Three-dimensional(3D) flower-like Co–Al layered double hydroxide(Co–Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water an...Three-dimensional(3D) flower-like Co–Al layered double hydroxide(Co–Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water and butyl alcohol. Owing to the unique hierarchical structure and modification by butyl alcohol, the electrochemical stability and the charge/mass transport of the Co–Al-LDHs was improved. When used in supercapacitors, the obtained Co–Al-LDHs deliver a high specific capacitance of 838 Fg^(-1) at a current density of 1 Ag^(-1)and excellent rate performance(753 Fg^(-1) at 30 Ag^(-1) and 677 Fg^(-1) at 100 Ag^(-1)), as well as excellent cycling stability with 95% retention of the initial capacitance even after 20,000 cycles at a current density of 5 Ag^(-1). This work provides a promising alternative strategy to enhance the electrochemical properties of supercapacitors.展开更多
Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(...Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.展开更多
Adsorption of 2, 4, 6-trichlorophenol（TCP） onto the calcined Mg/Al-CO_3 layered double hydroxide（CLDH） was investigated. The prepared Mg/Al-CO_3 layered double hydroxide（LDH） and CLDH were characterized by powde...Adsorption of 2, 4, 6-trichlorophenol（TCP） onto the calcined Mg/Al-CO_3 layered double hydroxide（CLDH） was investigated. The prepared Mg/Al-CO_3 layered double hydroxide（LDH） and CLDH were characterized by powder X-ray diffraction（XRD） and thermo gravimetric analyzer-differential scanning calorimeters（TG-DSC）. Moreover, 2,4,6-trichlorophenol（TCP） was removed effectively（94.7% of removal percentage in 9h） under the optimized experimental conditions. The adsorption kinetics data fitted the pseudosecond-order model well. The Freundlich, Langmuir, and Tempkin adsorption models were applied to the experimental equilibrium adsorption data at different temperatures of solution. The adsorption data fitted the Freundlieh adsorption isotherm with good values of the correlation coefficient. A mechanism of the adsorption process is proposed according to the intraparticle diffusion model, which indicates that the overall rate of adsorption can be described as three steps.展开更多
A homogeneous better-dispersed ultrathin nanosheets（ca. 5 nm） of cobalt-nickel layered double hydroxides（LDH） supported on nickel foam scaffold was synthesized using controllable electrodeposition approach for hig...A homogeneous better-dispersed ultrathin nanosheets（ca. 5 nm） of cobalt-nickel layered double hydroxides（LDH） supported on nickel foam scaffold was synthesized using controllable electrodeposition approach for high efficiency electrode materials of new supercapacitor. The morphology and electrochemical performances of the samples can be controlled by adjusting the precursor ratio, i.e., Ni（OAc）2/Co（NO3）2 molar ratio in the electrodeposition approach. With the increase of this molar ratio, the electrochemical performances give a volcano trend. When the optimized molar ratio is 0.64/0.36, the hybrid delivered a high specific capacitance of 1587.5 F g-1 at a current density of 0.5 A g-1, with good rate capability（1155 F g-1 was retained even at 10 A g-1） and a robust recycle stability（remaining 91.5% after 1000 cycles at 5 A g-1）. The good performance could be attributed to the enlarged interlayer spacing, ultrathin nanosheets and synergistic effects between Co（OH）2 and Ni（OH）2. Furthermore, an asymmetric supercapacitor with a high energy density of 34.5 Wh kg-1 at 425 W kg-1 and excellent cycling stability of 85.4% after 5000 charge-discharge cycles at 2 A g-1 was fabricated. We believe that this fantabulous new electrode material would have encouraging applications in electrochemical energy storage and a wide readership.展开更多
In this work a novel strategy has been developed to prepare well-dispersed amine-functionalized SiO2 nanodot-coated layered double hydroxide nano- composite （NH2-SiO2@LDH） via electrostatic interactions and condensa...In this work a novel strategy has been developed to prepare well-dispersed amine-functionalized SiO2 nanodot-coated layered double hydroxide nano- composite （NH2-SiO2@LDH） via electrostatic interactions and condensation of （3-aminopropyl）triethoxysilane （APTES）. This nanocomposite system is well dispersed in culture media and phosphate buffered saline, and exhibits low cytotoxicity and good biocompatibility. The fluorescence microscopy images and flow cytometry data indicate that such an NH2-SiO2@LDH nanocomposite is able to efficiently deliver small interfering RNA （siRNA） into the U2OS cell line to inhibit cell proliferation. Thus, NH2-SiOR@LDH nanocomposite has a great potential as a nanocarrier for efficient gene delivery.展开更多
