Developing of high-performance and low-cost electrocatalysts is of great significance to reduce the overpotential and accelerated the reaction rate of oxygen evolution in water splitting and related energy conversion ...Developing of high-performance and low-cost electrocatalysts is of great significance to reduce the overpotential and accelerated the reaction rate of oxygen evolution in water splitting and related energy conversion applications.Herein,Fe,O-dual doped Ni2P(Fe,O-Ni2P)nanoarray is successfully synthesized on carbon cloth demonstrating enhanced electrocatalytic activity and stability for oxygen evolution reaction(OER)under alkaline media.The as-synthesized Fe,O-Ni2P nanoarray exhibits obviously improved OER performance with a low overpotential of 210 mV at 10 mA cm^-2 current density and a Tafel slope of48 mV dec^-1,as well as long-term durability.The strong coupling interaction induced changes in electronic structure lead to relatively higher oxidation state and stronger oxidation ability of the Fe,O-Ni2P nanoarray,together with the high electrochemical surface area and good conductivity contribute to the superior OER performance.This work highlights the anion-cation dual doping strategy may be an effective method for fabrication of catalysts relating to energy conversion applications.展开更多
Electrocatalytic nitrogen reduction reaction (e NRR) at the ambient conditions is attractive for ammonia(NH_(3)) synthesis due to its energy-efficient and eco-friendly features. However, the extremely strong N≡N trip...Electrocatalytic nitrogen reduction reaction (e NRR) at the ambient conditions is attractive for ammonia(NH_(3)) synthesis due to its energy-efficient and eco-friendly features. However, the extremely strong N≡N triple-bonds in nitrogen molecules and the competitive hydrogen evolution reaction lead to the unsatisfactory NH_(3) yield and the Faradaic efficiency (FE) of e NRR, making the development of high-performance catalysts with adequate active sites and high selectivity essential for further development of e NRR.Addressing this, we herein report a Bi and K dual-doped titanium oxide (BTO@KTO) material, which is prepared by a cation exchange reaction between K_(2)Ti_(4)O_(5) and molten BiCl_(2), for high-performance e NRR catalysts. Benefiting from the controllable molten-salt cation exchange process, a highly active surface containing Bi/K sites and rich oxygen vacancies has been obtained on titanium oxide. Under the synergy of these two merits, an efficient e NRR catalysis, with the NH_(3) yield rate of 32.02 μg h^(-1)mg_(cat)^(-1) and the FE of 12.71%, has been achieved, much superior to that of pristine K_(2)Ti_(4)O_(9). This work thus offers a highperformance electrocatalyst for e NRR, and more importantly, a versatile cation-exchange strategy for efficiently manipulating materials’ functionalities.展开更多
The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herei...The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herein,we proposed an Al and O dual-doped strategy for Li_(3)PS_(4)SE to regulate the chemical/electrochemical stability of anionic PS_(4)^(3-)tetrahedra to mitigate structural hydrolysis and parasitic reactions at the SE/Li interface.The optimized Li_(3.08)A_(10.04)P_(0.96)S_(3.92)O_(0.08)SE presents the highestσLi+of 3.27 mS cm^(-1),which is~6.8 times higher than the pristine Li_(3)PS_(4)and excellently inhibits the structural hydrolysis for~25 min@25%humidity at RT.DFT calculations confirmed that the enhanced chemical stability was revealed to the intrinsically stable entities,e.g.,POS33-units.Moreover,Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE cycled stably in Li//Li symmetric cell over 1000 h@0.1 mA cm^(-2)/0.1 mA h cm^(-2),could be revealed to Li-Al alloy and Li_(2)Oat SE/Li interface impeding the growth of Li-dendrites during cycling.Resultantly,LNO@LCO/Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)/Li-In cell delivered initial discharge capacities of 129.8 mA h g^(-1)and 83.74%capacity retention over 300 cycles@0.2 C at RT.Moreover,the Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE presented>90%capacity retention over 200 and 300 cycles when the cell was tested with LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)cathode material vs.5 and 10 mg cm^(-2)@RT.展开更多
