Selective reduction of nitroarenes has long been a problem in organic synthesis,as a wide distribution of many different products could be generated from the multi-electron transfer processes.Development of a mild and...Selective reduction of nitroarenes has long been a problem in organic synthesis,as a wide distribution of many different products could be generated from the multi-electron transfer processes.Development of a mild and preciously controllable strong reductive catalytic system is the key challenge to realize selective reduction of nitroarenes.In this work,the authors disclose a photocatalytic strategy with formate as the electron donor via generation of the highly reductive CO_(2)radical anion species.Various arylhydroxylamines or anilines could be synthesized selectively under visible-light irradiation by simply switching the photocatalysts.Moreover,in the presence of formaldehyde,the N-methyl anilines or imidazoline derivative could also be constructed in one-pot manner.Nitroalkanes were also amendable in this photocatalytic system to selectively yield oximes.展开更多
Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to...Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance.Cation-disordered rocksalt(DRX)Li_(2)FeTiO_(4)shows promising properties as symmetric electrodes,based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window.Unfortunately,this cation-disordered structure would not provide a cross-path for the rapid migration of Li^(+),ultimately resulting in inferior electrochemical dynamics and cycle stability.Herein,Li_(2)FeTiO_(4)nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants.Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic(e.g.,stable Fe^(2+)/Fe^(3+),Ti^(3+)/Ti^(4+)and moderated Fe^(3+)/Fe^(4+))and anionic redox,and maintain the DRX structure well during the cycling process.The half cells with nano-sized Li_(2)FeTiO_(4)as the cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g,respectively.Besides,the Li_(2)FeTiO_(4)//Li_(2)FeTiO_(4)symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles.This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries.展开更多
In this study,the environmentally friendly precursor,tartaric acid(TA),was employed for the generation of CO_(2)anion radical(CO_(2)^(·-))in an advanced UV/TA/Fe^(3+)system to reduce the hazardous NO_(2)^(-)-N in...In this study,the environmentally friendly precursor,tartaric acid(TA),was employed for the generation of CO_(2)anion radical(CO_(2)^(·-))in an advanced UV/TA/Fe^(3+)system to reduce the hazardous NO_(2)^(-)-N in wastewater.To optimize this process,various factors,including the dosage of Fe^(3+),TA,and p H,were systematically investigated for their impact on the reduction process.Under the conditions of 3 mmol/L Fe^(3+)dosage,10 mmol/L TA dosage,and a pH of 2.5,NO_(2)^(-)-N was effectively removed from the water within 60 min,selectively transformed into N_(2),with a remarkable N_(2)selectivity of 91.2%.In the optimal conditions,the NO_(2)^(-)-N reduction mechanism in the UV/TA/Fe^(3+)system and the critical role of CO_(2)^(·-)were illustrated.Finally,this study explored the reduction of real nitrified seawater using the UV/TA/Fe^(3+)system.The results demonstrated that the UV/TA/Fe^(3+)system could completely eliminate NO_(2)^(-)-N and achieve a N_(2)selectivity of up to 90%,with minimal interference from coexisting ions.This work holds promising implications for the environmentally benign treatment of nitrite-polluted wastewater.展开更多
Aqueous zinc ion batteries(AZIBs)have excellent development prospects due to their high theoretical capacity and low cost.Nevertheless,the commercial separator represented by glass fiber(GF)in AZIBs usually exhibits u...Aqueous zinc ion batteries(AZIBs)have excellent development prospects due to their high theoretical capacity and low cost.Nevertheless,the commercial separator represented by glass fiber(GF)in AZIBs usually exhibits uneven porosity,poor zincophilicity,and insufficient functional groups,resulting in the emergence of the zinc anode dendrites and side reactions.Designing a separator with specific interfacial ion transport behavior is essential to achieve a highly stable reversible zinc anode.Herein,an anionic metal-organic framework(MOF)functionalized separator(GF-Bio-MOF-100)was presented to accelerate the desolvation process and modulate Zn^(2+)flux,thereby delivering the decreased nucleation overpotential and uniform Zn^(2+)deposition.The in-depth kinetics investigations combined with the in-situ Raman spectroscopy