The Heilongjiang Jianbiannongchang area is located at the confluence of the Great and Lesser Xing’an Ranges.This area has a complex magmatic and tectonic evolutionary history that has resulted in a complex and divers...The Heilongjiang Jianbiannongchang area is located at the confluence of the Great and Lesser Xing’an Ranges.This area has a complex magmatic and tectonic evolutionary history that has resulted in a complex and diverse geological background for mineralization.In this study,isometric logarithmic ratio(ILR)transformations of Au,Cu,Pb,Zn,and Sb contents were performed in the1:50,000 soil geochemical data of the Jianbiannongchang area.Robust principal component analysis(RPCA)was conducted based on ILR transformation.The local singularity and spectrum-area(S-A)methods were used to extract information on mineralogic anomalies.The results showed that:(1)the transformed data eliminated the influence of the original data closure effect,and the PC1and PC2 information obtained by applying RPCA reflected ore-producing element anomalies dominated by Au and Cu.(2)The local singularity method can enhance the information of the local strong and weak slow anomalies.After performing local singularity analysis on PC1 and PC2,the obtained local anomalies reflected the local singularity spatial anomaly patterns related to Cu and Au mineralization in this area,which is an effective method for trapping ore-producing anomalies.(3)Furthermore,the composite anomaly decomposition of PC1 and PC2 was performed using the S-A method,and the screened anomalous and background fields reflect the ore-producing anomalies related to Cu and Au mineralization.This information is in agreement with known Cu and Au mineralization.(4)The geochemical anomalies with mineralization potential were obtained outside the known mineralization sites by integrating the information of oreproducing anomalies extracted by the local singularity and S-A methods,providing the theoretical basis and exploration direction for future exploration in the study area.展开更多
Hydrogen evolution reaction(HER)and oxygen evolution/reduction reaction(OER/ORR)relying on high-performance and low-cost single-atom catalysts(SACs)driven by renewable energy sources offer a sustainable route to carbo...Hydrogen evolution reaction(HER)and oxygen evolution/reduction reaction(OER/ORR)relying on high-performance and low-cost single-atom catalysts(SACs)driven by renewable energy sources offer a sustainable route to carbon-neutral chemicals and fuels.Herein,first-principles calculations were performed to investigate the catalytic HER/OER/ORR activity of a novel graphitic carbon nitride monolayer(g-C_(7)N_(3))supported single transition metal(TM@g-C_(7)N_(3)).High stability as well as positively charged active site(TM-site)and desirable electrical conductivity lay the foundation for TM@g-C_(7)N_(3)acting as efficient HER/OER/ORR electrocatalysts.We screened out the non-noble-metal Rh@g-C_(7)N_(3)SAC exhibiting great potential as the trifunctional electrocatalysts for water splitting(η^(HER)=0.06 V andηOER=0.46 V)and a metal-air battery(η^(ORR)=0.28 V)on both kinetic and thermodynamic scales,whereas the Ni@g-C_(7)N_(3)can be served as a bifunctional OER/ORR catalyst with a low overpotential of 0.33 V/0.31 V,for both of which the high thermodynamic stability and oxidation barrier guarantee their outstanding performances at ambient conditions.The mechanism analysis indicates the filling of d-orbital electrons of TM-atom can play an important role in determining the value of an energy descriptor(ΔGOH*),and the suitableΔGOH*values make for the TM@g-C_(7)N_(3)candidates to possess favorable OER/ORR overpotential.Particularly,the Rh-d orbital of Rh@g-C_(7)N_(3)is evidently hybridized with the OH*-p orbital,resulting in the lone electrons initially distributed in the antibonding orbital pairing up and occupying the downward bonding orbital,ensuring OH*can be adsorbed on Rh@g-C_(7)N_(3)appropriately.Moreover,multiple-level descriptors including d-band center,COHP,Nd,andφare used to reveal the origin of the electrocatalytic activity.展开更多