The key to construct high-energy supercapacitors is to maximize the capacitance of electrode and the voltage of the device. Realizing this purpose by utilizing sustainable and low-cost resources is still a big challen...The key to construct high-energy supercapacitors is to maximize the capacitance of electrode and the voltage of the device. Realizing this purpose by utilizing sustainable and low-cost resources is still a big challenge. Herein, N, B co-doped carbon nanosheets are obtained through the proposed dual-template assisted approach by using methyl cellulose as the precursor. Due to the synergistic effects form the high surface area with the hierarchical porous structure, N/B dual doping, and a high degree of graphitization, the resultant carbon electrode exhibits a high capacitance of 572 F g^(-1)at 0.5 A g^(-1)and retains 281 F g^(-1)at 50 A g^(-1)in an acidic electrolyte. Furthermore, the symmetric device assembled using bacterial cellulose-based gel polymer electrolyte can deliver high energy density of 43 W h kg^(-1)and excellent cyclability with 97.8% capacity retention after 20 000 cycles in “water in salt” electrolyte. This work successfully realizes the fabrication of high-performance allcellulose-based quasi-solid-state supercapacitors, which brings a cost-effective insight into jointly designing electrodes and electrolytes for supporting highly efficient energy storage.展开更多
As a type of candidate for all-solid-state Li batteries,argyrodite solid electrolytes possess high ionic conductivity,but poor compatibility against Li metal.Here,we report novel Li_(6) PS_(5) I-based argyrodite sulfi...As a type of candidate for all-solid-state Li batteries,argyrodite solid electrolytes possess high ionic conductivity,but poor compatibility against Li metal.Here,we report novel Li_(6) PS_(5) I-based argyrodite sulfides with Sn-O dual doping,which is a powerful solution to comprehensively improve the performance of a material.The combination of O and Sn-aliovalent doping not only enables an improved ionic conductivity but more importantly realizes an intensively enhanced interfacial compatibility between argyrodite and Li metal and Li dendrite suppression capability.The assembled battery with Sn-O dual-doped electrolyte and Li anode demonstrates high capacity and decent cycling stability.Dual doping is thus believed to be an effective way to develop high performance sulfide solid electrolytes.展开更多
The(electro)chemical stability and Li dendrite suppression capability of sulfide solid electrolytes(SEs)need further improvement for developing all-solid-state Li batteries(ASSLBs).Here,we report advanced halogen-rich...The(electro)chemical stability and Li dendrite suppression capability of sulfide solid electrolytes(SEs)need further improvement for developing all-solid-state Li batteries(ASSLBs).Here,we report advanced halogen-rich argyrodites via I and Cl co-occupation on the crystal lattice.Notably,a proper I content forms a single phase,whereas an excessive I causes precipitation of two argyrodite phases like a superlattice structure.The resultant synergistic effect of the optimized composition allows to gain high ionic conductivities at room temperature and-20℃,and enhances the(electro)chemical stability against Li and Li dendrite suppression capability.The Li|argyrodite interface is very sensitive to the ratio of I and Cl.A LiCl-and LiI-rich double-layer interface is observed from the cell using the SE with optimized composition,whereas too high I content forms only a single interface layer with a mixture of Lil and LiCl.This double-layer interface is found to effectively mitigate the Li/SE reaction.The proper designed argyrodite enables ASSLBs to achieve good electrochemical properties at a broad temperature range regardless of the electrode materials.This co-occupation strategy provides a novel exploration for advanced halogen-rich argyrodite system.展开更多
