Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion batt...Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion batteries.In this paper,properties of intrinsic B or Si single-atom doped,and B-Si codoped graphene(GR)and graphdiyne(GDY)were investigated by using density functional theory-based calculations,in which the optimal doping configurations were explored for potential applications in adsorbing sulfur compounds.Results showed that both B or Si single-atom doping and B-Si codoping could substantially enhance the electron transport properties of GR and GDY,improving their surface activity.Notably,B and Si atoms displayed synergistic effects for the codoped configurations,where B-Si codoped GR/GDY exhibited much better performance in the adsorption of sulfurcontaining chemicals than single-atom doped systems.In addition,results demonstrated that,after B-Si codoping,the adsorption energy and charge transfer amounts of GDY with sulfur compounds were much larger than those of GR,indicating that B-Si codoped GDY might be a favorable material for more effectively interacting with sulfur reagents.展开更多
Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculate...Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculated using DMol3,since HMX and O are key substances in decomposition process.And the relationship between the adsorption energy of HMX,O on metal oxides(TiO_(2),Al_(2)O_(3),PbO,CuO,Fe_(2)O_(3),Co_(3)O_(4),Bi_(2)O_(3),NiO)and experimental T30 values(time required for the decomposition depth of HMX to reach 30%)was depicted as volcano plot.Thus,the T30 values of other metal oxides was predicted based on their adsorption energy on volcano plot and validated by previous experimental data.Further,the adsorption energy of HMX on ZrO_(2)and MnO_(2)was predicted based on the linear relationship between surface energy and adsorption energy,and T30 values were estimated based on volcano plot.The apparent activation energy data of HMX/MgO,HMX/SnO_(2),HMX/ZrO_(2),and HMX/MnO_(2)obtained from DSC experiments are basically consistent with our predicted T30 values,indicating that it is feasible to predict the catalytic activity based on the adsorption calculation,and it is expected that these simple structural properties can predict adsorption energy to reduce the large quantities of computation and experiment cost.展开更多
Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface chemistry.Despite tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage init...Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface chemistry.Despite tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage initial sticking probabilities(So).To find the origin of the large experiment-theory discrepancy,we have revisited the dissociative adsorption of HCl on Au(111)with a newly designed molecular beam-surface apparatus.The zero-coverage So derived from Cl-coverage measurements with varying HCl doses agree well with previous ones.However,we notice a sharp change of the coverage/dose slope with the HCl dosage at the low coverage regime,which may result in some uncertainties to the fitted So value.This seems consistent with a coverage-dependence of the dissociation barrier predicted by density functional theory at low Cl-coverages.Our results reveal the potential inconsistency of utilizing simulations with finite coverage to compare against experimental data with zero coverage in this system,and provide guidance for improving both experiment and theory in this regard.展开更多
The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold s...The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold showed that gel Amberlite IRA-400 resin with Type Ⅰ quaternary ammonium functional group had better adsorption performance.The increases of resin dosage,ammonia concentration and solution pH were favorable to gold adsorption,whereas the rises of cupric and thiosulfate concentrations were disadvantageous to gold loading.Microscopic characterization results indicated that gold was adsorbed in the form of [Au(S_(2)O_(3))_(2)]^(3–) complex anion by exchanging with the counter ion Cl^(–) in the functional group of the resin.Density functional theory calculation result manifested that gold adsorption was mainly depended on the hydrogen bond and van der Waals force generated between O atom in [Au(S_(2)O_(3))_(2)]^(3–) and H atom in the quaternary ammonium functional group of the resin.展开更多
The co-adsorption behaviors of SO2 and H2 O on face-centered cubic Cu(100) ideal surface were studied using the GGA-r PBE method of density functional theory(DFT) with slab models. The optimized structures of sing...The co-adsorption behaviors of SO2 and H2 O on face-centered cubic Cu(100) ideal surface were studied using the GGA-r PBE method of density functional theory(DFT) with slab models. The optimized structures of single H2 O and SO2 on Cu(100) surface were calculated at the coverage of 0.25 ML(molecular layer) and 0.5 ML. The results show that there was no obvious chemical adsorption of them on Cu(100) surface. The adsorbed structures, adsorption energy and electronic properties including difference charge density, valence charge density, Bader charge analysis and partial density of states(PDOS) of co-adsorbed structures of H2 O and SO2 were investigated to illustrate the interaction between adsorbates and surface. H2 O and SO2 can adsorb on surface of Cu atoms chemically via molecule form at the coverage of 0.25 ML, while H2 O dissociated into OH adsorbed on surface and H bonded with SO2 which keeps away from surface at the coverage of 0.5 ML.展开更多
Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied usin...Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test methods.Based on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,respectively.The effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption experiments.Results show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage fractures.The D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal dimensions.The three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption ability.Langmuir volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand Dp.This study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.展开更多
Alloys of uranium and molybdenum are considered as the future of nuclear fuel and defense materials.However,surface corrosion is a fundamental problem in practical applications and storage.In this study,the static and...Alloys of uranium and molybdenum are considered as the future of nuclear fuel and defense materials.However,surface corrosion is a fundamental problem in practical applications and storage.In this study,the static and dynamic evolution of carbon monoxide(CO)adsorption and dissociation onγ-U(100)surface with different Mo doping levels was investigated based on density functional theory and ab initio molecular dynamics.During the static calculation phase,parameters,such as adsorption energy,configuration,and Bader charge,were evaluated at all adsorption sites.Furthermore,the time-dependent behavior of CO molecule adsorption were investigated at the most favorable sites.The minimum energy paths for CO molecu-lar dissociation and atom migration were investigated using the transition state search method.The results demonstrated that the CO on the uranium surface mainly manifests as chemical adsorption before dissociation of the CO molecule.The CO molecule exhibited a tendency to rotate and tilt upright adsorption.However,it is difficult for CO adsorption on the surface in one of the configurations with CO molecule in vertical direction but oxygen(O)is closer to the surface.Bader charge illustrates that the charge transfers from slab atoms to the 2π*antibonding orbital of CO molecule and particularly occurs in carbon(C)atoms.The time is less than 100 fs for the adsorptions that forms embryos with tilt upright in dynamics evolution.The density of states elucidates that the overlapping hybridization of C and O 2p orbitals is mainly formed via the d orbitals of uranium and molybdenum(Mo)atoms in the dissociation and re-adsorption of CO molecule.In conclusion,Mo doping of the surface can decelerate the adsorption and dissociation of CO molecules.A Mo-doped surface,created through ion injection,enhanced the resistance to uranium-induced surface corrosion.展开更多
The density functional theory (DFT) and periodic slab model were used to get information concerning the adsorption of HCHO on the FeO(100) surface. A preferred η^2-(C,O)-di-σ four-membered ring adsorption conf...The density functional theory (DFT) and periodic slab model were used to get information concerning the adsorption of HCHO on the FeO(100) surface. A preferred η^2-(C,O)-di-σ four-membered ring adsorption conformation on the Fe-top site was found to be the most favorable structure with the predicted adsorption energy of 210.7 kJ/mol. The analysis of density of states, Mulliken population, and vibrational frequencies before and after adsorption showed clear weakening of the carbonyl bond, and high sp^3 character on the carbon atom.展开更多
Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, i...Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, is energetically preferred. The adsorption energies of HCN on the silver clusters reach a local maximum at n = 4, which is only about 0.450 eV, indicating that the adsorbed HCN molecule is weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.展开更多
As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO ...As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.展开更多
Carbon monoxide(CO) is a gaseous pollutant with adverse effects on human health and the environment. Kaolinite is a natural mineral resource that can be used for different applications, including that it can also be...Carbon monoxide(CO) is a gaseous pollutant with adverse effects on human health and the environment. Kaolinite is a natural mineral resource that can be used for different applications, including that it can also be used for retention of pollutant gases. The adsorption behavior of carbon monoxide molecules on the(001) surface of kaolinite was studied systematically by using density-functional theory and supercell models for a range coverage from 0.11 to 1.0 monolayers(ML). The CO adsorbed on the three-fold hollow, two-fold bridge, and one-fold top sites of the kaolinite(001) was tilted with respect to the surface. The strongest adsorbed site of carbon monoxide on the kaolinite(001) surface is the hollow site followed by the bridge and top site. The adsorption energy of CO decreased when increasing the coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighboring CO molecules. In addition to the adsorption structures and energetics, the lattice relaxation, the electronic density of states, and the different charge distribution have been investigated for different surface coverages.展开更多
