The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and meth...The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and methane to syngas in the temperature range 900–1050 °C. Experiments were carried out with different ceria shapes via two-step redox cycling composed of endothermic partial reduction of ceria with methane and complete exothermic re-oxidation of reduced ceria with H2 O/CO2 at the same operating temperature, thereby demonstrating the capability to operate the cycle isothermally. A parametric study considering different ceria macrostructure variants(ceria packed powder, ceria packed powder mixed with inert Al2 O3 particles, and ceria reticulated porous foam) and operating parameters(methane flow-rate, reduction temperature, or sintering temperature) was conducted in order to unravel their impact on the bed-averaged oxygen non-stoichiometry(δ), syngas yield, methane conversion, and solar reactor performance. The ceria cycling stability was also experimentally investigated to demonstrate repeatable syngas production by alternating the flow between CH4 and H2 O(or CO2). A decrease in sintering temperature of the ceria foam was beneficial for increasing syngas selectivity, methane conversion,and reactor performance. Increasing both CH4 concentration and reduction temperature enhanced δ with the maximum value up to 0.41 but concomitantly favored CH4 cracking reaction. The ceria reticulated porous foam showed better performance in terms of effective heat transfer, due to volumetric absorption of concentrated solar radiation and uniform heating with lower solar power consumption, thereby promoting the solar-to-fuel energy conversion efficiency that reached up to 5.60%. The energy upgrade factor achieved during cycle was up to 1.19. Stable patterns in the δ and syngas yield for consecutive cycles with the ceria foam validated material performance stability.展开更多
Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes compar...Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical(PEC) performances. Here, we demonstrate for the first time that super-long Cu_2O NWs, more than 4.5 μm,with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide(AAO) template method. In comparison with the photocathode with planar Cu_2O films, the photocathode with Cu_2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm^2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectrochemical electrode through depositing Pt NPs with atomic layer deposition(ALD) technology on the Cu_2O NWs, the plateau of photocurrent has been enlarged to –7 mA/cm^2 with the external quantum yield up to 34% at 410 nm. This study suggests that the photoelectrode based on Cu_2O NWs is a hopeful system for establishing high-efficiency water splitting system under visible light.展开更多
The vertically aligned one-dimensional(1 D)core-shell structure can maximize the exposure and use of the functionally active surface while maintaining the geometric effects caused by the underlying structure.Herein,we...The vertically aligned one-dimensional(1 D)core-shell structure can maximize the exposure and use of the functionally active surface while maintaining the geometric effects caused by the underlying structure.Herein,we have fabricated 1 D vertically aligned ZnO/V2O5 core-shell hetero-nanostructure nanorod arrays(NRs)for photoelectrochemical(PEC)water splitting.ZnO/V2O5 NRs were prepared through the hydrothermal growing of ZnO NRs and then radio frequency(RF)magnetron sputtering deposition of V2O5 for 300,600 and 900 s.The photocurrent density of ZnO/V2O5-based photoanodes was gradually increased with the sputtering time,reaching the maximum value of 1.21 m A/cm^2 at 1.23 V vs.reversible hydrogen electrode(RHE)for ZnO/V2O5-600,whereas for pure ZnO-based photoanode was 0.42 mA/cm^2.The incident photon to electron conversion efficiency(IPCE)of ZnO/V2O5-600 evaluated to be 82.3%which was 2.3 times higher than that of ZnO(36.4%).The improved PEC performance of ZnO/V2O5-600 is because the core-shell structure with a moderate thickness of the V2O5 layer has the extremely high carrier density,largest electrochemically active surface area(ECSA),largest carrier density,lowest charge recombination rate,and the longest lifetime of e-h pairs due to the formation of the staggered gap junction.This study provides an effective way to design and fabrication of hetero-nanostructures for highefficiency photoelectrodes.展开更多
Changes of CO 2/H 2O exchange parameters were continually measured in winter wheat under different water stress stages.The results showed that photosynthesis rate and transpiration rate of winter wheat in water stress...Changes of CO 2/H 2O exchange parameters were continually measured in winter wheat under different water stress stages.The results showed that photosynthesis rate and transpiration rate of winter wheat in water stress conditions were obviously lower than that in non stress conditions.After water stress,both of them slowly increased and even overtook that on sufficient irrigation treatment. Responses of winter wheat to water stress in different growth stages were different.To some extent, water stress can improve crop water use efficiency,speed up the process of milking.Under water stress condition,stomatal conductance limited diurnal changes of photosynthesis and transpiration in the morning but not in the afternoon.Transpiration is more sensitive to water stress than photosynthesis.展开更多
