Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.He...Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.Herein,a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres(HCS)as the inner layer and sodium fluoride(NaF)as the outer layer on commercial polypropylene separator(PP)is proposed(PP@HCS-NaF)to achieve stable cycling in SMB.At the molecular level,the inner HCS layer with a high content of pyrrolic-N induces the uniform Na^(+)flux as a potential Na^(+)redistributor for homogenous deposition,whereas its hollow mesoporous structure offers nanoporous buffers and ion channels to regulate Na^(+)ion distribution and uniform deposition.The outer layer(NaF)constructs the NaF-enriched robust solid electrolyte interphase layer,significantly lowering the Na^(+)ions diffusion barrier.Benefiting from these merits,higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators(i.e.PP@HCS or PP@NaF)in SMBs.The Na‖Cu half-cell with PP@HCS-NaF offers stable cycling(280 cycles)with a high CE(99.6%),and Na‖Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm^(-2)with a progressively stable overpotential of 9 mV.Remarkably,in Na‖NVP full-cells,the PP@HCS-NaF separator grants a stable capacity of~81 mA h g^(-1)after 3500 cycles at 1 C and an impressive rate capability performance(~70 mA h g^(-1)at 15 C).展开更多
ZSM-5 zeolite samples with a SiO2/Al2O3 ratio of 40 were synthesized by a hydrothermal method,and treated by 0.3 M tetrapropyl ammonium hydroxide(TPAOH)and 0.3 M sodium hydroxide(NaOH)solution separately to create hol...ZSM-5 zeolite samples with a SiO2/Al2O3 ratio of 40 were synthesized by a hydrothermal method,and treated by 0.3 M tetrapropyl ammonium hydroxide(TPAOH)and 0.3 M sodium hydroxide(NaOH)solution separately to create hollow structures.The synthesized ZSM-5 zeolite and treated ZSM-5 zeolite samples were evaluated for aromatization of 1-hexene in a continuous flow reactor.The prepared ZSM-5 zeolite samples were characterized by XRD,SEM,TEM,NMR,XPS,and other analyses.The results showed that the alkali treatment formed mesopores and hollow structures in the ZSM-5 crystals without destroying the topological structure.The acid amount of ZSM-5 zeolite was also increased after alkali treatment.Compared with the ZSM-5 zeolite treated by TPAOH,the ZSM-5 zeolite treated by NaOH had more mesopores and a higher total acid amount but a lower strong acid amount,resulting in higher aromatics yields and catalytic stability for 1-hexene aromatization.The characterization of spent ZSM-5 zeolites suggested that the spent treated ZSM-5 zeolites contained less coke,leading to a smaller reduction of micropore surface area and volume than in the spent parent ZSM-5,which contributed to the stability enhancement.展开更多
In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method...In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method involving high-pressure processing,stirring,and immiscible solutions,sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer.Functionalization control is achieved by defunctionalizing MXene at 650℃ under vacuum and H2 gas in a CVD furnace,followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD.Notably,the introduction of iodine,which has a larger atomic size,lower electronegativity,reduce shielding effect,and lower hydrophilicity(contact angle:99°),profoundly affecting MXene.It improves the surface area(36.2 cm^(2) g^(-1)),oxidation stability in aqueous/ambient environments(21 days/80 days),and film conductivity(749 S m^(-1)).Additionally,it significantly enhances the gas-sensing performance,including the sensitivity(0.1119Ωppm^(-1)),response(0.2% and 23%to 50 ppb and 200 ppm NO_(2)),and response/recovery times(90/100 s).The reduced shielding effect of the–I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO2.This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies.展开更多
Hydrogen generation through seawater electrolysis provides a promising,attractive pathway towards the utilization of sustainable energy.However,the catalytic activity and stability of oxygen evolution anode are severe...Hydrogen generation through seawater electrolysis provides a promising,attractive pathway towards the utilization of sustainable energy.However,the catalytic activity and stability of oxygen evolution anode are severely limited by the chloride-induced corrosion and competitive oxidation reactions.In this work,we demonstrate an anion-assisted performance improvement strategy by quick and universal screening of electrolyte additive via correlating Cl-repellency with the anionic properties.Particularly,the addition of phosphate ions is found to enable highly stable alkaline seawater splitting at industry-level current density(0.5 A cm^(-2))over 500 h using transition metal hydroxides as anodic electrocatalysts.In situ experiments and theoretical simulations further reveal that the dynamic anti-corrosion behaviors of surface-adsorbed phosphate ions are attributed to three factors including repelling Cl-ions without significantly blocking OH-diffusion,preventing transition metal dissolution and acting as a local pH buffer to compensate the fast OH-consumption under high current electrolysis.展开更多
基金supported by the National Natural Science Foundation of China(Grant Number 22350410379)Zhejiang Provincial Natural Science Foundation of China(LZ23B030003)+1 种基金the Fundamental Research Funds for the Central Universities(226-202400075)Ten Thousand Talent Program of Zhejiang Province.