Seawater electrolysis is an extremely attractive approach for harvesting clean hydrogen energy,but detrimental chlorine species(i.e.,chloride and hypochlorite)cause severe corrosion at the anode.Here,we report our rec...Seawater electrolysis is an extremely attractive approach for harvesting clean hydrogen energy,but detrimental chlorine species(i.e.,chloride and hypochlorite)cause severe corrosion at the anode.Here,we report our recent finding that benzoate anions-intercalated NiFe-layered double hydroxide nanosheet on carbon cloth(BZ-NiFe-LDH/CC)behaves as a highly efficient and durable monolithic catalyst for alkaline seawater oxidation,affords enlarged interlayer spacing of LDH,inhibits chlorine(electro)chemistry,and alleviates local pH drop of the electrode.It only needs an overpotential of 320 mV to reach a current density of 500 mA·cm^(−2)in 1 M KOH.In contrast to the fast activity decay of NiFe-LDH/CC counterpart during long-term electrolysis,BZ-NiFe-LDH/CC achieves stable 100-h electrolysis at an industrial-level current density of 500 mA·cm^(−2)in alkaline seawater.Operando Raman spectroscopy studies further identify structural changes of disorderedδ(NiIII-O)during the seawater oxidation process.展开更多
A clean method for preparing layered double hydroxides （LDHs） has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reactions. The reactions were carried...A clean method for preparing layered double hydroxides （LDHs） has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reactions. The reactions were carried out under hydrothermal conditions in either a high pressure autoclave or a microwave digester. The compositions, structural parameters and thermal behavior of the resulting LDHs are very similar to those of materials produced by using the separate nucleation and aging steps （SNAS） method. The major advantage of the new method is that no by-product is produced, so that filtration and washing processes are unnecessary. The consequent reduction in water consumption is beneficial to the environment.展开更多
The efficient conversion of CO_(2) into hydrocarbon fuels(CH_(4))with high selectivity is considered as a great challenge in photocatalysis owing to the multiple-electron transfer pathway and competitive H_(2) generat...The efficient conversion of CO_(2) into hydrocarbon fuels(CH_(4))with high selectivity is considered as a great challenge in photocatalysis owing to the multiple-electron transfer pathway and competitive H_(2) generation.Herein,we developed carbon dots(CDs)-modulated S-scheme heterojunction of CDs/NiAl-LDH@In_(2)O_(3)(C-DH@IN)through a facile in-situ hydrothermal method.Thanks to the multi-shell nanotube structure,the C-DH@IN shows an enhanced CH_(4) evolution rate of 10.67μmol h^(-1)g^(-1)and higher selectivity of CH_(4)(85.70%)compared with In_(2)O_(3) and Ni Al-LDH@In_(2)O_(3) binary catalyst in the pure water without sacrificial agent.Electron spin resonance(ESR)and in situ Fourier transform infrared spectra verify that the constructed S-scheme heterojunction can possess the strong redox capability and the HCOOand CH_(3)O-as critical intermediates play an important role in selective CO_(2) reduction to generate CH_(4).Furthermore,CDs with superior photoabsorption can boost the electron transfer and absorb H^(+),thus improving the integration of H^(+)and CO_(2) molecule.Therefore,this work emphasizes a facile strategy to achieve efficient CO_(2)-to-CH_(4) conversion based on construction of CDs-based heterojunction catalysts.展开更多
Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the sing...Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the single loss mechanism vastly restrict the application.Hence,it’s an effective strat-egy to solve these issues by introducing magnetic components.Notably,layer double hydroxide(LDH)is an appropriate template to obtain magnetic component materials.Considering that ferromagnetic met-als such as Fe,Co,Ni,and their corresponding metal oxides are usually treated as magnetic compo-nents which are promising candidates for EMW absorption materials.Therefore,in this work,a FeNi-layered double hydroxide-reduced graphene oxide(FeNi-LDH-rGO)aerogel was synthesized through a series of processes such as electrostatic self-assembly,hydrothermal,freeze-drying,and annealing.The magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell nanospheres were obtained from FeNi-LDH precursor,anchoring on rGO nanosheets after the annealing treatment.Furthermore,the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption prop-erty and impedance matching performance were explored.As a consequence,the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth(EAB)of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt%and a low density of 4.4 mg/cm^(3).In conclusion,the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell struc-ture nanospheres.展开更多
