and the surface.For heterosurfaces with two or three monolayers of NaCl,the charge transfer was almost com-pletely suppressed.The obtained partial density of states(PDOS)showed that hybridization between the electronic structures of the adsorbed MgP molecule and the metal surface can be significantly suppressed when NaCl layers were added.For the heterosurface with three lay-ers of NaCl,the PDOS around the Fermi level was almost identical with that of the free molecule,suggesting the electronic structure of the MgP molecule was nicely preserved.Influ-ence of the NaCl layers on the electronic structure of the MgP molecule was mainly found for molecular orbitals(MOs)away from the Fermi level as a result of the large band gap of the NaCl layers.
基金supported by the National Major Projects on Control and Rectification of Water Body Pollution(No. 2009ZX07106-001)the National High Technology Research and Development Program (863) of China(No.2006AA10Z411)the National Basic Research Program (973) of China(No. 2008CB418000)
文摘Phosphorus is an important limiting nutrient in many ecosystems. Consequently, there is increasing interest on phosphate uptake and algal growth due to the increasing frequency and magnitude of algal blooms induced by eutrophication. The co-existence of surface adsorbed and intracellular phosphorus pools indicate that phosphate uptake by phytoplankton is, to some extent, a two-stage kinetic process. However, almost all previous uptake models considered the internal uptake stage only and ignored the possible impact of surface adsorption. In this article, a two-stage kinetic uptake model considering both surface adsorption and P-stress on phosphate uptake by algae was constructed and compared to conventional one-stage models, based on experimental data on short-term uptake kinetics of a green algae S. quadricauda. Results indicated that with suitable parameters, the two-stage uptake model not only fit the experimental data better, but also gave more reasonable and realistic explanations to the phosphate uptake process. The results are meaningful as surface-adsorption of phosphate may affect the uptake process of phosphate and assist in understanding realistic phosphate uptake kinetics in phytoplankton.
文摘There are a few studies on the use of ferro-nanofluids for enhanced oil recovery,despite their magnetic properties;hence,it is needed to study the adsorption of iron oxide(Fe2 O3 and Fe3 O4) nanoparticles(NPs) on rock surfaces.This is important as the colloidal transport of NPs through the reservoir is subject to particle adsorption on the rock surface.Molecular dynamics simulation was used to determine the interfacial energy(strength) and adsorption of Fe2 O3 and Fe3 O4 nanofluids infused in reservoir sandstones.Fourier transform infrared spectroscopy and X-ray photon spectroscopy(XPS) were used to monitor interaction of silicate species with Fe2 O3 and Fe3 O4.The spectral changes show the variation of dominating silicate anions in the solution.Also,the XPS peaks for Si,C and Fe at 190,285 and 700 eV,respectively,are less distinct in the spectra of sandstone aged in the Fe3 O4 nanofluid,suggesting the intense adsorption of the Fe3 O4 with the crude oil.The measured IFT for brine/oil,Fe2 O3/oil and Fe3 O4/oil are 40,36.17 and 31 mN/m,respectively.Fe3 O4 infused with reservoir sandstone exhibits a higher silicate sorption capacity than Fe2 O3,due to their larger number of active surface sites and saturation magnetization,which accounts for the effectiveness of Fe3 O4 in reducing IFT.
基金supported by the National Key Program of Research and Development (2021YFB3501502, 2021YFB3501504)the National Natural Science Foundation of China (51631002, 92163107)the Beijing Natural Science Foundation (2214067)
文摘A model for describing the adsorption process of hydrogen on surface of tungsten oxide was proposed based on the first-principle calculations. Multiple factors such as type of active surface, adsorption site and distribution of oxygen vacancies were considered to evaluate the hydrogen adsorption capability of tungsten oxide. The adsorption Gibbs free energies, electronic structures and bonding characteristics under various conditions were examined to reveal the influence of oxygen vacancies on the surface. It is found that the capability of hydrogen adsorption of tungsten oxide can be significantly enhanced by adjusting the oxygen vacancy on the outermost layer of certain active surfaces. The modeling predicts that the surface structure stability and gas adsorption ability of tungsten oxide can be simultaneously improved through the formation of W–H bonds. The proposed strategy for moderating surface provides a new approach to obtain excellent gas-sensitive metal oxide materials.