文摘Separator modification is an effective approach to suppress dendrite growth to realize high-energy sodium metal batteries(SMBs)in practical applications,however,its success is mainly subject to surface modification.Herein,a separator with multifunctional layers composed of N-doped mesoporous hollow carbon spheres(HCS)as the inner layer and sodium fluoride(NaF)as the outer layer on commercial polypropylene separator(PP)is proposed(PP@HCS-NaF)to achieve stable cycling in SMB.At the molecular level,the inner HCS layer with a high content of pyrrolic-N induces the uniform Na^(+)flux as a potential Na^(+)redistributor for homogenous deposition,whereas its hollow mesoporous structure offers nanoporous buffers and ion channels to regulate Na^(+)ion distribution and uniform deposition.The outer layer(NaF)constructs the NaF-enriched robust solid electrolyte interphase layer,significantly lowering the Na^(+)ions diffusion barrier.Benefiting from these merits,higher electrochemical performances are achieved with multifunctional double-layered PP@HCS-NaF separators compared with single-layered separators(i.e.PP@HCS or PP@NaF)in SMBs.The Na‖Cu half-cell with PP@HCS-NaF offers stable cycling(280 cycles)with a high CE(99.6%),and Na‖Na symmetric cells demonstrate extended lifespans for over 6000 h at 1 mA cm^(-2)with a progressively stable overpotential of 9 mV.Remarkably,in Na‖NVP full-cells,the PP@HCS-NaF separator grants a stable capacity of~81 mA h g^(-1)after 3500 cycles at 1 C and an impressive rate capability performance(~70 mA h g^(-1)at 15 C).
基金We are grateful for financial support of the National Natural Science Foundation of China(21776312)the Fundamental Research Funds for the Central Universities(18CX02130A).
文摘ZSM-5 zeolite samples with a SiO2/Al2O3 ratio of 40 were synthesized by a hydrothermal method,and treated by 0.3 M tetrapropyl ammonium hydroxide(TPAOH)and 0.3 M sodium hydroxide(NaOH)solution separately to create hollow structures.The synthesized ZSM-5 zeolite and treated ZSM-5 zeolite samples were evaluated for aromatization of 1-hexene in a continuous flow reactor.The prepared ZSM-5 zeolite samples were characterized by XRD,SEM,TEM,NMR,XPS,and other analyses.The results showed that the alkali treatment formed mesopores and hollow structures in the ZSM-5 crystals without destroying the topological structure.The acid amount of ZSM-5 zeolite was also increased after alkali treatment.Compared with the ZSM-5 zeolite treated by TPAOH,the ZSM-5 zeolite treated by NaOH had more mesopores and a higher total acid amount but a lower strong acid amount,resulting in higher aromatics yields and catalytic stability for 1-hexene aromatization.The characterization of spent ZSM-5 zeolites suggested that the spent treated ZSM-5 zeolites contained less coke,leading to a smaller reduction of micropore surface area and volume than in the spent parent ZSM-5,which contributed to the stability enhancement.
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT)(No. 2021R1I1A1A0105621313, No. 2022R1F1A1074441, No. 2022K1A3A1A20014496, and No. 2022R1F1A1074083)supported by the Ministry of Education Funding (No. RIS 2021-004)supported by the Brain Pool program funded by the Ministry of Science and ICT through the National Research Foundation of Korea (RS-2023-00284318).
文摘In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing performance.Utilizing a hybrid method involving high-pressure processing,stirring,and immiscible solutions,sub-100 nm MXene flake thickness is achieved within the MXene film on the Si-wafer.Functionalization control is achieved by defunctionalizing MXene at 650℃ under vacuum and H2 gas in a CVD furnace,followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the CVD.Notably,the introduction of iodine,which has a larger atomic size,lower electronegativity,reduce shielding effect,and lower hydrophilicity(contact angle:99°),profoundly affecting MXene.It improves the surface area(36.2 cm^(2) g^(-1)),oxidation stability in aqueous/ambient environments(21 days/80 days),and film conductivity(749 S m^(-1)).Additionally,it significantly enhances the gas-sensing performance,including the sensitivity(0.1119Ωppm^(-1)),response(0.2% and 23%to 50 ppb and 200 ppm NO_(2)),and response/recovery times(90/100 s).The reduced shielding effect of the–I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward NO2.This approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies.
基金supported by the National Natural Science Foundation of China(22102076,21925503,21871149)the Ministry of Science and Technology of the People’s Republic of China(2017YFA0206700)+1 种基金the China Postdoctoral Science Foundation(2020M670621)the Ministry of Education of the People’s Republic of China(B12015)。
文摘Hydrogen generation through seawater electrolysis provides a promising,attractive pathway towards the utilization of sustainable energy.However,the catalytic activity and stability of oxygen evolution anode are severely limited by the chloride-induced corrosion and competitive oxidation reactions.In this work,we demonstrate an anion-assisted performance improvement strategy by quick and universal screening of electrolyte additive via correlating Cl-repellency with the anionic properties.Particularly,the addition of phosphate ions is found to enable highly stable alkaline seawater splitting at industry-level current density(0.5 A cm^(-2))over 500 h using transition metal hydroxides as anodic electrocatalysts.In situ experiments and theoretical simulations further reveal that the dynamic anti-corrosion behaviors of surface-adsorbed phosphate ions are attributed to three factors including repelling Cl-ions without significantly blocking OH-diffusion,preventing transition metal dissolution and acting as a local pH buffer to compensate the fast OH-consumption under high current electrolysis.
