Freshwater scarcity has emerged as a critical global environmental challenge.Flow-electrode capacitive deionization(FCDI)represents a promising technology for achieving efficient and low-energy seawater desalination.T...Freshwater scarcity has emerged as a critical global environmental challenge.Flow-electrode capacitive deionization(FCDI)represents a promising technology for achieving efficient and low-energy seawater desalination.This study presents a novel flow-electrode material,nitrogen-doped porous carbon(NPC),which is derived from biomass and demonstrates both cost-effectiveness and high performance.The NPC material is synthesized from bean shells through high-temperature pre-carbonization followed by activation with KHCO_(3),resulting in a rich porous structure,increased specific surface area,and high graphitization degree,which collectively confer superior capacitance performance compared to activated carbon(AC).Desalination experiments indicate that the FCDI performance of the NPC flow-electrode surpasses that of the AC flow-electrode.Specifically,at a voltage of 2.5 V in a 6 g·L^(-1)NaCl solution,the NPC system achieves an average salt removal rate(ASRR)of 104.9 μg·cm^(-2)·min^(-1),with a charge efficiency(CE)of 94.0%and an energy consumption(EC)of only 4.4 kJ·g^(-1).Furthermore,the NPC-based FCDI system exhibits commendable desalination cycling stability,maintaining relatively stable energy consumption and efficiency after prolonged continuous desalination cycles.This research holds significant implications for the advancement of environmentally friendly,low-cost,high-performance FCDI systems for large-scale applications.展开更多
1T phase MoS_(2)(1T-MoS_(2)) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction(HER)due to its high intrinsic activity but suffering from thermodynamical instability.Although great e...1T phase MoS_(2)(1T-MoS_(2)) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction(HER)due to its high intrinsic activity but suffering from thermodynamical instability.Although great efforts have been made to synthesize 1T-MoS_(2) and enhance its stability,it remains a big challenge to realize the phase control and stabilization of 1T-MoS_(2).Herein,based on crystal field theory analysis,we propose a new solution by designing an electrocatalyst of 1T-MoS_(2) nanosheets anchoring on black TiO2-xnanotube arrays in-situ grown on Ti plate(1T-MoS_(2)/TiO_(2-x)@Ti).The black TiO_(2-x)substrate is expected to play as electron donors to increase the charge in Mo 4 d orbits of 1T-MoS_(2) and thus weaken the asymmetric occupation of electrons in the Mo 4 d orbits.Experimental results demonstrate that black TiO_(2-x)nanotubes shift electrons to MoS_(2) and induce MoS_(2) to generate more 1 T phase due to stabilizing the 1T-MoS_(2) nanosheets compared with a Ti substrate.Thus 1T-MoS_(2/)TiO_(2-x)@Ti shows much improved HER performance with a small Tafel slope of 42 m V dec^(-1) and excellent catalytic stability with negligible degradation for 24 h.Theoretical calculations confirm that the black TiO_(2-x)substrate can effectively stabilize metastable 1T-MoS_(2) due to electrons transferring from black TiO_(2-x)to Mo 4 d orbits.This work sheds light on the instability of 1T-MoS_(2) and provides an essential method to stabilize and efficiently utilize 1T-MoS_(2) for HER.展开更多
This paper characterises and evaluates Si_(3)N_(4)/Ti composites during thermal treatment using an in situ neutron diffraction technique.The composites were developed using a conventional press and sinter technique.Pu...This paper characterises and evaluates Si_(3)N_(4)/Ti composites during thermal treatment using an in situ neutron diffraction technique.The composites were developed using a conventional press and sinter technique.Pure titanium(Ti)was chosen as the matrix,and different concentrations of Si_(3)N_(4)were used as the reinforcement.The effects of sintering temperature and the concentration of Si_(3)N_(4)in the Ti matrix were investigated with respect to phase constituents.The Si_(3)N_(4)mass fraction in the Ti matrix was found to be the key parameter for the reaction.Because of its instability in Ti at higher temperatures,in situ reactions between the reinforcing particles and matrix led to the formation of intermetallic compounds,such as Ti_(5)Si_(3)and possibly Ti3Si,in the composites containing higher weight fractions of Si_(3)N_(4).展开更多
