For the Hardy space H_E^2(R) over a ?at unitary vector bundle E on a ?nitely connected domain R, let TE be the bundle shift as [3]. If B is a reductive algebra containing every operator ψ(TE) for any rational functi...For the Hardy space H_E^2(R) over a ?at unitary vector bundle E on a ?nitely connected domain R, let TE be the bundle shift as [3]. If B is a reductive algebra containing every operator ψ(TE) for any rational function ψ with poles outside of R, then B is self adjoint.展开更多
Countries around the world have been making efforts to reduce pollutant emissions. However, the response of global black carbon(BC) aging to emission changes remains unclear. Using the Community Atmosphere Model versi...Countries around the world have been making efforts to reduce pollutant emissions. However, the response of global black carbon(BC) aging to emission changes remains unclear. Using the Community Atmosphere Model version 6 with a machine-learning-integrated four-mode version of the Modal Aerosol Module, we quantify global BC aging responses to emission reductions for 2011–2018 and for 2050 and 2100 under carbon neutrality. During 2011–18, global trends in BC aging degree(mass ratio of coatings to BC, R_(BC)) exhibited marked regional disparities, with a significant increase in China(5.4% yr^(-1)), which contrasts with minimal changes in the USA, Europe, and India. The divergence is attributed to opposing trends in secondary organic aerosol(SOA) and sulfate coatings, driven by regional changes in the emission ratios of corresponding coating precursors to BC(volatile organic compounds-VOCs/BC and SO_(2)/BC). Projections under carbon neutrality reveal that R_(BC) will increase globally by 47%(118%) in 2050(2100), with strong convergent increases expected across major source regions. The R_(BC) increase, primarily driven by enhanced SOA coatings due to sharper BC reductions relative to VOCs, will enhance the global BC mass absorption cross-section(MAC) by 11%(17%) in 2050(2100).Consequently, although the global BC burden will decline sharply by 60%(76%), the enhanced MAC partially offsets the magnitude of the decline in the BC direct radiative effect, resulting in the moderation of global BC DRE decreases to 88%(92%) of the BC burden reductions in 2050(2100). This study highlights the globally enhanced BC aging and light absorption capacity under carbon neutrality, thereby partly offsetting the impact of BC direct emission reductions on future changes in BC radiative effects globally.展开更多
In order to explore the reduction pathways of zinc oxide in LiCl molten salt and the optimal process,experiments were conducted in an alumina crucible using metallic lithium as the reducing agent and lithium chloride ...In order to explore the reduction pathways of zinc oxide in LiCl molten salt and the optimal process,experiments were conducted in an alumina crucible using metallic lithium as the reducing agent and lithium chloride molten salt as the reaction medium at 923 K.The study assessed the effects of lithium thermochemical reduction and electrolytic reduction of ZnO.The volatilization behavior of metal oxides in molten salts,the equivalent of a reducing agent,reduction time,amount of molten salt,stirring time,and the method of reduction feed were investigated for their impacts on the reduction yield and product composition.X-ray powder diffraction(XRD)analysis of the products showed that lithium reduction of ZnO not only produced metallic Zn but also formed a LiZn alloy.Electrolytic reduction can be used to obtain the metallic Zn product by controlling the potential below-2.2 V(vs Ag/Ag^(+)).Moreover,sintered oxides and higher electrode potentials could enhance the efficiency of electrolysis.Under the optimal reaction conditions determined experimentally,the lithium reduction experiment achieved a yield of 77.2%after a 12-h test,and the electrolytic reduction reached a yield of 85.4%after a 6-h test.展开更多
A method for the rapid reduction of acyl chlorides to aldehydes was developed using pinacolborane(HBpin)as the reducing agent.The method exhibits excellent generality for both aromatic and aliphatic substrates,affordi...A method for the rapid reduction of acyl chlorides to aldehydes was developed using pinacolborane(HBpin)as the reducing agent.The method exhibits excellent generality for both aromatic and aliphatic substrates,affording aldehydes in isolated yields of up to 88%with broad functional group tolerance,including cyano,halogen,alkenyl,ketone,and ester groups.Moreover,the method enables gram-scale aldehyde synthesis and shows high efficiency in reducing in situ generated acyl chlorides,thereby enhancing its synthetic practicality.展开更多
Nickel-catalyzed reductive cross-coupling(RCC)reactions between alkenes and alkyl electrophiles are undoubtedly the attractive approaches to new functionalized heterocycles.However,the alkylation reagents are still ra...Nickel-catalyzed reductive cross-coupling(RCC)reactions between alkenes and alkyl electrophiles are undoubtedly the attractive approaches to new functionalized heterocycles.However,the alkylation reagents are still rather limited for the arylalkylation of tethered alkenes via RCC reactions.Thus,developing more robust methods to access heterocycles from stable and readily available starting materials under RCC conditions is still highly challenging and desirable.A new nickelcatalyzed reductive arylalkylation of tethered alkenes with cyclosulfonium salts as C(sp^(3))electrophiles to access the sulfurcontaining oxindoles is developed.This tandem ring-opening/cyclization/reductive coupling protocol enables the efficient construction of various oxindoles bearing all-carbon quaternary centers under mild conditions with broad functional group tolerance.Notably,many drug derivatives are readily functionalized using the developed protocol.展开更多
This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramia...This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramians directly from the expansion coefficients of impulse responses.Leveraging these factors,we develop two model reduction algorithms that integrate the low-rank square root method with dominant subspace projection.Our method is computationally efficient and flexible,requiring only a few matrix-vector operations and a singular value decomposition of a low-dimensional matrix,thereby avoiding the need to solve differential Lyapunov equations.Numerical experiments confirm the effectiveness of the proposed approach.展开更多