demonstrate that the carbonyl group within the Bio-MOF-100 is capable of capturing the H_(2)O molecules of[Zn(H_(2)O)_(6)]^(2+)via the H-bond interaction,which further accelerates the desolvation process and transport kinetics of Zn^(2+).Meanwhile,the anionic framework of the GFBio-MOF-100 separator acts as an interfacial ion channel to regulate the Zn^(2+)flux and enables dendrite-free Zn^(2+)deposition and growth.Consequently,the Zn|GF-Bio-MOF-100|Zn symmetric cell exhibited a stable Zn^(2+)plating/stripping behavior and it could cycle for 2000 h at 0.3 mA cm^(-2).Additionally,the assembled Zn|GF-Bio-MOF-100|MnO_(2)full cell delivers a capacity retention of 83.9% after 1000 cycles at 0.5 A g^(-1).This work provides new insights into the design of functionalized separators for long-life AZIBs.展开更多
The coordination engineering of catalytic centers emerges as a pivotal strategy for precise electronic configuration modulation in photocatalytic CO_(2) reduction.Herein,the electronic structure of active sites in pol...The coordination engineering of catalytic centers emerges as a pivotal strategy for precise electronic configuration modulation in photocatalytic CO_(2) reduction.Herein,the electronic structure of active sites in polypyridine nickel catalysts is well modified through strategic ligand variation(bipyridine,terpyridine(TPY),2,6-di(1-pyrazolyl)pyridine)and anion coordination(NO_(3)^(-),Cl^(-),and CH_(3)COO^(-)),achieving enhanced CO_(2) performance.Crucially,covalent immobilization of these molecular catalysts within the COF-OH framework not only preserves their precisely defined and structurally adaptable characteristics but also demonstrates synergistic enhancement of CO_(2) adsorption capacity and charge transfer kinetics,as verified by CO_(2) adsorption isothermal analysis and ultrafast time-resolved transient absorption spectroscopy.Remarkably,COF-O-TPYNi(NO_(3)^(-))catalyst exhibits a CO_(2)-to-CO reduction activity of 9006.0μmol·g^(-1)·h^(-1)with 95.9%selectivity,superior to its counterpart catalysts,directly validating the mechanistic significance of precisely tailored coordination microenvironments around Ni active sites.Mechanistic studies through in situ XAFS,in situ ATR-SEIRAS and theoretical calculations reveal that this performance improvement over COF-O-TPYNi(NO_(3)^(-))is attributed to the reduced reaction energy barrier of*COOH generation.This work pioneers a coordination shell engineering paradigm for rational design of molecularly defined catalytic architectures.展开更多
The oxygen evolution reaction(OER)is the bottleneck in the overall photocatalytic splitting of water.The active sites(terminal titanium or bridging oxygen)and active species(molecular or dissociative water)of the init...The oxygen evolution reaction(OER)is the bottleneck in the overall photocatalytic splitting of water.The active sites(terminal titanium or bridging oxygen)and active species(molecular or dissociative water)of the initial step of the photocatalyzed OER on the prototypical photocatalyst TiO_(2),remain debatable.Herein,the photocatalytic chemistry of monolayer water on oxygen-pretreated TiO_(2)(110)(o-TiO_(2)(110))and reduced TiO_(2)(110)(r-TiO_(2)(110))surfaces initiated by 400 nm light illumination was investigated by time-dependent two-photon photoemission spectroscopy(TD-2PPE).The photoinduced reduction of the H_(2)O/o-TiO_(2)(110)interface rather than the H2O/r-TiO_(2)(110)interface was detected by TD-2PPE.The difference in 2PPE originated from the presence of the terminal hydroxyl anions(OHt^(-))on H_(2)O/o-TiO_(2)(110),as identified by X-ray photoelectron spectroscopy and temperature-programmed desorption.Therefore,the evolution of the electronic structure of H_(2)O/o-TiO_(2)(110)was attributed to the photocatalyzed oxidation of the terminal hydroxyl anions,which most likely formed gaseous·OH radicals,reducing the interface.This work suggested that the oxidation of hydroxyl anions on top of the terminal titanium ions on TiO_(2),which were excluded previously in solution,need to be considered in the mechanistic studies of the photocatalyzed OER.展开更多
