Heavy metal pollution is widespread in some areas of China and results in contamination of land, water, and air with which all living organisms interact. In this study, we used three heavy metallic ions(Cu2+, Pb2+ and...Heavy metal pollution is widespread in some areas of China and results in contamination of land, water, and air with which all living organisms interact. In this study, we used three heavy metallic ions(Cu2+, Pb2+ and Zn2+) to assess their toxicity effects on mortality, blood biomarker and growth traits(body length and body mass) of Rana zhenhaiensis tadpoles. The results showed that the toxicity levels of the three metallic ions were different when conducted with different experiment designs. For acute toxicity tests, Cu2+ was the most toxic with the highest tadpole mortality. The mortalities of tadpoles showed significant differences among the treatments at the same exposure time endpoints(24, 48, 72 and 96h). Results from repeated measures ANOVA indicated that metallic ion concentration, exposure time and their interactions significantly affected the mortalities of R. zhenhaiensis tadpoles. Also, the toxicity effects of all binary combinations of the three metallic ion treatments showed synergism. The half lethal concentrations(LC50) decreased with increasing exposure time during the experimental period, and the safe concentration(SC) values of Cu2+, Pb2+ and Zn2+ were different from each other. Combined and compared LC50 values with previous data reported, it is suggestes that the toxicity levels of metal pollution to anuran tadpoles should be species-and age-related. For blood biomarker tests, Zn2+ was the most toxic with the highest total frequencies of abnormal erythrocytic nucleus. All three metallic ions caused higher abnormal erythrocytic nucleus compared with control groups. In a chronic toxicity test, Pb2+ was the most toxic with lowest growth traits. Survival rate(except for 18 days), total body length and body mass showed significant differences among the treatments. These findings indicated that tadpoles of R. zhenhaiensis should be as a bioindicator of heavy metals pollution.展开更多
Precisely quantifying transition metal(TM) redox in bulk is a key to understand the fundamental of optimizing cathode materials in secondary batteries. At present, the commonly used methods to probe TM redox are hard ...Precisely quantifying transition metal(TM) redox in bulk is a key to understand the fundamental of optimizing cathode materials in secondary batteries. At present, the commonly used methods to probe TM redox are hard X-ray absorption spectroscopy(hXAS) and soft X-ray absorption spectroscopy(sXAS).However, they are both facing challenges to precisely quantify the valence states of some transition metals such as Mn. In this paper, Mn-L iPFY(inverse partial fluorescence yield) spectra extracted from Mn-L m RIXS(mapping of resonant inelastic X-ray scattering) is adopted to quantify Mn valence states. Mn-L i PFY spectra has been considered as a bulk-sensitive, non-distorted probe of TM valence states.However, the exact precision of this method is still unclear in quantifying practical battery electrodes.Herein, a series of LiMn_(2)O_(4) electrodes with different charge and discharge states are prepared. Based on their electrochemical capacity(generally considered to be very precise), the precision of Mn iPFY in quantifying bulk Mn valence state is confirmed, and the error range is unraveled. Mn-L mRIXS iPFY thus is identified as one of the best methods to quantify the bulk Mn valence state comparing with hXAS and sXAS.展开更多
Kinship and density are believed to affect important ecological processes such as intraspecific competition, predation, growth, development, cannibalism, habitat selection and mate choice. In this work, we used Chines...Kinship and density are believed to affect important ecological processes such as intraspecific competition, predation, growth, development, cannibalism, habitat selection and mate choice. In this work, we used Chinese tiger frog Hoplobatrachus chinensis tadpoles as an experimental model to investigate the effects of kinship and density on growth and development of this species over a 73 day period. The results showed that density can affect the growth and developmental traits(survival rate, larval period, size at the limb bud protrusion/metamorphic climax and body mass at different life stages) of H. chinensis tadpoles, while kinship does not. Tadpoles took longer to develop and potential metamorphosis was greater in high density groups of both sibling and non-siblings. The interaction of kinship and density did not significantly influenced growth traits of H. chinensis tadpoles during the experimental period. For coefficient variations of each growth trait, no differences were detected between sibling and non-sibling groups. These findings provide valuable information on the basic ecology of H. chinensis which will be helpful in future studies of other anuran species.展开更多