To better understand the role of the-NH_(2)group in adsorption process of phenolic wastewaters,NH_(2)-functionalized MIL-53(Al)composites with activated carbon(NH_(2)-M(Al)@(B)AC)were prepared.The results showed that ...To better understand the role of the-NH_(2)group in adsorption process of phenolic wastewaters,NH_(2)-functionalized MIL-53(Al)composites with activated carbon(NH_(2)-M(Al)@(B)AC)were prepared.The results showed that the-NH_(2)group could increase the mesopore volume for composites,which promotes mass transfer and full utilization of active sites,because hierarchical mesopore structure makes the adsorbent easier to enter the internal adsorption sites.Furthermore,the introduction of the-NH_(2)group can improve the adsorption capacity,decrease the activation energy,and enhance the interaction between the adsorbent and p-nitrophenol,demonstrating that the-NH_(2)group plays a crucial role in the adsorption of p-nitrophenol.The density functional theory calculation results show that the H-bond interaction between the-NH_(2)group in the adsorbent and the-NO_(2)in the p-nitrophenol(adsorption energy of -35.5 kJ·mol^(-1)),and base-acid interaction between the primary-NH_(2)group in the adsorbent and the acidic-OH group in the p-nitrophenol(adsorption energy of -27.3 kJ·mol^(-1))are predominant mechanisms for adsorption in terms of the NH_(2)-functionalized adsorbent.Both NH_(2)-functionalized M(Al)@AC and M(Al)@BAC composites exhibited higher p-nitrophenol adsorption capacity than corresponding nonfunctionalized composites.Among the composites,the NH_(2)-M(Al)@BAC had the highest p-nitrophenol adsorption capacity of 474 mg·g^(-1).展开更多
Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 (100) surface, the...Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 (100) surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe2+ and S2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference. The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2.展开更多
The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some pr...The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.展开更多
Systematic comparison between computer simulation results and those predicted by Scheutjens-Fleer (SF) self-consistent-field theory is presented for the adsorption of diblock copolymers from a non-selective solvent on...Systematic comparison between computer simulation results and those predicted by Scheutjens-Fleer (SF) self-consistent-field theory is presented for the adsorption of diblock copolymers from a non-selective solvent on attractive surface. It is shown that although SF is a mean-field theory, it can qualitatively describe the adsorption phenomena of diblock copolymers. However, systematic discrepancy between the theory and simulation still exists. The approximations inherited in the mean-field theory such as random mixing inside a layer and the allowance of direct back folding may be responsible to those deviations.展开更多
Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the n...Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the nowadays first-principles theory due to the lack of proper exchange-correlation functional describing the distinct interactions involved. We studied here the potential energy surfaces of ethylene adsorption on Ag(111), Rh(111) and Ir(111) using density functional theory calculations and (meta)-GGA functional including PBE, BEEF-vdW, SCAN, and SCAN+rVV10. For ethylene adsorption on noble metal Ag(111), it is found that BEEF-vdW, SCAN and SCAN+rVV10 predict the presence of the physisorption states only. For Rh(111), both SCAN and SCAN+rVV10 find that there is a precursor physisorption state before the chemisorption state. In contrast, there is no precursor state found based on potential energy surfaces from BEEF-vdW and PBE. Whereas for Ir(111), BEEF-vdW predicts the existence of a rather shallow precursor physisorption state, in addition to the chemisorption state. Irrespective to the transition metals considered, we find that SCAN+rVV10 gives the strongest binding strength, followed by SCAN, and PBE/BEEF-vdW, accordingly. The present work highlights great dependence of potential energy surface of ethylene adsorption on transition metal surfaces and exchange-correlation functionals.展开更多
The adsorption of flexible polyelectrolyte (PE) with the smeared charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory...The adsorption of flexible polyelectrolyte (PE) with the smeared charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory. The power law scaling relationships between the boundary layer thickness and the surface charge density and the charge fraction of PE chains revealed in the study are in good agreement with the existing analytical result. The curvature effect on the degree of charge compensation of the total amount of charges on the adsorbed PE chains over the surface charges is examined, and a clear understanding of it based on the dependences of the degree of charge compensation on the surface charge density and the charge fraction of PE chains is established.展开更多