基金the Natural Science Foundation of Shandong Province(No Y2002B09)
文摘The 5-parameter Morse pntential（5-MP） of the interaction between oxygen atoms and iron surfaces was constructed. The adsorption and diffusion of O atoms on Fe low-index and Fe（211 ） high-index surfaces were investigated by using 5-MP. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, and eigenvalues for vibration, were calculated. The calculation results show that O atoms are located at the fourfold hollow site of the Fe（100） surface with an eigenvibration at437 cm^-1. These results are in good agreement with the experimental and theoretical results obtained previously. With regard to the adsorption site of O-Fe（110） system, the authors of this study assume that the preferential adsorption state is the H3 site and not the LB site, which is not in agreement with the experimental inferences obtained earlier. However, on the Fe（ 111 ） and Fe（211 ） surfaces, O atoms predominantly occupy the quasi-3-fold site.
文摘The discrete variational Xα method (DV-Xα) within the framework of density-functional theory was applied to study O 2 molecule adsorption on NiTi (100) and (110) surfaces.The bond order and charge distribution between Ti and O atoms for two possible O 2 molecule adsorption ways on NiTi(100) and (110) surfaces were calculated.It is found that the adsorption way for O-O bond perpendicular to NiTi surface is preferred to that for O-O bond parallel to NiTi surface,and O 2 molecule only interacted with one nearest surface titanium atom during the adsorption process.Mulliken population and the partial density of state analysis show that the interaction between Ti and O atoms is mainly donated by O 2p and Ti 4s electrons on NiTi(110) surface,O 2p and Ti 4s,4p electrons on NiTi(100) surface,respectively.The total density of state analysis shows that NiTi(100) surface is more favorable for O 2 molecule adsorption.
基金the Foundation for Overseas Scholar Fellowshipthe Special Project on Science and Technology of Fujian Province (2005YZ1026)the One Hundred Talent Program in the Chinese Academy of Sciences and the National Natural Science Foundation of China (20501021)
文摘The crystal growth mechanism, kinetics, and microstructure development play a fundamental role in tailoring the materials with controllable size and morphology. In this study, by introducing the strong surface adsorption of the concentrated NaOH, two-stage crystal growth kinetics of ZnS nanoparficles was observed. In the first stage, the primary particles grow into a size over a hundred times of the original volume and the growth is controlled by the crystallographically specific oriented attachment. The first stage data were fitted by the ＂multistep OA kinetic model＂ built based on the molecular collision and reaction. In the second stage, following the dispersal of nanoparficles, an abrupt transition from asymptotic to parabola growth kinetics occurs, which can be fitted by a standard Ostwald ripening volume diffusion model. The presence of surface adsorption causes the two-stage growth kinetics and permits an almost exclusive OA-based growth to dominate in the first stage.
基金support by National Basic Research Program of China(No.2014CB748500)National Natural Science Foundation of China(Nos.51578239,51322805)
文摘An improved biosorbent of thiourea modified chitosan microsphere（TMCM） with high specific surface,favorable mechanical strength and excellent adsorption performance had been synthesized via microfluidic technology. Polyethylene glycol was used as a significant component added in aqueous solution of chitosan to produce such microspheres through droplets forming, chemical crosslinking and pores creating. For the improvement of adsorption capacity, thiourea was considered as an excellent choice in increasing amino functional group by graft modification. The SEM, FTIR and EDS were employed to detect distinct features of TMCM. Copper（Ⅱ） was used to test the adsorption performance of TMCM. The experimental results indicated that TMCM exhibited higher adsorption capacity（q_e= 60.6 mg g_（-1）） and faster adsorption rate than that non-modified chitosan microsphere（NMCM）.The adsorption kinetic was described well by the pseudo-second order kinetic model, which suggested that chemical adsorption along with electrons transferring was dominant in adsorption process.
基金supported by National Basic Research Program (973) of China (No. 2013CB933200)the National Natural Science Foundation of China (Nos. 21671197, 51472260)the Research Grant (No. 16ZR1440800) from Shanghai Science and Technology Commission
文摘Surface junctions between Bi OBr and BiVO4 were synthesized. The BiOBr/BiVO4 with 1 wt.%of Bi OBr exhibited the highest photocatalytic activity in the degradation of Rh B under visible-light irradiation. It was found that the highly efficient adsorption of Rh B molecules via the electrostatic attraction between Br-and cationic ／N（Et）2 group played a key role for the high photocatalytic activities of BiOBr/BiVO4. This efficient adsorption promoted the N-deethylation of Rh B and thus accelerated the photocatalytic degradation of Rh B.Moreover, the metal-to-metal charge transfer（MMCT） mechanism was proposed, which revealed the concrete path paved with Bi–O–Bi chains for the carrier migration in BiOBr/BiVO4. The interaction between photoexcited Rh B＊ and the Bi^（3＋） in BiVO4 provided the driving force for the migration of photo-generated carriers along the Bi–O–Bi chains. This work has not only demonstrated the important role of efficient adsorption in the photocatalytic degradation of organic contaminants, but also developed a facile strategy to improve the efficiency of photocatalysts.