Adjoint-based optimization method is a hotspot in turbomachinery.First,this paper presents principles of adjoint method from Lagrange multiplier viewpoint.Second,combining a continuous route with thin layer RANS equat...Adjoint-based optimization method is a hotspot in turbomachinery.First,this paper presents principles of adjoint method from Lagrange multiplier viewpoint.Second,combining a continuous route with thin layer RANS equations,we formulate adjoint equations and anti-physical boundary conditions.Due to the multi-stage environment in turbomachinery,an adjoint interrow mixing method is introduced.Numerical techniques of solving flow equations and adjoint equations are almost the same,and once they are converged respectively,the gradients of an objective function to design variables can be calculated using complex method efficiently.Third,integrating a shape perturbation parameterization and a simple steepest descent method,a frame of adjoint-based aerodynamic shape optimization for multi-stage turbomachinery is constructed.At last,an inverse design of an annular cascade is employed to validate the above approach,and adjoint field of an Aachen 1.5 stage turbine demonstrates the conservation and areflexia of the adjoint interrow mixing method.Then a direct redesign of a 1+1 counter-rotating turbine aiming to increase efficiency and apply constraints to mass flow rate and pressure ratio is taken.展开更多
Flame structures of a syngas swirl-stabilized diffusion flame in a model combustor were measured using the OH-PLIF method under different fuel and air swirl intensity.The flame operated under atmospheric pressure with...Flame structures of a syngas swirl-stabilized diffusion flame in a model combustor were measured using the OH-PLIF method under different fuel and air swirl intensity.The flame operated under atmospheric pressure with air and a typical low heating-value syngas with a composition of 28.5% CO,22.5% H2 and 49% N2 at a thermal power of 34 kW.Results indicate that increasing the air swirl intensity with the same fuel,swirl intensity flame structures showed little difference except a small reduction of flame length;but also,with the same air swirl intensity,fuel swirl intensity showed great influence on flame shape,length and reaction zone distribution.Therefore,compared with air swirl intensity,fuel swirl intensity appeared a key effect on the flame structure for the model combustor.Instantaneous OH-PLIF images showed that three distinct typical structures with an obvious difference of reaction zone distribution were found at low swirl intensity,while a much compacter flame structure with a single,stable and uniform reaction zone distribution was found at large fuel-air swirl intensity.It means that larger swirl intensity leads to efficient,stable combustion of the syngas diffusion flame.展开更多
In the present paper,the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are described.Firstly the CFD pr...In the present paper,the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are described.Firstly the CFD program was validated by an experimental case.Then the preliminary aerodynamic design of stage completed through in-house one-dimensional code.Three types of impellers and two sets of stages were computed and analyzed.It can be found that the swept shape of leading edge has prominent influence on the performance and can enlarge the flow range.Similarly,the performance of the stage with swept impeller is better than others.The total pressure ratio and adiabatic efficiency of final geometry achieve 7:1 and 80% respectively.The vane diffuser with same airfoils along span increases attack angle at higher span,and the local flow structure and performance is deteriorated.展开更多
Combustion performances of pure hydrogen in an experimental trapped vortex combustor have been tested underdifferent operating conditions. Pressure fluctuations, NOx emissions, OH distributions, and LBO (Lean Blow Out...Combustion performances of pure hydrogen in an experimental trapped vortex combustor have been tested underdifferent operating conditions. Pressure fluctuations, NOx emissions, OH distributions, and LBO (Lean Blow Out)were measured in the tests. Results indicate that the TVC test rig has successfully realized a double vortex constructionin the cavity zone in a wide range of flow conditions. Hydrogen combustion in the test rig has achievedan excellent LBO performance and relatively low NOx emissions. Through comparison of dynamic pressure data,OH fluctuation images, and NOx emissions, the optimal operating condition has been found out to be Φp=0.4,fuel split=0.4, and primary air/fuel premixed.展开更多
Sluggish separation and migration kinetics of the photogenerated carriers account for the low-efficiency of CO_(2) photoreduction into CH_(4). Design and construction two-dimensional (2D) in-plane heterostructures dem...Sluggish separation and migration kinetics of the photogenerated carriers account for the low-efficiency of CO_(2) photoreduction into CH_(4). Design and construction two-dimensional (2D) in-plane heterostructures demonstrate to be an appealing approach to address above obstacles. Herein, we fabricate 2D in-plane heterostructured Ag_(2)S-In_(2)S_(3) atomic layers via an ion-exchange strategy. Photoluminescence spectra, time-resolved photoluminescence spectra, and photoelectrochemical measurements firmly affirm the optimized carrier dynamics of the In_(2)S_(3) atomic layers after the introduction of in-plane heterostructure. In-situ Fourier transform infrared spectroscopy spectra and density functional theory (DFT) calculations disclose the in-plane heterostructure contributes to CO_(2) activation and modulates the adsorption strength of CO* intermediates to facilitate the formation of CHO* intermediates, which are further protonated to CH4. In consequence, the in-plane heterostructure achieves the CH_(4) evolution rate of 20 µmol·g^(−1)·h^(−1), about 16.7 times higher than that of the In2S3 atomic layers. In short, this work proves construction of in-plane heterostructures as a promising method for obtaining high-efficiency CO_(2)-to-CH_(4) photoconversion properties.展开更多
Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utili...Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utilize in-situ spectral techniques to unveil the H2O-mediated HCHO photooxidation mechanism.As an example,the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O at room temperature.In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of•OH radicals,possibly stemmed from H2O oxidation by the photoexcited holes.Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H218O isotope-labeling experiment directly evidence the formed•OH radicals as the source of oxygen atoms,trigger HCHO photooxidation to produce CO2,while in-situ Fourier transform infrared spectroscopy discloses the HCOO*radical is the main photooxidation intermediate.Density-functional-theory calculations further reveal the•OH formation process is the rate-limiting step,strongly verifying the critical role of H2O in promoting HCHO photooxidation.This work first clearly uncovers the H2O-mediated HCHO photooxidation mechanism,holding promise for high-efficiency indoor HCHO removal at ambient conditions.展开更多
The major obstacle for selective CO_(2)photoreduction to C_(2)hydrocarbons lies in the difficulty of C–C coupling,which is usually restrained by the repulsive dipole–dipole interaction between adjacent carbonaceous ...The major obstacle for selective CO_(2)photoreduction to C_(2)hydrocarbons lies in the difficulty of C–C coupling,which is usually restrained by the repulsive dipole–dipole interaction between adjacent carbonaceous intermediates.Herein,we first construct semiconducting atomic layers featuring abundant Metal^(n+)-Metal^(δ+)pair sites(0<δ<n),aiming to tailor asymmetric charge distribution on the carbonaceous intermediates and hence trigger their C–C coupling for selectively yielding C_(2)hydrocarbons.As an example,we first fabricate Co-doped NiS2 atomic layers possessing abundant Ni^(2+)-Ni^(δ+)(0<δ<2)pairs,where Co doping strategy can ensure higher amount of Ni^(2+)-Ni^(δ+)pair sites.In-situ Fourier-transform infrared spectroscopy,quasi in-situ Raman spectroscopy and density-functional-theory calculations disclose the Ni^(2+)-Ni^(δ+)pair sites endow the adjacent CO intermediates with distinct charge densities,thus decreasing their dipole–dipole repulsion and hence lowering the rate-limiting C–C coupling reaction barrier.As a result,in simulated flue gas(10%CO_(2)balance 90%N_(2)),the ethylene selectivity for Co-doped NiS_(2)atomic layers reaches up to 74.3%with an activity of 70μg·g^(−1)·h^(−1),outperforming previously reported photocatalysts under similar operating conditions.展开更多
基金funded by the National Natural Science Foundation of China(31270443)Natural Science Foundation of Zhejiang Province(LY13C030004)
文摘Heavy metal pollution is widespread in some areas of China and results in contamination of land, water, and air with which all living organisms interact. In this study, we used three heavy metallic ions(Cu2+, Pb2+ and Zn2+) to assess their toxicity effects on mortality, blood biomarker and growth traits(body length and body mass) of Rana zhenhaiensis tadpoles. The results showed that the toxicity levels of the three metallic ions were different when conducted with different experiment designs. For acute toxicity tests, Cu2+ was the most toxic with the highest tadpole mortality. The mortalities of tadpoles showed significant differences among the treatments at the same exposure time endpoints(24, 48, 72 and 96h). Results from repeated measures ANOVA indicated that metallic ion concentration, exposure time and their interactions significantly affected the mortalities of R. zhenhaiensis tadpoles. Also, the toxicity effects of all binary combinations of the three metallic ion treatments showed synergism. The half lethal concentrations(LC50) decreased with increasing exposure time during the experimental period, and the safe concentration(SC) values of Cu2+, Pb2+ and Zn2+ were different from each other. Combined and compared LC50 values with previous data reported, it is suggestes that the toxicity levels of metal pollution to anuran tadpoles should be species-and age-related. For blood biomarker tests, Zn2+ was the most toxic with the highest total frequencies of abnormal erythrocytic nucleus. All three metallic ions caused higher abnormal erythrocytic nucleus compared with control groups. In a chronic toxicity test, Pb2+ was the most toxic with lowest growth traits. Survival rate(except for 18 days), total body length and body mass showed significant differences among the treatments. These findings indicated that tadpoles of R. zhenhaiensis should be as a bioindicator of heavy metals pollution.