Efficacious regulation of the geometric and electronic structures of carbon nanomaterials via the introduction of defects and their synergy is essential to achieving good electrochemical performance.However,the guidel...Efficacious regulation of the geometric and electronic structures of carbon nanomaterials via the introduction of defects and their synergy is essential to achieving good electrochemical performance.However,the guidelines for designing hybrid materials with advantageous structures and the fundamental understanding of their electrocatalytic mechanisms remain unclear.Herein,superfine Pt and PtCu nanoparticles supported by novel S,N‐co‐doped multi‐walled CNT(MWCNTs)were prepared through the innovative pyrolysis of a poly(3,4‐ethylenedioxythiophene)/polyaniline copolymer as a source of S and N.The uniform wrapping of the copolymer around the MWCNTs provides a high density of evenly distributed defects on the surface after the pyrolysis treatment,facilitating the uniform distribution of ultrafine Pt and PtCu nanoparticles.Remarkably,the Pt_(1)Cu_(2)/SN‐MWCNTs show an obviously larger electroactive surface area and higher mass activity,stability,and CO poisoning resistance in methanol oxidation compared to Pt/SN‐MWCNTs,Pt/S‐MWCNTs,Pt/N‐MWCNTs,and commercial Pt/C.Density functional theory studies confirm that the co‐doping of S and N considerably deforms the CNTs and polarizes the adjacent C atoms.Consequently,both the adsorption of Pt1Cu2 onto the SN‐MWCNTs and the subsequent adsorption of methanol are enhanced;in addition,the catalytic activity of Pt_(1)Cu_(2)/SN‐MWCNTs for methanol oxidation is thermodynamically and kinetically more favorable than that of its CNT and N‐CNT counterparts.This work provides a novel method to fabricate high‐performance fuel cell electrocatalysts with highly dispersed and stable Pt‐based nanoparticles on a carbon substrate.展开更多
Aqueous rechargeable Zn//MnO_(2)batteries show promising prospects for grid-scale energy storage due to their intrinsic safety,abundant resource,and potential high performance.Unfortunately,the real capability of thes...Aqueous rechargeable Zn//MnO_(2)batteries show promising prospects for grid-scale energy storage due to their intrinsic safety,abundant resource,and potential high performance.Unfortunately,the real capability of these devices is far from satisfactory thanks to the low capacity and sluggish kinetics of the MnO_(2)cathode.Herein,we report a dual cation doping strategy by synthesis of MnO_(2)in the presence of Ti_(3)_(2)X MXenes and Ni^(2+)ions to essentially address these drawbacks.Such a process contributes to a Ti,Ni co-dopedα-MnO_(2)anchored on MXenes.The Ti^(3+)ions incorporated in the framework allow a partial multivalent variation for a large capacity while the Ni^(2+)ions promote the H^(+)transfer within the MnO_(2)matrix via the Grotthuss proton transport manner.As a result,the optimal dual cation doped MnO_(2)exhibits a large reversible capacity of 378 mAh·g-1 at 0.1 C and a high rate capability.Moreover,capacity retention as high as 92%is observed after cycling at 4 C for 1000 times,far superior to many of the previously reported results.This facile strategy demonstrated here may shed new insight into the rational design of electrodes based on high-performance Zn//MnO_(2)batteries.展开更多
Nanopowders of Znl_x_y_zMnxNiyLizO [(x = 0.04, y = 0, z = 0), (x = 0.04, y = 0.03, z = 0) and (x = 0.04, y = 0.03, z = 0.03)] have been synthesized by sol-gel precursor route using ethylene diamine tetraacetic a...Nanopowders of Znl_x_y_zMnxNiyLizO [(x = 0.04, y = 0, z = 0), (x = 0.04, y = 0.03, z = 0) and (x = 0.04, y = 0.03, z = 0.03)] have been synthesized by sol-gel precursor route using ethylene diamine tetraacetic acid (EDTA) as a metal chelating agent. X-ray diffraction analysis confirms the formation of wurtzite hexagonal structure for all the three compositions. Mn2+ doped ZnO exhibits room temperature ferromagnetism (RTFM), and it is found that further Ni2+ doping has decreased Ms because of limit of solid solubility of transition metal in ZnO. But codoping of monovalent Li1+, further increases the ferromagnetism (FM) value, due to introduction of free carriers compared to the dual doped samples. Photoluminescence (PL) spectra of the system, exhibit near band edge (NBE) emission peak at --464 nm due to the electron transition from interstitials to the valence band. Recombination of conduction electron with hole trapped at oxygen vacancy, leads to prominent defect emission peaks at --482 nm and 532 nm. The evidence of the formation of metaI-EDTA complexes are found from the Fourier transform infrared spectra at 2800-3800 cm-1 with shifting, splitting of the peak and also drastic variations in the intensity.展开更多
