The shortage of freshwater boosts the development of seawater desalination technology. As a novel method, the hydrate based desalination technology has been put forward for decades and achieved considerable developmen...The shortage of freshwater boosts the development of seawater desalination technology. As a novel method, the hydrate based desalination technology has been put forward for decades and achieved considerable development in the past years. This review focuses on the experimental progress at the aspects of the hydrate former choice, formation promotion and ion removal efficiency and conceptive innovation of hydrate separation and energy utilization. It should be noted that gaseous hydrate former with low formation pressure and insoluble liquid hydrate former are worthy for further study. Besides, the water migration caused by propane deserves to be investigated much more deeply for the potential value of wide application. Moreover, the utilization proposal of LNG cold energy brings more possibility of commercial application. In a word, the hydrate based desalination technology is hopefully an environment friendly, low-cost and widely used desalination technology in the near future.展开更多
Methane hydrate is considered as a potential energy source in the future due to its abundant reserves and high energy density.To investigate the influence of initial hydrate saturation,production pressure,and the temp...Methane hydrate is considered as a potential energy source in the future due to its abundant reserves and high energy density.To investigate the influence of initial hydrate saturation,production pressure,and the temperature of thermal stimulation on gas production rate and cumulative gas production percentage,we conducted the methane hydrate dissociation experiments using depressurization,thermal stimulation and a combination of two methods in this study.It is found that when the gas production pressures are the same,the higher the hydrate initial saturation,the greater change in hydrate reservoir temperature.Therefore,it is easier to appear the phenomenon of icing and hydrate reformation when the hydrate saturation is higher.For example,the reservoir temperature dropped to below zero in depressurization process when the hydrate saturation was about 37%.However,the same phenomenon didn’t appear as the saturation was about 12%.This may be due to more free gas in the reservoir with hydrate saturated of 37%.We also find that the temperature variation of reservoir can be reduced effectively by combination of depressurization and thermal stimulation method.And the average gas production rate is highest with combined method in the experiments.When the pressure of gas production is 2 MPa,compared with depressurization,the average of gas production can increase 54%when the combined method is used.The efficiency of gas production is very low when thermal stimulation was used alone.When the temperature of thermal stimulation is 11℃,the average rate of gas production in the experiment of thermal stimulation is less than 1/3 of that in the experiment of the combined method.展开更多
Excellent comprehensive mechanical properties including good formability,high strength and high ductility are prior demands for Al-Mg-Si-Cu alloys.This study utilizes calculation of phase diagram(CALPHAD)to simplify t...Excellent comprehensive mechanical properties including good formability,high strength and high ductility are prior demands for Al-Mg-Si-Cu alloys.This study utilizes calculation of phase diagram(CALPHAD)to simplify the alloy design and meet these demands.Specifically,CALPHAD was used to finely tune the Mg/Si atomic ratio in solid solution and accurately control the type and content of second phases,especially to avoid the formation of the harmful constituent phaseβ-Al Fe Si.Constituents and dispersoids of only-Al Fe Mn Si phase were found in the alloy prepared.An optimized microstructure with fine grains,micro scale constituents,densely distributed submicron scale dispersoids and extremely dense nano precipitates provides effective impediment to dislocation gliding and induces transgranular fracture.Therefore,the designed alloy has better comprehensive mechanical properties than other 6 xxx series aluminum alloys,including excellent formability,strength and ductility.The low T4P strength of 149 MPa as well as the high elongation of 26.1%implies the alloy’s applicability to automobile body panel forming.The yield strength was rapidly improved from 149 MPa to 277 MPa during the paint bake ageing,because the number density of precipitates is twice as high as that of some other 6xxx alloys.Meanwhile,the elongation was kept at a high level of 20.0%.展开更多