The adsorption of NO on the M/c-ZrOu(110) (M = Ru, Rh) surface has been studied with periodic slab model by PWgl approach of GGA within the framework of density functional theory. The results of geometry optimizat...The adsorption of NO on the M/c-ZrOu(110) (M = Ru, Rh) surface has been studied with periodic slab model by PWgl approach of GGA within the framework of density functional theory. The results of geometry optimization indicated that the hollow site is energetically stable for Ru and Rh atoms' adsorption on the c-ZrO2(110) surface with adsorption energies of 207.4 and 106.3 kJ/mol, respectively. When NO is adsorbed on the M/ZrO2(110) surface, the N-down adsorption is the most stable. We also studied the adsorption of double NO on the M/c-ZrOu(110) surface. Complete linear synchronous transit and quadratic synchronous transit approaches were used to search the transition state for dissociation reaction. NO has two possible dissociation passways: (1) 2NO → N2 (g) + 20 (ads), (2) 2NO→ N20 (g) + O (ads), and the former is easier than the latter based on the calculation results.展开更多
A theoretical study was carried out on the adsorption of hydrocyanic acid on small Aun (n ≤ 7) clusters using density functional methods. For HCN adsorption on gold clusters, no dependence was found with respect to...A theoretical study was carried out on the adsorption of hydrocyanic acid on small Aun (n ≤ 7) clusters using density functional methods. For HCN adsorption on gold clusters, no dependence was found with respect to the even-odd alternation in relation to the number of gold atoms in the cluster. The HCN molecule is adsorbed at simple adsorption sites (1-fold coordination), perpendicular to the adsorption site. The largest adsorption energy is only about 74.61 kJ·mol^-1, which indicates that the HCN molecule does not decompose and the C-N bond retains triple bond, and that the C-H and C-N stretching frequencies are only weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.展开更多
We applied periodic density-functional theory to investigate the adsorption of C2H2 on the Cu/Pt bimetallic and monometallic surfaces, including Cu-Pt-Pt and Pt--Cu-Pt representing the monolayer Cu on the Pt surface a...We applied periodic density-functional theory to investigate the adsorption of C2H2 on the Cu/Pt bimetallic and monometallic surfaces, including Cu-Pt-Pt and Pt--Cu-Pt representing the monolayer Cu on the Pt surface and subsurface Cu in the Pt surface, respectively. For the Pt(111) and Pt-Cu-Pt surfaces, C2H2 is preferentially a 3-fold “parallel-bridge” configuration, and a "p-bridge" structure exists above the Cu(111) and Cu-Pt-Pt surfaces. The adsorption energy of C2H2 on these surfaces decreases in the order Pt(111) 〉 Cu-Pt-Pt 〉 Pt-Cu-Pt 〉 Cu(11). The analysis of density of states, charge, and vibrational frequencies showed obviously weakening of the adsorbed C-C bond and high sp2 character on the carbon atom. Furthermore, when the top-layer compositions are equal, the nearer the EF d-band center is, the larger the C2H2 adsorption energy will be.展开更多
基金the support of the National Natural Science Foundation of China(Grant No.51472074).
文摘Understanding the adsorption interactions between carbon materials and sulfur compounds has far-reaching impacts,in addition to their well-known important role in energy storage and conversion,such as lithium-ion batteries.In this paper,properties of intrinsic B or Si single-atom doped,and B-Si codoped graphene(GR)and graphdiyne(GDY)were investigated by using density functional theory-based calculations,in which the optimal doping configurations were explored for potential applications in adsorbing sulfur compounds.Results showed that both B or Si single-atom doping and B-Si codoping could substantially enhance the electron transport properties of GR and GDY,improving their surface activity.Notably,B and Si atoms displayed synergistic effects for the codoped configurations,where B-Si codoped GR/GDY exhibited much better performance in the adsorption of sulfurcontaining chemicals than single-atom doped systems.In addition,results demonstrated that,after B-Si codoping,the adsorption energy and charge transfer amounts of GDY with sulfur compounds were much larger than those of GR,indicating that B-Si codoped GDY might be a favorable material for more effectively interacting with sulfur reagents.
基金supported by Key Science and Technology Innovation Team of Shaanxi Province(No.2022TD-33)National Natural Science Foundation of China(Grant Nos.21373161,21504067)。
文摘Traditional selection of combustion catalysis is time-consuming and labor-intensive.Theoretical calculation is expected to resolve this problem.The adsorption energy of HMX and O atoms on 13 metal oxides was calculated using DMol3,since HMX and O are key substances in decomposition process.And the relationship between the adsorption energy of HMX,O on metal oxides(TiO_(2),Al_(2)O_(3),PbO,CuO,Fe_(2)O_(3),Co_(3)O_(4),Bi_(2)O_(3),NiO)and experimental T30 values(time required for the decomposition depth of HMX to reach 30%)was depicted as volcano plot.Thus,the T30 values of other metal oxides was predicted based on their adsorption energy on volcano plot and validated by previous experimental data.Further,the adsorption energy of HMX on ZrO_(2)and MnO_(2)was predicted based on the linear relationship between surface energy and adsorption energy,and T30 values were estimated based on volcano plot.The apparent activation energy data of HMX/MgO,HMX/SnO_(2),HMX/ZrO_(2),and HMX/MnO_(2)obtained from DSC experiments are basically consistent with our predicted T30 values,indicating that it is feasible to predict the catalytic activity based on the adsorption calculation,and it is expected that these simple structural properties can predict adsorption energy to reduce the large quantities of computation and experiment cost.