基金the support from the key research and development and promotion of special projects (scientific and technological research) of Henan province (212102210188)the National Natural Science Foundation of China (51604244)the Energy Storage Materials and Processes Key Laboratory of Henan Province Open Fund (2021003)。
文摘Precisely quantifying transition metal(TM) redox in bulk is a key to understand the fundamental of optimizing cathode materials in secondary batteries. At present, the commonly used methods to probe TM redox are hard X-ray absorption spectroscopy(hXAS) and soft X-ray absorption spectroscopy(sXAS).However, they are both facing challenges to precisely quantify the valence states of some transition metals such as Mn. In this paper, Mn-L iPFY(inverse partial fluorescence yield) spectra extracted from Mn-L m RIXS(mapping of resonant inelastic X-ray scattering) is adopted to quantify Mn valence states. Mn-L i PFY spectra has been considered as a bulk-sensitive, non-distorted probe of TM valence states.However, the exact precision of this method is still unclear in quantifying practical battery electrodes.Herein, a series of LiMn_(2)O_(4) electrodes with different charge and discharge states are prepared. Based on their electrochemical capacity(generally considered to be very precise), the precision of Mn iPFY in quantifying bulk Mn valence state is confirmed, and the error range is unraveled. Mn-L mRIXS iPFY thus is identified as one of the best methods to quantify the bulk Mn valence state comparing with hXAS and sXAS.
基金supported by the grants from the National Natural Science Foundation of China (30970435,31270443)the Natural Science Foundation of Zhejiang, China (LY13C030004)
文摘Kinship and density are believed to affect important ecological processes such as intraspecific competition, predation, growth, development, cannibalism, habitat selection and mate choice. In this work, we used Chinese tiger frog Hoplobatrachus chinensis tadpoles as an experimental model to investigate the effects of kinship and density on growth and development of this species over a 73 day period. The results showed that density can affect the growth and developmental traits(survival rate, larval period, size at the limb bud protrusion/metamorphic climax and body mass at different life stages) of H. chinensis tadpoles, while kinship does not. Tadpoles took longer to develop and potential metamorphosis was greater in high density groups of both sibling and non-siblings. The interaction of kinship and density did not significantly influenced growth traits of H. chinensis tadpoles during the experimental period. For coefficient variations of each growth trait, no differences were detected between sibling and non-sibling groups. These findings provide valuable information on the basic ecology of H. chinensis which will be helpful in future studies of other anuran species.
文摘Adjoint-based optimization method is a hotspot in turbomachinery.First,this paper presents principles of adjoint method from Lagrange multiplier viewpoint.Second,combining a continuous route with thin layer RANS equations,we formulate adjoint equations and anti-physical boundary conditions.Due to the multi-stage environment in turbomachinery,an adjoint interrow mixing method is introduced.Numerical techniques of solving flow equations and adjoint equations are almost the same,and once they are converged respectively,the gradients of an objective function to design variables can be calculated using complex method efficiently.Third,integrating a shape perturbation parameterization and a simple steepest descent method,a frame of adjoint-based aerodynamic shape optimization for multi-stage turbomachinery is constructed.At last,an inverse design of an annular cascade is employed to validate the above approach,and adjoint field of an Aachen 1.5 stage turbine demonstrates the conservation and areflexia of the adjoint interrow mixing method.Then a direct redesign of a 1+1 counter-rotating turbine aiming to increase efficiency and apply constraints to mass flow rate and pressure ratio is taken.