基金Supported by the Natural Science Foundation of Shandong Province,China(No.Y2002B09).
文摘The O-Ag（210） surface adsorption system was studied via the five-parameter Morse potential theory. Mean- while, the 20-Ag （ 210） system was investigated v/a the extended London-Eyring-Polanyi-Sato （LEPS） potential theo- ry to learn the interaction between the adsorption states. Calculated results demonstrate that there are two stable on- surface adsorption sites（B and H） for 0 atoms on Ag（210） stepped surface. And the perpendicular vibrations are 30. 3 and 42.9 meV, which are close to that observed in high resolution electron energy loss spectroscopy （HREELS）. Also, there exists an octabedral subsurface adsorption state with a high vibrational frequency, and the interaction between the on-surface and subsurface 0 species is slight. The mode at 54.6 meV, which is close to that observed in HREELS（54-56 meV）, is because of the vibration of the 0 atom on B site under the influence of that on H site.
基金the National Natural Science Foundation of China(Nos.11875205 and 21973070)the Natural Science Foundation of Zhejiang Province(No.LY19E010004)the Basic scientific research project of Wenzhou Key Laboratory(No.H2020012).
文摘In this work,the nanostructures and phase diagrams of lamella-forming and cylinder-forming ABC linear triblock copolymers confined in spherical cavities are investigated on the basis of real-space self-consistent field theory.We designate specific monomer-monomer interactions and block composition and study morphology transformation under spherical confinement with a neutral surface.Various potentially valuable morphological structures,such as two-or three-colored spheres,rotational structures,and biconcave disklike structures,are identified in the phase diagrams constructed on confining diameters.Single confinement induces an obvious transformation of self-assembled structures,which still retain some of the conformational properties of bulk structures.We then focus on phase morphology under preferential surfaces.Absorption can smooth out differences in block ratios,and similar structures can be assembled from block copolymers with different proportions.We incorporate a non-centrosymmetric feature into our spherical confinement model and design a Janus adsorption field to explore unpredictable microphase behavior.Results show that the unbalance of the block ratio causes adsorption to exert a stable shaping effect on conformation.The influence of confinement on the degree of freedom of polymer chains disrupts the influence of adsorption on the complexity and transformation activity of self-assembled structures.The theoretical results correspond to recent experimental observations and contribute to the field functional material synthesis.
基金Supported by the Natural Science Foundation of Shandong Province(No. Y2002B09)
文摘The 5-parameter Morse potential（5-MP） of the interactions between Cl atoms and Ni surfaces was constructed. The adsorption and diffusion of Cl atoms on Ni low index-surfaces were investigated with 5-MP in detail. All the critical characteristics of the system, such as adsorption site, adsorption geometry, binding energy, eigenvalues for vibration, etc. were obtained. The calculated results show that chlorine atoms are likely to be adsorbed on the high symmetry- sites. Cl atoms locate on the four-fold hollow sites of the intact Ni（100） surface, while they tend to occupy threefold sites on the Ni（ 111 ） surface. The four-fold hollow sites are the most stable adsorption sites on the Ni （110） surface for Cl, although the three-fold sites and the long-bridge sites are stable adsorption sites on the Ni（110） surface for the atoms of the first and second periods. For the Cl-Ni surface adsorption system, the surface binding energy of a Cl atom is relevant to the coarse degree of the cluster surface, and the binding energies have an order of Ni （ 111 ） 〈 Ni（100） 〈Ni（100）.
文摘The surface tension and cenductivity of tetracthylarnmomum perfluorooctanesulfonate (TEPFOS) solu-tions in mixed solvents were determined The criticsl micelle concentrations (cmc) and surface adsorption of TEPFOS in various solvents (Dimetbylsulfoxlde and DMSO, formamide and FA, and DMSO-H2O and FA H2O mixtures) were calculated from the above experimental date. The results show that the surface activity of TEPFOS is much higher than that of typical hydrocarbon surfactant, sodium dodecylsulfate (SDS); the melecalar interaction (in terms of colubility araneter or surface tension) of solvent is the decisive factor in sffecting the cmc of TEPFOS , in the apretic solvent DMSO, the value of entropy change during micelliza-tion of TEPFOS may beecme subsantially negative; the surfaof adsorption amount of TEPFOS is the largest in H2O, smaller in FA , and the smallest in DMSO.