基金supported by the National Natural Science Foundation of China(No.22173042,No.21973037,No.22073089,and No.22327801)the In-novation program for Quantum Science and Technolo-gy(No.2021ZD0303304)+2 种基金the Guangdong Science and Technology Program(No.2019ZT08L455 and No.2019JC01X091)the Shenzhen Science and Technology Program(No.ZDSYS2020421111001787)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0450101).
文摘Dissociative adsorption of HCl on Au(111)has become one of unsolved puzzles in surface chemistry.Despite tremendous efforts in the past years,varioustheoretical models still greatly overestimate the zero-coverage initial sticking probabilities(So).To find the origin of the large experiment-theory discrepancy,we have revisited the dissociative adsorption of HCl on Au(111)with a newly designed molecular beam-surface apparatus.The zero-coverage So derived from Cl-coverage measurements with varying HCl doses agree well with previous ones.However,we notice a sharp change of the coverage/dose slope with the HCl dosage at the low coverage regime,which may result in some uncertainties to the fitted So value.This seems consistent with a coverage-dependence of the dissociation barrier predicted by density functional theory at low Cl-coverages.Our results reveal the potential inconsistency of utilizing simulations with finite coverage to compare against experimental data with zero coverage in this system,and provide guidance for improving both experiment and theory in this regard.
基金the financial support from the Natural Science Foundation of Hunan Province, China (No. 2023JJ40723)China Postdoctoral Science Foundation (No. 2022M723549)the National Natural Science Foundation of China (Nos. 52174271, 51504293)。
文摘The adsorption behaviors and mechanisms of gold from thiosulfate solution on strong-base anion exchange resin were systematically investigated.The comparison experiment of adsorption ability and selectivity for gold showed that gel Amberlite IRA-400 resin with Type Ⅰ quaternary ammonium functional group had better adsorption performance.The increases of resin dosage,ammonia concentration and solution pH were favorable to gold adsorption,whereas the rises of cupric and thiosulfate concentrations were disadvantageous to gold loading.Microscopic characterization results indicated that gold was adsorbed in the form of [Au(S_(2)O_(3))_(2)]^(3–) complex anion by exchanging with the counter ion Cl^(–) in the functional group of the resin.Density functional theory calculation result manifested that gold adsorption was mainly depended on the hydrogen bond and van der Waals force generated between O atom in [Au(S_(2)O_(3))_(2)]^(3–) and H atom in the quaternary ammonium functional group of the resin.
基金Project(51222106)supported by the National Natural Science Foundation of ChinaProject(230201306500002)supported by the Fundamental Research Funds for the Central Universities+1 种基金ChinaProject(2014CB643300)supported by National Basic Research Program of China
文摘The co-adsorption behaviors of SO2 and H2 O on face-centered cubic Cu(100) ideal surface were studied using the GGA-r PBE method of density functional theory(DFT) with slab models. The optimized structures of single H2 O and SO2 on Cu(100) surface were calculated at the coverage of 0.25 ML(molecular layer) and 0.5 ML. The results show that there was no obvious chemical adsorption of them on Cu(100) surface. The adsorbed structures, adsorption energy and electronic properties including difference charge density, valence charge density, Bader charge analysis and partial density of states(PDOS) of co-adsorbed structures of H2 O and SO2 were investigated to illustrate the interaction between adsorbates and surface. H2 O and SO2 can adsorb on surface of Cu atoms chemically via molecule form at the coverage of 0.25 ML, while H2 O dissociated into OH adsorbed on surface and H bonded with SO2 which keeps away from surface at the coverage of 0.5 ML.