This paper reports the preparation of three di‑iron complexes containing a thiazole moiety.Esterification of complex[Fe_(2)(CO)_(6)(μ‑SCH_(2)CH(CH_(2)OH)S)](1)with 4‑methylthiazole‑5‑carboxylic acid gave the correspo...This paper reports the preparation of three di‑iron complexes containing a thiazole moiety.Esterification of complex[Fe_(2)(CO)_(6)(μ‑SCH_(2)CH(CH_(2)OH)S)](1)with 4‑methylthiazole‑5‑carboxylic acid gave the corresponding ester[Fe_(2)(CO)_(6)(μ‑tedt)](2),where tedt=SCH_(2)CH(CH_(2)OOC(5‑C_(3)HNSCH_(3)))S.Further reactions of complex 2 with tri(ptolyl)phosphine(tp)or tris(4‑fluorophenyl)phosphine(fp)gave the phosphine‑substituted derivatives[Fe_(2)(CO)_(5)(tp)(μ‑tedt)](3)and[Fe_(2)(CO)_(5)(fp)(μ‑tedt)](4).The structures of the newly prepared complexes were elucidated by elemental analysis,NMR,IR,and X‑ray photoelectron spectroscopy.Moreover,single‑crystal X‑ray diffraction analysis confirmed their molecular structures,showing that they contain a di‑iron core ligated by a bridged dithiolate bearing a thiazole moiety and terminal carbonyls.The electrochemical and electrocatalytic proton reduction were probed by cyclic voltammetry,revealing that three complexes can catalyze the reduction of protons to H_(2) under the electrochemical conditions.For comparison,complex 4 possessed the best efficiency with a turnover frequency of 23.5 s^(-1)at 10 mmol·L^(-1)HOAc concentration.In addition,the fungicidal activity of these complexes was also investigated in this study.CCDC:2477511,2;2477512,3;2477513,4.展开更多
Exploring cost-effective and efficient catalysts for oxygen reduction reaction(ORR)poses a significant challenge,espe-cially in the pursuit of alternatives to precious metals like platinum.Significant advancements hav...Exploring cost-effective and efficient catalysts for oxygen reduction reaction(ORR)poses a significant challenge,espe-cially in the pursuit of alternatives to precious metals like platinum.Significant advancements have driven electrochem-ists to develop efficient ORR catalysts using abundant materials,particularly iron(Fe)-based,known for their exceptional performance in ORR.While the crucial function of Fe in boosting ORR catalytic activity is recognized,the connection between material attributes and catalytic performance remains enigmatic.Understanding the dynamic processes involved in oxygen electrocatalysis is paramount for designing precious-metals-free ORR electrocatalysts.Mössbauer spectroscopy stands out as a powerful technique for deciphering the structural characteristics of Fe species in catalysis,facilitating the identification of active sites and the clarification of catalytic mechanisms.By showcasing noteworthy case studies within this review,we demonstrate the application of in-situ/operando 57Fe Mössbauer spectroscopy across diverse Fe-involved materials in ORR catalysis.This sheds light on various aspects of ORR catalysis,such as identifying active sites,assessing stability,and understanding the reaction mechanism.Our inquiry drives towards the opportunities and hurdles associ-ated with Mössbauer spectroscopy,unveiling potential breakthroughs and avenues for enhancement within this pivotal research realm.展开更多
Proton exchange membrane fuel cells(PEMFCs)are considered as a promising renewable power source.However,the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied p...Proton exchange membrane fuel cells(PEMFCs)are considered as a promising renewable power source.However,the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied performance mainly due to the sluggish oxygen reduction reaction(ORR)kinetics even on state-of-the-art Pt catalyst.Octahedral PtNi nanoparticles(oct-PtNi NPs)with excellent ORR activity in a half-cell have been widely studied,while their performance in membrane electrode assembly(MEA)has much less reported.Herein,we investigated the MEA performance using the carbon supported oct-PtNi NPs(oct-PtNi/C)as the cathode catalyst.Under the mild acid washing condition,the surface Ni atoms of oct-PtNi/C were largely removed,and the performance of the MEA using the acid-leaching oct-PtNi/C(PNC-A)as the cathode catalyst was greatly improved.The maximum power density of the MEA reached 1.0 W·cm^(-2) with the cath-ode Pt loading of 0.2 mg·cm^(-2),which is 15%higher than that using Pt/C as the catalyst.After 30k cycles in the accelerated degradation test(ADT),the MEA using PNC-A as the catalyst showed a performance retention of 82%,higher than that of Pt/C(74%).The results reported here verify the possibility of using PNC-A as an advanced cathode catalyst in PEMFCs,thus enhancing the performance of PEMFCs while lowering the amount of expensive Pt.展开更多
Under the context of global energy transition and carbon neutrality,controlling nitrogen oxide(NO_(x))emissions from biomass combustion is of great significance,and the development of high-efficiency low-temperature c...Under the context of global energy transition and carbon neutrality,controlling nitrogen oxide(NO_(x))emissions from biomass combustion is of great significance,and the development of high-efficiency low-temperature catalysts has become a current research focus.In this study,Nb was used to dope and modify the Mn_(7)-Cu_(3)/BCN catalyst to construct the Mn_(7)-Cu_(3)-Nb_(x)/BCN system.The doping amount was optimized through selective catalytic reduction(SCR)activity tests.The reaction mechanism was explored by combining in situ DRIFTS and density functional theory(DFT)simulations.Experimental findings revealed that the catalyst doped with 0.05%Nb achieved the optimal performance,sustaining a NO conversion efficiency of≥94%within the temperature window of 150−275℃while demonstrating improved resistance to alkali metal K poisoning.Mechanistic analyses showed that at low temperatures,the catalyst facilitated the SCR reaction via both the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)pathways,with the synergistic interaction between multiple active sites driving the efficient conversion of NH3 and NO.DFT calculations further confirmed that both pathways had the characteristics of low reaction energy barriers and significant exothermicity,ensuring the high activity and feasibility of the low-temperature reaction.The findings provided foundational theoretical support for the design of Nb-doped Mn-Cu-supported catalysts and the exploration of the underlying working mechanisms.展开更多