基金supported by the National Key R&D Program (2022YFB2502000)the Zhejiang Provincial Natural Science Foundation of China (LZ23B030003)the Fundamental Research Funds for the Central Universities (2021FZZX001-08,2021FZZX001-09)。
文摘Aqueous zinc-ion batteries(ZIBs) are considered promising power sources for grid storage,but they face several issues,including dendrite growth,corrosion,hydrogen evolution,etc.,which are related to the Zn metal/liquid electrolyte interface.To address these challenges,many researchers have focused on modifying the Zn anode with surface adsorption.However,the underlying mechanism between the Zn surface and adsorbed/protective molecules has not been thoroughly explored.In this study,we built a multiscale simulation platform that integrates state-of-art simulation methods to comprehensively investigate the adsorption process of amino acids on the Zn metal surface.Our major finding is that adsorption sites,adsorbate–surface angle,and average distance are critical parameters for the stability and strength of surface adsorption.Additionally,ab initio molecular dynamics reveal the kinetics of the surface adsorption and molecule reorientation processes.Specifically,it can be discovered that the amino acids prefer to align parallel to the Zn metal surface,leading to better surface protection against corrosion and preventing dendrite growth.These findings pave the way for an in-depth understanding of the surface adsorption process,as well as providing concrete design principles for stable Zn metal anodes.
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars (D4200111).
文摘A general expression of the dynamic surface adsorption [Г（t）] on the expanding spherical surface was derived by solving the corresponding diffusion equation under different initial and boundary conditions. Different from the result of the still spherical surface, two factors （smaller than 1） appeared in the equation for the short time adsorption. Using the derived results, the adsorption kinetics of aqueous decanoyl-N-methylglucamine （Mega-10） solution was studied. In the short time region （t→0）, a good agreement of experimental results with the theory was reached and the adsorption was controlled by diffusion.
基金Supported by the Natural Science Foundation of Shandong Province,China(No.Y2006B29)
文摘The adsorptions of nitrogen atoms on Ru（0001）, （1010） low index surfaces and （1120）, （1121） stepped surfaces were investigated by the five-parameter Morse potential（5-MP） method in details, Calculated results demonstrate that N atoms show a tendency to be adsorbed at threefold sites. No subsurface state was found for N atoms on Ru（1010） surface. There exist 6 stable adsorption sites for N atoms on Ru（1121） stepped surface which can be classified into 3 types： the on-surface adsorption state, the facet adsorption state and the subsurface state. Moreover, two new perpendicular vibrations at 97 and 98 meV are predicted. All calculated results are in good accord with HR-EELS experiments.
基金Supported by the National Natural Science Foundation of China under Grant No 11074050
文摘We carry out the first time-resolved measurement of Rb atoms desorbing from octadecyltrichlorosilane coated sur- faces by polarizing the atoms near the surface using an evanescent wave pump pulse and watching the subsequent intensity change of another evanescent wave probe beam, and find the mean adsorption （dwell） time to be about 400ns at a cell body temperature of 112℃. The adsorption energy is found to be 0.19eV from the surface tem- perature dependence of the adsorption time. This method can be extended to study the adsorption/desorption process of other alkali atoms on other surfaces of transparent substrates with an ultimate time resolution limited by the flight time of atoms in the evanescent wave which is of the order of nanoseconds.
基金Supported by the National Natural Science Foundation of China under Grant No 51177134
文摘First-principles calculations are carried out to study the relaxation of 6H-SiC （0001） surface and chemisorption models of Si adatoms on four high-symmetry adsorption sites. The surface results show that Si-termination is the preferred termination of the 6H-SiC（0001） polar surface and is more stable than the C-terminated 61-1- SiC（0001） polar surface over a wide range of allowed chemical potentials. Four stable atomic configurations （top, bridge, hcp and fcc） are considered, and the adsorption energies and geometries, Mulliken charge population, and partial density of state （PDOS） properties are analyzed. Adsorption energy results show that the top site is the most stable site. The structural properties of Si adsorption on the SiC （0001） surface shows that increasing stability means decreasing bond lengths. Charge populations analysis and PDOS results imply that there is strong interaction between Si adatoms and 6H-SiC （0001） surface.