In this study, a numerical model is developed to investigate the hydrate dissociation and gas production in porous media by depressurization. A series of simulation runs are conducted to study the impacts of permeabil...In this study, a numerical model is developed to investigate the hydrate dissociation and gas production in porous media by depressurization. A series of simulation runs are conducted to study the impacts of permeability characteristics, including permeability reduction exponent, absolute permeability, hydrate accumulation habits and hydrate saturation, sand average grain size and irreducible water saturation. The effects of the distribution of hydrate in porous media are examined by adapting conceptual models of hydrate accumulation habits into simulations to govern the evolution of permeability with hydrate decomposition, which is also compared with the conventional reservoir permeability model, i.e. Corey model. The simulations show that the hydrate dissociation rate increases with the decrease of permeability reduction exponent, hydrate saturation and the sand average grain size. Compared with the conceptual models of hydrate accumulation habits, our simulations indicate that Corey model overpredicts the gas production and the performance of hydrate coating models is superior to that of hydrate filling models in gas production, which behavior does follow by the order of capillary coating〉pore coating〉pore filling〉capillary filling. From the analysis of tl/2, some interesting results are suggested as follows： （1） there is a ＂switch＂ value （the ＂switch＂ absolute permeability） for laboratory-scale hydrate dissociation in porous media, the absolute permeability has almost no influence on the gas production behavior when the permeability exceeds the ＂switch＂ value. In this study, the ＂switch＂ value of absolute permeability can be estimated to be between 10 and 50 md. （2） An optimum value of initial effective water saturation Sw,e exists where hydrate dissociation rate reaches the maximum and the optimum value largely coincides with the value of irreducible water saturation Swr,e. For the case of Sw,e〈,Swr,e, or Sw,e〉Swr,e, there are different control mechanisms dominating the process of hydrate dissociation and gas production.展开更多
Computational tools on top of first principle calculations have played an indispensable role in revealing the molecular details,thermodynamics,and kinetics in catalytic reactions.Here we proposed a highly efficient dy...Computational tools on top of first principle calculations have played an indispensable role in revealing the molecular details,thermodynamics,and kinetics in catalytic reactions.Here we proposed a highly efficient dynamic strategy for the calculation of thermodynamic and kinetic properties in heterogeneous catalysis on the basis of efficient potential energy surface(PES)and MD simulations.Taking CO adsorbate on Ru(0001)surface as the illustrative model system,we demonstrated the PES-based MD can efficiently generate reliable two-dimensional potential-of-mean-force(PMF)surfaces in a wide range of temperatures,and thus temperature-dependent thermodynamic properties can be obtained in a comprehensive investigation on the whole PMF surface.Moreover,MD offers an effective way to describe the surface kinetics such as adsorbate on-surface movement,which goes beyond the most popular static approach based on free energy barrier and transition state theory(TST).We further revealed that the dynamic strategy significantly improves the predictions of both thermodynamic and kinetic properties as compared to the popular ideal statistic mechanics approaches such as harmonic analysis and TST.It is expected that this accurate yet efficient dynamic strategy can be powerful in understanding mechanisms and reactivity of a catalytic surface system,and further guides the rational design of heterogeneous catalysts.展开更多
Gas hydrate is a promising alternative for gas capture and storage due to its high gas storage capacity achieved with only structured water molecules.Nucleation is the critical controlling step in gas hydrate formatio...Gas hydrate is a promising alternative for gas capture and storage due to its high gas storage capacity achieved with only structured water molecules.Nucleation is the critical controlling step in gas hydrate formation.Adding an alien solid surface is an effective approach to regulate gas hydrate nucleation.However,how the solid surface compositions control the gas hydrate nucleation remains unclear.Benefiting from the fact that the surface compositions of graphene oxide(GO)can be finely tuned,we report the effect of functional groups of size-selected GO flakes on methane hydrate nucleation.The carbonyl and carboxyl of GO flakes showed a more prominent promotion for methane hydrate nucleation than the hydroxyl of GO flakes.Surface energy,zeta potential,Raman spectra,and molecular dynamics simulation analysis were used to reveal the regulation mechanism of the functional groups of size-selected GO flakes on methane hydrate nucleation.The GO flakes with abundant carbonyl and carboxyl exhibited higher charge density than those enriched in hydroxyl.The negatively charged GO flakes can induce water molecules to form an ordered hydrogen-bonded arrangement via charge-dipole interactions.Therefore,the water molecules surrounding the carboxyl and carbonyl showed a more ordered hydrogen-bonded structure than those around the hydroxyl of GO flakes.The ordered water arrangement,similar to methane hydrate cages,significantly accelerated methane hydrate nucleation.Our study shows how the surface chemistry of solids control gas hydrate nucleation and sheds light on the design of effective heterogeneous nucleators for gas hydrate.展开更多
