Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide(ZnO)nanospheres and zinc manganese oxide(ZnMn_(2)O_(4))nanowires were produced by a hydrothermal method,and supersoni-cally sprayed together...Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide(ZnO)nanospheres and zinc manganese oxide(ZnMn_(2)O_(4))nanowires were produced by a hydrothermal method,and supersoni-cally sprayed together with reduced graphene oxide(rGO)nanosheets onto Ni foil to fabricate flexible su-percapacitors.The supersonic impact facilitated the exfoliation of the rGO nanosheets,thereby increasing the surface area and adhesion of the composite particles to the substrate.The rGO nanosheets were vertically aligned during the supersonic impact and formed localized zones,enabling optimal accommodation of the ZnO/ZnMn_(2)O_(4)particles.This localization,with the addition of rGO,reduced the agglomeration of ZnO/ZnMn_(2)O_(4)particles.The molar concentration of MnSO_(4)used in the synthesis of ZnO/ZnMn_(2)O_(4)was varied from 0.05 to 0.15 mol/L to determine the optimal MnSO_(4)concentration that would result in the highest energy storage capacitance.The unique nanostructure of ZnO/ZnMn_(2)O_(4)and the self-alignment of rGO sheets facilitated a favorable environment for high energy storage capability with a specific capaci-tance of 276.3 mF·cm^(−2)at a current density of 0.5 mA·cm^(−2)and an energy density of 98.2μWh·cm^(−2)at a power density of 1600μW·cm^(−2).The width of the potential window was increased to 1.2 V,imply-ing a significant increase in the energy storage capability of the supercapacitor.Capacitance retention of 88%was achieved after 10,000 charge/discharge cycles for the supercapacitor fabricated using an optimal MnSO_(4)concentration(0.10 mol/L)during the composite synthesis.展开更多
In this study,the hydrogen evolution performance of CdS nanorods is improved using ZnCo_(2)O_(4).ZnCo_(2)O_(4)nanospheres are synthesized using the hydrothermal and calcination methods,and CdS nanorods are synthesized...In this study,the hydrogen evolution performance of CdS nanorods is improved using ZnCo_(2)O_(4).ZnCo_(2)O_(4)nanospheres are synthesized using the hydrothermal and calcination methods,and CdS nanorods are synthesized using the solvothermal method.From the perspective of morphology,numerous CdS nanorods are anchored on the ZnCo_(2)O_(4)microspheres.According to the experimental results of photocatalytic hydrogen evolution,the final hydrogen evolution capacity of 7417.5μmol·g^(-1)·h^(-1)is slightly more than two times that of the single CdS,which proves the feasibility of our study.Through various characterization methods,it is proved that the composite sample has suitable optoelectronic properties.In addition,ZnCo_(2)O_(4)itself exhibits good conductivity and low impedance,which shortens the charge-transfer path.Overall,the introduction of ZnCo_(2)O_(4)expands the adsorption range of light and improves the performance of photocatalytic hydrogen evolution.This design can provide reference for developing high-efficiency photocatalysts.展开更多
Due to the involvement of four-electron transfer process at photoanode,water oxidation is the ratelimiting step in water splitting reaction.To settle this dilemma,ZnCo_(2)O_(4)nanoparticles are combined with BiVO_(4)t...Due to the involvement of four-electron transfer process at photoanode,water oxidation is the ratelimiting step in water splitting reaction.To settle this dilemma,ZnCo_(2)O_(4)nanoparticles are combined with BiVO_(4)to form a p-n ZnCo_(2)O_(4)/BiVO;heterojunction photoanode,which is proved by an input voltage-output current test.The built-in electric field formed within the heterojunction structure promotes the effective separation of electrons and holes.ZnCo_(2)O_(4)is also an effective water oxidation cocatalyst,since it could cause the holes entering the electrode/electrolyte interface rapidly for the subsequent water oxidation reaction.The photocurrent density of ZnCo_(2)O_(4)/BiVO_(4)composite photoanode reaches 3.0 mA/cm^(2) at 1.23 V vs.RHE in 0.5 mol/L sodium sulfate under AM 1.5 G simulated sunlight,about 2.1 times greater than that of BiVO_(4)(1.4 mA/cm^(2)).These results suggest the potential of ZnCo_(2)O_(4)nanoparticles for improving photoelectrochemical water splitting anode materials.展开更多