The pursuit of two-dimensional single-atom catalysts(SACs)is of significant importance for advancing the energy conversion and storage technologies by providing efficient,stable,and low-cost alternatives for precious ...The pursuit of two-dimensional single-atom catalysts(SACs)is of significant importance for advancing the energy conversion and storage technologies by providing efficient,stable,and low-cost alternatives for precious metals in the hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and oxygen reduction reaction(ORR).The synergy between tunable ligands,abundant transition metal active sites,and diverse substrate materials facilitate in attaining both stability and enhanced catalytic activity.This study provides a thorough examination of the catalytic HER/OER/ORR activities in 161 TM@C_(15)N_(6)XY_(2)H_(5)SACs,combining density functional theory with machine learning(ML).Thirteen configurations were identified,comprising 11 single-function OER/ORR catalysts,a bifunctional OER/ORR catalyst,namely Cu@C_(15)N_(6)O_(3)H_(5),and Au@C_(15)N_(6)OS_(2)H_(5),which demonstrated trifunctional HER/OER/ORR catalytic activity.A pronounced hybridization between Cu/Au-d orbitals and O-p orbitals of oxygenated adsorbates directs the lone electrons to antibonding states before transitioning to bonding orbitals,enabling efficient adsorption of oxygenated intermediates on the surface.The data obtained through ML applications indicate that the atomic radius(r_(TM))and electronegativity(χ)of TM are the primary descriptors for the HER activity,while the d-electron count(θ)and atomic radius(rTM)of the atoms are the key descriptors for the OER/ORR activities.Through the SISSO method,a clear and robust correlation between intrinsic properties and adsorption energy was derived,enabling predictions at each step.Additionally,the constant-potential model showed that electric double-layer capacitance modulated the reaction barrier;meanwhile,pH^(-) and voltage-dependent adsorption free energies indicated that acidic and alkaline conditions(pH 5.3/9.9,Cu@C_(15)N_(6)O_(3)H_(5)/Au@C_(15)N_(6)OS_(2)H_(5))enhanced the OER efficiency,while pH 0 is optimal for the ORR.展开更多
The 8.2 ka B.P.event and 9.2 ka B.P.event are prominent abrupt climate events in the Early Holocene.However,the characteristics and mechanisms of the East Asian summer monsoon (EASM) during the two events remain uncle...The 8.2 ka B.P.event and 9.2 ka B.P.event are prominent abrupt climate events in the Early Holocene.However,the characteristics and mechanisms of the East Asian summer monsoon (EASM) during the two events remain unclear.This study provides precisely-dated and high-resolution hydroclimate reconstructions during the early Holocene from stalagmite (YQ18) multi-proxy records (δ^(18)O,δ^(13)C,Mg/Ca,and δ^(234)U) in Yuquan Cave,Central China.The observed EASM weakening and regional drought during the 8.2 ka B.P.and 9.2 ka B.P.events indicate that the dry and wet conditions in the study area are mainly controlled by changes in the EASM intensity.The YQ18 records show that the 8.2 ka B.P.weak monsoon event occurred from~8.38–8.06 ka B.P,lasting for about 320 years,with a double valley structure.The 9.2 ka B.P.event occurred in about 9.33–9.06 ka B.P.and lasted for about 270 years,characterized by a single valley structure.The monsoon declining and regional drying during the 8.2 ka B.P.event (with an amplitude of~0.88‰in δ^(18)O and ~1.42‰in δ^(13)C) are more severe than those during the 9.2 ka B.P.events (with an amplitude of ~0.44‰in δ^(18)O and~1.18‰inδ^(13)C).The comparison between the YQ18 records and the climate records in the northern high latitudes supports the view that the freshwater injections in the North Atlantic weakened the Atlantic Meridional Overturning Circulation,resulting in southward shifts in the Intertropical Convergence Zone by changing the interhemispheric temperature gradient and weakening the EASM.The two freshwater injections in the North Atlantic play an important role in the double valley structure of the 8.2 ka B.P.event.Meanwhile,the large-scale freshwater injection and volcanic eruptions likely strengthened and prolonged the 8.2 ka B.P.event.Therefore,this study highlights the sensitive response of the EASM to external forcing and internal climate variability,providing important references for understanding monsoon anomalies under contemporary anthropogenic influences.展开更多
基金supported by the Project of the Natural Science Foundation of Liaoning Province(2020-BS-258)the Scientific Research Fund Project of the Educational Department of Liaoning Provincial(LJ2020JCL010)+1 种基金The project was supported by the discipline innovation team of Liaoning Technical University(LNTU20TD-14)the Key Research and Development Project of Heilongjiang Province(GA21A204).