The Bi0.5Na0.02Sb1.48-xInxTe3alloys(x =0.02-0.20) were synthesized by vacuum melting and hot pressing methods at 753 K,60 MPa for 30 min.Effects of Na and In dual partial substitutions for Sb on the thermoelectric p...The Bi0.5Na0.02Sb1.48-xInxTe3alloys(x =0.02-0.20) were synthesized by vacuum melting and hot pressing methods at 753 K,60 MPa for 30 min.Effects of Na and In dual partial substitutions for Sb on the thermoelectric properties were investigated from 300 to 500 K.Substituting Sb with Na and In can enhance the Seebeck coefficient effectively near room temperature.The electrical resistivity of the Na and In dual-doping samples is higher within the whole test temperature range.The Bi0.5Na0.02Sb1.48-xInxTe3samples(x = 0.02,0.06) play a great role in optimizing the thermal conductivity.As for the Bi0.5Na0.02Sb1.46In0.02Te3alloy,the minimum value of thermal conductivity reaches 0.53 W·m-1·K-1at 320 K.The thermoelectric performance of the Na and In dualdoped samples is greatly improved,and a figure of merit ZT of 1.26 is achieved at 300 K for the Bi0.5Na0.02Sb1.42In0.06Te3,representing 26%enhancement with respect to ZT = 1.0 of the undoped sample.展开更多
基金financial support from the National Science Foundation of China(51671094,21606189)China Postdoctoral Science Foundation(2017M612174)+1 种基金Shandong Provincial Natural Science Foundation(ZR2015BQ011)the Science and Technology Project of University of Jinan(XKY1826)。
文摘Developing of high-performance and low-cost electrocatalysts is of great significance to reduce the overpotential and accelerated the reaction rate of oxygen evolution in water splitting and related energy conversion applications.Herein,Fe,O-dual doped Ni2P(Fe,O-Ni2P)nanoarray is successfully synthesized on carbon cloth demonstrating enhanced electrocatalytic activity and stability for oxygen evolution reaction(OER)under alkaline media.The as-synthesized Fe,O-Ni2P nanoarray exhibits obviously improved OER performance with a low overpotential of 210 mV at 10 mA cm^-2 current density and a Tafel slope of48 mV dec^-1,as well as long-term durability.The strong coupling interaction induced changes in electronic structure lead to relatively higher oxidation state and stronger oxidation ability of the Fe,O-Ni2P nanoarray,together with the high electrochemical surface area and good conductivity contribute to the superior OER performance.This work highlights the anion-cation dual doping strategy may be an effective method for fabrication of catalysts relating to energy conversion applications.
基金supported by the National Natural Science Foundation of China (22179093)。
文摘Electrocatalytic nitrogen reduction reaction (e NRR) at the ambient conditions is attractive for ammonia(NH_(3)) synthesis due to its energy-efficient and eco-friendly features. However, the extremely strong N≡N triple-bonds in nitrogen molecules and the competitive hydrogen evolution reaction lead to the unsatisfactory NH_(3) yield and the Faradaic efficiency (FE) of e NRR, making the development of high-performance catalysts with adequate active sites and high selectivity essential for further development of e NRR.Addressing this, we herein report a Bi and K dual-doped titanium oxide (BTO@KTO) material, which is prepared by a cation exchange reaction between K_(2)Ti_(4)O_(5) and molten BiCl_(2), for high-performance e NRR catalysts. Benefiting from the controllable molten-salt cation exchange process, a highly active surface containing Bi/K sites and rich oxygen vacancies has been obtained on titanium oxide. Under the synergy of these two merits, an efficient e NRR catalysis, with the NH_(3) yield rate of 32.02 μg h^(-1)mg_(cat)^(-1) and the FE of 12.71%, has been achieved, much superior to that of pristine K_(2)Ti_(4)O_(9). This work thus offers a highperformance electrocatalyst for e NRR, and more importantly, a versatile cation-exchange strategy for efficiently manipulating materials’ functionalities.