Laves phases,with the topologically close-packed structure and a chemical formula of Ab_(2),constitute the largest single class of intermetallics.Planar defects in Laves phases are widely investigated,especially for s...Laves phases,with the topologically close-packed structure and a chemical formula of Ab_(2),constitute the largest single class of intermetallics.Planar defects in Laves phases are widely investigated,especially for stacking behavior transformations through synchroshear.Here,we report the coexistence of C14,C36 and C15 structures in MgZn_2 precipitates by using atomic resolution scanning transmission electron microscopy,verifying the previously predicted Laves phase transformation sequence of C14→C36→C15 also applies to MgZn_2.One type of stacking fault couple in precipitates has been found to alone reduce the lattice mismatch with matrix,while some other stacking fault couples need to self-accommodate with irregular planar defects(rhombic units and flattened hexagonal units),or with five-fold symmetry structures to relieve the strain concentration.Precipitates thus grow towards an equiaxed or even round morphology,rather than the plate morphology as conventionally believed.Molecular dynamics calculations are performed to support our analysis.These findings reveal the principles governing the concurrent occurrence of various defects in laves structures,acting as an update of the widely accepted perception of random occurrence of defects during crystal growth.展开更多
Based on the models of hydrate phase equilibrium in bulk water and porous media,an improved model was proposed to predict the methane hydrate equilibrium in marine sediment environment.In the suggested model,mechanica...Based on the models of hydrate phase equilibrium in bulk water and porous media,an improved model was proposed to predict the methane hydrate equilibrium in marine sediment environment.In the suggested model,mechanical equilibrium of force between the interfaces in hydrate-liquid-vapor system was considered.When electrolyte was present in pore water,interfacial energy between hydrate and liquid was corrected by an equation that is expressed as the function of temperature and electrolyte concentration.The activity of water is calculated based on the Pitzer model and the interfacial energy between liquid and gas is solved using the Li method.The prediction results show good agreement with the experimental data.By comparison with other models,it is proved that this model can improve the accuracy for predicting hydrate phase equilibrium in marine sediment environment.展开更多
CO_(2) capture and sequestration via the hydrate method has attracted much attention because of its high sequestration density and energy density.However,the influencing mechanism of the promoters on the formation of ...CO_(2) capture and sequestration via the hydrate method has attracted much attention because of its high sequestration density and energy density.However,the influencing mechanism of the promoters on the formation of CO_(2) hydrate was not yet clarified.Also,there was no comprehensive review of the effect of promoters on CO_(2) hydrate formation from laboratory-scale studies.Therefore,this paper reviewed the effect of promoters on CO_(2) capture and sequestration via the hydrate method from the laboratory research scale.Typical CO_(2) hydrate formation processes were summarized in detail.And the characteristic parameters of CO_(2) hydrate were analyzed.Then,the different types of promoters were carefully overviewed.In particular,the influencing mechanisms of promoters on CO_(2) hydrates were highlighted and compared.Thermodynamic promoters mainly affected the conditions of hydrate formation,while kinetic promoters mainly acted at the gas-liquid contact interface.However,the promotional mechanism of CO_(2) hydrate promoters was controversial and the solution formulation units were not consistent.In addition,the effects of different promoters on CO_(2) capture,separation,and sequestration were also summarized.The existing studies ignored the CO_(2) hydrate formation experiments under in-situ conditions in the presence of promoters.The influence of different promoters on the sequestration effect was critically evaluated through parameters such as phase equilibrium curves,induction time,gas consumption,and sequestration density.A uniform evaluation standard for CO_(2) hydrate promoters was lacking.Finally,future development recommendations should focus on large-scale,low-energy,commercial,in-situ,environmentally friendly,and intelligent research directions.The review may provide some theoretical guidance for the commercial application of CO_(2) hydrate.展开更多