The removal and recovery of low-concentration phosphates from water have become crucial due to the dual challenges of eutrophication and the phosphorus crisis.Herein,we engineered a highly efficient and recyclable pho...The removal and recovery of low-concentration phosphates from water have become crucial due to the dual challenges of eutrophication and the phosphorus crisis.Herein,we engineered a highly efficient and recyclable phosphate trapping agent of La_(2-x)CexO_(2)CO_(3) solid solution.The incorporation of Ce enhances the surface area and surface potential of La_(2-x)CexO_(2)CO_(3),providing abundant adsorption sites for phosphate.Surprisingly,we found that adjusting the Ce proportion affects the carbonate content,thereby influencing the anion-exchange capacity between carbonate and phosphate.Specifically,at 3% Ce content(3%-CeL),the carbonate ratio is maximized,resulting in an optimal sorption capacity(196.4mg P/g)and a rapid removal rate(under 40min)for phosphate,unaffected by interfering ions.Remarkably,3%-CeL achieved nearly 100%phosphate removal efficiency in diverse water samples from sewage treatment plants,rivers,reservoirs,and groundwater.After five adsorption-desorption cycles,the phosphate removal and recovery efficiency of 3%-CeL remained above 90%.Mechanistic studies revealed that 3%Ce content yielded the highest proportion of Ce^(4+)/Ce^(3+),enabling greater carbonate binding for anion-exchange.This study proposes a high-performance phosphate trapping agentwith broad applicability for treating actual waters and provides a new perspective on enhancing low-concentration phosphate removal in La-based materials through manipulating Ce ratio and valence.展开更多
A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaC...A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.展开更多
MgH_(2) is regarded as a potential hydrolysis material for the hydrogen generation due to its high theoretical hydrogen yield,abundant source on earth and environmentally friendly hydrolysates.However,the quickly form...MgH_(2) is regarded as a potential hydrolysis material for the hydrogen generation due to its high theoretical hydrogen yield,abundant source on earth and environmentally friendly hydrolysates.However,the quickly formed passive magnesium hydroxide layer on the surface of MgH_(2) will hinder its further hydrolysis reaction,leading to sluggish reaction kinetics and low H_(2) yield.In this paper,we explore the improvement of different anions and cations in solutions for the hydrolysis of MgH_(2).It is found that the cations in the solution promote the reaction rate of MgH_(2) hydrolysis through the hydrolysate-induced growth effect,among which the fastest hydrogen yield can get 1664 m L/g within a few minutes in the Fe_(2)(SO_(4))_(3) solution.As for the anions,it enables different microstructures of the Mg(OH)_(2) hydrolysate which give rise to enhanced water utilization.Specially,for the mixed 0.5 M MgCl_(2)+0.05 M MgSO_(4) solution,the water utilization rate attains the optimum value of 51.3%,much higher than that of the single MgCl_(2) or MgSO_(4) solutions.These findings are of great significance for the application of MgH_(2) hydrolysis as hydrogen generation.展开更多
The separation of Co 2+ from Zn 2+ , Cd 2+ by anion exchange chromatography was discussed. The chromatographic column containing anion resin 201×7 which was saturated with a solution of ammonium chloride. The eff...The separation of Co 2+ from Zn 2+ , Cd 2+ by anion exchange chromatography was discussed. The chromatographic column containing anion resin 201×7 which was saturated with a solution of ammonium chloride. The effects of the eluant acidity and eluant composition on the separation were investigated. The results indicate that this anion exchange chromatography is suitable to the separation of Co 2+ from Zn 2+ , Cd 2+ , and the condition of separation is simple and convenient. When the column is saturated with NH 4Cl solution (2.0 mol/L, pH=4.0), the separation can be completed effectively. Zn 2+ and Cd 2+ can also be separa ted when different eluants are used and the pure solution with high concentration of Zn 2+ , Cd 2+ respectively can be obtained ea sily.展开更多
It is well-known that the electrolytes can influence the electrochemical reduction of carbon dioxide(ERCO2)in aqueous media.In this work,we explore the effects of alkali metal cations and anions(Li^+,Na^+,K^+,Rb^+,Cs^...It is well-known that the electrolytes can influence the electrochemical reduction of carbon dioxide(ERCO2)in aqueous media.In this work,we explore the effects of alkali metal cations and anions(Li^+,Na^+,K^+,Rb^+,Cs^+,HCO3^-,Cl^-,Br^-,I^-)on the current density and product selectivity for the ERCO2 into formic acid(HCOOH)on the SnO2/carbon paper(Sn O2/C)electrode.Results of the ERCO2 experiments show that for the cations,the promotion effects on current density and faradaic efficiencies(FEs)are in the order of Li^+b Na^+b K^+b Cs^+b Rb^+.For the anions,the current density values are in the order of Na HCO3 b NaClb Na Br b Na I and KHCO3 b KCl≈KI b KBr,respectively,and that on the FEs for the formation of the HCOOH(FEHCOOH)is HCO3-b Cl-b Br-b I-.Based on this result,the effects of alkali metal cations and anions on ERCO2 are discussed.展开更多