In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology o...In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology of LDH films were investigated by X-ray diffraction(XRD),Fourier transform infrared(FTIR)and scanning electronic microscopy(SEM),and the corrosion behavior of LDH films was further studied by electrochemical impedance spectroscopy(EIS).The influence of Al^(3+)concentration on the growth behavior of LDH was also discussed.The results indicated that the nest-like structure of MgAl-LDH film was composed of interconnected MgAl-LDH nanosheets.Besides,the LDH obtained in0.032 mol·L^(-1)Al^(3+)solution,possessing dense laminated structure,could effectively seal the porous surface of anodic oxide film.EIS results revealed that the samples coated with LDH films showed a higher electrochemical impedance,and thus,the corrosion resistance of samples coated with LDH films was signally improved compared with the anodized alloy.展开更多
Graphite phase carbon nitride(g-C_(3)N_(4))is a promising catalyst for artificial photocatalytic carbon dioxide(CO_(2))reduction.However,the fast carrier recombination and the inadequacy of the CO_(2)reduction active ...Graphite phase carbon nitride(g-C_(3)N_(4))is a promising catalyst for artificial photocatalytic carbon dioxide(CO_(2))reduction.However,the fast carrier recombination and the inadequacy of the CO_(2)reduction active site in g-C_(3)N_(4)block the escalation of the perfor-mance.In this work,NiCo layered double hydroxide(NiCo LDH)nanoflowers were self-assembled with ultrathin graphite phase carbon nitride(g-C_(3)N_(4))by an ultrasonic stirring strategy utilizing the Zeta potential difference.The formed NiCo LDH/ultrathin g-C_(3)N_(4)nanosheets(LDH-CN)photocatalysts own the merits of rich active sites and Z-scheme heterojunction,which lead to the enhanced CO_(2)reduction activity and selectivity.The highest yields of CO and CH_(4)were 114.24 and 26.48μmol·h^(-1)·g^(-1),which were much greater than those of g-C_(3)N_(4)and LDH.Meanwhile,the enhanced selectivity for CO confirmed the strong redox ability in the LDH-CN caused by the Z-scheme.The heterojunction-induced built-in electrical field can promote the separation and migration of photoinduced electrons and holes.This study provides a theoretical basis for designing high-performance photocatalysts.展开更多
Modifying electrocatalysts nanostructures and tuning their electronic properties through defects-oriented synthetic strategies are:essential to improve the oxygen evolution reaction(OER)performance of electrocatalysts...Modifying electrocatalysts nanostructures and tuning their electronic properties through defects-oriented synthetic strategies are:essential to improve the oxygen evolution reaction(OER)performance of electrocatalysts.Current synthetic strategies about.electrocatalysts mainly target the single or double structural defects,while the researches about the synergistic effect of multiple'structural defects are rare.In this work,the ultrathin NiFe layered double hydroxide nanosheets with a holey structure,oxygen;vacancies and Ni^(3+)defects on nickel foam(NiFe-LDH-NSs/NF)are prepared by employing a simple and green H202-assisted etching 1 method.The synergistic effect ofthe above three defects leads to the exposure of.more active sites and significant improvement of:the intrinsic activity.The optimized catalyst exhibits an excellent OER performance with an extraordinarily low overpotential of 170 mV;at to mA·cm^(-2) and a small Tafel slope of 39.3 mV·dec^(-1) in 1 M KOH solution.Density functional theory calculations reveal this OER;performance arises from pseudo re-oxidized metal-stable Ni^(3+)near oxygen vacancies(O_(vac)),which suppresses 3d-e_(g) of Ni-site and!elevates d-band center towards the competitively low electron-transferbarrier.This work provides a new insight to fabricate advanced electrocatalysts for renewable energy conversion technologies.展开更多
基金supported by the National Basic Research Program of China(2014CB239702)Research project of environmental protection in Jiangsu province(2016060)Science and Technology Commission of Shanghai Municipality(14DZ2250800)
文摘Three-dimensional(3D) flower-like Co–Al layered double hydroxide(Co–Al-LDH) architectures composed of atomically thin nanosheets were successfully synthesized via a hydrothermal method in a mixed solvent of water and butyl alcohol. Owing to the unique hierarchical structure and modification by butyl alcohol, the electrochemical stability and the charge/mass transport of the Co–Al-LDHs was improved. When used in supercapacitors, the obtained Co–Al-LDHs deliver a high specific capacitance of 838 Fg^(-1) at a current density of 1 Ag^(-1)and excellent rate performance(753 Fg^(-1) at 30 Ag^(-1) and 677 Fg^(-1) at 100 Ag^(-1)), as well as excellent cycling stability with 95% retention of the initial capacitance even after 20,000 cycles at a current density of 5 Ag^(-1). This work provides a promising alternative strategy to enhance the electrochemical properties of supercapacitors.