This study presents the successful synthesis of a novel Z-scheme heterojunction composite film consisting of Ag/Bi_(2)MoO_(6)/BiOBr through electrochemical processes and ionexchange techniques,followed by the photodep...This study presents the successful synthesis of a novel Z-scheme heterojunction composite film consisting of Ag/Bi_(2)MoO_(6)/BiOBr through electrochemical processes and ionexchange techniques,followed by the photodeposition of noble metal silver(Ag)onto the composite structure.The catalytic efficiency of semiconductor photocatalysts is greatly improved by utilizing the localized surface plasmon resonance(LSPR)effect observed in Ag nanoparticles(NPs).Furthermore,the noble metal Ag serves as an intermediary bridge facilitating charge transfer between Bi_(2)MoO_(6)and BiOBr,while the formation of a Schottky barrier effectively inhibits the recombination of photo-generated electron-hole pairs.As a result,the Ag-deposited Bi_(2)MoO_(6)/BiOBr film exhibits superior photocatalytic performance in the reduction of CO_(2)compared to its unmodified counterpart.Our experimental results indicate a non-linear relationship between Ag deposition and the efficiency of photocatalytic CO_(2)reduction to CO,characterized by an initial increase in efficiency followed by a decline.The optimized 1.5%-Ag/Bi_(2)MoO_(6)/BiOBr film demonstrates exceptional photocatalytic activity,attaining a CO production rate of 13.65μmol/(g·h).This research explores the fundamental mechanisms that lead to improved photocatalytic CO_(2)reduction capabilities of the Ag/Bi_(2)MoO_(6)/BiOBr film.Our research offers important perspectives for the thoughtful design and production of highly efficient photocatalysts,which are essential for advancing sustainable energy solutions.展开更多
CO_(2)reduction technology can promote the resource utilization of carbon and help alleviate global warming and energy supply pressure.It is an effective way to achieve energy conversion and utilization.Covalent organ...CO_(2)reduction technology can promote the resource utilization of carbon and help alleviate global warming and energy supply pressure.It is an effective way to achieve energy conversion and utilization.Covalent organic frameworks(COFs)are porous crystalline materials formed by connecting organic monomers through covalent bonds.They have the characteristics of functional diversity and rich chemical properties.Their advantages,such as high porosity,a wide range of visible light absorption,and excellent charge separation efficiency,give them good potential in CO_(2)capture,separation,and conversion.Currently,Cu is a key metal in the catalytic CO_(2)reduction reaction(CO_(2)RR)for the preparation of high-value-added chemicals.The preparation of highly stable and large-pore Cu-based COFs using COFs as an ideal sacrificial template for loading Cu can be used to develop high-performance electrocatalysts and photocatalysts.In this review,we discuss the latest advancements in this field,including the development of various Cu-based COFs and their applications as catalysts for CO_(2)RR.Here,we mainly introduce the synthesis strategies,some important characterization information,and the applications of electrocatalytic and photocatalytic CO_(2)conversion using these previously reported Cu-based COFs.展开更多
The catalytic transferred of small molecules into high-value chemical products in green methods are highly perused,and has obtained huge attention.In this field,great progress has been achieved during the past five ye...The catalytic transferred of small molecules into high-value chemical products in green methods are highly perused,and has obtained huge attention.In this field,great progress has been achieved during the past five years.Followed by the roadmap(Chinese Chemical Letters,2019,30,2089-2109)written by us before five years,we think that it should be updated to give more insights in this field.Thus,we write the present roadmap based on the fast changed background.In this roadmap,oxygen and carbon dioxide reduction reactions(including at high temperature),photocatalytic hydrogen generation and carbon dioxide reduction reactions,(photo)electrocatalytic reduction of O_(2)to H_(2)O_(2)and NH_(3)generated from N_(2) are discussed.The progress and challenges in above catalytic processes are given.We believe this manuscript will give the researchers more suggestions and help them to obtain useful information in this field.展开更多
Experts and officials shared their insights on poverty reduction cooperation and sustainable development during the 2025 International Seminar on Global Poverty Reduction Partnerships.
MXene derivatives are notable two-dimensional nanomaterials with numerous prospective applications in the domains of energy development.MXene derivative,MBene,diversifies its focus on energy storage and harvesting due...MXene derivatives are notable two-dimensional nanomaterials with numerous prospective applications in the domains of energy development.MXene derivative,MBene,diversifies its focus on energy storage and harvesting due to its exceptional electrical conductivity,structural flexibility,and mechanical properties.This comprehensive review describes the sandwich-like structure of the synthesized MBene,derived from its multilayered parent material and its distinct chemical framework to date.The fields of focus encompass the investigation of novel MBenes,the study of phase-changing mechanisms,and the examination of hex-MBenes,ortho-MBenes,tetra-MBenes,tri-MBenes,and MXenes with identical transition metal components.A critical analysis is also provided on the electrochemical mechanism and performance of MBene in energy storage(Li/Na/Mg/Ca/Li–S batteries and supercapacitors),as well as conversion and harvesting(CO_(2) reduction,and nitrogen reduction reactions).The persistent difficulties associated with conducting experimental synthesis and establishing artificial intelligence-based forecasts are extensively deliberated alongside the potential and forthcoming prospects of MBenes.This review provides a single platform for an overview of the MBene’s potential in energy storage and harvesting.展开更多
Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in ac...Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.展开更多