The sluggish kinetics of the oxygen evolution reaction(OER)severely limits the efficiency of electrochemical water splitting for sustainable hydrogen production.Developing cost-effective and efficient OER electrocatal...The sluggish kinetics of the oxygen evolution reaction(OER)severely limits the efficiency of electrochemical water splitting for sustainable hydrogen production.Developing cost-effective and efficient OER electrocatalysts based on earth-abundant elements is thus highly desirable.Herein,we report a nanoporous(CoNiFe)OOH electrocatalyst decorated with Zn(OH)_(4)^(2−)anions,synthesized via electrochemical surface reconstruction of ZnO-decorated CoNiFe medium-entropy alloys(MEAs).The reconstructed(CoNiFe)OOH adsorbed with Zn(OH)_(4)^(2−)anions serves as the real active phase,featuring abundant catalytic sites and enhanced OH−accessibility.Adsorbed Zn(OH)_(4)^(2−)anions promote OH−transfer and facilitate electron redistribution at the active sites,particularly enhancing Co site activity,as revealed by density functional theory(DFT)calculations.As a result,the optimized CoNiFeZn@NF-EO electrode exhibits outstanding OER performance,achieving a low overpotential of 264 mV at 10 mA·cm^(−2),a Tafel slope of 46.6 mV·dec^(−1),and remarkable long-term stability in alkaline electrolyte.This work provides new insights into the synergistic effect between surface reconstruction and Zn-based species,offering a promising strategy for designing high-performance OER electrocatalysts.展开更多
Developing selective electrodes for lithium extraction from brines remains challenging.This work reports room-temperature synthesized cubic copper hexacyanoferrate(Cu HCF)nanoparticles for hybrid capacitive deionizati...Developing selective electrodes for lithium extraction from brines remains challenging.This work reports room-temperature synthesized cubic copper hexacyanoferrate(Cu HCF)nanoparticles for hybrid capacitive deionization(HCDI).The Cu HCF framework exhibits a high surface area(715.84 m^(2)·g^(-1)),dual redoxactive sites([Fe^(Ⅲ)(CN)_(6)]^(4-)/[Fe^(Ⅱ)(CN)_(6)]^(3-)and Cu^(+)/Cu^(2+)),and excellent cyclability(99.4%capacity retention after 1000 cycles).In HCDI system,the Cu HCF cathode demonstrates remarkable Li^(+)ions selectivity,achieving a 25.5 mg·g^(-1)adsorption capacity in 500 mg·L^(-1)Li Cl solution with 94%charge efficiency at1.2 V.Notably,in mixed Li^(+)/Mg^(2+)solutions(30:1 molar ratio),Cu HCF nanoparticles maintain a high separation coefficient of 3.1,attributed to the synergistic effects of ionic sieving and preferential redox interactions.Mechanistic studies confirm Li^(+)(de)intercalation via reversible[Fe^(Ⅲ)(CN)_(6)]^(4-)/[Fe^(Ⅱ)(CN)_(6)]^(3-)and Cu^(2+)/Cu^(+)transitions.Density functional theory calculations reveal Li^(+)exhibits lower adsorption energy than Mg^(2+)(-3.72 e V vs.-1.49 e V),which fundamentally explains the preferential extraction capability of Li^(+)ions over Mg^(2+)ions during the separation process.This study advances ion-selective pseudocapacitor design for sustainable lithium extraction from high-salinity resources.展开更多
Developing highly efficient and stable non-precious metal catalysts for water splitting is urgently required.In this work,we report a facile one-step molten salt method for the preparation of self-supporting Ni-doped ...Developing highly efficient and stable non-precious metal catalysts for water splitting is urgently required.In this work,we report a facile one-step molten salt method for the preparation of self-supporting Ni-doped Mo_(2)C on carbon fiber paper(Ni–Mo_(2)CCB/CFP)for hydrogen evolution reaction(HER).The effects of nickel nitrate concentration on the phase composition,morphology,and electrocatalytic HER performance of Ni-doped Mo_(2)C@CFP electrocatalysts was investigated.With the continuous increase of Ni(NO_(3))_(2)concentration,the morphology of Mo_(2)C gradually changes from granular to flower-like,providing larger specific surface area and more active sites.Doping nickel(Ni)into the crystal lattice of Mo_(2)C largely reduces the impedance of the electrocatalysts and enhances their electrocatalytic activity.The as-developed Mo_(2)C–3 M Ni(NO_(3))_(2)/CFP electrocatalyst exhibits high catalytic activity with a small overpotential of 56 mV at a current density of 10 mA·cm^(-2).This catalyst has a fast HER kinetics,as demonstrated by a very small Tafel slope of 27.4 mV·dec^(-1),and persistent long-term stability.A further higher Ni concentration had an adverse effect on the electrocatalytic performance.Density functional theory(DFT)calculations further verified the experimental results.Ni doping could reduce the binding energy of Mo–H,facilitating the desorption of the adsorbed hydrogen(Hads)on the surface,thereby improving the intrinsic catalytic activity of Ni-doped Mo_(2)C-based catalysts.Nevertheless,excessive Ni doping would inhibit the catalytic activity of the electrocatalysts.This work not only provides a simple strategy for the facile preparation of non-precious metal electrocatalysts with high catalytic activity,but also unveils the influence mechanism of the Ni doping concentration on the HER performance of the electrocatalysts from the theoretical perspective.展开更多