Van der Waals semiconductor heterostructures(VSHs)composed of two or more two-dimensional(2D)materials with different band gaps exhibit huge potential for exploiting high-performance multifunctional devices.The applic...Van der Waals semiconductor heterostructures(VSHs)composed of two or more two-dimensional(2D)materials with different band gaps exhibit huge potential for exploiting high-performance multifunctional devices.The application of 2D VSHs in atomically thin devices highly depends on the control of their carrier type and density.Herein,on the basis of comprehensive first-principles calculations,we report a new strategy to manipulate the doping polarity and carrier density in a class of 2D VSHs consisting of atomically thin transition metal dichalcogenides(TMDs)andα-In_(2)X_(3)(X=S,Se)ferroelectrics via switchable polarization field.Our calculated results indicate that the band bending of In_(2)X_(3)layer driven by the FE polarization can be utilized for engineering the band alignment and doping polarity of TMD/In_(2)X_(3)VSHs,which enables us to control their carrier density and type of the VSHs by the orientation and magnitude of local FE polarization field.Inspired by these findings,we demonstrate that doping-free p–n junctions achieved in MoTe2/In2Se3 VSHs exhibit high carrier density(1013–1014 cm–2),and the inversion of the VHSs from n–p junctions to p–i–n junctions has been realized by the polarization switching from upward to downward states.This work provides a nonvolatile and nondestructive doping strategy for obtaining programmable p–n van der Waals(vdW)junctions and opens the possibilities for self-powered and multifunctional device applications.展开更多
基金Supported by the National Natural Science Foundation of China(51436003,51822603,51576025)the National Key Research and Development Plan of China(2017YFC0307303,2016YFC0304001)+2 种基金the Fok Ying-Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(161050)the Fundamental Research Funds for the Central Universities of China(DUT18ZD403)the Young Sci-tech Stars Project of Dalian City of China(2016RQ009)
文摘The shortage of freshwater boosts the development of seawater desalination technology. As a novel method, the hydrate based desalination technology has been put forward for decades and achieved considerable development in the past years. This review focuses on the experimental progress at the aspects of the hydrate former choice, formation promotion and ion removal efficiency and conceptive innovation of hydrate separation and energy utilization. It should be noted that gaseous hydrate former with low formation pressure and insoluble liquid hydrate former are worthy for further study. Besides, the water migration caused by propane deserves to be investigated much more deeply for the potential value of wide application. Moreover, the utilization proposal of LNG cold energy brings more possibility of commercial application. In a word, the hydrate based desalination technology is hopefully an environment friendly, low-cost and widely used desalination technology in the near future.
基金Supported by the National Natural Science Foundation of China(51436003,51822603,51576025)the National Key Research and Development Program of China(2017YFC0307303,2016YFC0304001)+1 种基金the Fok Ying Tong Education Foundation for Young Teachers in the Higher Education Institutions of China(161050)the Fundamental Research Funds for the Central Universities of China(DUT18ZD403)
文摘Methane hydrate is considered as a potential energy source in the future due to its abundant reserves and high energy density.To investigate the influence of initial hydrate saturation,production pressure,and the temperature of thermal stimulation on gas production rate and cumulative gas production percentage,we conducted the methane hydrate dissociation experiments using depressurization,thermal stimulation and a combination of two methods in this study.It is found that when the gas production pressures are the same,the higher the hydrate initial saturation,the greater change in hydrate reservoir temperature.Therefore,it is easier to appear the phenomenon of icing and hydrate reformation when the hydrate saturation is higher.For example,the reservoir temperature dropped to below zero in depressurization process when the hydrate saturation was about 37%.However,the same phenomenon didn’t appear as the saturation was about 12%.This may be due to more free gas in the reservoir with hydrate saturated of 37%.We also find that the temperature variation of reservoir can be reduced effectively by combination of depressurization and thermal stimulation method.And the average gas production rate is highest with combined method in the experiments.When the pressure of gas production is 2 MPa,compared with depressurization,the average of gas production can increase 54%when the combined method is used.The efficiency of gas production is very low when thermal stimulation was used alone.When the temperature of thermal stimulation is 11℃,the average rate of gas production in the experiment of thermal stimulation is less than 1/3 of that in the experiment of the combined method.