基金The first author would like to express sincere appreciation for the scholarship provided by China Scholarship Council(No.202006430006)and University of Wollongongfinancially supported by the ACARP Project C28006+1 种基金the National Key Research and Development Program of China(No.2018YFC0808301)the Natural Science Foundation of Beijing Municipality,China(No.8192036)。
文摘Well-developed pores and cracks in coal reservoirs are the main venues for gas storage and migration.To investigate the multi-scale pore fractal characteristics,six coal samples of different rankings were studied using high-pressure mercury injection(HPMI),low-pressure nitrogen adsorption(LPGA-N2),and scanning electron microscopy(SEM)test methods.Based on the Frankel,Halsey and Hill(FHH)fractal theory,the Menger sponge model,Pores and Cracks Analysis System(PCAS),pore volume complexity(D_(v)),coal surface irregularity(Ds)and pore distribution heterogeneity(D_(p))were studied and evaluated,respectively.The effect of three fractal dimensions on the gas adsorption ability was also analyzed with high-pressure isothermal gas adsorption experiments.Results show that pore structures within these coal samples have obvious fractal characteristics.A noticeable segmentation effect appears in the Dv1and Dv2fitting process,with the boundary size ranging from 36.00 to 182.95 nm,which helps differentiate diffusion pores and seepage fractures.The D values show an asymmetric U-shaped trend as the coal metamorphism increases,demonstrating that coalification greatly affects the pore fractal dimensions.The three fractal dimensions can characterize the difference in coal microstructure and reflect their influence on gas adsorption ability.Langmuir volume(V_(L))has an evident and positive correlation with Dsvalues,whereas Langmuir pressure(P_(L))is mainly affected by the combined action of Dvand Dp.This study will provide valuable knowledge for the appraisal of coal seam gas reservoirs of differently ranked coals.
基金supported by the National Natural Science Foundation of China (Nos.11975135 and 12005017)the National Basic Research Program of China (No.2020YFB1901800)
文摘Alloys of uranium and molybdenum are considered as the future of nuclear fuel and defense materials.However,surface corrosion is a fundamental problem in practical applications and storage.In this study,the static and dynamic evolution of carbon monoxide(CO)adsorption and dissociation onγ-U(100)surface with different Mo doping levels was investigated based on density functional theory and ab initio molecular dynamics.During the static calculation phase,parameters,such as adsorption energy,configuration,and Bader charge,were evaluated at all adsorption sites.Furthermore,the time-dependent behavior of CO molecule adsorption were investigated at the most favorable sites.The minimum energy paths for CO molecu-lar dissociation and atom migration were investigated using the transition state search method.The results demonstrated that the CO on the uranium surface mainly manifests as chemical adsorption before dissociation of the CO molecule.The CO molecule exhibited a tendency to rotate and tilt upright adsorption.However,it is difficult for CO adsorption on the surface in one of the configurations with CO molecule in vertical direction but oxygen(O)is closer to the surface.Bader charge illustrates that the charge transfers from slab atoms to the 2π*antibonding orbital of CO molecule and particularly occurs in carbon(C)atoms.The time is less than 100 fs for the adsorptions that forms embryos with tilt upright in dynamics evolution.The density of states elucidates that the overlapping hybridization of C and O 2p orbitals is mainly formed via the d orbitals of uranium and molybdenum(Mo)atoms in the dissociation and re-adsorption of CO molecule.In conclusion,Mo doping of the surface can decelerate the adsorption and dissociation of CO molecules.A Mo-doped surface,created through ion injection,enhanced the resistance to uranium-induced surface corrosion.
基金supported by the program for the NCETFJ (No. HX2006-103)the NSFC (Nos. 10676007 and 90922022)+1 种基金the Science and TechnologyFoundation of Fujian Education Bureau (No. JA08019)the Foundation of State Key Laboratory of Coal Combustion (No. FSKLCC0814)
文摘The density functional theory (DFT) and periodic slab model were used to get information concerning the adsorption of HCHO on the FeO(100) surface. A preferred η^2-(C,O)-di-σ four-membered ring adsorption conformation on the Fe-top site was found to be the most favorable structure with the predicted adsorption energy of 210.7 kJ/mol. The analysis of density of states, Mulliken population, and vibrational frequencies before and after adsorption showed clear weakening of the carbonyl bond, and high sp^3 character on the carbon atom.
基金supported by the National Natural Science Foundation of China(21203027,21073035,21373048)Funds of Fujian Province(2012J01032,2012J01041)Fuzhou University(2012-XQ-11)
文摘Density functional theory calculations have been performed to study the interaction of small silver clusters, Ag2-Ag9, with HCN. The adsorption of HCN on-top site of the silver cluster, among various possible sites, is energetically preferred. The adsorption energies of HCN on the silver clusters reach a local maximum at n = 4, which is only about 0.450 eV, indicating that the adsorbed HCN molecule is weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.
