Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is cruci...Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.展开更多
Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer...Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.展开更多
Monolithic carbon electrodes with robust mechanical integrity and porous architecture are highly desired for capacitive deionization but remain challenging.Owing to the excellent mechanical strength and electroconduct...Monolithic carbon electrodes with robust mechanical integrity and porous architecture are highly desired for capacitive deionization but remain challenging.Owing to the excellent mechanical strength and electroconductivity,commercial carbon fibers cloth demonstrates great potential as high-performance electrodes for ions storage.Despite this,its direct application on capacitive deionization is rarely reported in terms of limited pore structure and natural hydrophobicity.Herein,a powerful metal-organic framework-engaged structural regulation strategy is developed to boost the desalination properties of carbon fibers.The obtained porous carbon fibers features hierarchical porous structure and hydrophilic surface providing abundant ions-accessible sites,and continuous graphitized carbon core ensuring rapid electrons transport.The catalytic-etching mechanism involving oxidation of Co and subsequent carbonthermal reduction is proposed and highly relies on annealing temperature and holding time.When directly evaluated as a current collector-free capacitive deionization electrode,the porous carbon fibers demonstrates much superior desalination capability than pristine carbon fibers,and remarkable cyclic stability up to 20 h with negligible degeneration.Particularly,the PCF-1000 showcases the highest areal salt adsorption capacity of 0.037 mg cm^(−2) among carbon microfibers.Moreover,monolithic porous carbon fibers-carbon nanotubes with increased active sites and good structural integrity by in-situ growth of carbon nanotubes are further fabricated to enhance the desalination performance(0.051 mg cm^(−2)).This work demonstrates the great potential of carbon fibers in constructing high-efficient and robust monolithic electrode for capacitive deionization.展开更多
The“battery type”inorganic electrode has been demonstrated the highly efficient sodium ion intercalation capacity for capacitive deionization.In this work,the CoMn_(2)O_(4)(CMO)microspheres with porous core-shell st...The“battery type”inorganic electrode has been demonstrated the highly efficient sodium ion intercalation capacity for capacitive deionization.In this work,the CoMn_(2)O_(4)(CMO)microspheres with porous core-shell structure are prepared via co-precipitation and followed by annealing.The effects of annealing temperatures on the morphology,pore structure,valence state,and electrochemical behavior of CMO are explored.As electrode for capacitive deionization,the salt removal capacity and current efficiency of optimized AC||CMO device reaches up to 60.7 mg g^(−1) and 97.6%,respectively,and the capacity retention rate is 74.1%after 50 cycles.Remarkably,both the in-situ X-ray diffraction and ex-situ X-ray diffraction analysis features that the intercalation/de-intercalation of sodium ions are governed by(103)and(221)crystal planes of CMO.Accordingly,the density functional theory calculations realize that the adsorption energies of Na+onto(103)and(221)crystal planes are higher than that of any other crystal planes,manifesting the priorities in adsorption of sodium atoms.Furthermore,the X-ray photoelectron spectra of pristine and post-CMO electrode highlights that the reversible conversion of Mn^(3+)/Mn^(4+)couple is resulted from the intercalation/de-intercalation of Na^(+),while this is irreversible for Co^(3+)/Co^(2+)couple.Beyond that,the CMO electrode has been proven the selectivity removal of Na^(+) over K^(+)and Mg^(2+)in a multi-cation stream.展开更多