基金supported by the National Natural Science Foundation of China(Nos.21203008,21975025,12274025)the Hainan Province Science and Technology Special Fund(Nos.ZDYF2021SHFZ232,ZDYF2023GXJS022)the Hainan Province Postdoctoral Science Foundation(No.300333)。
文摘The sulfide-based solid-state electrolytes(SEs)reactivity toward moisture and Li-metal are huge barriers that impede their large-scale manufactu ring and applications in all-solid-state lithium batteries(ASSLBs).Herein,we proposed an Al and O dual-doped strategy for Li_(3)PS_(4)SE to regulate the chemical/electrochemical stability of anionic PS_(4)^(3-)tetrahedra to mitigate structural hydrolysis and parasitic reactions at the SE/Li interface.The optimized Li_(3.08)A_(10.04)P_(0.96)S_(3.92)O_(0.08)SE presents the highestσLi+of 3.27 mS cm^(-1),which is~6.8 times higher than the pristine Li_(3)PS_(4)and excellently inhibits the structural hydrolysis for~25 min@25%humidity at RT.DFT calculations confirmed that the enhanced chemical stability was revealed to the intrinsically stable entities,e.g.,POS33-units.Moreover,Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE cycled stably in Li//Li symmetric cell over 1000 h@0.1 mA cm^(-2)/0.1 mA h cm^(-2),could be revealed to Li-Al alloy and Li_(2)Oat SE/Li interface impeding the growth of Li-dendrites during cycling.Resultantly,LNO@LCO/Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)/Li-In cell delivered initial discharge capacities of 129.8 mA h g^(-1)and 83.74%capacity retention over 300 cycles@0.2 C at RT.Moreover,the Li_(3.08)Al_(0.04)P_(0.96)S_(3.92)O_(0.08)SE presented>90%capacity retention over 200 and 300 cycles when the cell was tested with LiNi_(0.8)Co_(0.15)Al_(0.05)O_(2)(NCA)cathode material vs.5 and 10 mg cm^(-2)@RT.
基金supported by the National Natural Science Foundation of China (No.22179123 and 21471139)the Shandong Provincial Natural Science Foundation,China (ZR2020ME038)+2 种基金the Fundamental Research Funds for the Central Universities (No.201941010)the Shandong Provincial Key R&D Plan and the Public Welfare Special Program,China (2019GGX102038)the Qingdao City Programs for Science and Technology Plan Projects (19-6-2-77-cg)。
文摘The key to construct high-energy supercapacitors is to maximize the capacitance of electrode and the voltage of the device. Realizing this purpose by utilizing sustainable and low-cost resources is still a big challenge. Herein, N, B co-doped carbon nanosheets are obtained through the proposed dual-template assisted approach by using methyl cellulose as the precursor. Due to the synergistic effects form the high surface area with the hierarchical porous structure, N/B dual doping, and a high degree of graphitization, the resultant carbon electrode exhibits a high capacitance of 572 F g^(-1)at 0.5 A g^(-1)and retains 281 F g^(-1)at 50 A g^(-1)in an acidic electrolyte. Furthermore, the symmetric device assembled using bacterial cellulose-based gel polymer electrolyte can deliver high energy density of 43 W h kg^(-1)and excellent cyclability with 97.8% capacity retention after 20 000 cycles in “water in salt” electrolyte. This work successfully realizes the fabrication of high-performance allcellulose-based quasi-solid-state supercapacitors, which brings a cost-effective insight into jointly designing electrodes and electrolytes for supporting highly efficient energy storage.