基金support from the National Natural Science Foundation of China(51402100,21905088,21573066 and U19A2017)the Provincial Natural Science Foundation of Hunan(2020JJ5044,2022JJ10006)。
文摘Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.
基金Funded by the National Natural Science Foundation of China(No.21476269)
文摘Adsorption of 2, 4, 6-trichlorophenol（TCP） onto the calcined Mg/Al-CO_3 layered double hydroxide（CLDH） was investigated. The prepared Mg/Al-CO_3 layered double hydroxide（LDH） and CLDH were characterized by powder X-ray diffraction（XRD） and thermo gravimetric analyzer-differential scanning calorimeters（TG-DSC）. Moreover, 2,4,6-trichlorophenol（TCP） was removed effectively（94.7% of removal percentage in 9h） under the optimized experimental conditions. The adsorption kinetics data fitted the pseudosecond-order model well. The Freundlich, Langmuir, and Tempkin adsorption models were applied to the experimental equilibrium adsorption data at different temperatures of solution. The adsorption data fitted the Freundlieh adsorption isotherm with good values of the correlation coefficient. A mechanism of the adsorption process is proposed according to the intraparticle diffusion model, which indicates that the overall rate of adsorption can be described as three steps.
基金supported by the National Natural Science Foundation of China (21476145)
文摘A homogeneous better-dispersed ultrathin nanosheets（ca. 5 nm） of cobalt-nickel layered double hydroxides（LDH） supported on nickel foam scaffold was synthesized using controllable electrodeposition approach for high efficiency electrode materials of new supercapacitor. The morphology and electrochemical performances of the samples can be controlled by adjusting the precursor ratio, i.e., Ni（OAc）2/Co（NO3）2 molar ratio in the electrodeposition approach. With the increase of this molar ratio, the electrochemical performances give a volcano trend. When the optimized molar ratio is 0.64/0.36, the hybrid delivered a high specific capacitance of 1587.5 F g-1 at a current density of 0.5 A g-1, with good rate capability（1155 F g-1 was retained even at 10 A g-1） and a robust recycle stability（remaining 91.5% after 1000 cycles at 5 A g-1）. The good performance could be attributed to the enlarged interlayer spacing, ultrathin nanosheets and synergistic effects between Co（OH）2 and Ni（OH）2. Furthermore, an asymmetric supercapacitor with a high energy density of 34.5 Wh kg-1 at 425 W kg-1 and excellent cycling stability of 85.4% after 5000 charge-discharge cycles at 2 A g-1 was fabricated. We believe that this fantabulous new electrode material would have encouraging applications in electrochemical energy storage and a wide readership.
文摘In this work a novel strategy has been developed to prepare well-dispersed amine-functionalized SiO2 nanodot-coated layered double hydroxide nano- composite （NH2-SiO2@LDH） via electrostatic interactions and condensation of （3-aminopropyl）triethoxysilane （APTES）. This nanocomposite system is well dispersed in culture media and phosphate buffered saline, and exhibits low cytotoxicity and good biocompatibility. The fluorescence microscopy images and flow cytometry data indicate that such an NH2-SiO2@LDH nanocomposite is able to efficiently deliver small interfering RNA （siRNA） into the U2OS cell line to inhibit cell proliferation. Thus, NH2-SiOR@LDH nanocomposite has a great potential as a nanocarrier for efficient gene delivery.
基金supported by the National Natural Science Foundation of China(No.21575137).
文摘Seawater electrolysis is an extremely attractive approach for harvesting clean hydrogen energy,but detrimental chlorine species(i.e.,chloride and hypochlorite)cause severe corrosion at the anode.Here,we report our recent finding that benzoate anions-intercalated NiFe-layered double hydroxide nanosheet on carbon cloth(BZ-NiFe-LDH/CC)behaves as a highly efficient and durable monolithic catalyst for alkaline seawater oxidation,affords enlarged interlayer spacing of LDH,inhibits chlorine(electro)chemistry,and alleviates local pH drop of the electrode.It only needs an overpotential of 320 mV to reach a current density of 500 mA·cm^(−2)in 1 M KOH.In contrast to the fast activity decay of NiFe-LDH/CC counterpart during long-term electrolysis,BZ-NiFe-LDH/CC achieves stable 100-h electrolysis at an industrial-level current density of 500 mA·cm^(−2)in alkaline seawater.Operando Raman spectroscopy studies further identify structural changes of disorderedδ(NiIII-O)during the seawater oxidation process.