基金supported by the National Natural Science Foundation of China(22178388,21776315)the Taishan Scholars Program of Shandong Province(tsqn201909065)the Fundamental Research Funds for the Central Universities(19CX05001A).
文摘As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.
基金Project supported by the Young Elite Scientist Sponsorship Program by CAST and the National Natural Science Foundation of China(Grant No.51574296)
文摘Carbon monoxide(CO) is a gaseous pollutant with adverse effects on human health and the environment. Kaolinite is a natural mineral resource that can be used for different applications, including that it can also be used for retention of pollutant gases. The adsorption behavior of carbon monoxide molecules on the(001) surface of kaolinite was studied systematically by using density-functional theory and supercell models for a range coverage from 0.11 to 1.0 monolayers(ML). The CO adsorbed on the three-fold hollow, two-fold bridge, and one-fold top sites of the kaolinite(001) was tilted with respect to the surface. The strongest adsorbed site of carbon monoxide on the kaolinite(001) surface is the hollow site followed by the bridge and top site. The adsorption energy of CO decreased when increasing the coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighboring CO molecules. In addition to the adsorption structures and energetics, the lattice relaxation, the electronic density of states, and the different charge distribution have been investigated for different surface coverages.
基金supported by the National Natural Science Foundation of China(22008134)。
文摘To better understand the role of the-NH_(2)group in adsorption process of phenolic wastewaters,NH_(2)-functionalized MIL-53(Al)composites with activated carbon(NH_(2)-M(Al)@(B)AC)were prepared.The results showed that the-NH_(2)group could increase the mesopore volume for composites,which promotes mass transfer and full utilization of active sites,because hierarchical mesopore structure makes the adsorbent easier to enter the internal adsorption sites.Furthermore,the introduction of the-NH_(2)group can improve the adsorption capacity,decrease the activation energy,and enhance the interaction between the adsorbent and p-nitrophenol,demonstrating that the-NH_(2)group plays a crucial role in the adsorption of p-nitrophenol.The density functional theory calculation results show that the H-bond interaction between the-NH_(2)group in the adsorbent and the-NO_(2)in the p-nitrophenol(adsorption energy of -35.5 kJ·mol^(-1)),and base-acid interaction between the primary-NH_(2)group in the adsorbent and the acidic-OH group in the p-nitrophenol(adsorption energy of -27.3 kJ·mol^(-1))are predominant mechanisms for adsorption in terms of the NH_(2)-functionalized adsorbent.Both NH_(2)-functionalized M(Al)@AC and M(Al)@BAC composites exhibited higher p-nitrophenol adsorption capacity than corresponding nonfunctionalized composites.Among the composites,the NH_(2)-M(Al)@BAC had the highest p-nitrophenol adsorption capacity of 474 mg·g^(-1).
文摘Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studied by using density functional theory methods. The results show that in the formation of FeS2 (100) surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe2+ and S2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference. The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2.
文摘The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.
基金Supported by the National Natural Science Foundation of China(No. 20025618)the Doctoral Research Foundation by Ministry of Education of China (No.1999025103) and the Dawn Project of Education Committee of Shanghai.
文摘Systematic comparison between computer simulation results and those predicted by Scheutjens-Fleer (SF) self-consistent-field theory is presented for the adsorption of diblock copolymers from a non-selective solvent on attractive surface. It is shown that although SF is a mean-field theory, it can qualitatively describe the adsorption phenomena of diblock copolymers. However, systematic discrepancy between the theory and simulation still exists. The approximations inherited in the mean-field theory such as random mixing inside a layer and the allowance of direct back folding may be responsible to those deviations.
基金supported by the National Key R&D Program of China (No.2017YFB0602205 and No.2018YFA0208603)the National Natural Science Foundation of China (No.91645202)the Chinese Academy of Sciences (No.QYZDJ-SSW-SLH054)
文摘Accurate description of the adsorption process of reactants on metal surfaces from theory is crucial for mechanistic understanding of activity and selectivity of metal catalysts, but it remains challengeable for the nowadays first-principles theory due to the lack of proper exchange-correlation functional describing the distinct interactions involved. We studied here the potential energy surfaces of ethylene adsorption on Ag(111), Rh(111) and Ir(111) using density functional theory calculations and (meta)-GGA functional including PBE, BEEF-vdW, SCAN, and SCAN+rVV10. For ethylene adsorption on noble metal Ag(111), it is found that BEEF-vdW, SCAN and SCAN+rVV10 predict the presence of the physisorption states only. For Rh(111), both SCAN and SCAN+rVV10 find that there is a precursor physisorption state before the chemisorption state. In contrast, there is no precursor state found based on potential energy surfaces from BEEF-vdW and PBE. Whereas for Ir(111), BEEF-vdW predicts the existence of a rather shallow precursor physisorption state, in addition to the chemisorption state. Irrespective to the transition metals considered, we find that SCAN+rVV10 gives the strongest binding strength, followed by SCAN, and PBE/BEEF-vdW, accordingly. The present work highlights great dependence of potential energy surface of ethylene adsorption on transition metal surfaces and exchange-correlation functionals.