The adsorption of CO_(2) on MgAl layered double hydroxides(MgAl-LDHs) based adsorbents has been an effective way to capture CO_(2),however the adsorption capacity was hampered due to the pore structure and the dispers...The adsorption of CO_(2) on MgAl layered double hydroxides(MgAl-LDHs) based adsorbents has been an effective way to capture CO_(2),however the adsorption capacity was hampered due to the pore structure and the dispersibility of adsorption active sites.To address the problem,we investigate the effect of intercalated anion and alkaline etching time on the structure,morphology and CO_(2) uptake performances of MgAl-LDHs.MgAl-LDHs are synthesized by the onepot hydrothermal method,followed by alkaline etching of NaOH,and characterized by x-ray diffraction,N_(2) adsorption,scanning electron microscopy and Fourier transform infrared spectroscopy.The CO_(2) adsorption tests of the samples are performed on a thermogravimetric analyzer,and the adsorption data are fitted by the first-order,pseudo-second-order and Elovich models,respectively.The results demonstrate that among the three intercalated samples,MgAl(Cl) using chloride salts as precursors possesses the highest adsorption capacity of CO_(2),owing to high crystallinity and porous structure,while MgAl(Ac) employing acetate salts as precursors displays the lowest CO_(2) uptake because of poor crystallinity,disorderly stacked structure and unsatisfactory pore structure.With regard to alkaline etching,the surface of the treated MgAl(Cl) is partly corroded,thus the specific surface area and pore volume increase,which is conducive to the exposure of adsorption active sites.Correspondingly,the adsorption performance of the alkaline-etched adsorbents is significantly improved,and MgAl(Cl)-6 has the highest CO_(2) uptake.With the alkaline etching time further increasing,the CO_(2) adsorption capacity of MgAl(Cl)-9 sharply decreases,mainly due to the collapse of pore structure and the fragmentized sheet-structure.Hence,the CO_(2) adsorption performance is greatly influenced by alkaline etching time,and appropriate alkaline etching time can facilitate the contact between CO_(2) molecules and the adsorbent.展开更多
Topomerization of [9] annulen anion （1） and its 2-fluoro-, 2-chloro- and 2- bromo-defivatives （2, 3 and 4, respectively） are studied at the HF/6-31G＊ and B3LYP/6-31 1＋＋G＊＊ levels of theory. The relative ease ...Topomerization of [9] annulen anion （1） and its 2-fluoro-, 2-chloro- and 2- bromo-defivatives （2, 3 and 4, respectively） are studied at the HF/6-31G＊ and B3LYP/6-31 1＋＋G＊＊ levels of theory. The relative ease of topomerization is dependent on the charge distribution and planarity of the ground state and the transition state of 9-membered rings as well as the size and electronegativity of halogen substituent. Consequently, the endo-2-halo-[9] annulen anion topomers become unstable and easily convert to related exo-topomers. Hence, according to the DFT calcu- lations, the order of topomerization energy barrier for endo = exo topomerization is lendo 〉 2endo 〉 3endo.展开更多
基金financially supported by the Jiangsu Province Shuangchuang Ph.D Award(No.JSSCBS20211267,Pei Xu)the Natural Science Research Project of Jiangsu Universities(No.23KJB150037,Pei Xu)+1 种基金sponsored by the Jiangsu Specially-Appointed Professor program(Xu Zhu)the start-up funding provided by Xuzhou Medical University。
文摘Selective reduction of nitroarenes has long been a problem in organic synthesis,as a wide distribution of many different products could be generated from the multi-electron transfer processes.Development of a mild and preciously controllable strong reductive catalytic system is the key challenge to realize selective reduction of nitroarenes.In this work,the authors disclose a photocatalytic strategy with formate as the electron donor via generation of the highly reductive CO_(2)radical anion species.Various arylhydroxylamines or anilines could be synthesized selectively under visible-light irradiation by simply switching the photocatalysts.Moreover,in the presence of formaldehyde,the N-methyl anilines or imidazoline derivative could also be constructed in one-pot manner.Nitroalkanes were also amendable in this photocatalytic system to selectively yield oximes.