文摘A clean method for preparing layered double hydroxides （LDHs） has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reactions. The reactions were carried out under hydrothermal conditions in either a high pressure autoclave or a microwave digester. The compositions, structural parameters and thermal behavior of the resulting LDHs are very similar to those of materials produced by using the separate nucleation and aging steps （SNAS） method. The major advantage of the new method is that no by-product is produced, so that filtration and washing processes are unnecessary. The consequent reduction in water consumption is beneficial to the environment.
基金supported by the National Natural Science Foundation of China(Nos.21876015,21703019)Qinglan Project Foundation of Jiangsu Province。
文摘The efficient conversion of CO_(2) into hydrocarbon fuels(CH_(4))with high selectivity is considered as a great challenge in photocatalysis owing to the multiple-electron transfer pathway and competitive H_(2) generation.Herein,we developed carbon dots(CDs)-modulated S-scheme heterojunction of CDs/NiAl-LDH@In_(2)O_(3)(C-DH@IN)through a facile in-situ hydrothermal method.Thanks to the multi-shell nanotube structure,the C-DH@IN shows an enhanced CH_(4) evolution rate of 10.67μmol h^(-1)g^(-1)and higher selectivity of CH_(4)(85.70%)compared with In_(2)O_(3) and Ni Al-LDH@In_(2)O_(3) binary catalyst in the pure water without sacrificial agent.Electron spin resonance(ESR)and in situ Fourier transform infrared spectra verify that the constructed S-scheme heterojunction can possess the strong redox capability and the HCOOand CH_(3)O-as critical intermediates play an important role in selective CO_(2) reduction to generate CH_(4).Furthermore,CDs with superior photoabsorption can boost the electron transfer and absorb H^(+),thus improving the integration of H^(+)and CO_(2) molecule.Therefore,this work emphasizes a facile strategy to achieve efficient CO_(2)-to-CH_(4) conversion based on construction of CDs-based heterojunction catalysts.
文摘Graphene has been extensively utilized in the domain of electromagnetic wave(EMW)absorption ma-terials because of its excellent electrical conductivity.However,the inferior impedance matching per-formance and the single loss mechanism vastly restrict the application.Hence,it’s an effective strat-egy to solve these issues by introducing magnetic components.Notably,layer double hydroxide(LDH)is an appropriate template to obtain magnetic component materials.Considering that ferromagnetic met-als such as Fe,Co,Ni,and their corresponding metal oxides are usually treated as magnetic compo-nents which are promising candidates for EMW absorption materials.Therefore,in this work,a FeNi-layered double hydroxide-reduced graphene oxide(FeNi-LDH-rGO)aerogel was synthesized through a series of processes such as electrostatic self-assembly,hydrothermal,freeze-drying,and annealing.The magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell nanospheres were obtained from FeNi-LDH precursor,anchoring on rGO nanosheets after the annealing treatment.Furthermore,the effects of different mass ratios of LDH to GO as well as different annealing temperatures of LDH-rGO aerogel on the EMW absorption prop-erty and impedance matching performance were explored.As a consequence,the fabricated ultralight 600LDH-rGO 2:1 aerogel shows a broad effective absorption bandwidth(EAB)of 7.04 GHz at a thickness of 2.3 mm with a low filling content of only 6 wt%and a low density of 4.4 mg/cm^(3).In conclusion,the synthetic LDH-rGO aerogels offer an effective strategy for preparing EMW absorption materials that own three-dimensional porous network structure and unique magnetic NiFe_(2)O_(4)@FeNi_(3)core-shell struc-ture nanospheres.