基金supported by the National Key R&D Program of China(No.2018YFB0104300)the Natural Science Foundation of Hebei Province(No.E2018203301)。
文摘As a type of candidate for all-solid-state Li batteries,argyrodite solid electrolytes possess high ionic conductivity,but poor compatibility against Li metal.Here,we report novel Li_(6) PS_(5) I-based argyrodite sulfides with Sn-O dual doping,which is a powerful solution to comprehensively improve the performance of a material.The combination of O and Sn-aliovalent doping not only enables an improved ionic conductivity but more importantly realizes an intensively enhanced interfacial compatibility between argyrodite and Li metal and Li dendrite suppression capability.The assembled battery with Sn-O dual-doped electrolyte and Li anode demonstrates high capacity and decent cycling stability.Dual doping is thus believed to be an effective way to develop high performance sulfide solid electrolytes.
基金supported by the National Natural Science Foundation of China(52172243)。
文摘The(electro)chemical stability and Li dendrite suppression capability of sulfide solid electrolytes(SEs)need further improvement for developing all-solid-state Li batteries(ASSLBs).Here,we report advanced halogen-rich argyrodites via I and Cl co-occupation on the crystal lattice.Notably,a proper I content forms a single phase,whereas an excessive I causes precipitation of two argyrodite phases like a superlattice structure.The resultant synergistic effect of the optimized composition allows to gain high ionic conductivities at room temperature and-20℃,and enhances the(electro)chemical stability against Li and Li dendrite suppression capability.The Li|argyrodite interface is very sensitive to the ratio of I and Cl.A LiCl-and LiI-rich double-layer interface is observed from the cell using the SE with optimized composition,whereas too high I content forms only a single interface layer with a mixture of Lil and LiCl.This double-layer interface is found to effectively mitigate the Li/SE reaction.The proper designed argyrodite enables ASSLBs to achieve good electrochemical properties at a broad temperature range regardless of the electrode materials.This co-occupation strategy provides a novel exploration for advanced halogen-rich argyrodite system.
文摘Efficacious regulation of the geometric and electronic structures of carbon nanomaterials via the introduction of defects and their synergy is essential to achieving good electrochemical performance.However,the guidelines for designing hybrid materials with advantageous structures and the fundamental understanding of their electrocatalytic mechanisms remain unclear.Herein,superfine Pt and PtCu nanoparticles supported by novel S,N‐co‐doped multi‐walled CNT(MWCNTs)were prepared through the innovative pyrolysis of a poly(3,4‐ethylenedioxythiophene)/polyaniline copolymer as a source of S and N.The uniform wrapping of the copolymer around the MWCNTs provides a high density of evenly distributed defects on the surface after the pyrolysis treatment,facilitating the uniform distribution of ultrafine Pt and PtCu nanoparticles.Remarkably,the Pt_(1)Cu_(2)/SN‐MWCNTs show an obviously larger electroactive surface area and higher mass activity,stability,and CO poisoning resistance in methanol oxidation compared to Pt/SN‐MWCNTs,Pt/S‐MWCNTs,Pt/N‐MWCNTs,and commercial Pt/C.Density functional theory studies confirm that the co‐doping of S and N considerably deforms the CNTs and polarizes the adjacent C atoms.Consequently,both the adsorption of Pt1Cu2 onto the SN‐MWCNTs and the subsequent adsorption of methanol are enhanced;in addition,the catalytic activity of Pt_(1)Cu_(2)/SN‐MWCNTs for methanol oxidation is thermodynamically and kinetically more favorable than that of its CNT and N‐CNT counterparts.This work provides a novel method to fabricate high‐performance fuel cell electrocatalysts with highly dispersed and stable Pt‐based nanoparticles on a carbon substrate.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21975258,22179145,22005341,and 21878336)the startup support grant from China University of Petroleum(East China)Shandong Provincial Natural Science Foundation(Nos.ZR2020ZD08 and ZR2018ZC1458).