基金support by the National High Technology R&D Project of China (No. 2006AA05A104)National Natural Science Foundation of China (No. 50806076,50876110)to the research work
文摘Flame structures of a syngas swirl-stabilized diffusion flame in a model combustor were measured using the OH-PLIF method under different fuel and air swirl intensity.The flame operated under atmospheric pressure with air and a typical low heating-value syngas with a composition of 28.5% CO,22.5% H2 and 49% N2 at a thermal power of 34 kW.Results indicate that increasing the air swirl intensity with the same fuel,swirl intensity flame structures showed little difference except a small reduction of flame length;but also,with the same air swirl intensity,fuel swirl intensity showed great influence on flame shape,length and reaction zone distribution.Therefore,compared with air swirl intensity,fuel swirl intensity appeared a key effect on the flame structure for the model combustor.Instantaneous OH-PLIF images showed that three distinct typical structures with an obvious difference of reaction zone distribution were found at low swirl intensity,while a much compacter flame structure with a single,stable and uniform reaction zone distribution was found at large fuel-air swirl intensity.It means that larger swirl intensity leads to efficient,stable combustion of the syngas diffusion flame.
文摘In the present paper,the design of a transonic centrifugal compressor stage with the inlet relative Mach number about 1.3 and detailed flow field investigation by three-dimensional CFD are described.Firstly the CFD program was validated by an experimental case.Then the preliminary aerodynamic design of stage completed through in-house one-dimensional code.Three types of impellers and two sets of stages were computed and analyzed.It can be found that the swept shape of leading edge has prominent influence on the performance and can enlarge the flow range.Similarly,the performance of the stage with swept impeller is better than others.The total pressure ratio and adiabatic efficiency of final geometry achieve 7:1 and 80% respectively.The vane diffuser with same airfoils along span increases attack angle at higher span,and the local flow structure and performance is deteriorated.
基金National Natural Science Foundation of China (No. 50576098)the National High Technology R&D Project of China (No.2006AA05A104)
文摘Combustion performances of pure hydrogen in an experimental trapped vortex combustor have been tested underdifferent operating conditions. Pressure fluctuations, NOx emissions, OH distributions, and LBO (Lean Blow Out)were measured in the tests. Results indicate that the TVC test rig has successfully realized a double vortex constructionin the cavity zone in a wide range of flow conditions. Hydrogen combustion in the test rig has achievedan excellent LBO performance and relatively low NOx emissions. Through comparison of dynamic pressure data,OH fluctuation images, and NOx emissions, the optimal operating condition has been found out to be Φp=0.4,fuel split=0.4, and primary air/fuel premixed.
基金This work was financially supported by the National Key R&D Program of China(Nos.2019YFA0210004,2017YFA0207301,and 2017YFA0303500)the National Natural Science Foundation of China(Nos.21975242,U2032212,21890754,and 21805267)+7 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-SLH011)the Fok Ying-Tong Education Foundation(No.161012)the University Synergy Innovation Program of Anhui Province(GXXT-2020-001)Users with Excellence Program of Hefei Science Center CAS(2020HSC-UE001)Supercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘Sluggish separation and migration kinetics of the photogenerated carriers account for the low-efficiency of CO_(2) photoreduction into CH_(4). Design and construction two-dimensional (2D) in-plane heterostructures demonstrate to be an appealing approach to address above obstacles. Herein, we fabricate 2D in-plane heterostructured Ag_(2)S-In_(2)S_(3) atomic layers via an ion-exchange strategy. Photoluminescence spectra, time-resolved photoluminescence spectra, and photoelectrochemical measurements firmly affirm the optimized carrier dynamics of the In_(2)S_(3) atomic layers after the introduction of in-plane heterostructure. In-situ Fourier transform infrared spectroscopy spectra and density functional theory (DFT) calculations disclose the in-plane heterostructure contributes to CO_(2) activation and modulates the adsorption strength of CO* intermediates to facilitate the formation of CHO* intermediates, which are further protonated to CH4. In consequence, the in-plane heterostructure achieves the CH_(4) evolution rate of 20 µmol·g^(−1)·h^(−1), about 16.7 times higher than that of the In2S3 atomic layers. In short, this work proves construction of in-plane heterostructures as a promising method for obtaining high-efficiency CO_(2)-to-CH_(4) photoconversion properties.