Coke oven gas(COG)and natural gas(NG),both high-calorific by-products derived from the steel industry,have gained prominence as alternative fuels in the sintering process,thereby supporting dual objectives of emission...Coke oven gas(COG)and natural gas(NG),both high-calorific by-products derived from the steel industry,have gained prominence as alternative fuels in the sintering process,thereby supporting dual objectives of emission reduction and carbon neutrality.While existing research on hydrogen-rich gas injection has predominantly concentrated on conventional thin-bed sintering,investigations into its application within thick-bed sintering remain comparatively scarce.Thick-bed sintering,recognized for enhancing energy efficiency and increasing sinter output,encounters challenges such as uneven heat distribution and diminished permeability,which can negatively impact process efficiency and product quality.To address these issues,sinter pot experiments were conducted to assess the effects of NG and COG injection on thick-bed sintering performance.Findings reveal that NG injection in thick beds mirrors the behavior observed in conventional thin-bed sintering,effectively optimizing the process and achieving a carbon reduction potential exceeding 10%.In contrast,COG injection in thick-bed conditions demonstrates notable differences,substantially lowering the solid fuel consumption rate but detrimentally affecting sinter strength and overall production.However,by optimizing the timing of COG injection,it is feasible to improve sinter yield while concurrently reducing solid fuel usage.These outcomes provide valuable insights for the advancement of gas injection technologies in thick-bed sintering,thereby contributing to energy conservation and emission mitigation efforts within the sintering industry.展开更多
Electrochemical nitrate reduction reaction(NO_(3)RR)is a sustainable strategy to treat wastewater and produce ammonia.However,it is still a challenge to prepare electrocatalysts with high activity and selectivity.Here...Electrochemical nitrate reduction reaction(NO_(3)RR)is a sustainable strategy to treat wastewater and produce ammonia.However,it is still a challenge to prepare electrocatalysts with high activity and selectivity.Herein,the CuO_(x) nanowires supported Ru nanoclusters(Ru-CuO_(x))were fabricated via a three-step procedure for efficient nitrate conversion and highly selective ammonia generation.The prepared RuCuO_(x) shows a high ammonia yield rate of 2286.5μg h^(-1) cm^(-2) at-0.7 V vs.RHE and Faradaic efficiency(FE)of 80.1%at-0.4 V vs.RHE.Additionally,the nitrate conversion rate exceeds 90%at the potential range from-0.2 to-0.7 V vs.RHE,and the ammonia selectivity can reach 97.7%at-0.7 V vs.RHE in100 mg L^(-1) NaNO_(3) solution.The systematic characterizations clarify that the introduction of Ru not only regulates the electronic structure of CuO_(x) and accelerates the reconstruction of CuO_(x) to Cu but also promotes H2O dissociation to generate active hydrogen.Moreover.in-situ Raman spectroscopy reveals that the formed Ru-Cu is considered the actual active species during the NO_(3)RR.Density functional theory(DFT)calculations further prove that the obtained Ru-Cu facilitates the adsorption of nitrate and lowers the Gibbs free energy of the rate-determining step,thus improving the NO_(3)RR performance.展开更多
The energy transition inspired by carbon neutrality targets and the increasing threat of extreme events raise multi-objective development requirements for power systems.This paper proposes a multi-objective resource a...The energy transition inspired by carbon neutrality targets and the increasing threat of extreme events raise multi-objective development requirements for power systems.This paper proposes a multi-objective resource allocation model to determine the type,number and location of flexible resources to increase the values of resilience,carbon reduction and renewable energy consumption.To evaluate the values of resilience,a restoration model for transmission systems is established that considers the coordination of fossil-fuel generators,energy storage systems(ESSs)and renewable energy generators in building restoration paths.The collaborative power-carbon-tradable green certificate(TGC)market model is then applied to evaluate the resource values in terms of carbon reduction and renewable energy consumption.Finally,the model is formulated as a mixed-integer linear programming(MILP)with a nonconvex feasible domain,and the normalized normal constraint(NNC)method is applied to obtain approximate Pareto frontiers for decision makers.Case studies validate the effectiveness of the proposed model in improving multi-factor values and analyze the impact of resource regulation capacity on values of restoration and carbon reduction.展开更多
In comparison with their 2D and 3D counterparts,1D covalent organic frameworks(COFs)have rarely been investigated due to the synthetic challenge arising from the strict necessary matching in the molecular symmetry bet...In comparison with their 2D and 3D counterparts,1D covalent organic frameworks(COFs)have rarely been investigated due to the synthetic challenge arising from the strict necessary matching in the molecular symmetry between corresponding building blocks and linking units in addition to the unmanageable packing of 1D organic chains once formed.Herein,two novel imide-linked 1D COFs with phthalocyanine building blocks,namely NiPc-CZDM-COF and NiPc-CZDL-COF,were fabricated from the hydrothermal synthesis reaction of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(II)(NiPc(COOH)_(8))with 9H-carbazole-3,6-diamine(CZDM)and 4,4′-(9H-carbazole-3,6-diyl)dianiline(CZDL),respectively.Two COFs have high crystallinity on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Due to their high ratio of exposed active centers on the edge sites of porous ribbons,both NiPc-CZDM-COF and NiPc-CZDL-COF electrodes display high utilization efficiency of NiPc electroactive sites of 8.0%and 7.5% according to the electrochemical measurement,resulting in their excellent capacity toward electrocatalytic nitrate reduction with the nitrate-to-NH3 Faradaic efficiency of nearly 100%.In particular,NiPc-CZDM-COF electrode exhibits superior electrocatalytic performance with high NH_(3) partial current density of−246 mA/cm^(2),ammonia yield rate of 19.5 mg cm^(−2) h^(−1),and turnover frequency of 5.8 s^(−1) at−1.2 V in an H-type cell associated with its higher conductivity.This work reveals the good potential of 1D porous crystalline materials in electrocatalysis.展开更多
基金Project Supported by Scientific and Technological Research Program of Chongqing Municipal Education Commission(KJQN201801110)Chongqing Science and Technology Commission(CSTC2015jcyjA00045,cstc2018jcyjA2248)and NSFC(11871127)
文摘For the Hardy space H_E^2(R) over a ?at unitary vector bundle E on a ?nitely connected domain R, let TE be the bundle shift as [3]. If B is a reductive algebra containing every operator ψ(TE) for any rational function ψ with poles outside of R, then B is self adjoint.