Department of Chemistry&Biology,Hechi Teacher’s College,Yizhou546300)abstract:The new complex formulated[Co（DPC）abstract: 2 ]-Co（H 2 O）abstract: 5 ]·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract...Department of Chemistry&Biology,Hechi Teacher’s College,Yizhou546300)abstract:The new complex formulated[Co（DPC）abstract: 2 ]-Co（H 2 O）abstract: 5 ]·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of[Co（DPC）abstract: 2 ]possess an approximate D 2d symmetry,while the part of[OCo （2）OH 2 5 ]has an approximate C2symmetry.展开更多
基金The King Mongkut’s Institute of Technology Ladkrabang(KMITL),Thailandthe Franco-Thai scholarship program。
文摘The chemical looping reforming of methane through the nonstoichiometric ceria redox cycle(CeO2/CeO2-δ) has been experimentally investigated in a directly irradiated solar reactor to convert both solar energy and methane to syngas in the temperature range 900–1050 °C. Experiments were carried out with different ceria shapes via two-step redox cycling composed of endothermic partial reduction of ceria with methane and complete exothermic re-oxidation of reduced ceria with H2 O/CO2 at the same operating temperature, thereby demonstrating the capability to operate the cycle isothermally. A parametric study considering different ceria macrostructure variants(ceria packed powder, ceria packed powder mixed with inert Al2 O3 particles, and ceria reticulated porous foam) and operating parameters(methane flow-rate, reduction temperature, or sintering temperature) was conducted in order to unravel their impact on the bed-averaged oxygen non-stoichiometry(δ), syngas yield, methane conversion, and solar reactor performance. The ceria cycling stability was also experimentally investigated to demonstrate repeatable syngas production by alternating the flow between CH4 and H2 O(or CO2). A decrease in sintering temperature of the ceria foam was beneficial for increasing syngas selectivity, methane conversion,and reactor performance. Increasing both CH4 concentration and reduction temperature enhanced δ with the maximum value up to 0.41 but concomitantly favored CH4 cracking reaction. The ceria reticulated porous foam showed better performance in terms of effective heat transfer, due to volumetric absorption of concentrated solar radiation and uniform heating with lower solar power consumption, thereby promoting the solar-to-fuel energy conversion efficiency that reached up to 5.60%. The energy upgrade factor achieved during cycle was up to 1.19. Stable patterns in the δ and syngas yield for consecutive cycles with the ceria foam validated material performance stability.
基金supported by European Research Council(HiNaPc:737616)European Research Council(ThreeDsurface:240144)+8 种基金BMBF(ZIK-3DNanoDevice:03Z1MN11)DFG(LE2249_4-1)BMBF(Meta-ZIK-BioLithoMorphie:03Z1M511)National Natural Science Foundation of China(Nos.21577086,51702130,21503209)Natural Science Foundation of Jiangsu Province(BK 20170550)Jiangsu Specially-Appointed Professor ProgramHundred-Talent Program(Chinese Academy of Sciences)Beijing Natural Science Foundation(No.2162042)Key Research Program of Frontier Science,CAS(No.QYZDBSSW-SLH006)
文摘Nanowire(NW) structures is an alternative candidate for constructing the next generation photoelectrochemical water splitting system, due to the outstanding optical and electrical properties. NW photoelectrodes comparing to traditional semiconductor photoelectrodes shows the comparatively shorter transfer distance of photo-induced carriers and the increase amount of the surface reaction sites, which is beneficial for lowering the recombination probability of charge carriers and improving their photoelectrochemical(PEC) performances. Here, we demonstrate for the first time that super-long Cu_2O NWs, more than 4.5 μm,with highly efficient water splitting performance, were synthesized using a cost-effective anodic alumina oxide(AAO) template method. In comparison with the photocathode with planar Cu_2O films, the photocathode with Cu_2O NWs demonstrates a significant enhancement in photocurrent, from –1.00 to –2.75 mA/cm^2 at –0.8 V versus Ag/AgCl. After optimization of the photoelectrochemical electrode through depositing Pt NPs with atomic layer deposition(ALD) technology on the Cu_2O NWs, the plateau of photocurrent has been enlarged to –7 mA/cm^2 with the external quantum yield up to 34% at 410 nm. This study suggests that the photoelectrode based on Cu_2O NWs is a hopeful system for establishing high-efficiency water splitting system under visible light.
