Co–Mo catalysts applied on the hydrodesulfurization(HDS) for FCC gasoline were prepared with Zn–Al layered double hydroxides(LDHs) to improve their performances,and the effects of pore structures and acidity on ...Co–Mo catalysts applied on the hydrodesulfurization(HDS) for FCC gasoline were prepared with Zn–Al layered double hydroxides(LDHs) to improve their performances,and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn–Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH-,CO2-,Al3+,and Zn2+. The neutralization p H is a main factor to affect the pore structures and acidity of Zn–Al/LDHs,and a series of Zn–Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas(SBET) and acidities,three Co Mo/LDHs catalysts were prepared,and their HDS performances were compared with traditional Co Mo/Al2O3 catalysts. The results indicated that catalysts prepared with high SBETpossessed high HDS activity,and Br?nsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than Co Mo/Al2O3,and could restrain the reactions of re-combination between olefin and H2 S which could be due to the existence of Br?nsted acid sites.展开更多
Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the...Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.展开更多
To prevent and mitigate environmental degradation,high-performance and cost-effective electrochemical flexible energy storage systems need to be urgently developed.This demand has led to an increase in research on ele...To prevent and mitigate environmental degradation,high-performance and cost-effective electrochemical flexible energy storage systems need to be urgently developed.This demand has led to an increase in research on electrode materials for high-capacity flexible supercapacitors and secondary batteries,which have greatly aided the development of contemporary digital communications and electric vehicles.The use of layered double hydroxides(LDHs)as electrode materials has shown productive results over the last decade,owing to their easy production,versatile composition,low cost,and excellent physicochemical features.This review highlights the distinctive 2D sheet-like structures and electrochemical characteristics of LDH materials,as well as current developments in their fabrication strategies for expanding the application scope of LDHs as electrode materials for flexible supercapacitors and alkali metal(Li,Na,K)ion batteries.展开更多
Layered double hydroxide(LDH)is regarded as an advanced platform material in catalysis and attracts vast attrition recently.As a kind of two-dimensional layered material,it exhibits great advantages including cation-t...Layered double hydroxide(LDH)is regarded as an advanced platform material in catalysis and attracts vast attrition recently.As a kind of two-dimensional layered material,it exhibits great advantages including cation-tunability in layer,lattice limitation,topological transformation,ion exchange and intercalation characteristics.It also can be used as building blocks for composite catalytic materials.Over 100 years,a large number of works have been accomplished and researchers made great progress on investigating the LDH-based catalytic materials.In this review,we summarize representative achievements and significant progress in recent years,which mainly include constructing high entropy catalytic material,high dispersion/stability and interfacial supported catalytic material,composite catalytic materials and nano-reactor based on LDH.Furthermore,through collecting the excellent works,we conclude the future development potential of LDH and provide a perspective.展开更多
The explore and development of electrocatalysts have gained significant attention due to their indispensable status in energy storage and conversion systems, such as fuel cells, metal–air batteries and solar water sp...The explore and development of electrocatalysts have gained significant attention due to their indispensable status in energy storage and conversion systems, such as fuel cells, metal–air batteries and solar water splitting cells. Layered double hydroxides(LDHs) and their derivatives(e.g., transition metal alloys, oxides, sulfides, nitrides and phosphides) have been adopted as catalysts for various electrochemical reactions, such as oxygen reduction, oxygen evolution, hydrogen evolution, and COreduction, which show excellent activity and remarkable durability in electrocatalytic process. In this review, the synthesis strategies, structural characters and electrochemical performances for the LDHs and their derivatives are described. In addition, we also discussed the effect of electronic and geometry structures to their electrocatalytic activity. The further development of high-performance electrocatalysts based on LDHs and their derivatives is covered by both a short summary and future outlook from the viewpoint of the material design and practical application.展开更多