基金supported by the National Natural Science Foundation of China(No.22278347)the Excellent Doctoral Student Research Innovation Project of Xinjiang University of China(No.XJU2022BS048)the Postgraduate Innovation Project of Xinjiang Uygur Autonomous Region of China(No.XJ2023G027)。
文摘Symmetric secondary batteries are expected to become promising storage devices on account of their low cost,environmentally friendly and high safety.Nevertheless,the further development of symmetric batteries needs to rely on bipolar electrodes with superior performance.Cation-disordered rocksalt(DRX)Li_(2)FeTiO_(4)shows promising properties as symmetric electrodes,based on the ability of iron to undergo multiple electrochemical reactions over a wide voltage window.Unfortunately,this cation-disordered structure would not provide a cross-path for the rapid migration of Li^(+),ultimately resulting in inferior electrochemical dynamics and cycle stability.Herein,Li_(2)FeTiO_(4)nanoparticles assembled by ultrafine nanocrystals are synthesized via a sol-gel method through an orderly reaction regulation strategy of precursor reactants.Such ultrafine nanocrystals increase the active sites to promote the reversibility of multi-cationic(e.g.,stable Fe^(2+)/Fe^(3+),Ti^(3+)/Ti^(4+)and moderated Fe^(3+)/Fe^(4+))and anionic redox,and maintain the DRX structure well during the cycling process.The half cells with nano-sized Li_(2)FeTiO_(4)as the cathode/anode exhibit a high reversible capacity of 127.8/500.8 mAh/g,respectively.Besides,the Li_(2)FeTiO_(4)//Li_(2)FeTiO_(4)symmetric full cell could provide a reversible capacity of 95.4 mAh/g at 0.1 A/g after 200 cycles.This hierarchical self-assembly by nanocrystal strategy could offer effective guidance for high-performance electrode design for rechargeable secondary batteries.
基金financially supported by National Natural Science Foundation of China(No.22208081)Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.226Z3102G)Fundamental Research Funds of Hebei University of Technology(No.JBKYTD2001)。
文摘In this study,the environmentally friendly precursor,tartaric acid(TA),was employed for the generation of CO_(2)anion radical(CO_(2)^(·-))in an advanced UV/TA/Fe^(3+)system to reduce the hazardous NO_(2)^(-)-N in wastewater.To optimize this process,various factors,including the dosage of Fe^(3+),TA,and p H,were systematically investigated for their impact on the reduction process.Under the conditions of 3 mmol/L Fe^(3+)dosage,10 mmol/L TA dosage,and a pH of 2.5,NO_(2)^(-)-N was effectively removed from the water within 60 min,selectively transformed into N_(2),with a remarkable N_(2)selectivity of 91.2%.In the optimal conditions,the NO_(2)^(-)-N reduction mechanism in the UV/TA/Fe^(3+)system and the critical role of CO_(2)^(·-)were illustrated.Finally,this study explored the reduction of real nitrified seawater using the UV/TA/Fe^(3+)system.The results demonstrated that the UV/TA/Fe^(3+)system could completely eliminate NO_(2)^(-)-N and achieve a N_(2)selectivity of up to 90%,with minimal interference from coexisting ions.This work holds promising implications for the environmentally benign treatment of nitrite-polluted wastewater.