基金supported by the National Natural Science Foundation of China (42505149,41925023,U2342223,42105069,and 91744208)the China Postdoctoral Science Foundation (2025M770303)+1 种基金the Fundamental Research Funds for the Central Universities (14380230)the Jiangsu Funding Program for Excellent Postdoctoral Talent,and Jiangsu Collaborative Innovation Center of Climate Change。
文摘Countries around the world have been making efforts to reduce pollutant emissions. However, the response of global black carbon(BC) aging to emission changes remains unclear. Using the Community Atmosphere Model version 6 with a machine-learning-integrated four-mode version of the Modal Aerosol Module, we quantify global BC aging responses to emission reductions for 2011–2018 and for 2050 and 2100 under carbon neutrality. During 2011–18, global trends in BC aging degree(mass ratio of coatings to BC, R_(BC)) exhibited marked regional disparities, with a significant increase in China(5.4% yr^(-1)), which contrasts with minimal changes in the USA, Europe, and India. The divergence is attributed to opposing trends in secondary organic aerosol(SOA) and sulfate coatings, driven by regional changes in the emission ratios of corresponding coating precursors to BC(volatile organic compounds-VOCs/BC and SO_(2)/BC). Projections under carbon neutrality reveal that R_(BC) will increase globally by 47%(118%) in 2050(2100), with strong convergent increases expected across major source regions. The R_(BC) increase, primarily driven by enhanced SOA coatings due to sharper BC reductions relative to VOCs, will enhance the global BC mass absorption cross-section(MAC) by 11%(17%) in 2050(2100).Consequently, although the global BC burden will decline sharply by 60%(76%), the enhanced MAC partially offsets the magnitude of the decline in the BC direct radiative effect, resulting in the moderation of global BC DRE decreases to 88%(92%) of the BC burden reductions in 2050(2100). This study highlights the globally enhanced BC aging and light absorption capacity under carbon neutrality, thereby partly offsetting the impact of BC direct emission reductions on future changes in BC radiative effects globally.
文摘In order to explore the reduction pathways of zinc oxide in LiCl molten salt and the optimal process,experiments were conducted in an alumina crucible using metallic lithium as the reducing agent and lithium chloride molten salt as the reaction medium at 923 K.The study assessed the effects of lithium thermochemical reduction and electrolytic reduction of ZnO.The volatilization behavior of metal oxides in molten salts,the equivalent of a reducing agent,reduction time,amount of molten salt,stirring time,and the method of reduction feed were investigated for their impacts on the reduction yield and product composition.X-ray powder diffraction(XRD)analysis of the products showed that lithium reduction of ZnO not only produced metallic Zn but also formed a LiZn alloy.Electrolytic reduction can be used to obtain the metallic Zn product by controlling the potential below-2.2 V(vs Ag/Ag^(+)).Moreover,sintered oxides and higher electrode potentials could enhance the efficiency of electrolysis.Under the optimal reaction conditions determined experimentally,the lithium reduction experiment achieved a yield of 77.2%after a 12-h test,and the electrolytic reduction reached a yield of 85.4%after a 6-h test.
文摘A method for the rapid reduction of acyl chlorides to aldehydes was developed using pinacolborane(HBpin)as the reducing agent.The method exhibits excellent generality for both aromatic and aliphatic substrates,affording aldehydes in isolated yields of up to 88%with broad functional group tolerance,including cyano,halogen,alkenyl,ketone,and ester groups.Moreover,the method enables gram-scale aldehyde synthesis and shows high efficiency in reducing in situ generated acyl chlorides,thereby enhancing its synthetic practicality.
基金Project supported by the National Natural Science Foundation of China(No.22271170)the Taishan Scholars Program from Shandong Province(No.tsqn202408197)the Natural Science Foundation of Shandong Province(No.ZR2024QB154)。
文摘Nickel-catalyzed reductive cross-coupling(RCC)reactions between alkenes and alkyl electrophiles are undoubtedly the attractive approaches to new functionalized heterocycles.However,the alkylation reagents are still rather limited for the arylalkylation of tethered alkenes via RCC reactions.Thus,developing more robust methods to access heterocycles from stable and readily available starting materials under RCC conditions is still highly challenging and desirable.A new nickelcatalyzed reductive arylalkylation of tethered alkenes with cyclosulfonium salts as C(sp^(3))electrophiles to access the sulfurcontaining oxindoles is developed.This tandem ring-opening/cyclization/reductive coupling protocol enables the efficient construction of various oxindoles bearing all-carbon quaternary centers under mild conditions with broad functional group tolerance.Notably,many drug derivatives are readily functionalized using the developed protocol.
文摘This paper presents an efficient model reduction technique for linear time-varying systems based on shifted Legendre polynomials.The approach constructs approximate low-rank decomposition factors of finite-time Gramians directly from the expansion coefficients of impulse responses.Leveraging these factors,we develop two model reduction algorithms that integrate the low-rank square root method with dominant subspace projection.Our method is computationally efficient and flexible,requiring only a few matrix-vector operations and a singular value decomposition of a low-dimensional matrix,thereby avoiding the need to solve differential Lyapunov equations.Numerical experiments confirm the effectiveness of the proposed approach.
文摘This paper reports the preparation of three di‑iron complexes containing a thiazole moiety.Esterification of complex[Fe_(2)(CO)_(6)(μ‑SCH_(2)CH(CH_(2)OH)S)](1)with 4‑methylthiazole‑5‑carboxylic acid gave the corresponding ester[Fe_(2)(CO)_(6)(μ‑tedt)](2),where tedt=SCH_(2)CH(CH_(2)OOC(5‑C_(3)HNSCH_(3)))S.Further reactions of complex 2 with tri(ptolyl)phosphine(tp)or tris(4‑fluorophenyl)phosphine(fp)gave the phosphine‑substituted derivatives[Fe_(2)(CO)_(5)(tp)(μ‑tedt)](3)and[Fe_(2)(CO)_(5)(fp)(μ‑tedt)](4).The structures of the newly prepared complexes were elucidated by elemental analysis,NMR,IR,and X‑ray photoelectron spectroscopy.Moreover,single‑crystal X‑ray diffraction analysis confirmed their molecular structures,showing that they contain a di‑iron core ligated by a bridged dithiolate bearing a thiazole moiety and terminal carbonyls.The electrochemical and electrocatalytic proton reduction were probed by cyclic voltammetry,revealing that three complexes can catalyze the reduction of protons to H_(2) under the electrochemical conditions.For comparison,complex 4 possessed the best efficiency with a turnover frequency of 23.5 s^(-1)at 10 mmol·L^(-1)HOAc concentration.In addition,the fungicidal activity of these complexes was also investigated in this study.CCDC:2477511,2;2477512,3;2477513,4.