基金This work was financially supported by National Key R&D Program of China(Nos.2019YFA0210004 and 2017YFA0207301)the National Natural Science Foundation of China(Nos.21975242 and 21890754)+5 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS(No.QYZDYSSW-SLH011)the Fok Ying-Tong Education Foundation(No.161012)Supercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utilize in-situ spectral techniques to unveil the H2O-mediated HCHO photooxidation mechanism.As an example,the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O at room temperature.In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of•OH radicals,possibly stemmed from H2O oxidation by the photoexcited holes.Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H218O isotope-labeling experiment directly evidence the formed•OH radicals as the source of oxygen atoms,trigger HCHO photooxidation to produce CO2,while in-situ Fourier transform infrared spectroscopy discloses the HCOO*radical is the main photooxidation intermediate.Density-functional-theory calculations further reveal the•OH formation process is the rate-limiting step,strongly verifying the critical role of H2O in promoting HCHO photooxidation.This work first clearly uncovers the H2O-mediated HCHO photooxidation mechanism,holding promise for high-efficiency indoor HCHO removal at ambient conditions.
基金financially supported by the National Key R&D Program of China(2019YFA0210004,2017YFA0207301)the National Natural Science Foundation of China(22125503,21975242,U2032212,21890754)+8 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(CAS,XDB36000000)the Youth Innovation Promotion Association of CAS(CX2340007003)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology(2020HSC-CIP003)the Key Research Program of Frontier Sciences of CAS(QYZDYSSW-SLH011)the Fok Ying-Tong Education Foundation(161012)the Users with Excellence Program of Hefei Science Center(2020HSC-UE001)the University Synergy Innovation Program of Anhui Province(GXXT-2020-001)Anhui Provincial Natural Science Foundation(2108085QB69)the Fundamental Research Funds for the Central Universities(WK2060000006)。
基金National Key R&D Program of China(Nos.2019YFA0210004 and 2017YFA0207301)National Natural Science Foundation of China(Nos.21975242,U2032212,21890754,and 21805267)+4 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB36000000)Youth Innovation Promotion Association of CAS(No.CX2340007003)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(No.2020HSC-CIP003)Key Research Program of Frontier Sciences of CAS(No.QYZDY-SSW-SLH011)the Fok Ying-Tong Education Foundation(No.161012).
文摘The major obstacle for selective CO_(2)photoreduction to C_(2)hydrocarbons lies in the difficulty of C–C coupling,which is usually restrained by the repulsive dipole–dipole interaction between adjacent carbonaceous intermediates.Herein,we first construct semiconducting atomic layers featuring abundant Metal^(n+)-Metal^(δ+)pair sites(0<δ<n),aiming to tailor asymmetric charge distribution on the carbonaceous intermediates and hence trigger their C–C coupling for selectively yielding C_(2)hydrocarbons.As an example,we first fabricate Co-doped NiS2 atomic layers possessing abundant Ni^(2+)-Ni^(δ+)(0<δ<2)pairs,where Co doping strategy can ensure higher amount of Ni^(2+)-Ni^(δ+)pair sites.In-situ Fourier-transform infrared spectroscopy,quasi in-situ Raman spectroscopy and density-functional-theory calculations disclose the Ni^(2+)-Ni^(δ+)pair sites endow the adjacent CO intermediates with distinct charge densities,thus decreasing their dipole–dipole repulsion and hence lowering the rate-limiting C–C coupling reaction barrier.As a result,in simulated flue gas(10%CO_(2)balance 90%N_(2)),the ethylene selectivity for Co-doped NiS_(2)atomic layers reaches up to 74.3%with an activity of 70μg·g^(−1)·h^(−1),outperforming previously reported photocatalysts under similar operating conditions.