基金supported by the National Key Research and Development Program of China(2016YFB0301100)the National Natural Science Foundation of China(51701029,51531002,51474043)+2 种基金China Postdoctoral Science Foundation Funded Project(2017M620410,2018T110942)the ChongqingPostdoctoral Scientific Research Foundation(Xm2017010)the Chongqing Research Program of Basic Research and Frontier Technology(cstc2016jcyjA0388,cstc2017jcyjBX0040)。
文摘In situ-grown Mg-Al layered double hydroxide(LDH)films were obtained on an anodized AZ31 substrate,with the immersion of sample in different concentrations of Al^(3+)solution.The structure,composition and morphology of LDH films were investigated by X-ray diffraction(XRD),Fourier transform infrared(FTIR)and scanning electronic microscopy(SEM),and the corrosion behavior of LDH films was further studied by electrochemical impedance spectroscopy(EIS).The influence of Al^(3+)concentration on the growth behavior of LDH was also discussed.The results indicated that the nest-like structure of MgAl-LDH film was composed of interconnected MgAl-LDH nanosheets.Besides,the LDH obtained in0.032 mol·L^(-1)Al^(3+)solution,possessing dense laminated structure,could effectively seal the porous surface of anodic oxide film.EIS results revealed that the samples coated with LDH films showed a higher electrochemical impedance,and thus,the corrosion resistance of samples coated with LDH films was signally improved compared with the anodized alloy.
基金financially supported by the National Natural Science Foundation of China (Nos.22005123, 21776118,22178152 and 22008095)Jiangsu University Foundation (No.20JDG16)+4 种基金Jiangsu Funds for Distinguished Young Scientists (No.BK20190045)the Special Foundation of China Postdoctoral (No.2020TQ0127)Jiangsu Province Postdoctoral Science Foundation (Nos.2021K396C and 2021K382C)Jiangsu Agricultural Science and Technology Independent Innovation Fund (No.CX (21)3067)the Postgraduate High-tech Research Key Laboratory of Zhenjiang (No.SS2018002)
文摘Graphite phase carbon nitride(g-C_(3)N_(4))is a promising catalyst for artificial photocatalytic carbon dioxide(CO_(2))reduction.However,the fast carrier recombination and the inadequacy of the CO_(2)reduction active site in g-C_(3)N_(4)block the escalation of the perfor-mance.In this work,NiCo layered double hydroxide(NiCo LDH)nanoflowers were self-assembled with ultrathin graphite phase carbon nitride(g-C_(3)N_(4))by an ultrasonic stirring strategy utilizing the Zeta potential difference.The formed NiCo LDH/ultrathin g-C_(3)N_(4)nanosheets(LDH-CN)photocatalysts own the merits of rich active sites and Z-scheme heterojunction,which lead to the enhanced CO_(2)reduction activity and selectivity.The highest yields of CO and CH_(4)were 114.24 and 26.48μmol·h^(-1)·g^(-1),which were much greater than those of g-C_(3)N_(4)and LDH.Meanwhile,the enhanced selectivity for CO confirmed the strong redox ability in the LDH-CN caused by the Z-scheme.The heterojunction-induced built-in electrical field can promote the separation and migration of photoinduced electrons and holes.This study provides a theoretical basis for designing high-performance photocatalysts.
基金supports from the National Natural Science Foundation of China(Nos.21531006 and 21773163)the State Key Laboratory of Organometallic Chemistry of Shanghai Institute of Organic Chemistry(No.KF2021005)Collaborative Innovation Center of Suzhou Nano Science and Technology,the“Priority Academic Program Development”of Jiangsu Higher Education Institutions,and the Project of Scientific and Technologic Infrastructure of Suzhou(No.SZS201905).
文摘Modifying electrocatalysts nanostructures and tuning their electronic properties through defects-oriented synthetic strategies are:essential to improve the oxygen evolution reaction(OER)performance of electrocatalysts.Current synthetic strategies about.electrocatalysts mainly target the single or double structural defects,while the researches about the synergistic effect of multiple'structural defects are rare.In this work,the ultrathin NiFe layered double hydroxide nanosheets with a holey structure,oxygen;vacancies and Ni^(3+)defects on nickel foam(NiFe-LDH-NSs/NF)are prepared by employing a simple and green H202-assisted etching 1 method.The synergistic effect ofthe above three defects leads to the exposure of.more active sites and significant improvement of:the intrinsic activity.The optimized catalyst exhibits an excellent OER performance with an extraordinarily low overpotential of 170 mV;at to mA·cm^(-2) and a small Tafel slope of 39.3 mV·dec^(-1) in 1 M KOH solution.Density functional theory calculations reveal this OER;performance arises from pseudo re-oxidized metal-stable Ni^(3+)near oxygen vacancies(O_(vac)),which suppresses 3d-e_(g) of Ni-site and!elevates d-band center towards the competitively low electron-transferbarrier.This work provides a new insight to fabricate advanced electrocatalysts for renewable energy conversion technologies.