Water and energy shortages came due to rapid population growth, living standards and rapid development in the agriculture and industrial sectors. Desalination tends to be one of the most promising water solutions;howe...Water and energy shortages came due to rapid population growth, living standards and rapid development in the agriculture and industrial sectors. Desalination tends to be one of the most promising water solutions;however, it is a process of intense energy. Membrane Capacitive Deionization (MCDI) has received considerable interest as a promising desalination technology, and MCDI research has increased significantly over the last 10 years. In addition, there are no guidelines for the design of Capacitive Deionization (CDI) implementation strategies for individual applications. This study, therefore;provides an alternative of CDI’s recent application developments, with emphasis placed on hybrid systems to address the technological needs of different relevant fields. The MCDI’s energy consumption is compared with the reverse osmosis literature data based on experimental data from laboratory-scale system. The study demonstrates that MCDI technology is a promising technology in the next few years with an extreme competition in water recovery, energy consumption and salt removal for reverse osmosis.展开更多
Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple ...Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.展开更多
目的依据现有完善的语言评估方式,观察人工耳蜗植入患儿语言康复情况,研究早期植入人工耳蜗患儿语言习得能力及影响康复效果的因素。方法选取首都医科大学附属北京同仁医院158例语前聋患儿为研究对象,人工耳蜗植入年龄平均17.6±8....目的依据现有完善的语言评估方式,观察人工耳蜗植入患儿语言康复情况,研究早期植入人工耳蜗患儿语言习得能力及影响康复效果的因素。方法选取首都医科大学附属北京同仁医院158例语前聋患儿为研究对象,人工耳蜗植入年龄平均17.6±8.8个月,应用汉语沟通发展量表(mandarin communicative development inventory,MCDI)研究开机时、开机后6、12、24、36个月的差异;按照植入年龄分为A组(0~18个月龄)、B组(19~36个月龄),根据内耳形态分为C组(内耳正常)、D组(内耳畸形),分析在植入人工耳蜗后开机时及开机后6、12个月患儿语言能力得分。结果患儿在康复后语言能力普遍有所提升,但提升速度存在差异。除句子与语句部分得分外,其余得分在开机时与开机后6个月之间有显著差异(P<0.05),在开机后24个或36个月接近满分。A、B组MCDI会说的词汇得分在开机后12个月无显著差异(P>0.05),C、D组在开机时无显著差异(P>0.05)。结论在开机前期,患儿语言能力增长较为迅速,18个月前植入与19~36个月植入人工耳蜗对患儿的语言发育能力在开机后12个月无显著差异,内耳畸形对患儿开机后的语言发育有显著影响。展开更多
文摘Electrode materials with high desalination capacity and long-term cyclic stability are the focus of capacitive deionization(CDI) community. Understanding the causes of performance decay in traditional carbons is crucial to design a high-performance material. Based on this, here, nitrogen-doped activated carbon(NAC) was prepared by pyrolyzing the blend of activated carbon powder(ACP) and melamine for the positive electrode of asymmetric CDI. By comparing the indicators changes such as conductivity, salt adsorption capacity, pH, and charge efficiency of the symmetrical ACP-ACP device to the asymmetric ACP-NAC device under different CDI cycles, as well as the changes of the electrochemical properties of anode and cathode materials after long-term operation, the reasons for the decline of the stability of the CDI performance were revealed. It was found that the carboxyl functional groups generated by the electro-oxidation of anode carbon materials make the anode zero-charge potential(E_(pzc)) shift positively,which results in the uneven distribution of potential windows of CDI units and affects the adsorption capacity. Furthermore, by understanding the electron density on C atoms surrounding the N atoms, we attribute the increased cyclic stability to the enhanced negativity of the charge of carbon atoms adjacent to quaternary-N and pyridinic-oxide-N.
基金supported by the Shenzhen Science and Technology Program(JCYJ20230808105111022,JCYJ20220818095806013)Natural Science Foundation of Guangdong(2023A1515012267)+1 种基金the National Natural Science Foundation of China(22178223)the Royal Society/NSFC cost share program(IEC\NSFC\223372).