The hierarchical structure of molybdenum disulfide(MoS2)nanosheet arrays stemmed from nickelcobalt layered double hydroxide(NiCo-LDH)/carbon cloth was prepared by growing the MoS_(2) nanosheet arrays onto the NiCo-LDH...The hierarchical structure of molybdenum disulfide(MoS2)nanosheet arrays stemmed from nickelcobalt layered double hydroxide(NiCo-LDH)/carbon cloth was prepared by growing the MoS_(2) nanosheet arrays onto the NiCo-LDH template which was pre-deposited onto the carbon cloth substrate.In this electrode configuration,carbon cloth is the three dimensional and conductive skeleton;NiCo-LDH nanosheets,as the template,ensure the oriented growth of MoS2 nanosheet arrays.Therefore,more MoS_(2) active sites are exposed and the catalyst exhibits good hydrogen evolution reaction activity.展开更多
Lithium-ion(Li-ion) battery and lithium-sulfur(Li-S) battery have attracted significant attention as promising components for large-scale energy storage because of high theoretical capacity of Li,excellent energy dens...Lithium-ion(Li-ion) battery and lithium-sulfur(Li-S) battery have attracted significant attention as promising components for large-scale energy storage because of high theoretical capacity of Li,excellent energy density or environmental friendness for two kinds of batteries.However,there still exist some respective obstacles for commercial applications,such as limited theoretical capacity,high cost and low conductivity of Li-ion cells or shuttle effect of lithium polysulfides of Li-S cells.As typical twodimensional materials,layered double hydroxides(LDHs) exhibit excellent potential in the field of energy storage due to facile tunability of composition,structure and morphology as well as convenient composite and strong catalytic properties.Consequently,various LDHs toward novel separators or interlayers,cathodes,anodes,and interesting catalytic templates are researched to resolve these challenges.In this review,the recent progress for LDHs applied in Li-ion batteries and Li-S batteries including the synthesis methods,designs and applications is presented and reviewed.Meanwhile,the existing challenges and future perspectives associated with material designs and practical applications of LDHs for these two classes of cells are discussed.WeWe hope that the review can attract more attention and inspire more profound researches toward the LDH-based electrochemical materials for energy storage.展开更多
In this work,a facile and effective strategy to prepare three-dimensional(3D)hierarchical flower-like Mg–Al layered double hydroxides(3D-LDH)was developed via a one-step double-drop coprecipitation method usingγ-Al ...In this work,a facile and effective strategy to prepare three-dimensional(3D)hierarchical flower-like Mg–Al layered double hydroxides(3D-LDH)was developed via a one-step double-drop coprecipitation method usingγ-Al 2O 3particles as a template.The characterization and experimental results showed that the calcined product,3D-LDO,features a large specific surface area of 204.2 m^(2)/g,abundant active sites,and excellent adsorption performance for Congo red(CR),methyl orange(MO),and methyl blue(MB).The maximum adsorption capacities of 3D-LDO for CR,MO,and MB were 1428.6,476.2,and 1666.7 mg/g,respectively;such performance is superior to that of most reported adsorbents.The adsorption mechanism of organic anionic dyes by 3D-LDO was extensively investigated and attributed to surface adsorption,the memory effect of 3D-LDO,and the unique 3D hierarchical flower-like structure of the adsorbent.Recycling performance tests revealed that3D-LDO has satisfactory reusability for the three organic anionic dyes.展开更多
The oxygen evolution reaction(OER)with sluggish reaction kinetics and large overpotential is the critical reaction in water splitting that is promising for energy storage and conversion.Layered double hydroxides(LDHs)...The oxygen evolution reaction(OER)with sluggish reaction kinetics and large overpotential is the critical reaction in water splitting that is promising for energy storage and conversion.Layered double hydroxides(LDHs),due to their unique lamellar structure and flexibility of chemical component,are very competing material candidates for OER.Herein,the morphology structure and the electronic structure of LDHs were simultaneously tuned to improve the OER catalytic activity by mild solvothermal reduction using ethylene glycol.The increased surface area,the introduction of oxygen vacancies and the construction of hierarchical structure greatly enhanced the electro-catalytic activity of LDHs for OER.The as-prepared LDHs showed a lower over-potential as low as 276 mV at a current density of 10 mA cm-2,and a small Tafel slope of 40.3 mV dec-1 accompanied with good stability.This work provides an efficient way to the design and optimization of advanced catalysts in the future.展开更多