具有高容量的LiNiO_(2)(LNO)是高能锂离子电池最受欢迎的正极材料之一,但是其存在结构和界面稳定性差,循环性能不理想等问题.常规Mg、Al元素掺杂可有效改善稳定性,但会导致可逆容量及倍率性能的损失.本文通过分段的共沉淀法制备了铝镁...具有高容量的LiNiO_(2)(LNO)是高能锂离子电池最受欢迎的正极材料之一,但是其存在结构和界面稳定性差,循环性能不理想等问题.常规Mg、Al元素掺杂可有效改善稳定性,但会导致可逆容量及倍率性能的损失.本文通过分段的共沉淀法制备了铝镁不均匀掺杂的LNO二次球形前驱体,利用不均匀掺杂减少了掺杂剂用量并诱导实现了前驱体表面形貌的重构,煅烧后形成具有疏松多孔表层形貌的二次颗粒.改性后的LNO正极具有良好的循环稳定性(全电池150次循环后容量保持率为95.1%)和大倍率放电能力(10 C时达到177.9 mA h g^(-1)),这是由于比表面积的增加促进了锂离子传输,以及镁、铝的掺杂缓解了LNO循环过程中的有害相变.该工作揭示了通过设计掺杂元素的分布可以有效地调节LNO的形貌、结构和性能,为合成高性能的LNO正极材料提供了新的策略.展开更多
基金supported by the National Natural Science Foundation of China(52202093)the National College Student Innovation and Entrepreneurship Training Program of Jiangsu University of Science and Technology(202410289005Z).
文摘Freshwater scarcity has emerged as a critical global environmental challenge.Flow-electrode capacitive deionization(FCDI)represents a promising technology for achieving efficient and low-energy seawater desalination.This study presents a novel flow-electrode material,nitrogen-doped porous carbon(NPC),which is derived from biomass and demonstrates both cost-effectiveness and high performance.The NPC material is synthesized from bean shells through high-temperature pre-carbonization followed by activation with KHCO_(3),resulting in a rich porous structure,increased specific surface area,and high graphitization degree,which collectively confer superior capacitance performance compared to activated carbon(AC).Desalination experiments indicate that the FCDI performance of the NPC flow-electrode surpasses that of the AC flow-electrode.Specifically,at a voltage of 2.5 V in a 6 g·L^(-1)NaCl solution,the NPC system achieves an average salt removal rate(ASRR)of 104.9 μg·cm^(-2)·min^(-1),with a charge efficiency(CE)of 94.0%and an energy consumption(EC)of only 4.4 kJ·g^(-1).Furthermore,the NPC-based FCDI system exhibits commendable desalination cycling stability,maintaining relatively stable energy consumption and efficiency after prolonged continuous desalination cycles.This research holds significant implications for the advancement of environmentally friendly,low-cost,high-performance FCDI systems for large-scale applications.
基金supported by the New Zealand China Doctoral Research Scholarship (Grant no. 201706080124)support from the China Scholarships Council (CSC) for his study at the University of Auckland
文摘1T phase MoS_(2)(1T-MoS_(2)) is a promising substitute of platinum electrocatalyst for hydrogen evolution reaction(HER)due to its high intrinsic activity but suffering from thermodynamical instability.Although great efforts have been made to synthesize 1T-MoS_(2) and enhance its stability,it remains a big challenge to realize the phase control and stabilization of 1T-MoS_(2).Herein,based on crystal field theory analysis,we propose a new solution by designing an electrocatalyst of 1T-MoS_(2) nanosheets anchoring on black TiO2-xnanotube arrays in-situ grown on Ti plate(1T-MoS_(2)/TiO_(2-x)@Ti).The black TiO_(2-x)substrate is expected to play as electron donors to increase the charge in Mo 4 d orbits of 1T-MoS_(2) and thus weaken the asymmetric occupation of electrons in the Mo 4 d orbits.Experimental results demonstrate that black TiO_(2-x)nanotubes shift electrons to MoS_(2) and induce MoS_(2) to generate more 1 T phase due to stabilizing the 1T-MoS_(2) nanosheets compared with a Ti substrate.Thus 1T-MoS_(2/)TiO_(2-x)@Ti shows much improved HER performance with a small Tafel slope of 42 m V dec^(-1) and excellent catalytic stability with negligible degradation for 24 h.Theoretical calculations confirm that the black TiO_(2-x)substrate can effectively stabilize metastable 1T-MoS_(2) due to electrons transferring from black TiO_(2-x)to Mo 4 d orbits.This work sheds light on the instability of 1T-MoS_(2) and provides an essential method to stabilize and efficiently utilize 1T-MoS_(2) for HER.