基金supported by National Research Foundation(NRF)of Korean grant funded by the Korea government(MSIP)(Grant number:2017R1E1A1A01074550)。
文摘The vertically aligned one-dimensional(1 D)core-shell structure can maximize the exposure and use of the functionally active surface while maintaining the geometric effects caused by the underlying structure.Herein,we have fabricated 1 D vertically aligned ZnO/V2O5 core-shell hetero-nanostructure nanorod arrays(NRs)for photoelectrochemical(PEC)water splitting.ZnO/V2O5 NRs were prepared through the hydrothermal growing of ZnO NRs and then radio frequency(RF)magnetron sputtering deposition of V2O5 for 300,600 and 900 s.The photocurrent density of ZnO/V2O5-based photoanodes was gradually increased with the sputtering time,reaching the maximum value of 1.21 m A/cm^2 at 1.23 V vs.reversible hydrogen electrode(RHE)for ZnO/V2O5-600,whereas for pure ZnO-based photoanode was 0.42 mA/cm^2.The incident photon to electron conversion efficiency(IPCE)of ZnO/V2O5-600 evaluated to be 82.3%which was 2.3 times higher than that of ZnO(36.4%).The improved PEC performance of ZnO/V2O5-600 is because the core-shell structure with a moderate thickness of the V2O5 layer has the extremely high carrier density,largest electrochemically active surface area(ECSA),largest carrier density,lowest charge recombination rate,and the longest lifetime of e-h pairs due to the formation of the staggered gap junction.This study provides an effective way to design and fabrication of hetero-nanostructures for highefficiency photoelectrodes.
文摘Changes of CO 2/H 2O exchange parameters were continually measured in winter wheat under different water stress stages.The results showed that photosynthesis rate and transpiration rate of winter wheat in water stress conditions were obviously lower than that in non stress conditions.After water stress,both of them slowly increased and even overtook that on sufficient irrigation treatment. Responses of winter wheat to water stress in different growth stages were different.To some extent, water stress can improve crop water use efficiency,speed up the process of milking.Under water stress condition,stomatal conductance limited diurnal changes of photosynthesis and transpiration in the morning but not in the afternoon.Transpiration is more sensitive to water stress than photosynthesis.
文摘Department of Chemistry&Biology,Hechi Teacher’s College,Yizhou546300)abstract:The new complex formulated[Co（DPC）abstract: 2 ]-Co（H 2 O）abstract: 5 ]·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of·2H 2 O（HDPC - is pyridine-2,6-dicarboxylate）abstract:has been synthesized and the crystal structu re was determined by X-ray diffraction.The crystal structure of the complex bel ongs to monoclinic system with space group P2 1 /c,a=0.83850（10）abstract:nm,b=2.7386（4）abstract:nm,c=0.9610（2）abstract:nm,β =98.280（10）abstract:°,V=2.1838（6）abstract:nm 3 ,Z=4,D c =1.746g·cm -3 ,μ =1.597mm -1 .In the crystal the two Co 2+ are in distort-ed octahedrons.The part of[Co（DPC）abstract: 2 ]possess an approximate D 2d symmetry,while the part of[OCo （2）OH 2 5 ]has an approximate C2symmetry.