Two different interlayer structured glyphosate (GLY) intercalated MgAl layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various re...Two different interlayer structured glyphosate (GLY) intercalated MgAl layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various reac- tion pH values. The slow/controlled release properties have been tested in Na2CO3 aqueous solution. The release mecha- nism has been interpreted on the basis of the ion-exchange between the guest GLY anions in the lamellar host and 23CO ? in the release media, and the diffusion process of GLY anions in the interstice and interlayer of GLY intercalates, i.e diffusion through the particles, is the rate-limiting step of GLY release process. The GLY intercalate assembled at lower pH, possessing higher interlayer gallery height and vertical monolayered arrangement of guest anions in the interlayer with larger packing density, exhibits better slow release property than that assembled at higher pH. The re- sults reveal that the layered double hydroxides have potential application in the pesticide slow/controlled release area.展开更多
Layered double hydroxides (LDHs) are effective molecular carriers in cytological research, gene therapy, and transgenic applications. Herein, we investigated the internalization behavior of the LDH-DNA biocon- jugat...Layered double hydroxides (LDHs) are effective molecular carriers in cytological research, gene therapy, and transgenic applications. Herein, we investigated the internalization behavior of the LDH-DNA biocon- jugates via a microscopic approach and analyzed the internalization pathway by dissipative particle dynamics (DPD) simulations. We experimentally found that LDH can efficiently carry DNA into the nucleus of cell in BY-2 suspension cells. Furthermore, atomic force microscopy and X-ray diffraction anal- ysis demonstrated that the LDH-DNA bioconjugates mainly exist as a DNA-LDH-DNA sandwich complex, while the LDH-DNA-LDH sandwich complex and DNA-LDH complex cannot be excluded. The DPD simu- lations further indicated that only the DNA-LDH-DNA sandwich structure could penetrate the plasma membrane (PM), while PM is impermeable to the LDH-DNA-LDH sandwich complex and the DNA-LDH complex. This work provides novel perspective for understanding the membrane penetration mechanism of LDH nano-sheets and new insights into the design of novel molecular delivery systems.展开更多
A novel organic-inorganic composite, sorbic acid intercalated zinc aluminum layered double hydroxides (SA-ZnAl-LDHs) has been successfully assembled by a sim- ple direct coprecipitation method. A holistic approach in-...A novel organic-inorganic composite, sorbic acid intercalated zinc aluminum layered double hydroxides (SA-ZnAl-LDHs) has been successfully assembled by a sim- ple direct coprecipitation method. A holistic approach in- cluding normal XRD, FT-IR, and UV-Vis measurements and simultaneous TG/DTA/MS and in situ HT-XRD techniques was employed to explore the supramolecular intercalation structure and the thermal decomposition properties of as-synthesized SA-ZnAl-LDHs material.展开更多
To further improve the removal ability of layered double hydroxide(LDH) for iodide(I^-) anions from wastewater, we prepared hierarchically porous Cu5Mg10Al5-LDH and used as a matrix for in suit growth of Cu/Cu2O on it...To further improve the removal ability of layered double hydroxide(LDH) for iodide(I^-) anions from wastewater, we prepared hierarchically porous Cu5Mg10Al5-LDH and used as a matrix for in suit growth of Cu/Cu2O on its surface, forming Cu/Cu2O-LDH, which was characterized and applied as an adsorbent.Results displayed high I^-saturation uptake capability(137.8 mg/g) of Cu/Cu2O-LDH compared with Cu5Mg10Al5-LDH(26.4 mg/g) even thermal activated LDH(76.1 mg/g).Thermodynamic analysis showed that the reaction between I^-anions and Cu/Cu2O-LDH is a spontaneous and exothermic.Uptake kinetics analysis exhibited that adsorption equilibrium can be reached after 265 min.Additionally, the adsorbent showed satisfactory selectivity in the presence of competitive anions(e.g., SO4^2-), and could achieve good adsorption performance in a wide pH range of 3–8.A cooperative adsorption mechanism was proposed on the basis of the following two aspects:(1) ion exchange between iodide and interlayer anions;(2) the adsorption performance of Cu, Cu(Ⅱ) and Cu2O for I^-.Meanwhile, the difference between the adsorption mechanism of Cu/Cu2O-LDH, Cu5Mg10Al5-LDH and Cu5Mg10Al5-CLDH adsorbents was also elaborated and verified.展开更多