文摘Low-electrode capacitive deionization(FCDI)is an emerging desalination technology with great potential for removal and/or recycling ions from a range of waters.However,it still suffers from inefficient charge transfer and ion transport kinetics due to weak turbulence and low electric intensity in flow electrodes,both restricted by the current collectors.Herein,a new tip-array current collector(designated as T-CC)was developed to replace the conventional planar current collectors,which intensifies both the charge transfer and ion transport significantly.The effects of tip arrays on flow and electric fields were studied by both computational simulations and electrochemical impedance spectroscopy,which revealed the reduction of ion transport barrier,charge transport barrier and internal resistance.With the voltage increased from 1.0 to 1.5 and 2.0 V,the T-CC-based FCDI system(T-FCDI)exhibited average salt removal rates(ASRR)of 0.18,0.50,and 0.89μmol cm^(-2) min^(-1),respectively,which are 1.82,2.65,and 2.48 folds higher than that of the conventional serpentine current collectors,and 1.48,1.67,and 1.49 folds higher than that of the planar current collectors.Meanwhile,with the solid content in flow electrodes increased from 1 to 5 wt%,the ASRR for T-FCDI increased from 0.29 to 0.50μmol cm^(-2) min^(-1),which are 1.70 and 1.67 folds higher than that of the planar current collectors.Additionally,a salt removal efficiency of 99.89%was achieved with T-FCDI and the charge efficiency remained above 95%after 24 h of operation,thus showing its superior long-term stability.
基金We gratefully acknowledge financial supports from the Natural Science Founda-tion of Shandong Province (No.ZR2020QE066)Taishan Scholar Project (No.ts201511080)+1 种基金the fellowship of China Postdoctoral Science Foundation (No.2020M672081)Opening Project of State Key Laboratory of Advanced Tech-nology for Float Glass (No.2020KF08).
文摘Monolithic carbon electrodes with robust mechanical integrity and porous architecture are highly desired for capacitive deionization but remain challenging.Owing to the excellent mechanical strength and electroconductivity,commercial carbon fibers cloth demonstrates great potential as high-performance electrodes for ions storage.Despite this,its direct application on capacitive deionization is rarely reported in terms of limited pore structure and natural hydrophobicity.Herein,a powerful metal-organic framework-engaged structural regulation strategy is developed to boost the desalination properties of carbon fibers.The obtained porous carbon fibers features hierarchical porous structure and hydrophilic surface providing abundant ions-accessible sites,and continuous graphitized carbon core ensuring rapid electrons transport.The catalytic-etching mechanism involving oxidation of Co and subsequent carbonthermal reduction is proposed and highly relies on annealing temperature and holding time.When directly evaluated as a current collector-free capacitive deionization electrode,the porous carbon fibers demonstrates much superior desalination capability than pristine carbon fibers,and remarkable cyclic stability up to 20 h with negligible degeneration.Particularly,the PCF-1000 showcases the highest areal salt adsorption capacity of 0.037 mg cm^(−2) among carbon microfibers.Moreover,monolithic porous carbon fibers-carbon nanotubes with increased active sites and good structural integrity by in-situ growth of carbon nanotubes are further fabricated to enhance the desalination performance(0.051 mg cm^(−2)).This work demonstrates the great potential of carbon fibers in constructing high-efficient and robust monolithic electrode for capacitive deionization.
基金This work was supported by the National Natural Science Foundation of China (No.21862016)Project of Ningxia key R&D plan (No.2017BY064).
文摘The“battery type”inorganic electrode has been demonstrated the highly efficient sodium ion intercalation capacity for capacitive deionization.In this work,the CoMn_(2)O_(4)(CMO)microspheres with porous core-shell structure are prepared via co-precipitation and followed by annealing.The effects of annealing temperatures on the morphology,pore structure,valence state,and electrochemical behavior of CMO are explored.As electrode for capacitive deionization,the salt removal capacity and current efficiency of optimized AC||CMO device reaches up to 60.7 mg g^(−1) and 97.6%,respectively,and the capacity retention rate is 74.1%after 50 cycles.Remarkably,both the in-situ X-ray diffraction and ex-situ X-ray diffraction analysis features that the intercalation/de-intercalation of sodium ions are governed by(103)and(221)crystal planes of CMO.Accordingly,the density functional theory calculations realize that the adsorption energies of Na+onto(103)and(221)crystal planes are higher than that of any other crystal planes,manifesting the priorities in adsorption of sodium atoms.Furthermore,the X-ray photoelectron spectra of pristine and post-CMO electrode highlights that the reversible conversion of Mn^(3+)/Mn^(4+)couple is resulted from the intercalation/de-intercalation of Na^(+),while this is irreversible for Co^(3+)/Co^(2+)couple.Beyond that,the CMO electrode has been proven the selectivity removal of Na^(+) over K^(+)and Mg^(2+)in a multi-cation stream.