基金the Australian Institute of Nuclear Science and Engineering(AINSE)Ltd.for providing financial assistance(Award No.P7317)to enable work on WOMBAT to be conducted.Peng Cao acknowledges the support from the International Cooperation Programs of Guangzhou City(Grant number 20190710030)Guangdong Province,China(Grant No.108A050506010).
文摘This paper characterises and evaluates Si_(3)N_(4)/Ti composites during thermal treatment using an in situ neutron diffraction technique.The composites were developed using a conventional press and sinter technique.Pure titanium(Ti)was chosen as the matrix,and different concentrations of Si_(3)N_(4)were used as the reinforcement.The effects of sintering temperature and the concentration of Si_(3)N_(4)in the Ti matrix were investigated with respect to phase constituents.The Si_(3)N_(4)mass fraction in the Ti matrix was found to be the key parameter for the reaction.Because of its instability in Ti at higher temperatures,in situ reactions between the reinforcing particles and matrix led to the formation of intermetallic compounds,such as Ti_(5)Si_(3)and possibly Ti3Si,in the composites containing higher weight fractions of Si_(3)N_(4).
基金supported by the National Natural Science Foundation of China(Nos.52202093 and 52304325)the Natural Science Research of Jiangsu Higher Education Institutions of China(No.22KJB430021)Jiangsu Provincial Double Innovation Doctor Program(No.JSSCBS20221258).
文摘The sluggish kinetics of the oxygen evolution reaction(OER)severely limits the efficiency of electrochemical water splitting for sustainable hydrogen production.Developing cost-effective and efficient OER electrocatalysts based on earth-abundant elements is thus highly desirable.Herein,we report a nanoporous(CoNiFe)OOH electrocatalyst decorated with Zn(OH)_(4)^(2−)anions,synthesized via electrochemical surface reconstruction of ZnO-decorated CoNiFe medium-entropy alloys(MEAs).The reconstructed(CoNiFe)OOH adsorbed with Zn(OH)_(4)^(2−)anions serves as the real active phase,featuring abundant catalytic sites and enhanced OH−accessibility.Adsorbed Zn(OH)_(4)^(2−)anions promote OH−transfer and facilitate electron redistribution at the active sites,particularly enhancing Co site activity,as revealed by density functional theory(DFT)calculations.As a result,the optimized CoNiFeZn@NF-EO electrode exhibits outstanding OER performance,achieving a low overpotential of 264 mV at 10 mA·cm^(−2),a Tafel slope of 46.6 mV·dec^(−1),and remarkable long-term stability in alkaline electrolyte.This work provides new insights into the synergistic effect between surface reconstruction and Zn-based species,offering a promising strategy for designing high-performance OER electrocatalysts.
基金supported by the National Natural Science Foundation of China(52202093)Postgraduate research&practice innovation program of Jiangsu province(SJCX25_2553)+1 种基金the China Postdoctoral Science Foundation(2023M731357)the open project of Anhui Province Key Laboratory of Efficient Conversion and Solid-State Storage of Hydrogen&Electricity(ECSSHE2024KF03)。
文摘Developing selective electrodes for lithium extraction from brines remains challenging.This work reports room-temperature synthesized cubic copper hexacyanoferrate(Cu HCF)nanoparticles for hybrid capacitive deionization(HCDI).The Cu HCF framework exhibits a high surface area(715.84 m^(2)·g^(-1)),dual redoxactive sites([Fe^(Ⅲ)(CN)_(6)]^(4-)/[Fe^(Ⅱ)(CN)_(6)]^(3-)and Cu^(+)/Cu^(2+)),and excellent cyclability(99.4%capacity retention after 1000 cycles).In HCDI system,the Cu HCF cathode demonstrates remarkable Li^(+)ions selectivity,achieving a 25.5 mg·g^(-1)adsorption capacity in 500 mg·L^(-1)Li Cl solution with 94%charge efficiency at1.2 V.Notably,in mixed Li^(+)/Mg^(2+)solutions(30:1 molar ratio),Cu HCF nanoparticles maintain a high separation coefficient of 3.1,attributed to the synergistic effects of ionic sieving and preferential redox interactions.Mechanistic studies confirm Li^(+)(de)intercalation via reversible[Fe^(Ⅲ)(CN)_(6)]^(4-)/[Fe^(Ⅱ)(CN)_(6)]^(3-)and Cu^(2+)/Cu^(+)transitions.Density functional theory calculations reveal Li^(+)exhibits lower adsorption energy than Mg^(2+)(-3.72 e V vs.-1.49 e V),which fundamentally explains the preferential extraction capability of Li^(+)ions over Mg^(2+)ions during the separation process.This study advances ion-selective pseudocapacitor design for sustainable lithium extraction from high-salinity resources.