基金financially supported by the National Natural Science Foundation of China (22350410386,W2412116,22375200,U22A202175,21961142006)。
文摘Exploring cost-effective and efficient catalysts for oxygen reduction reaction(ORR)poses a significant challenge,espe-cially in the pursuit of alternatives to precious metals like platinum.Significant advancements have driven electrochem-ists to develop efficient ORR catalysts using abundant materials,particularly iron(Fe)-based,known for their exceptional performance in ORR.While the crucial function of Fe in boosting ORR catalytic activity is recognized,the connection between material attributes and catalytic performance remains enigmatic.Understanding the dynamic processes involved in oxygen electrocatalysis is paramount for designing precious-metals-free ORR electrocatalysts.Mössbauer spectroscopy stands out as a powerful technique for deciphering the structural characteristics of Fe species in catalysis,facilitating the identification of active sites and the clarification of catalytic mechanisms.By showcasing noteworthy case studies within this review,we demonstrate the application of in-situ/operando 57Fe Mössbauer spectroscopy across diverse Fe-involved materials in ORR catalysis.This sheds light on various aspects of ORR catalysis,such as identifying active sites,assessing stability,and understanding the reaction mechanism.Our inquiry drives towards the opportunities and hurdles associ-ated with Mössbauer spectroscopy,unveiling potential breakthroughs and avenues for enhancement within this pivotal research realm.
基金supported by grants from the Natural Science Foundation of China(22362031 and 21805121)the Science and Technology Project of Yunnan Province(2019FD137)。
文摘Proton exchange membrane fuel cells(PEMFCs)are considered as a promising renewable power source.However,the massive commercial application of PEMFCs has been greatly hindered by their high expense and less-satisfied performance mainly due to the sluggish oxygen reduction reaction(ORR)kinetics even on state-of-the-art Pt catalyst.Octahedral PtNi nanoparticles(oct-PtNi NPs)with excellent ORR activity in a half-cell have been widely studied,while their performance in membrane electrode assembly(MEA)has much less reported.Herein,we investigated the MEA performance using the carbon supported oct-PtNi NPs(oct-PtNi/C)as the cathode catalyst.Under the mild acid washing condition,the surface Ni atoms of oct-PtNi/C were largely removed,and the performance of the MEA using the acid-leaching oct-PtNi/C(PNC-A)as the cathode catalyst was greatly improved.The maximum power density of the MEA reached 1.0 W·cm^(-2) with the cath-ode Pt loading of 0.2 mg·cm^(-2),which is 15%higher than that using Pt/C as the catalyst.After 30k cycles in the accelerated degradation test(ADT),the MEA using PNC-A as the catalyst showed a performance retention of 82%,higher than that of Pt/C(74%).The results reported here verify the possibility of using PNC-A as an advanced cathode catalyst in PEMFCs,thus enhancing the performance of PEMFCs while lowering the amount of expensive Pt.
基金Supported by National Key Research and Development Program of China(2020YFD1100302)。
文摘Under the context of global energy transition and carbon neutrality,controlling nitrogen oxide(NO_(x))emissions from biomass combustion is of great significance,and the development of high-efficiency low-temperature catalysts has become a current research focus.In this study,Nb was used to dope and modify the Mn_(7)-Cu_(3)/BCN catalyst to construct the Mn_(7)-Cu_(3)-Nb_(x)/BCN system.The doping amount was optimized through selective catalytic reduction(SCR)activity tests.The reaction mechanism was explored by combining in situ DRIFTS and density functional theory(DFT)simulations.Experimental findings revealed that the catalyst doped with 0.05%Nb achieved the optimal performance,sustaining a NO conversion efficiency of≥94%within the temperature window of 150−275℃while demonstrating improved resistance to alkali metal K poisoning.Mechanistic analyses showed that at low temperatures,the catalyst facilitated the SCR reaction via both the Eley-Rideal(E-R)and Langmuir-Hinshelwood(L-H)pathways,with the synergistic interaction between multiple active sites driving the efficient conversion of NH3 and NO.DFT calculations further confirmed that both pathways had the characteristics of low reaction energy barriers and significant exothermicity,ensuring the high activity and feasibility of the low-temperature reaction.The findings provided foundational theoretical support for the design of Nb-doped Mn-Cu-supported catalysts and the exploration of the underlying working mechanisms.
基金Supported by the National Natural Science Foundation of China(21978196)Natural Science Foundation of Shanxi Province(201801D211008,202403021211018)+1 种基金Shanxi Provincial Education Department(S202413597023)Jincheng High Efficiency Conversion and Utilization Technology Innovation Center of CO2 Energy and Biomass Energy。
文摘This study presents the successful synthesis of a novel Z-scheme heterojunction composite film consisting of Ag/Bi_(2)MoO_(6)/BiOBr through electrochemical processes and ionexchange techniques,followed by the photodeposition of noble metal silver(Ag)onto the composite structure.The catalytic efficiency of semiconductor photocatalysts is greatly improved by utilizing the localized surface plasmon resonance(LSPR)effect observed in Ag nanoparticles(NPs).Furthermore,the noble metal Ag serves as an intermediary bridge facilitating charge transfer between Bi_(2)MoO_(6)and BiOBr,while the formation of a Schottky barrier effectively inhibits the recombination of photo-generated electron-hole pairs.As a result,the Ag-deposited Bi_(2)MoO_(6)/BiOBr film exhibits superior photocatalytic performance in the reduction of CO_(2)compared to its unmodified counterpart.Our experimental results indicate a non-linear relationship between Ag deposition and the efficiency of photocatalytic CO_(2)reduction to CO,characterized by an initial increase in efficiency followed by a decline.The optimized 1.5%-Ag/Bi_(2)MoO_(6)/BiOBr film demonstrates exceptional photocatalytic activity,attaining a CO production rate of 13.65μmol/(g·h).This research explores the fundamental mechanisms that lead to improved photocatalytic CO_(2)reduction capabilities of the Ag/Bi_(2)MoO_(6)/BiOBr film.Our research offers important perspectives for the thoughtful design and production of highly efficient photocatalysts,which are essential for advancing sustainable energy solutions.