文摘Aqueous rechargeable Zn//MnO_(2)batteries show promising prospects for grid-scale energy storage due to their intrinsic safety,abundant resource,and potential high performance.Unfortunately,the real capability of these devices is far from satisfactory thanks to the low capacity and sluggish kinetics of the MnO_(2)cathode.Herein,we report a dual cation doping strategy by synthesis of MnO_(2)in the presence of Ti_(3)_(2)X MXenes and Ni^(2+)ions to essentially address these drawbacks.Such a process contributes to a Ti,Ni co-dopedα-MnO_(2)anchored on MXenes.The Ti^(3+)ions incorporated in the framework allow a partial multivalent variation for a large capacity while the Ni^(2+)ions promote the H^(+)transfer within the MnO_(2)matrix via the Grotthuss proton transport manner.As a result,the optimal dual cation doped MnO_(2)exhibits a large reversible capacity of 378 mAh·g-1 at 0.1 C and a high rate capability.Moreover,capacity retention as high as 92%is observed after cycling at 4 C for 1000 times,far superior to many of the previously reported results.This facile strategy demonstrated here may shed new insight into the rational design of electrodes based on high-performance Zn//MnO_(2)batteries.
文摘Nanopowders of Znl_x_y_zMnxNiyLizO [(x = 0.04, y = 0, z = 0), (x = 0.04, y = 0.03, z = 0) and (x = 0.04, y = 0.03, z = 0.03)] have been synthesized by sol-gel precursor route using ethylene diamine tetraacetic acid (EDTA) as a metal chelating agent. X-ray diffraction analysis confirms the formation of wurtzite hexagonal structure for all the three compositions. Mn2+ doped ZnO exhibits room temperature ferromagnetism (RTFM), and it is found that further Ni2+ doping has decreased Ms because of limit of solid solubility of transition metal in ZnO. But codoping of monovalent Li1+, further increases the ferromagnetism (FM) value, due to introduction of free carriers compared to the dual doped samples. Photoluminescence (PL) spectra of the system, exhibit near band edge (NBE) emission peak at --464 nm due to the electron transition from interstitials to the valence band. Recombination of conduction electron with hole trapped at oxygen vacancy, leads to prominent defect emission peaks at --482 nm and 532 nm. The evidence of the formation of metaI-EDTA complexes are found from the Fourier transform infrared spectra at 2800-3800 cm-1 with shifting, splitting of the peak and also drastic variations in the intensity.
基金financially supported by the National Natural Science Foundation of China (No. 51161009)the Research Project of Jiangxi Provincial Education Department (No. GJJ13722 and GJJ11615)
文摘The Bi0.5Na0.02Sb1.48-xInxTe3alloys(x =0.02-0.20) were synthesized by vacuum melting and hot pressing methods at 753 K,60 MPa for 30 min.Effects of Na and In dual partial substitutions for Sb on the thermoelectric properties were investigated from 300 to 500 K.Substituting Sb with Na and In can enhance the Seebeck coefficient effectively near room temperature.The electrical resistivity of the Na and In dual-doping samples is higher within the whole test temperature range.The Bi0.5Na0.02Sb1.48-xInxTe3samples(x = 0.02,0.06) play a great role in optimizing the thermal conductivity.As for the Bi0.5Na0.02Sb1.46In0.02Te3alloy,the minimum value of thermal conductivity reaches 0.53 W·m-1·K-1at 320 K.The thermoelectric performance of the Na and In dualdoped samples is greatly improved,and a figure of merit ZT of 1.26 is achieved at 300 K for the Bi0.5Na0.02Sb1.42In0.06Te3,representing 26%enhancement with respect to ZT = 1.0 of the undoped sample.