The two-dimensional(2D)nanosheet zinc cobaltate(ZnCo_(2)O_(4))was added into polyether block amide(Pebax)matrix to prepare mixing matrix membrane(MMM)for separating carbon dioxide(CO_(2))/methane(CH4)gas mixture.The 2...The two-dimensional(2D)nanosheet zinc cobaltate(ZnCo_(2)O_(4))was added into polyether block amide(Pebax)matrix to prepare mixing matrix membrane(MMM)for separating carbon dioxide(CO_(2))/methane(CH4)gas mixture.The 2D porous ZnCo_(2)O_(4)nanosheets were composed of chemically interconnected metal oxide nanoparticles.The ZnCo_(2)O_(4)nanoparticles in the nanosheets constructed large-quantity pores of 11.78 nm and provided abundant transfer channels for gas molecule.Moreover,the synergistic effect of bimetallic Zn^(2+)and Co^(2+)would promote the generation of oxygen vacancies(Oδ-),which could provide more CO_(2)(Cδ+)adsorption sites,thereby increased the selectivity of the membrane.The large aspect ratio of the ultra-thin ZnCo_(2)O_(4)nanosheets showed better dispersion in the membrane.The pure gas separation performance data showed the CO_(2)permeability and CO_(2)/CH4 selectivity of Pebax/ZnCo_(2)O_(4)membrane were 139.10 Barrer and 15.38,respectively,when the filling amount was 0.5 wt%.Compared with pure Pebax membrane,the separation performance(permeability and selectivity)were increased with 165.67%and 75.57%,respectively.展开更多
Un-doped and ZnAl_(x)O_(1.5x+1):0.1 mol%Tb^(3+)(ZAOT)nano-powders were synthesized via citrate sol-gel method.The AIx moles were varied in the range of 0.25≤x≤5.0.The X-ray powder diffraction(XRD)data reveal that fo...Un-doped and ZnAl_(x)O_(1.5x+1):0.1 mol%Tb^(3+)(ZAOT)nano-powders were synthesized via citrate sol-gel method.The AIx moles were varied in the range of 0.25≤x≤5.0.The X-ray powder diffraction(XRD)data reveal that for x<1.5,the prepared samples crystal structure consists of mixed phases of the cubic ZnAl_(2)O_(4) and hexagonal ZnO phases,while for x>1.5 the structure consists of single phase of cubic ZnAl_(2)O_(4).The Raman and Fourier-trans form infrared(FTIR)vibrational spectroscopy show the presence of vibrations emanating ZnAl_(2)O_(4) spinel.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)show the presence of irregular sphere at x>2.0 attributed to ZnAl_(2)O_(4).The photoluminescence(PL)spectroscopy reveals emissions from both the host and Tb^(3+)transitions.Emissions from Tb^(3+)are observed at 382,414,439,458 nm and 489,545,585,621 nm,which were attributed to the^(5)D_(3)→^(7)F_(6,5,4,2) and ^(5^)D_(4)→^(7)F_(6,5,4,3),respectively.The results confirm that the Tb^(3+)occupation site depends on the Alx moles.The International Commission on Illumination(CIE)colour chromaticity shows that the emission colour can be tuned from blue to green by varying the AIx moles.展开更多
基金supported by the National Natural Science Foundation of China(50572051,50672041)National High-Tech Research and Development Program of China(863)(2006AA03Z218)National Key Basic Research Program of China(973)(2007CB607504)~~
基金This work was financially supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(Nos.NRF-2020R1A5A1018153,NRF-2021R1A2C2010530,and 2020K1A3A1A74114847)This research was also supported by Technology R&D Project through the Korea Health Industry Development Institute(KHIDI),funded by the Ministry of Health&Wel-fare,Republic of Korea(No.HI21C0049010021).
文摘Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide(ZnO)nanospheres and zinc manganese oxide(ZnMn_(2)O_(4))nanowires were produced by a hydrothermal method,and supersoni-cally sprayed together with reduced graphene oxide(rGO)nanosheets onto Ni foil to fabricate flexible su-percapacitors.The supersonic impact facilitated the exfoliation of the rGO nanosheets,thereby increasing the surface area and adhesion of the composite particles to the substrate.The rGO nanosheets were vertically aligned during the supersonic impact and formed localized zones,enabling optimal accommodation of the ZnO/ZnMn_(2)O_(4)particles.This localization,with the addition of rGO,reduced the agglomeration of ZnO/ZnMn_(2)O_(4)particles.The molar concentration of MnSO_(4)used in the synthesis of ZnO/ZnMn_(2)O_(4)was varied from 0.05 to 0.15 mol/L to determine the optimal MnSO_(4)concentration that would result in the highest energy storage capacitance.The unique nanostructure of ZnO/ZnMn_(2)O_(4)and the self-alignment of rGO sheets facilitated a favorable environment for high energy storage capability with a specific capaci-tance of 276.3 mF·cm^(−2)at a current density of 0.5 mA·cm^(−2)and an energy density of 98.2μWh·cm^(−2)at a power density of 1600μW·cm^(−2).The width of the potential window was increased to 1.2 V,imply-ing a significant increase in the energy storage capability of the supercapacitor.Capacitance retention of 88%was achieved after 10,000 charge/discharge cycles for the supercapacitor fabricated using an optimal MnSO_(4)concentration(0.10 mol/L)during the composite synthesis.
基金supported by the National Natural Science Foundation of China(Grant No.22062001)the graduate innovation project of North Minzu University(Grant No.YCX22166).