文摘CO_(2)reduction technology can promote the resource utilization of carbon and help alleviate global warming and energy supply pressure.It is an effective way to achieve energy conversion and utilization.Covalent organic frameworks(COFs)are porous crystalline materials formed by connecting organic monomers through covalent bonds.They have the characteristics of functional diversity and rich chemical properties.Their advantages,such as high porosity,a wide range of visible light absorption,and excellent charge separation efficiency,give them good potential in CO_(2)capture,separation,and conversion.Currently,Cu is a key metal in the catalytic CO_(2)reduction reaction(CO_(2)RR)for the preparation of high-value-added chemicals.The preparation of highly stable and large-pore Cu-based COFs using COFs as an ideal sacrificial template for loading Cu can be used to develop high-performance electrocatalysts and photocatalysts.In this review,we discuss the latest advancements in this field,including the development of various Cu-based COFs and their applications as catalysts for CO_(2)RR.Here,we mainly introduce the synthesis strategies,some important characterization information,and the applications of electrocatalytic and photocatalytic CO_(2)conversion using these previously reported Cu-based COFs.
基金supported by the National Natural Science Foundation of China(Nos.22268003,22102095,52204320,U20A20246 and 12275199,U22A20418,22075196,21972110,52202208)National Key Research and Development Program of China(Nos.2023YFA1507903,2022YFB3803600,2022YFB4002501)+9 种基金SINOPEC(Beijing)Research Institute of Chemical Industry Co.,Ltd.(No.223239)the Fundamental Research Funds for the Central Universities(No.CCNU22JC017)the Postdoctoral Science Foundation of China(No.2021M692535)the Natural Science Foundation of Shaanxi Province(No.2022JQ-095)the Basic Research Project Foundation of Xi’an Jiaotong University(No.xzy012024012)the Youth Foundation of State Key Laboratory of Electrical Insulation and Power Equipment(No.EIPE2131)the Russian Science Foundation(No.22-13-00035)the Ministry of Science and Higher Education within the framework of a State Assignment of the Ioffe Institute,Russian Academy of Sciences(No.FFUG-2024-0036)Yunnan Fundamental Research Projects(No.202305AF150116)the Research Project Supported by Shanxi Scholarship Council of China(No.2022-050)。
文摘The catalytic transferred of small molecules into high-value chemical products in green methods are highly perused,and has obtained huge attention.In this field,great progress has been achieved during the past five years.Followed by the roadmap(Chinese Chemical Letters,2019,30,2089-2109)written by us before five years,we think that it should be updated to give more insights in this field.Thus,we write the present roadmap based on the fast changed background.In this roadmap,oxygen and carbon dioxide reduction reactions(including at high temperature),photocatalytic hydrogen generation and carbon dioxide reduction reactions,(photo)electrocatalytic reduction of O_(2)to H_(2)O_(2)and NH_(3)generated from N_(2) are discussed.The progress and challenges in above catalytic processes are given.We believe this manuscript will give the researchers more suggestions and help them to obtain useful information in this field.
文摘Experts and officials shared their insights on poverty reduction cooperation and sustainable development during the 2025 International Seminar on Global Poverty Reduction Partnerships.
基金supported by the National Natural Science Foundation of China(No.52302241 and 22225801)the Major Science and Technology Programs of Henan Province(241100240200)the China Postdoctoral Science Foundation(No.2023M730940).
文摘MXene derivatives are notable two-dimensional nanomaterials with numerous prospective applications in the domains of energy development.MXene derivative,MBene,diversifies its focus on energy storage and harvesting due to its exceptional electrical conductivity,structural flexibility,and mechanical properties.This comprehensive review describes the sandwich-like structure of the synthesized MBene,derived from its multilayered parent material and its distinct chemical framework to date.The fields of focus encompass the investigation of novel MBenes,the study of phase-changing mechanisms,and the examination of hex-MBenes,ortho-MBenes,tetra-MBenes,tri-MBenes,and MXenes with identical transition metal components.A critical analysis is also provided on the electrochemical mechanism and performance of MBene in energy storage(Li/Na/Mg/Ca/Li–S batteries and supercapacitors),as well as conversion and harvesting(CO_(2) reduction,and nitrogen reduction reactions).The persistent difficulties associated with conducting experimental synthesis and establishing artificial intelligence-based forecasts are extensively deliberated alongside the potential and forthcoming prospects of MBenes.This review provides a single platform for an overview of the MBene’s potential in energy storage and harvesting.
基金supported by the National Key R&D Program of China(No.2023YFE0112100)the Science and Technology Planning Project of Fujian Province(No.2023Y4015)the Marine and Fishery Devel-opment Special Fund of Xiamen(No.23YYST064QCB36).
文摘Hexavalent chromium(Cr(Ⅵ)) is an extremely toxic pollutant in aqueous environment.Chemical reduction is the most employed method in decontamination of Cr(Ⅵ).However,the chemical reduction was usually conducted in acidic media,resulting in considerable waste of acid reagents and the following neutralizing agents.In this study,kinetics and mechanisms of Cr(Ⅵ) reduction by sulfite in alkaline conditions(pH:7-10) were investigated.It reveals that Cr(Ⅵ) reduction follows pseudo-zero-order kinetics,where the rate constants increased markedly with an in situ irradiation of Far-UVC(UV_(222)).Decreasing pH levels slightly favored the reduction.Iodide ion displayed a notable accelerating effect,which not only save the energy input but also minimize the reductant usage.Chloride,sulfate,and carbonate ions exhibit little effect on the reduction,whereas nitrate and nitrite ions,dissolved oxygen as well as Cu(Ⅱ) suppressed the reduction significantly,implying that hydrated electrons produced by UV222 played the most important role in the reaction.Compared to the UV254/sulfite/iodide process,UV222/sulfite/iodide demonstrates clear advantages in the reduction kinetics and the sulfite utilization efficiency,underscoring its potential for effective Cr(Ⅵ) remediation in various environmental settings.
基金supported by the National Natural Science Foundation of China(Grant No.52474347)Postdoctoral Science Foundation of China(Grant No.2024T171095)the Fundamental Research Funds for the Central Universities(Grant No.2024CDJXY003).