Salt freezing damage has severe impacts on durability of cement-based materials(CBMs).Calcined layered double hydroxide(CLDH),as an efficient environmental-friendly adsorption material,can impart excellent salt freezi...Salt freezing damage has severe impacts on durability of cement-based materials(CBMs).Calcined layered double hydroxide(CLDH),as an efficient environmental-friendly adsorption material,can impart excellent salt freezing resistance to CBMs.In this work,salt freezing resistance improvement of CBMs incorporated with CLDH was experimentally evaluated by chloride binding capacity,mass loss rate,relative dynamic elastic modulus,setting time,compressive strength,and micro structure tests.Beside these,the salt freezing damage model was established to effectively express the quantitative relationship between influencing factors and evaluation indexes of the salt freezing resistance of CBMs.Results show that CLDH can reconstruct its original layered structure to form reconstructed layered double hydroxide(RLDH).RLDH combines with chloride ions to form RLDH-Cl recrystallization,which can improve chloride binding capacity and pore structures of CBMs to relieve the salt freezing damage.The salt freezing damage model indicates that the suitable CLDH content can evidently alleviate the salt freezing damage,which facilitates the quantitative analysis of the effect of CLDH on the salt freezing resistance of CBMs.展开更多
Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this wo...Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.展开更多
Research progresses in the layered double hydroxides [M2+(1-x)M3+x(OH)2]x+An-x/n.mH2O intercalatedwith metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are main...Research progresses in the layered double hydroxides [M2+(1-x)M3+x(OH)2]x+An-x/n.mH2O intercalatedwith metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are mainly intercalated with polyoxometalate (POM) ions, a LiAl-LDH photochemical assembly containing TiO2 and CH3(CH2)12COO- anions, together with Zn(TPPC) (porphy-rin derivate) and macrocyclic ligand-containing porphyrin derivate anions. Emphasis is put on the synthesis methods for intercalation of the anions into the interlayer regions, the characterization techniques and structures for the layeredcompounds and the newest research progress in the fields such as catalysis. The review also forecasts the prospects of the field.展开更多
文摘Co–Mo catalysts applied on the hydrodesulfurization(HDS) for FCC gasoline were prepared with Zn–Al layered double hydroxides(LDHs) to improve their performances,and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn–Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH-,CO2-,Al3+,and Zn2+. The neutralization p H is a main factor to affect the pore structures and acidity of Zn–Al/LDHs,and a series of Zn–Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas(SBET) and acidities,three Co Mo/LDHs catalysts were prepared,and their HDS performances were compared with traditional Co Mo/Al2O3 catalysts. The results indicated that catalysts prepared with high SBETpossessed high HDS activity,and Br?nsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than Co Mo/Al2O3,and could restrain the reactions of re-combination between olefin and H2 S which could be due to the existence of Br?nsted acid sites.
文摘Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.
基金the National Natural Science Foundation of China(NSFC Grant No.62174152).
文摘To prevent and mitigate environmental degradation,high-performance and cost-effective electrochemical flexible energy storage systems need to be urgently developed.This demand has led to an increase in research on electrode materials for high-capacity flexible supercapacitors and secondary batteries,which have greatly aided the development of contemporary digital communications and electric vehicles.The use of layered double hydroxides(LDHs)as electrode materials has shown productive results over the last decade,owing to their easy production,versatile composition,low cost,and excellent physicochemical features.This review highlights the distinctive 2D sheet-like structures and electrochemical characteristics of LDH materials,as well as current developments in their fabrication strategies for expanding the application scope of LDHs as electrode materials for flexible supercapacitors and alkali metal(Li,Na,K)ion batteries.
基金supported by the National Key R&D Program of China(Nos.2023YFA1507800,2023YFA1507801)the National Natural Science Foundation of China(Nos.22288102,22208008)the Fundamental Research Funds for the Central Universities,China(No.ZY2423).
文摘Layered double hydroxide(LDH)is regarded as an advanced platform material in catalysis and attracts vast attrition recently.As a kind of two-dimensional layered material,it exhibits great advantages including cation-tunability in layer,lattice limitation,topological transformation,ion exchange and intercalation characteristics.It also can be used as building blocks for composite catalytic materials.Over 100 years,a large number of works have been accomplished and researchers made great progress on investigating the LDH-based catalytic materials.In this review,we summarize representative achievements and significant progress in recent years,which mainly include constructing high entropy catalytic material,high dispersion/stability and interfacial supported catalytic material,composite catalytic materials and nano-reactor based on LDH.Furthermore,through collecting the excellent works,we conclude the future development potential of LDH and provide a perspective.