文摘In this study,the hydrogen evolution performance of CdS nanorods is improved using ZnCo_(2)O_(4).ZnCo_(2)O_(4)nanospheres are synthesized using the hydrothermal and calcination methods,and CdS nanorods are synthesized using the solvothermal method.From the perspective of morphology,numerous CdS nanorods are anchored on the ZnCo_(2)O_(4)microspheres.According to the experimental results of photocatalytic hydrogen evolution,the final hydrogen evolution capacity of 7417.5μmol·g^(-1)·h^(-1)is slightly more than two times that of the single CdS,which proves the feasibility of our study.Through various characterization methods,it is proved that the composite sample has suitable optoelectronic properties.In addition,ZnCo_(2)O_(4)itself exhibits good conductivity and low impedance,which shortens the charge-transfer path.Overall,the introduction of ZnCo_(2)O_(4)expands the adsorption range of light and improves the performance of photocatalytic hydrogen evolution.This design can provide reference for developing high-efficiency photocatalysts.
基金financially supported by the National Natural Science Foundation of China (Nos. 21808189 and 21663027)Natural Science Basic Research Fund of Shaanxi Province (No.2020JZ20)Fundamental Research Funds for the Central Universities of Chang’an University (No. 300102299304)。
文摘Due to the involvement of four-electron transfer process at photoanode,water oxidation is the ratelimiting step in water splitting reaction.To settle this dilemma,ZnCo_(2)O_(4)nanoparticles are combined with BiVO_(4)to form a p-n ZnCo_(2)O_(4)/BiVO;heterojunction photoanode,which is proved by an input voltage-output current test.The built-in electric field formed within the heterojunction structure promotes the effective separation of electrons and holes.ZnCo_(2)O_(4)is also an effective water oxidation cocatalyst,since it could cause the holes entering the electrode/electrolyte interface rapidly for the subsequent water oxidation reaction.The photocurrent density of ZnCo_(2)O_(4)/BiVO_(4)composite photoanode reaches 3.0 mA/cm^(2) at 1.23 V vs.RHE in 0.5 mol/L sodium sulfate under AM 1.5 G simulated sunlight,about 2.1 times greater than that of BiVO_(4)(1.4 mA/cm^(2)).These results suggest the potential of ZnCo_(2)O_(4)nanoparticles for improving photoelectrochemical water splitting anode materials.
基金the National High Technology Research and Development Program of China(2012AA03A611)the National Natural Science Foundation of China,grant No.21868031.
文摘The two-dimensional(2D)nanosheet zinc cobaltate(ZnCo_(2)O_(4))was added into polyether block amide(Pebax)matrix to prepare mixing matrix membrane(MMM)for separating carbon dioxide(CO_(2))/methane(CH4)gas mixture.The 2D porous ZnCo_(2)O_(4)nanosheets were composed of chemically interconnected metal oxide nanoparticles.The ZnCo_(2)O_(4)nanoparticles in the nanosheets constructed large-quantity pores of 11.78 nm and provided abundant transfer channels for gas molecule.Moreover,the synergistic effect of bimetallic Zn^(2+)and Co^(2+)would promote the generation of oxygen vacancies(Oδ-),which could provide more CO_(2)(Cδ+)adsorption sites,thereby increased the selectivity of the membrane.The large aspect ratio of the ultra-thin ZnCo_(2)O_(4)nanosheets showed better dispersion in the membrane.The pure gas separation performance data showed the CO_(2)permeability and CO_(2)/CH4 selectivity of Pebax/ZnCo_(2)O_(4)membrane were 139.10 Barrer and 15.38,respectively,when the filling amount was 0.5 wt%.Compared with pure Pebax membrane,the separation performance(permeability and selectivity)were increased with 165.67%and 75.57%,respectively.
基金Project supported by the South African National Research Foundation(NRF)Thuthuka programme(UID 99266,113947)NRF Incentive Funding for Rated Researchers(IPRR)(114924)NRF Black Academics Advancement Programme(BAAP)(138233)。
文摘Un-doped and ZnAl_(x)O_(1.5x+1):0.1 mol%Tb^(3+)(ZAOT)nano-powders were synthesized via citrate sol-gel method.The AIx moles were varied in the range of 0.25≤x≤5.0.The X-ray powder diffraction(XRD)data reveal that for x<1.5,the prepared samples crystal structure consists of mixed phases of the cubic ZnAl_(2)O_(4) and hexagonal ZnO phases,while for x>1.5 the structure consists of single phase of cubic ZnAl_(2)O_(4).The Raman and Fourier-trans form infrared(FTIR)vibrational spectroscopy show the presence of vibrations emanating ZnAl_(2)O_(4) spinel.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)show the presence of irregular sphere at x>2.0 attributed to ZnAl_(2)O_(4).The photoluminescence(PL)spectroscopy reveals emissions from both the host and Tb^(3+)transitions.Emissions from Tb^(3+)are observed at 382,414,439,458 nm and 489,545,585,621 nm,which were attributed to the^(5)D_(3)→^(7)F_(6,5,4,2) and ^(5^)D_(4)→^(7)F_(6,5,4,3),respectively.The results confirm that the Tb^(3+)occupation site depends on the Alx moles.The International Commission on Illumination(CIE)colour chromaticity shows that the emission colour can be tuned from blue to green by varying the AIx moles.