基金Project supports by the National Natural Science Foundation of China(Grant Nos.21074062 and 11174163)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Ministry of Education of Chinathe Scientific Research Fund of Zhejiang Provincial Educational Department,China(Grant No.Y200907455)
文摘The adsorption of flexible polyelectrolyte (PE) with the smeared charge distribution onto an oppositely charged sphere immersed in a PE solution is studied numerically with the continuum self-consistent field theory. The power law scaling relationships between the boundary layer thickness and the surface charge density and the charge fraction of PE chains revealed in the study are in good agreement with the existing analytical result. The curvature effect on the degree of charge compensation of the total amount of charges on the adsorbed PE chains over the surface charges is examined, and a clear understanding of it based on the dependences of the degree of charge compensation on the surface charge density and the charge fraction of PE chains is established.
基金Supported by NNSFC(10676007,90922022)Foundation of State Key Laboratory of Coal Combustion(FSKLCC0814)+1 种基金NCETFJ(2006-HX-103,2006-HX-97) Foundation of Fuzhou University(2008-XQ-07,XRC-0732)
文摘The adsorption of NO on the M/c-ZrOu(110) (M = Ru, Rh) surface has been studied with periodic slab model by PWgl approach of GGA within the framework of density functional theory. The results of geometry optimization indicated that the hollow site is energetically stable for Ru and Rh atoms' adsorption on the c-ZrO2(110) surface with adsorption energies of 207.4 and 106.3 kJ/mol, respectively. When NO is adsorbed on the M/ZrO2(110) surface, the N-down adsorption is the most stable. We also studied the adsorption of double NO on the M/c-ZrOu(110) surface. Complete linear synchronous transit and quadratic synchronous transit approaches were used to search the transition state for dissociation reaction. NO has two possible dissociation passways: (1) 2NO → N2 (g) + 20 (ads), (2) 2NO→ N20 (g) + O (ads), and the former is easier than the latter based on the calculation results.
基金Supported by the NNSFC (20673019, 20773024)the funds of Fuzhou University (2008-XQ-07, XRC-0732)
文摘A theoretical study was carried out on the adsorption of hydrocyanic acid on small Aun (n ≤ 7) clusters using density functional methods. For HCN adsorption on gold clusters, no dependence was found with respect to the even-odd alternation in relation to the number of gold atoms in the cluster. The HCN molecule is adsorbed at simple adsorption sites (1-fold coordination), perpendicular to the adsorption site. The largest adsorption energy is only about 74.61 kJ·mol^-1, which indicates that the HCN molecule does not decompose and the C-N bond retains triple bond, and that the C-H and C-N stretching frequencies are only weakly perturbed. The adsorbed C-N and C-H stretching frequencies are blue- and red-shifted compared with the values of free HCN, respectively.
基金supported by the National Natural Science Foundation of China (21203027, 21073035)Funds of Fujian Province (2012J01032, 2012J01041)Scientific Development Fund of Fuzhou University (2012-XQ-11)
文摘We applied periodic density-functional theory to investigate the adsorption of C2H2 on the Cu/Pt bimetallic and monometallic surfaces, including Cu-Pt-Pt and Pt--Cu-Pt representing the monolayer Cu on the Pt surface and subsurface Cu in the Pt surface, respectively. For the Pt(111) and Pt-Cu-Pt surfaces, C2H2 is preferentially a 3-fold “parallel-bridge” configuration, and a "p-bridge" structure exists above the Cu(111) and Cu-Pt-Pt surfaces. The adsorption energy of C2H2 on these surfaces decreases in the order Pt(111) 〉 Cu-Pt-Pt 〉 Pt-Cu-Pt 〉 Cu(11). The analysis of density of states, charge, and vibrational frequencies showed obviously weakening of the adsorbed C-C bond and high sp2 character on the carbon atom. Furthermore, when the top-layer compositions are equal, the nearer the EF d-band center is, the larger the C2H2 adsorption energy will be.