基金This work was financially supported by the National Natural Science Foundation of China(Grant Nos.51862024,51772140,and 51962023)Key Research and Development Program of Jiangxi Province(Grant No.20203BBE53066).
文摘Developing highly efficient and stable non-precious metal catalysts for water splitting is urgently required.In this work,we report a facile one-step molten salt method for the preparation of self-supporting Ni-doped Mo_(2)C on carbon fiber paper(Ni–Mo_(2)CCB/CFP)for hydrogen evolution reaction(HER).The effects of nickel nitrate concentration on the phase composition,morphology,and electrocatalytic HER performance of Ni-doped Mo_(2)C@CFP electrocatalysts was investigated.With the continuous increase of Ni(NO_(3))_(2)concentration,the morphology of Mo_(2)C gradually changes from granular to flower-like,providing larger specific surface area and more active sites.Doping nickel(Ni)into the crystal lattice of Mo_(2)C largely reduces the impedance of the electrocatalysts and enhances their electrocatalytic activity.The as-developed Mo_(2)C–3 M Ni(NO_(3))_(2)/CFP electrocatalyst exhibits high catalytic activity with a small overpotential of 56 mV at a current density of 10 mA·cm^(-2).This catalyst has a fast HER kinetics,as demonstrated by a very small Tafel slope of 27.4 mV·dec^(-1),and persistent long-term stability.A further higher Ni concentration had an adverse effect on the electrocatalytic performance.Density functional theory(DFT)calculations further verified the experimental results.Ni doping could reduce the binding energy of Mo–H,facilitating the desorption of the adsorbed hydrogen(Hads)on the surface,thereby improving the intrinsic catalytic activity of Ni-doped Mo_(2)C-based catalysts.Nevertheless,excessive Ni doping would inhibit the catalytic activity of the electrocatalysts.This work not only provides a simple strategy for the facile preparation of non-precious metal electrocatalysts with high catalytic activity,but also unveils the influence mechanism of the Ni doping concentration on the HER performance of the electrocatalysts from the theoretical perspective.
基金supported by the National Natural Science Foundation of China(21925503 and 21835004)Jiangsu Specially-Appointed Professorship Foundation(1064902003)+1 种基金the Doctoral Scientific Research Foundation of Jiangsu University of Science and Technology(1062932001 and 1062932211)the Program for High-Level Entrepreneurial and Innovative Talents Introduction of Jiangsu Province(Double Innovation PhD,1064902009)。
文摘具有高容量的LiNiO_(2)(LNO)是高能锂离子电池最受欢迎的正极材料之一,但是其存在结构和界面稳定性差,循环性能不理想等问题.常规Mg、Al元素掺杂可有效改善稳定性,但会导致可逆容量及倍率性能的损失.本文通过分段的共沉淀法制备了铝镁不均匀掺杂的LNO二次球形前驱体,利用不均匀掺杂减少了掺杂剂用量并诱导实现了前驱体表面形貌的重构,煅烧后形成具有疏松多孔表层形貌的二次颗粒.改性后的LNO正极具有良好的循环稳定性(全电池150次循环后容量保持率为95.1%)和大倍率放电能力(10 C时达到177.9 mA h g^(-1)),这是由于比表面积的增加促进了锂离子传输,以及镁、铝的掺杂缓解了LNO循环过程中的有害相变.该工作揭示了通过设计掺杂元素的分布可以有效地调节LNO的形貌、结构和性能,为合成高性能的LNO正极材料提供了新的策略.
