Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)are two typical titanate-based sodium-storage materials,featuring the high theoretical capacity and favorable structure stability,respectively.Regulating the ratio of them in the...Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)are two typical titanate-based sodium-storage materials,featuring the high theoretical capacity and favorable structure stability,respectively.Regulating the ratio of them in the composite material is the key to strengthen its electrochemical characteristics.Herein,based on the high specific surface area and abundant surface functional groups of carbon dots(CDs),sodium titanate precursors containing CDs were in situ prepared by one-step hydrothermal method.After the thermal conversion of the precursors,a composite material(NNTO/C)of Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)was obtained,containing conductive carbon derived from CDs.The introduc⁃tion of conductive carbon not only adjusts the composition ratio of the mixed phases,but also provides a small charge transfer impedance(Rct,7.48Ω)and a big specific surface area(100.8 m^(2)/g).As a result,NNTO/C composites exhibit better sodium storage behavior while playing the synergistic interaction of mixed phases.When employed as the anode,after 200 cycles at 0.05 A/g,NNTO/C still maintains a specific capacity of 143.8 mA‧h/g.After 400 cycles at 1.00 A/g,the specific capacity remains as high as 108 mA‧h/g.This study suggests an innovative thinking for designing two-phase structures of electrode materials and the greater use of CDs in electrochemical energy storage.展开更多
Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)an...Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.展开更多
文摘Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)are two typical titanate-based sodium-storage materials,featuring the high theoretical capacity and favorable structure stability,respectively.Regulating the ratio of them in the composite material is the key to strengthen its electrochemical characteristics.Herein,based on the high specific surface area and abundant surface functional groups of carbon dots(CDs),sodium titanate precursors containing CDs were in situ prepared by one-step hydrothermal method.After the thermal conversion of the precursors,a composite material(NNTO/C)of Na_(2)Ti_(3)O_(7)and Na_(2)Ti_(6)O_(13)was obtained,containing conductive carbon derived from CDs.The introduc⁃tion of conductive carbon not only adjusts the composition ratio of the mixed phases,but also provides a small charge transfer impedance(Rct,7.48Ω)and a big specific surface area(100.8 m^(2)/g).As a result,NNTO/C composites exhibit better sodium storage behavior while playing the synergistic interaction of mixed phases.When employed as the anode,after 200 cycles at 0.05 A/g,NNTO/C still maintains a specific capacity of 143.8 mA‧h/g.After 400 cycles at 1.00 A/g,the specific capacity remains as high as 108 mA‧h/g.This study suggests an innovative thinking for designing two-phase structures of electrode materials and the greater use of CDs in electrochemical energy storage.
文摘Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.