文摘The Heilongjiang Jianbiannongchang area is located at the confluence of the Great and Lesser Xing’an Ranges.This area has a complex magmatic and tectonic evolutionary history that has resulted in a complex and diverse geological background for mineralization.In this study,isometric logarithmic ratio(ILR)transformations of Au,Cu,Pb,Zn,and Sb contents were performed in the1:50,000 soil geochemical data of the Jianbiannongchang area.Robust principal component analysis(RPCA)was conducted based on ILR transformation.The local singularity and spectrum-area(S-A)methods were used to extract information on mineralogic anomalies.The results showed that:(1)the transformed data eliminated the influence of the original data closure effect,and the PC1and PC2 information obtained by applying RPCA reflected ore-producing element anomalies dominated by Au and Cu.(2)The local singularity method can enhance the information of the local strong and weak slow anomalies.After performing local singularity analysis on PC1 and PC2,the obtained local anomalies reflected the local singularity spatial anomaly patterns related to Cu and Au mineralization in this area,which is an effective method for trapping ore-producing anomalies.(3)Furthermore,the composite anomaly decomposition of PC1 and PC2 was performed using the S-A method,and the screened anomalous and background fields reflect the ore-producing anomalies related to Cu and Au mineralization.This information is in agreement with known Cu and Au mineralization.(4)The geochemical anomalies with mineralization potential were obtained outside the known mineralization sites by integrating the information of oreproducing anomalies extracted by the local singularity and S-A methods,providing the theoretical basis and exploration direction for future exploration in the study area.
基金supported by the National Natural Science Foundation of China(No.21905175).
文摘Hydrogen evolution reaction(HER)and oxygen evolution/reduction reaction(OER/ORR)relying on high-performance and low-cost single-atom catalysts(SACs)driven by renewable energy sources offer a sustainable route to carbon-neutral chemicals and fuels.Herein,first-principles calculations were performed to investigate the catalytic HER/OER/ORR activity of a novel graphitic carbon nitride monolayer(g-C_(7)N_(3))supported single transition metal(TM@g-C_(7)N_(3)).High stability as well as positively charged active site(TM-site)and desirable electrical conductivity lay the foundation for TM@g-C_(7)N_(3)acting as efficient HER/OER/ORR electrocatalysts.We screened out the non-noble-metal Rh@g-C_(7)N_(3)SAC exhibiting great potential as the trifunctional electrocatalysts for water splitting(η^(HER)=0.06 V andηOER=0.46 V)and a metal-air battery(η^(ORR)=0.28 V)on both kinetic and thermodynamic scales,whereas the Ni@g-C_(7)N_(3)can be served as a bifunctional OER/ORR catalyst with a low overpotential of 0.33 V/0.31 V,for both of which the high thermodynamic stability and oxidation barrier guarantee their outstanding performances at ambient conditions.The mechanism analysis indicates the filling of d-orbital electrons of TM-atom can play an important role in determining the value of an energy descriptor(ΔGOH*),and the suitableΔGOH*values make for the TM@g-C_(7)N_(3)candidates to possess favorable OER/ORR overpotential.Particularly,the Rh-d orbital of Rh@g-C_(7)N_(3)is evidently hybridized with the OH*-p orbital,resulting in the lone electrons initially distributed in the antibonding orbital pairing up and occupying the downward bonding orbital,ensuring OH*can be adsorbed on Rh@g-C_(7)N_(3)appropriately.Moreover,multiple-level descriptors including d-band center,COHP,Nd,andφare used to reveal the origin of the electrocatalytic activity.
基金the funding support from the Natural Science Foundation of Shanghai(23ZR1443900)the National Natural Science Foundation of China(Grant No.22109098).