基金supported by the National Natural Science Foundation of China(Nos.U146211821601011)+2 种基金the 973 Program(Grant No.2014CB932102)the Fundamental Research Funds for the Central Universities(buctrc201506PYCC1704)
文摘The explore and development of electrocatalysts have gained significant attention due to their indispensable status in energy storage and conversion systems, such as fuel cells, metal–air batteries and solar water splitting cells. Layered double hydroxides(LDHs) and their derivatives(e.g., transition metal alloys, oxides, sulfides, nitrides and phosphides) have been adopted as catalysts for various electrochemical reactions, such as oxygen reduction, oxygen evolution, hydrogen evolution, and COreduction, which show excellent activity and remarkable durability in electrocatalytic process. In this review, the synthesis strategies, structural characters and electrochemical performances for the LDHs and their derivatives are described. In addition, we also discussed the effect of electronic and geometry structures to their electrocatalytic activity. The further development of high-performance electrocatalysts based on LDHs and their derivatives is covered by both a short summary and future outlook from the viewpoint of the material design and practical application.
基金financial support for this work from the Strategic Priority Research Program of CAS(XDB36030000)the National Natural Science Foundation of China(21422303,21573049,21872043,22002028)+3 种基金the National Basic Research Plan of China(2016YFA0201600)the Beijing Natural Science Foundation(2142036)the Youth Innovation Promotion Associationthe Special Program of “One Belt One Road”of CAS。
文摘The hierarchical structure of molybdenum disulfide(MoS2)nanosheet arrays stemmed from nickelcobalt layered double hydroxide(NiCo-LDH)/carbon cloth was prepared by growing the MoS_(2) nanosheet arrays onto the NiCo-LDH template which was pre-deposited onto the carbon cloth substrate.In this electrode configuration,carbon cloth is the three dimensional and conductive skeleton;NiCo-LDH nanosheets,as the template,ensure the oriented growth of MoS2 nanosheet arrays.Therefore,more MoS_(2) active sites are exposed and the catalyst exhibits good hydrogen evolution reaction activity.
基金the National Natural Science Foundation of China(51973157,51673148 and 51678411)the Special Grade of the Financial Support from the China Postdoctoral Science Foundation(2020 T130469)+1 种基金the China Postdoctoral Science Foundation Grant(2019 M651047)the Science and Technology Plans of Tianjin(No.17PTSYJC00040 and18PTSYJC00180)for their financial support。
文摘Lithium-ion(Li-ion) battery and lithium-sulfur(Li-S) battery have attracted significant attention as promising components for large-scale energy storage because of high theoretical capacity of Li,excellent energy density or environmental friendness for two kinds of batteries.However,there still exist some respective obstacles for commercial applications,such as limited theoretical capacity,high cost and low conductivity of Li-ion cells or shuttle effect of lithium polysulfides of Li-S cells.As typical twodimensional materials,layered double hydroxides(LDHs) exhibit excellent potential in the field of energy storage due to facile tunability of composition,structure and morphology as well as convenient composite and strong catalytic properties.Consequently,various LDHs toward novel separators or interlayers,cathodes,anodes,and interesting catalytic templates are researched to resolve these challenges.In this review,the recent progress for LDHs applied in Li-ion batteries and Li-S batteries including the synthesis methods,designs and applications is presented and reviewed.Meanwhile,the existing challenges and future perspectives associated with material designs and practical applications of LDHs for these two classes of cells are discussed.WeWe hope that the review can attract more attention and inspire more profound researches toward the LDH-based electrochemical materials for energy storage.
基金supported by the National Key R&D Program of China(No.2017YFB0602702-02)。
文摘In this work,a facile and effective strategy to prepare three-dimensional(3D)hierarchical flower-like Mg–Al layered double hydroxides(3D-LDH)was developed via a one-step double-drop coprecipitation method usingγ-Al 2O 3particles as a template.The characterization and experimental results showed that the calcined product,3D-LDO,features a large specific surface area of 204.2 m^(2)/g,abundant active sites,and excellent adsorption performance for Congo red(CR),methyl orange(MO),and methyl blue(MB).The maximum adsorption capacities of 3D-LDO for CR,MO,and MB were 1428.6,476.2,and 1666.7 mg/g,respectively;such performance is superior to that of most reported adsorbents.The adsorption mechanism of organic anionic dyes by 3D-LDO was extensively investigated and attributed to surface adsorption,the memory effect of 3D-LDO,and the unique 3D hierarchical flower-like structure of the adsorbent.Recycling performance tests revealed that3D-LDO has satisfactory reusability for the three organic anionic dyes.