基金financially supported by the National Natural Science Foundation of China(Nos.51531009,51711530713 and 51501230)the Central South University(No.2018gczd033).
文摘Excellent comprehensive mechanical properties including good formability,high strength and high ductility are prior demands for Al-Mg-Si-Cu alloys.This study utilizes calculation of phase diagram(CALPHAD)to simplify the alloy design and meet these demands.Specifically,CALPHAD was used to finely tune the Mg/Si atomic ratio in solid solution and accurately control the type and content of second phases,especially to avoid the formation of the harmful constituent phaseβ-Al Fe Si.Constituents and dispersoids of only-Al Fe Mn Si phase were found in the alloy prepared.An optimized microstructure with fine grains,micro scale constituents,densely distributed submicron scale dispersoids and extremely dense nano precipitates provides effective impediment to dislocation gliding and induces transgranular fracture.Therefore,the designed alloy has better comprehensive mechanical properties than other 6 xxx series aluminum alloys,including excellent formability,strength and ductility.The low T4P strength of 149 MPa as well as the high elongation of 26.1%implies the alloy’s applicability to automobile body panel forming.The yield strength was rapidly improved from 149 MPa to 277 MPa during the paint bake ageing,because the number density of precipitates is twice as high as that of some other 6xxx alloys.Meanwhile,the elongation was kept at a high level of 20.0%.
基金supported by the National Science and Technology Major Project,China (Grant No. 2011ZX05026-004-07)the National High Technology Research and Development Program of China (863 Program,Grant No. 2006AA09209-5)Major State Basic Research Development Program of China (973 Program,Grant No. 2009CB219507)
文摘In this study, a numerical model is developed to investigate the hydrate dissociation and gas production in porous media by depressurization. A series of simulation runs are conducted to study the impacts of permeability characteristics, including permeability reduction exponent, absolute permeability, hydrate accumulation habits and hydrate saturation, sand average grain size and irreducible water saturation. The effects of the distribution of hydrate in porous media are examined by adapting conceptual models of hydrate accumulation habits into simulations to govern the evolution of permeability with hydrate decomposition, which is also compared with the conventional reservoir permeability model, i.e. Corey model. The simulations show that the hydrate dissociation rate increases with the decrease of permeability reduction exponent, hydrate saturation and the sand average grain size. Compared with the conceptual models of hydrate accumulation habits, our simulations indicate that Corey model overpredicts the gas production and the performance of hydrate coating models is superior to that of hydrate filling models in gas production, which behavior does follow by the order of capillary coating〉pore coating〉pore filling〉capillary filling. From the analysis of tl/2, some interesting results are suggested as follows： （1） there is a ＂switch＂ value （the ＂switch＂ absolute permeability） for laboratory-scale hydrate dissociation in porous media, the absolute permeability has almost no influence on the gas production behavior when the permeability exceeds the ＂switch＂ value. In this study, the ＂switch＂ value of absolute permeability can be estimated to be between 10 and 50 md. （2） An optimum value of initial effective water saturation Sw,e exists where hydrate dissociation rate reaches the maximum and the optimum value largely coincides with the value of irreducible water saturation Swr,e. For the case of Sw,e〈,Swr,e, or Sw,e〉Swr,e, there are different control mechanisms dominating the process of hydrate dissociation and gas production.
基金financially supported by Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(No.2021ZR109)the National Natural Science Foundation of China(Nos.21973094,22173104,22173105)the Opening Project of PCOSS of Xiamen University(No.201908)。
文摘Computational tools on top of first principle calculations have played an indispensable role in revealing the molecular details,thermodynamics,and kinetics in catalytic reactions.Here we proposed a highly efficient dynamic strategy for the calculation of thermodynamic and kinetic properties in heterogeneous catalysis on the basis of efficient potential energy surface(PES)and MD simulations.Taking CO adsorbate on Ru(0001)surface as the illustrative model system,we demonstrated the PES-based MD can efficiently generate reliable two-dimensional potential-of-mean-force(PMF)surfaces in a wide range of temperatures,and thus temperature-dependent thermodynamic properties can be obtained in a comprehensive investigation on the whole PMF surface.Moreover,MD offers an effective way to describe the surface kinetics such as adsorbate on-surface movement,which goes beyond the most popular static approach based on free energy barrier and transition state theory(TST).We further revealed that the dynamic strategy significantly improves the predictions of both thermodynamic and kinetic properties as compared to the popular ideal statistic mechanics approaches such as harmonic analysis and TST.It is expected that this accurate yet efficient dynamic strategy can be powerful in understanding mechanisms and reactivity of a catalytic surface system,and further guides the rational design of heterogeneous catalysts.