文摘Water and energy shortages came due to rapid population growth, living standards and rapid development in the agriculture and industrial sectors. Desalination tends to be one of the most promising water solutions;however, it is a process of intense energy. Membrane Capacitive Deionization (MCDI) has received considerable interest as a promising desalination technology, and MCDI research has increased significantly over the last 10 years. In addition, there are no guidelines for the design of Capacitive Deionization (CDI) implementation strategies for individual applications. This study, therefore;provides an alternative of CDI’s recent application developments, with emphasis placed on hybrid systems to address the technological needs of different relevant fields. The MCDI’s energy consumption is compared with the reverse osmosis literature data based on experimental data from laboratory-scale system. The study demonstrates that MCDI technology is a promising technology in the next few years with an extreme competition in water recovery, energy consumption and salt removal for reverse osmosis.
基金We gratefully acknowledge financial supports from the National Natural Science Foundation of China(No.52202371,51905125,52102364)the Natural Science Foundation of Shandong Province(No.ZR2020QE066)+2 种基金Opening Project of State Key Laboratory of Advanced Technology for Float Glass(No.2020KF08)SDUT&Zibo City Integration Development Project(No.2021SNPT0045)the fellowship of China Postdoctoral Science Foundation(No.2020M672081).
文摘Biomass-derived carbon has demonstrated great potentials as advanced electrode for capacitive deionization(CDI),owing to good electroconductivity,easy availability,intrinsic pores/channels.However,conventional simple pyrolysis of biomass always generates inadequate porosity with limited surface area.Moreover,biomass-derived carbon also suffers from poor wettability and single physical adsorption of ions,resulting in limited desalination performance.Herein,pore structure optimization and element co-doping are integrated on banana peels(BP)-derived carbon to construct hierarchically porous and B,N co-doped carbon with large ions-accessible surface area.A unique expansionactivation(EA)strategy is proposed to modulate the porosity and specific surface area of carbon.Furthermore,B,N co-doping could increase the ions-accessible sites with improved hydrophilicity,and promote ions adsorption.Benefitting from the synergistic effect of hierarchical porosity and B,N co-doping,the resultant electrode manifest enhanced CDI performance for NaCl with large desalination capacity(29.5 mg g^(-1)),high salt adsorption rate(6.2 mg g^(-1)min^(-1)),and versatile adsorption ability for other salts.Density functional theory reveals the enhanced deionization mechanism by pore and B,N co-doping.This work proposes a facile EA strategy for pore structure modulation of biomass-derived carbon,and demonstrates great potentials of integrating pore and heteroatoms-doping on constructing high-performance CDI electrode.
文摘目的依据现有完善的语言评估方式,观察人工耳蜗植入患儿语言康复情况,研究早期植入人工耳蜗患儿语言习得能力及影响康复效果的因素。方法选取首都医科大学附属北京同仁医院158例语前聋患儿为研究对象,人工耳蜗植入年龄平均17.6±8.8个月,应用汉语沟通发展量表(mandarin communicative development inventory,MCDI)研究开机时、开机后6、12、24、36个月的差异;按照植入年龄分为A组(0~18个月龄)、B组(19~36个月龄),根据内耳形态分为C组(内耳正常)、D组(内耳畸形),分析在植入人工耳蜗后开机时及开机后6、12个月患儿语言能力得分。结果患儿在康复后语言能力普遍有所提升,但提升速度存在差异。除句子与语句部分得分外,其余得分在开机时与开机后6个月之间有显著差异(P<0.05),在开机后24个或36个月接近满分。A、B组MCDI会说的词汇得分在开机后12个月无显著差异(P>0.05),C、D组在开机时无显著差异(P>0.05)。结论在开机前期,患儿语言能力增长较为迅速,18个月前植入与19~36个月植入人工耳蜗对患儿的语言发育能力在开机后12个月无显著差异,内耳畸形对患儿开机后的语言发育有显著影响。