文摘The pursuit of two-dimensional single-atom catalysts(SACs)is of significant importance for advancing the energy conversion and storage technologies by providing efficient,stable,and low-cost alternatives for precious metals in the hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and oxygen reduction reaction(ORR).The synergy between tunable ligands,abundant transition metal active sites,and diverse substrate materials facilitate in attaining both stability and enhanced catalytic activity.This study provides a thorough examination of the catalytic HER/OER/ORR activities in 161 TM@C_(15)N_(6)XY_(2)H_(5)SACs,combining density functional theory with machine learning(ML).Thirteen configurations were identified,comprising 11 single-function OER/ORR catalysts,a bifunctional OER/ORR catalyst,namely Cu@C_(15)N_(6)O_(3)H_(5),and Au@C_(15)N_(6)OS_(2)H_(5),which demonstrated trifunctional HER/OER/ORR catalytic activity.A pronounced hybridization between Cu/Au-d orbitals and O-p orbitals of oxygenated adsorbates directs the lone electrons to antibonding states before transitioning to bonding orbitals,enabling efficient adsorption of oxygenated intermediates on the surface.The data obtained through ML applications indicate that the atomic radius(r_(TM))and electronegativity(χ)of TM are the primary descriptors for the HER activity,while the d-electron count(θ)and atomic radius(rTM)of the atoms are the key descriptors for the OER/ORR activities.Through the SISSO method,a clear and robust correlation between intrinsic properties and adsorption energy was derived,enabling predictions at each step.Additionally,the constant-potential model showed that electric double-layer capacitance modulated the reaction barrier;meanwhile,pH^(-) and voltage-dependent adsorption free energies indicated that acidic and alkaline conditions(pH 5.3/9.9,Cu@C_(15)N_(6)O_(3)H_(5)/Au@C_(15)N_(6)OS_(2)H_(5))enhanced the OER efficiency,while pH 0 is optimal for the ORR.
基金supported by the National Key Research and Development Program of China(2023YFF0804704)the National Natural Science Foundation of China(Grant Nos.41931178 & 42071105)。
文摘The 8.2 ka B.P.event and 9.2 ka B.P.event are prominent abrupt climate events in the Early Holocene.However,the characteristics and mechanisms of the East Asian summer monsoon (EASM) during the two events remain unclear.This study provides precisely-dated and high-resolution hydroclimate reconstructions during the early Holocene from stalagmite (YQ18) multi-proxy records (δ^(18)O,δ^(13)C,Mg/Ca,and δ^(234)U) in Yuquan Cave,Central China.The observed EASM weakening and regional drought during the 8.2 ka B.P.and 9.2 ka B.P.events indicate that the dry and wet conditions in the study area are mainly controlled by changes in the EASM intensity.The YQ18 records show that the 8.2 ka B.P.weak monsoon event occurred from~8.38–8.06 ka B.P,lasting for about 320 years,with a double valley structure.The 9.2 ka B.P.event occurred in about 9.33–9.06 ka B.P.and lasted for about 270 years,characterized by a single valley structure.The monsoon declining and regional drying during the 8.2 ka B.P.event (with an amplitude of~0.88‰in δ^(18)O and ~1.42‰in δ^(13)C) are more severe than those during the 9.2 ka B.P.events (with an amplitude of ~0.44‰in δ^(18)O and~1.18‰inδ^(13)C).The comparison between the YQ18 records and the climate records in the northern high latitudes supports the view that the freshwater injections in the North Atlantic weakened the Atlantic Meridional Overturning Circulation,resulting in southward shifts in the Intertropical Convergence Zone by changing the interhemispheric temperature gradient and weakening the EASM.The two freshwater injections in the North Atlantic play an important role in the double valley structure of the 8.2 ka B.P.event.Meanwhile,the large-scale freshwater injection and volcanic eruptions likely strengthened and prolonged the 8.2 ka B.P.event.Therefore,this study highlights the sensitive response of the EASM to external forcing and internal climate variability,providing important references for understanding monsoon anomalies under contemporary anthropogenic influences.