基金supported by the Fundamental Research Funds for the Central Universities (531107051102)the National Natural Science Foundation of China (51402100, 21573066, 21522305)+1 种基金the Provincial Natural Science Foundation of Hunan (2016TP1009)the Shenzhen Discovery Funding (JCYJ20170306141659388)
文摘The oxygen evolution reaction(OER)with sluggish reaction kinetics and large overpotential is the critical reaction in water splitting that is promising for energy storage and conversion.Layered double hydroxides(LDHs),due to their unique lamellar structure and flexibility of chemical component,are very competing material candidates for OER.Herein,the morphology structure and the electronic structure of LDHs were simultaneously tuned to improve the OER catalytic activity by mild solvothermal reduction using ethylene glycol.The increased surface area,the introduction of oxygen vacancies and the construction of hierarchical structure greatly enhanced the electro-catalytic activity of LDHs for OER.The as-prepared LDHs showed a lower over-potential as low as 276 mV at a current density of 10 mA cm-2,and a small Tafel slope of 40.3 mV dec-1 accompanied with good stability.This work provides an efficient way to the design and optimization of advanced catalysts in the future.
基金supported by the N ational Natural Science Foundation of China(Grant No.20106002).
文摘Two different interlayer structured glyphosate (GLY) intercalated MgAl layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various reac- tion pH values. The slow/controlled release properties have been tested in Na2CO3 aqueous solution. The release mecha- nism has been interpreted on the basis of the ion-exchange between the guest GLY anions in the lamellar host and 23CO ? in the release media, and the diffusion process of GLY anions in the interstice and interlayer of GLY intercalates, i.e diffusion through the particles, is the rate-limiting step of GLY release process. The GLY intercalate assembled at lower pH, possessing higher interlayer gallery height and vertical monolayered arrangement of guest anions in the interlayer with larger packing density, exhibits better slow release property than that assembled at higher pH. The re- sults reveal that the layered double hydroxides have potential application in the pesticide slow/controlled release area.
基金supported by the Fundamental Research Funds for the Central Universities (2016JX01, BLX2015-01)the National Natural Science Foundation of China (31671489, 31601149 and 31271433)+2 种基金the Beijing Nova Programme (Z131109000413013)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fundthe Chemical Grid Program and Excellent Talent of Beijing University of Chemical Technology
文摘Layered double hydroxides (LDHs) are effective molecular carriers in cytological research, gene therapy, and transgenic applications. Herein, we investigated the internalization behavior of the LDH-DNA biocon- jugates via a microscopic approach and analyzed the internalization pathway by dissipative particle dynamics (DPD) simulations. We experimentally found that LDH can efficiently carry DNA into the nucleus of cell in BY-2 suspension cells. Furthermore, atomic force microscopy and X-ray diffraction anal- ysis demonstrated that the LDH-DNA bioconjugates mainly exist as a DNA-LDH-DNA sandwich complex, while the LDH-DNA-LDH sandwich complex and DNA-LDH complex cannot be excluded. The DPD simu- lations further indicated that only the DNA-LDH-DNA sandwich structure could penetrate the plasma membrane (PM), while PM is impermeable to the LDH-DNA-LDH sandwich complex and the DNA-LDH complex. This work provides novel perspective for understanding the membrane penetration mechanism of LDH nano-sheets and new insights into the design of novel molecular delivery systems.
基金This work was supported by the Key Project of the National Natural Science Foundation of China(Grant No.2O1060021)the Ivlinistry of Education Science and Technology Research Project of China IGrant No.Key 104239).
文摘A novel organic-inorganic composite, sorbic acid intercalated zinc aluminum layered double hydroxides (SA-ZnAl-LDHs) has been successfully assembled by a sim- ple direct coprecipitation method. A holistic approach in- cluding normal XRD, FT-IR, and UV-Vis measurements and simultaneous TG/DTA/MS and in situ HT-XRD techniques was employed to explore the supramolecular intercalation structure and the thermal decomposition properties of as-synthesized SA-ZnAl-LDHs material.