基金supported by the National Natural Science Foundation of China(No.22278328)the Key Research and Development Program of Shaanxi Province(No.2023-YBGY-292)。
文摘Aqueous zinc ion batteries(AZIBs)have excellent development prospects due to their high theoretical capacity and low cost.Nevertheless,the commercial separator represented by glass fiber(GF)in AZIBs usually exhibits uneven porosity,poor zincophilicity,and insufficient functional groups,resulting in the emergence of the zinc anode dendrites and side reactions.Designing a separator with specific interfacial ion transport behavior is essential to achieve a highly stable reversible zinc anode.Herein,an anionic metal-organic framework(MOF)functionalized separator(GF-Bio-MOF-100)was presented to accelerate the desolvation process and modulate Zn^(2+)flux,thereby delivering the decreased nucleation overpotential and uniform Zn^(2+)deposition.The in-depth kinetics investigations combined with the in-situ Raman spectroscopy demonstrate that the carbonyl group within the Bio-MOF-100 is capable of capturing the H_(2)O molecules of[Zn(H_(2)O)_(6)]^(2+)via the H-bond interaction,which further accelerates the desolvation process and transport kinetics of Zn^(2+).Meanwhile,the anionic framework of the GFBio-MOF-100 separator acts as an interfacial ion channel to regulate the Zn^(2+)flux and enables dendrite-free Zn^(2+)deposition and growth.Consequently,the Zn|GF-Bio-MOF-100|Zn symmetric cell exhibited a stable Zn^(2+)plating/stripping behavior and it could cycle for 2000 h at 0.3 mA cm^(-2).Additionally,the assembled Zn|GF-Bio-MOF-100|MnO_(2)full cell delivers a capacity retention of 83.9% after 1000 cycles at 0.5 A g^(-1).This work provides new insights into the design of functionalized separators for long-life AZIBs.
文摘The coordination engineering of catalytic centers emerges as a pivotal strategy for precise electronic configuration modulation in photocatalytic CO_(2) reduction.Herein,the electronic structure of active sites in polypyridine nickel catalysts is well modified through strategic ligand variation(bipyridine,terpyridine(TPY),2,6-di(1-pyrazolyl)pyridine)and anion coordination(NO_(3)^(-),Cl^(-),and CH_(3)COO^(-)),achieving enhanced CO_(2) performance.Crucially,covalent immobilization of these molecular catalysts within the COF-OH framework not only preserves their precisely defined and structurally adaptable characteristics but also demonstrates synergistic enhancement of CO_(2) adsorption capacity and charge transfer kinetics,as verified by CO_(2) adsorption isothermal analysis and ultrafast time-resolved transient absorption spectroscopy.Remarkably,COF-O-TPYNi(NO_(3)^(-))catalyst exhibits a CO_(2)-to-CO reduction activity of 9006.0μmol·g^(-1)·h^(-1)with 95.9%selectivity,superior to its counterpart catalysts,directly validating the mechanistic significance of precisely tailored coordination microenvironments around Ni active sites.Mechanistic studies through in situ XAFS,in situ ATR-SEIRAS and theoretical calculations reveal that this performance improvement over COF-O-TPYNi(NO_(3)^(-))is attributed to the reduced reaction energy barrier of*COOH generation.This work pioneers a coordination shell engineering paradigm for rational design of molecularly defined catalytic architectures.
基金supported by the National Key Research and Development Program of China(No.2021YFA1500601)the National Natural Science Foundation of China(Nos.22322306 and 22288201)+3 种基金the Chinese Academy of Sciences(Nos.YSBR007,XDB0970000)the Key Research Project of Shaanxi Provincial Science and Technology Department(No.2023-YBNY-158)the Xi’an Science and Technology Project(No.22NYYF016)the 111 Project。
文摘The oxygen evolution reaction(OER)is the bottleneck in the overall photocatalytic splitting of water.The active sites(terminal titanium or bridging oxygen)and active species(molecular or dissociative water)of the initial step of the photocatalyzed OER on the prototypical photocatalyst TiO_(2),remain debatable.Herein,the photocatalytic chemistry of monolayer water on oxygen-pretreated TiO_(2)(110)(o-TiO_(2)(110))and reduced TiO_(2)(110)(r-TiO_(2)(110))surfaces initiated by 400 nm light illumination was investigated by time-dependent two-photon photoemission spectroscopy(TD-2PPE).The photoinduced reduction of the H_(2)O/o-TiO_(2)(110)interface rather than the H2O/r-TiO_(2)(110)interface was detected by TD-2PPE.The difference in 2PPE originated from the presence of the terminal hydroxyl anions(OHt^(-))on H_(2)O/o-TiO_(2)(110),as identified by X-ray photoelectron spectroscopy and temperature-programmed desorption.Therefore,the evolution of the electronic structure of H_(2)O/o-TiO_(2)(110)was attributed to the photocatalyzed oxidation of the terminal hydroxyl anions,which most likely formed gaseous·OH radicals,reducing the interface.This work suggested that the oxidation of hydroxyl anions on top of the terminal titanium ions on TiO_(2),which were excluded previously in solution,need to be considered in the mechanistic studies of the photocatalyzed OER.