基金financially supported by the National Natural Science Foundation of China(52020105007 and 51606027)the Fundamental Research Funds for the Central Universities(DUT22LAB112)+1 种基金the Liaoning Provincial Natural Science Foundation of China(2020-MS-119)supported by the Xinghai Talent funding and the Dalian High-Level Talent Innovation Program(2021RQ035)。
文摘Gas hydrate is a promising alternative for gas capture and storage due to its high gas storage capacity achieved with only structured water molecules.Nucleation is the critical controlling step in gas hydrate formation.Adding an alien solid surface is an effective approach to regulate gas hydrate nucleation.However,how the solid surface compositions control the gas hydrate nucleation remains unclear.Benefiting from the fact that the surface compositions of graphene oxide(GO)can be finely tuned,we report the effect of functional groups of size-selected GO flakes on methane hydrate nucleation.The carbonyl and carboxyl of GO flakes showed a more prominent promotion for methane hydrate nucleation than the hydroxyl of GO flakes.Surface energy,zeta potential,Raman spectra,and molecular dynamics simulation analysis were used to reveal the regulation mechanism of the functional groups of size-selected GO flakes on methane hydrate nucleation.The GO flakes with abundant carbonyl and carboxyl exhibited higher charge density than those enriched in hydroxyl.The negatively charged GO flakes can induce water molecules to form an ordered hydrogen-bonded arrangement via charge-dipole interactions.Therefore,the water molecules surrounding the carboxyl and carbonyl showed a more ordered hydrogen-bonded structure than those around the hydroxyl of GO flakes.The ordered water arrangement,similar to methane hydrate cages,significantly accelerated methane hydrate nucleation.Our study shows how the surface chemistry of solids control gas hydrate nucleation and sheds light on the design of effective heterogeneous nucleators for gas hydrate.
基金supported financially by the National Natural Science Foundation of China(Nos.51820105001,51771234,51531009 and 51790482)the Fundamental Research Funds for the Central Universities(No.GK201803016)。
文摘Laves phases,with the topologically close-packed structure and a chemical formula of Ab_(2),constitute the largest single class of intermetallics.Planar defects in Laves phases are widely investigated,especially for stacking behavior transformations through synchroshear.Here,we report the coexistence of C14,C36 and C15 structures in MgZn_2 precipitates by using atomic resolution scanning transmission electron microscopy,verifying the previously predicted Laves phase transformation sequence of C14→C36→C15 also applies to MgZn_2.One type of stacking fault couple in precipitates has been found to alone reduce the lattice mismatch with matrix,while some other stacking fault couples need to self-accommodate with irregular planar defects(rhombic units and flattened hexagonal units),or with five-fold symmetry structures to relieve the strain concentration.Precipitates thus grow towards an equiaxed or even round morphology,rather than the plate morphology as conventionally believed.Molecular dynamics calculations are performed to support our analysis.These findings reveal the principles governing the concurrent occurrence of various defects in laves structures,acting as an update of the widely accepted perception of random occurrence of defects during crystal growth.
基金supported by the Key program of National Natural Science Foundation of China (50736001)the High-tech Research and Development Program of China (2006AA09A209-5)the Major State Basic Research Development Program of China (2009CB219507)
文摘Based on the models of hydrate phase equilibrium in bulk water and porous media,an improved model was proposed to predict the methane hydrate equilibrium in marine sediment environment.In the suggested model,mechanical equilibrium of force between the interfaces in hydrate-liquid-vapor system was considered.When electrolyte was present in pore water,interfacial energy between hydrate and liquid was corrected by an equation that is expressed as the function of temperature and electrolyte concentration.The activity of water is calculated based on the Pitzer model and the interfacial energy between liquid and gas is solved using the Li method.The prediction results show good agreement with the experimental data.By comparison with other models,it is proved that this model can improve the accuracy for predicting hydrate phase equilibrium in marine sediment environment.