基金supported by the National Natural Science Foundation of China(Nos.11805101 and 11205089)the Jiangsu Engineering Technology Research Center of Environmental Cleaning Materials(No.KFK1504)the Environmental Protection Research Project of Jiangsu Province(No.JSZC-D2018-044).
文摘To further improve the removal ability of layered double hydroxide(LDH) for iodide(I^-) anions from wastewater, we prepared hierarchically porous Cu5Mg10Al5-LDH and used as a matrix for in suit growth of Cu/Cu2O on its surface, forming Cu/Cu2O-LDH, which was characterized and applied as an adsorbent.Results displayed high I^-saturation uptake capability(137.8 mg/g) of Cu/Cu2O-LDH compared with Cu5Mg10Al5-LDH(26.4 mg/g) even thermal activated LDH(76.1 mg/g).Thermodynamic analysis showed that the reaction between I^-anions and Cu/Cu2O-LDH is a spontaneous and exothermic.Uptake kinetics analysis exhibited that adsorption equilibrium can be reached after 265 min.Additionally, the adsorbent showed satisfactory selectivity in the presence of competitive anions(e.g., SO4^2-), and could achieve good adsorption performance in a wide pH range of 3–8.A cooperative adsorption mechanism was proposed on the basis of the following two aspects:(1) ion exchange between iodide and interlayer anions;(2) the adsorption performance of Cu, Cu(Ⅱ) and Cu2O for I^-.Meanwhile, the difference between the adsorption mechanism of Cu/Cu2O-LDH, Cu5Mg10Al5-LDH and Cu5Mg10Al5-CLDH adsorbents was also elaborated and verified.
基金This work is supported by Science and Technology Development Project of Xinjiang Production and Construction Corps (No. 2021DB005)Project of Department of Transport of Shaanxi Province (21-53K)+1 种基金the Central Plains Thousand People Plan of Henan Province (204200510004)the Fundamental Research Funds for the Central Universities, CHD (300102312724, 300102312402). The authors also thank to the reviewers for their valuable comments and suggestions concerning our manuscript.
文摘Salt freezing damage has severe impacts on durability of cement-based materials(CBMs).Calcined layered double hydroxide(CLDH),as an efficient environmental-friendly adsorption material,can impart excellent salt freezing resistance to CBMs.In this work,salt freezing resistance improvement of CBMs incorporated with CLDH was experimentally evaluated by chloride binding capacity,mass loss rate,relative dynamic elastic modulus,setting time,compressive strength,and micro structure tests.Beside these,the salt freezing damage model was established to effectively express the quantitative relationship between influencing factors and evaluation indexes of the salt freezing resistance of CBMs.Results show that CLDH can reconstruct its original layered structure to form reconstructed layered double hydroxide(RLDH).RLDH combines with chloride ions to form RLDH-Cl recrystallization,which can improve chloride binding capacity and pore structures of CBMs to relieve the salt freezing damage.The salt freezing damage model indicates that the suitable CLDH content can evidently alleviate the salt freezing damage,which facilitates the quantitative analysis of the effect of CLDH on the salt freezing resistance of CBMs.
基金This work was supported by the National Natural Science Foundation of China (NSFC), the National Key Research and Development Project (Nos. 2016YFF0204402 and 2016YFC0801302), the Program for Changjiang Scholars, and innovative Research Team in the University, and the Fundamental Research Funds for the Central Universities, and the long term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China. S. S. gratefully acknowledges Villum Foundation.
文摘Nickel-iron layered double hydroxide (NiFe-LDH) nanosheets have shown optimal oxygen evolution reaction (OER) performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential (high reducing ability), such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential (low reducing ability), such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 20071007)and the Foundation for University Key Teachers by the Ministry of Education of China.
文摘Research progresses in the layered double hydroxides [M2+(1-x)M3+x(OH)2]x+An-x/n.mH2O intercalatedwith metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are mainly intercalated with polyoxometalate (POM) ions, a LiAl-LDH photochemical assembly containing TiO2 and CH3(CH2)12COO- anions, together with Zn(TPPC) (porphy-rin derivate) and macrocyclic ligand-containing porphyrin derivate anions. Emphasis is put on the synthesis methods for intercalation of the anions into the interlayer regions, the characterization techniques and structures for the layeredcompounds and the newest research progress in the fields such as catalysis. The review also forecasts the prospects of the field.