基金supported by the National Key Research and Development Program of China(Nos.2022YFC3703700,2021YFA0910300,and 2021YFC3200902)the National Natural Science Foundation of China(No.22125606)+1 种基金the Special Project of Ecological Environmental Technology for Carbon Dioxide Emissions Peak and Carbon Neutrality(No.RCEESTDZ-2021-21)China South-to-North Water Diversion Corporation Limited Research Project(No.NSBDZX/SH/KY/2022-001).
文摘The removal and recovery of low-concentration phosphates from water have become crucial due to the dual challenges of eutrophication and the phosphorus crisis.Herein,we engineered a highly efficient and recyclable phosphate trapping agent of La_(2-x)CexO_(2)CO_(3) solid solution.The incorporation of Ce enhances the surface area and surface potential of La_(2-x)CexO_(2)CO_(3),providing abundant adsorption sites for phosphate.Surprisingly,we found that adjusting the Ce proportion affects the carbonate content,thereby influencing the anion-exchange capacity between carbonate and phosphate.Specifically,at 3% Ce content(3%-CeL),the carbonate ratio is maximized,resulting in an optimal sorption capacity(196.4mg P/g)and a rapid removal rate(under 40min)for phosphate,unaffected by interfering ions.Remarkably,3%-CeL achieved nearly 100%phosphate removal efficiency in diverse water samples from sewage treatment plants,rivers,reservoirs,and groundwater.After five adsorption-desorption cycles,the phosphate removal and recovery efficiency of 3%-CeL remained above 90%.Mechanistic studies revealed that 3%Ce content yielded the highest proportion of Ce^(4+)/Ce^(3+),enabling greater carbonate binding for anion-exchange.This study proposes a high-performance phosphate trapping agentwith broad applicability for treating actual waters and provides a new perspective on enhancing low-concentration phosphate removal in La-based materials through manipulating Ce ratio and valence.
文摘A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.
基金supported by the National Key Research and Development Program of China(2017YFA0204600)the National Science Fund for Distinguished Young Scholars(51625102)+2 种基金the National Natural Science Foundation of China(51971065)the Innovation Program of Shanghai Municipal Education Commission(2019–01–07–00–07-E00028)the financial support from ARC(DP170101773)。
文摘MgH_(2) is regarded as a potential hydrolysis material for the hydrogen generation due to its high theoretical hydrogen yield,abundant source on earth and environmentally friendly hydrolysates.However,the quickly formed passive magnesium hydroxide layer on the surface of MgH_(2) will hinder its further hydrolysis reaction,leading to sluggish reaction kinetics and low H_(2) yield.In this paper,we explore the improvement of different anions and cations in solutions for the hydrolysis of MgH_(2).It is found that the cations in the solution promote the reaction rate of MgH_(2) hydrolysis through the hydrolysate-induced growth effect,among which the fastest hydrogen yield can get 1664 m L/g within a few minutes in the Fe_(2)(SO_(4))_(3) solution.As for the anions,it enables different microstructures of the Mg(OH)_(2) hydrolysate which give rise to enhanced water utilization.Specially,for the mixed 0.5 M MgCl_(2)+0.05 M MgSO_(4) solution,the water utilization rate attains the optimum value of 51.3%,much higher than that of the single MgCl_(2) or MgSO_(4) solutions.These findings are of great significance for the application of MgH_(2) hydrolysis as hydrogen generation.
文摘The separation of Co 2+ from Zn 2+ , Cd 2+ by anion exchange chromatography was discussed. The chromatographic column containing anion resin 201×7 which was saturated with a solution of ammonium chloride. The effects of the eluant acidity and eluant composition on the separation were investigated. The results indicate that this anion exchange chromatography is suitable to the separation of Co 2+ from Zn 2+ , Cd 2+ , and the condition of separation is simple and convenient. When the column is saturated with NH 4Cl solution (2.0 mol/L, pH=4.0), the separation can be completed effectively. Zn 2+ and Cd 2+ can also be separa ted when different eluants are used and the pure solution with high concentration of Zn 2+ , Cd 2+ respectively can be obtained ea sily.