基金supported by the National Natural Science Foundation of China(52206076,51822603,U19B2005,52306205,52304098)Liao Ning Revitalization Talents Program(XLYC1907096)+5 种基金National Key Research and Development Plan of China(2021YFC2800902)the and the Fundamental Research Funds for the Central Universities of China(DUT21ZD103)Ph.D.Programs Foundation of Liao Ning(2023-BS-060)Study on the marine solidification technology of CO_(2) hydrate(KJGG-2022-12-CCUS-0302)Natural Science Foundation of Guangdong Province(2023A1515012761,2023A1515012316,2022A1515110338)Shenzhen Science and Technology Program(JCYJ20220530113011027,JCYJ20220818095605012).
文摘CO_(2) capture and sequestration via the hydrate method has attracted much attention because of its high sequestration density and energy density.However,the influencing mechanism of the promoters on the formation of CO_(2) hydrate was not yet clarified.Also,there was no comprehensive review of the effect of promoters on CO_(2) hydrate formation from laboratory-scale studies.Therefore,this paper reviewed the effect of promoters on CO_(2) capture and sequestration via the hydrate method from the laboratory research scale.Typical CO_(2) hydrate formation processes were summarized in detail.And the characteristic parameters of CO_(2) hydrate were analyzed.Then,the different types of promoters were carefully overviewed.In particular,the influencing mechanisms of promoters on CO_(2) hydrates were highlighted and compared.Thermodynamic promoters mainly affected the conditions of hydrate formation,while kinetic promoters mainly acted at the gas-liquid contact interface.However,the promotional mechanism of CO_(2) hydrate promoters was controversial and the solution formulation units were not consistent.In addition,the effects of different promoters on CO_(2) capture,separation,and sequestration were also summarized.The existing studies ignored the CO_(2) hydrate formation experiments under in-situ conditions in the presence of promoters.The influence of different promoters on the sequestration effect was critically evaluated through parameters such as phase equilibrium curves,induction time,gas consumption,and sequestration density.A uniform evaluation standard for CO_(2) hydrate promoters was lacking.Finally,future development recommendations should focus on large-scale,low-energy,commercial,in-situ,environmentally friendly,and intelligent research directions.The review may provide some theoretical guidance for the commercial application of CO_(2) hydrate.
基金supported by the National Natural Science Foundation of China(Grant No.62174151 and 61775201)the Fund of Zhejiang Provincial Natural Science Foundation of China(Grant No.LZ22F040003 and LY22A040002).
文摘Van der Waals semiconductor heterostructures(VSHs)composed of two or more two-dimensional(2D)materials with different band gaps exhibit huge potential for exploiting high-performance multifunctional devices.The application of 2D VSHs in atomically thin devices highly depends on the control of their carrier type and density.Herein,on the basis of comprehensive first-principles calculations,we report a new strategy to manipulate the doping polarity and carrier density in a class of 2D VSHs consisting of atomically thin transition metal dichalcogenides(TMDs)andα-In_(2)X_(3)(X=S,Se)ferroelectrics via switchable polarization field.Our calculated results indicate that the band bending of In_(2)X_(3)layer driven by the FE polarization can be utilized for engineering the band alignment and doping polarity of TMD/In_(2)X_(3)VSHs,which enables us to control their carrier density and type of the VSHs by the orientation and magnitude of local FE polarization field.Inspired by these findings,we demonstrate that doping-free p–n junctions achieved in MoTe2/In2Se3 VSHs exhibit high carrier density(1013–1014 cm–2),and the inversion of the VHSs from n–p junctions to p–i–n junctions has been realized by the polarization switching from upward to downward states.This work provides a nonvolatile and nondestructive doping strategy for obtaining programmable p–n van der Waals(vdW)junctions and opens the possibilities for self-powered and multifunctional device applications.