文摘Coke oven gas(COG)and natural gas(NG),both high-calorific by-products derived from the steel industry,have gained prominence as alternative fuels in the sintering process,thereby supporting dual objectives of emission reduction and carbon neutrality.While existing research on hydrogen-rich gas injection has predominantly concentrated on conventional thin-bed sintering,investigations into its application within thick-bed sintering remain comparatively scarce.Thick-bed sintering,recognized for enhancing energy efficiency and increasing sinter output,encounters challenges such as uneven heat distribution and diminished permeability,which can negatively impact process efficiency and product quality.To address these issues,sinter pot experiments were conducted to assess the effects of NG and COG injection on thick-bed sintering performance.Findings reveal that NG injection in thick beds mirrors the behavior observed in conventional thin-bed sintering,effectively optimizing the process and achieving a carbon reduction potential exceeding 10%.In contrast,COG injection in thick-bed conditions demonstrates notable differences,substantially lowering the solid fuel consumption rate but detrimentally affecting sinter strength and overall production.However,by optimizing the timing of COG injection,it is feasible to improve sinter yield while concurrently reducing solid fuel usage.These outcomes provide valuable insights for the advancement of gas injection technologies in thick-bed sintering,thereby contributing to energy conservation and emission mitigation efforts within the sintering industry.
基金the Natural Science Foundation of China(Grant No.NSFC-22072062,22202098)the Science and Technology Project of China Northern Rare Earth(BFXT-2023-D-0048 and BFXT-2022-D-0078)。
文摘Electrochemical nitrate reduction reaction(NO_(3)RR)is a sustainable strategy to treat wastewater and produce ammonia.However,it is still a challenge to prepare electrocatalysts with high activity and selectivity.Herein,the CuO_(x) nanowires supported Ru nanoclusters(Ru-CuO_(x))were fabricated via a three-step procedure for efficient nitrate conversion and highly selective ammonia generation.The prepared RuCuO_(x) shows a high ammonia yield rate of 2286.5μg h^(-1) cm^(-2) at-0.7 V vs.RHE and Faradaic efficiency(FE)of 80.1%at-0.4 V vs.RHE.Additionally,the nitrate conversion rate exceeds 90%at the potential range from-0.2 to-0.7 V vs.RHE,and the ammonia selectivity can reach 97.7%at-0.7 V vs.RHE in100 mg L^(-1) NaNO_(3) solution.The systematic characterizations clarify that the introduction of Ru not only regulates the electronic structure of CuO_(x) and accelerates the reconstruction of CuO_(x) to Cu but also promotes H2O dissociation to generate active hydrogen.Moreover.in-situ Raman spectroscopy reveals that the formed Ru-Cu is considered the actual active species during the NO_(3)RR.Density functional theory(DFT)calculations further prove that the obtained Ru-Cu facilitates the adsorption of nitrate and lowers the Gibbs free energy of the rate-determining step,thus improving the NO_(3)RR performance.
基金supported by the Science and Technology Project of the State Grid Corporation of China“Research on Comprehensive Value Evaluation Method of Flexible Adjusting Resources under Carbon-electricity-certificate Market Coupling Environment”(No.5108-202455038A-1-1-ZN).
文摘The energy transition inspired by carbon neutrality targets and the increasing threat of extreme events raise multi-objective development requirements for power systems.This paper proposes a multi-objective resource allocation model to determine the type,number and location of flexible resources to increase the values of resilience,carbon reduction and renewable energy consumption.To evaluate the values of resilience,a restoration model for transmission systems is established that considers the coordination of fossil-fuel generators,energy storage systems(ESSs)and renewable energy generators in building restoration paths.The collaborative power-carbon-tradable green certificate(TGC)market model is then applied to evaluate the resource values in terms of carbon reduction and renewable energy consumption.Finally,the model is formulated as a mixed-integer linear programming(MILP)with a nonconvex feasible domain,and the normalized normal constraint(NNC)method is applied to obtain approximate Pareto frontiers for decision makers.Case studies validate the effectiveness of the proposed model in improving multi-factor values and analyze the impact of resource regulation capacity on values of restoration and carbon reduction.
基金supported by the Natural Science Foundation(NSF)of China(Nos.22205015,22175020,and 22235001)the National Postdoctoral Program for Innovative Talents(No.BX20220032)+2 种基金the China Postdoctoral Science Foundation Funded Project(No.2022BG013)the Fundamental Research Funds for the Central Universities(Nos.00007709,00007770,and FRFBR-23-02B)University of Science and Technology Beijing is gratefully acknowledged.
文摘In comparison with their 2D and 3D counterparts,1D covalent organic frameworks(COFs)have rarely been investigated due to the synthetic challenge arising from the strict necessary matching in the molecular symmetry between corresponding building blocks and linking units in addition to the unmanageable packing of 1D organic chains once formed.Herein,two novel imide-linked 1D COFs with phthalocyanine building blocks,namely NiPc-CZDM-COF and NiPc-CZDL-COF,were fabricated from the hydrothermal synthesis reaction of 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato nickel(II)(NiPc(COOH)_(8))with 9H-carbazole-3,6-diamine(CZDM)and 4,4′-(9H-carbazole-3,6-diyl)dianiline(CZDL),respectively.Two COFs have high crystallinity on the basis of powder X-ray diffraction analysis and high-resolution transmission electron microscopy.Due to their high ratio of exposed active centers on the edge sites of porous ribbons,both NiPc-CZDM-COF and NiPc-CZDL-COF electrodes display high utilization efficiency of NiPc electroactive sites of 8.0%and 7.5% according to the electrochemical measurement,resulting in their excellent capacity toward electrocatalytic nitrate reduction with the nitrate-to-NH3 Faradaic efficiency of nearly 100%.In particular,NiPc-CZDM-COF electrode exhibits superior electrocatalytic performance with high NH_(3) partial current density of−246 mA/cm^(2),ammonia yield rate of 19.5 mg cm^(−2) h^(−1),and turnover frequency of 5.8 s^(−1) at−1.2 V in an H-type cell associated with its higher conductivity.This work reveals the good potential of 1D porous crystalline materials in electrocatalysis.