基金financially supported by International Academic Cooperation and Exchange Program of Shanghai Science and Technology Committee(18160723600)Scientific Research and Technology Development Plan of Guangxi(GUIKE AD17195084)。
文摘It is well-known that the electrolytes can influence the electrochemical reduction of carbon dioxide(ERCO2)in aqueous media.In this work,we explore the effects of alkali metal cations and anions(Li^+,Na^+,K^+,Rb^+,Cs^+,HCO3^-,Cl^-,Br^-,I^-)on the current density and product selectivity for the ERCO2 into formic acid(HCOOH)on the SnO2/carbon paper(Sn O2/C)electrode.Results of the ERCO2 experiments show that for the cations,the promotion effects on current density and faradaic efficiencies(FEs)are in the order of Li^+b Na^+b K^+b Cs^+b Rb^+.For the anions,the current density values are in the order of Na HCO3 b NaClb Na Br b Na I and KHCO3 b KCl≈KI b KBr,respectively,and that on the FEs for the formation of the HCOOH(FEHCOOH)is HCO3-b Cl-b Br-b I-.Based on this result,the effects of alkali metal cations and anions on ERCO2 are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.21606058)the Natural Science Foundation of Guangxi,China(Grant Nos.2017GXNSFBA198193 and 2017GXNSFBA198124)the Startup Foundation for Doctors of Guilin University of Technology(Grant No.GLUTQD2015008)。
文摘The adsorption of CO_(2) on MgAl layered double hydroxides(MgAl-LDHs) based adsorbents has been an effective way to capture CO_(2),however the adsorption capacity was hampered due to the pore structure and the dispersibility of adsorption active sites.To address the problem,we investigate the effect of intercalated anion and alkaline etching time on the structure,morphology and CO_(2) uptake performances of MgAl-LDHs.MgAl-LDHs are synthesized by the onepot hydrothermal method,followed by alkaline etching of NaOH,and characterized by x-ray diffraction,N_(2) adsorption,scanning electron microscopy and Fourier transform infrared spectroscopy.The CO_(2) adsorption tests of the samples are performed on a thermogravimetric analyzer,and the adsorption data are fitted by the first-order,pseudo-second-order and Elovich models,respectively.The results demonstrate that among the three intercalated samples,MgAl(Cl) using chloride salts as precursors possesses the highest adsorption capacity of CO_(2),owing to high crystallinity and porous structure,while MgAl(Ac) employing acetate salts as precursors displays the lowest CO_(2) uptake because of poor crystallinity,disorderly stacked structure and unsatisfactory pore structure.With regard to alkaline etching,the surface of the treated MgAl(Cl) is partly corroded,thus the specific surface area and pore volume increase,which is conducive to the exposure of adsorption active sites.Correspondingly,the adsorption performance of the alkaline-etched adsorbents is significantly improved,and MgAl(Cl)-6 has the highest CO_(2) uptake.With the alkaline etching time further increasing,the CO_(2) adsorption capacity of MgAl(Cl)-9 sharply decreases,mainly due to the collapse of pore structure and the fragmentized sheet-structure.Hence,the CO_(2) adsorption performance is greatly influenced by alkaline etching time,and appropriate alkaline etching time can facilitate the contact between CO_(2) molecules and the adsorbent.
文摘Topomerization of [9] annulen anion （1） and its 2-fluoro-, 2-chloro- and 2- bromo-defivatives （2, 3 and 4, respectively） are studied at the HF/6-31G＊ and B3LYP/6-31 1＋＋G＊＊ levels of theory. The relative ease of topomerization is dependent on the charge distribution and planarity of the ground state and the transition state of 9-membered rings as well as the size and electronegativity of halogen substituent. Consequently, the endo-2-halo-[9] annulen anion topomers become unstable and easily convert to related exo-topomers. Hence, according to the DFT calcu- lations, the order of topomerization energy barrier for endo = exo topomerization is lendo 〉 2endo 〉 3endo.
