The safe operating voltage and low volume variation of Li_(3)VO_(4)(LVO)make it an ideal anode material for lithium(Li)-ion batteries.However,the insufficient understanding of the inner storage mechanism hinders the d...The safe operating voltage and low volume variation of Li_(3)VO_(4)(LVO)make it an ideal anode material for lithium(Li)-ion batteries.However,the insufficient understanding of the inner storage mechanism hinders the design of LVO-based electrodes.Herein,we investigate,for the first time,the Li-ion storage activity in LVO via Cl doping.Moreover,N-doped C coating was simultaneously achieved in the Cl doping process,resulting in synergistically improved reaction kinetics.As a result,the as-prepared Cl-doped Li_(3)VO_(4) coated with N-doped C(Cl-LVO@NC)electrodes deliver a discharge capacity of 884.1 mAh/g after 200 cycles at 0.2 A/g,which is the highest among all of the LVO-based electrodes.The Cl-LVO@NC electrodes also exhibit high-capacity retention of 331.1 mAh/g at 8.0 A/g and full capacity recovery after 5 periods of rate testing over 400 cycles.After 5000 cycles at 4.0 A/g,the discharge capacity can be maintained at 423.2 mAh/g,which is superior to most LVO-based electrodes.The Li-ion storage activity in LVO via Cl doping and significant improvement in the high-rate Li-ion storage reported in this work can be used as references for the design of advanced LVO-based electrodes for high-power applications.展开更多
Band structure modification plays an important role in improving the thermoelectric performance of SnTe.Herein band sharpening as one of the band structure modifications is achieved by Cl doping and reduces the effect...Band structure modification plays an important role in improving the thermoelectric performance of SnTe.Herein band sharpening as one of the band structure modifications is achieved by Cl doping and reduces the effective mass(from 0.168m_(e)to∼0.06me),which introduces a super high carrier mobility(over 2000 cm^(2)V^(−1)s^(−1))and in turn optimizes the electrical conductivity but deteriorates the Seebeck coefficient.However,the numerical calculation based on the two-band model reveals that the Seebeck coefficient recovers to a normal level close to that of pristine SnTe by temperature-driven band convergence.As a result,a maximum power factor of∼21μW cm^(−1)K^(−2)at 873 K is achieved in the SnTe_(0.94)Cl_(0.06)sample,approximately 30%higher than that of pristine SnTe.Furthermore,numerous micro-nano precipitates are observed in Cl-doped samples,giving rise to a drastic temperature dependence of the lattice thermal conductivity,thereby leading to an ultralow lattice thermal conductivity of∼0.31 W m^(−1)K^(−1)at 523 K in the SnTe0.88Cl0.12 sample which is close to the Born–von Kaman periodic boundary conditions for the minimum limit.Unexpectedly,the Cl doping activates an obvious bipolar effect at high temperature.In spite of the bipolar effect contributing to the total thermal conductivity,the figure of merit ZT is still improved from∼0.4 for pristine SnTe to∼0.78 for the SnTe_(0.88)Cl_(0.12)sample at 873 K due to the high power factor.展开更多
In this paper,a novel ionic liquid-assisted solvothermal method to prepare Cl-doped bismuth oxycarbonate(Bi_(2)O_(2)CO_(3))is presented.The ionic liquid of[Hnmp]Cl not only enhances the solvothermal process to help th...In this paper,a novel ionic liquid-assisted solvothermal method to prepare Cl-doped bismuth oxycarbonate(Bi_(2)O_(2)CO_(3))is presented.The ionic liquid of[Hnmp]Cl not only enhances the solvothermal process to help the formation of Bi_(2)O_(2)CO_(3),but also provides chloride element as a dopant.XRD and XPS show that all three samples are Bi_(2)O_(2)CO_(3) with high purity.XPS,solid EPR,and TEM results prove that Cl is doped into the Bi_(2)O_(2)CO_(3) lattice and oxygen vacancies are generated.DRS results show that after Cl doping,the absorption of visible light by Bi_(2)O_(2)CO_(3) is enhanced.Surface photovoltage(SPV)and transient photocurrent tests show that as the doping amount of Cl increases,the separation efficiency of photogenerated electron-hole pairs over Bi_(2)O_(2)CO_(3) improves.The photocatalytic activity of Bi_(2)O_(2)CO_(3) is evaluated by the degradation of rhodamine B,which is increased after Cl doping.This work would broaden the application of ionic liquids in the solvothermal process and deepen the understanding of anionic ion doping in Bi_(2)O_(2)CO_(3).展开更多
The recent claim of potential room-temperature superconductivity in Pb_(10−x)Cu_(x)(PO_(4))_(6)O has attracted widespread attention.However,the signature of superconductivity is later attributed to the Cu_(2)S impurit...The recent claim of potential room-temperature superconductivity in Pb_(10−x)Cu_(x)(PO_(4))_(6)O has attracted widespread attention.However,the signature of superconductivity is later attributed to the Cu_(2)S impurity formed during the multiple-step synthesis procedure.Here we report a simple one-step approach for synthesizing single-phase chloride analogue Cu-doped Pb10(PO_(4))_(6)Cl_(2) using PbO,PbCl_(2),CuCl_(2),and NH_(4)H_(2)PO_(4) as starting materials.Irrespective of the initial stoichiometry,Cu doping always leads to a lattice expansion in Pb10(PO_(4))_(6)Cl_(2).This indicates that Cu prefers to reside in the hexagonal channels rather than as substitutes at the Pb sites,and the chemical formula is expressed as Pb10(PO_(4))_(6)Cu_(x)Cl_(2).All the Pb10(PO_(4))_(6)Cu_(x)Cl_(2)(0≤x≤1.0)samples are found to be semiconductors with wide band gaps of 4.46–4.59 eV,and the Cu-doped ones(x=0.5 and 1.0)exhibit a paramagnetic behavior without any phase transition between 400 and 1.8 K.Our study calls for a reinvestigation of the Cu location in Pb_(10−x)Cu_(x)(PO_(4))_(6)O and supports the absence of superconductivity in this oxyapatite.展开更多
基金supported by the National Natural Science Foundation of China(No.52101262)Distinguished Youth Foundation of Hubei Province(2019CFA084)+1 种基金Educational offi ce of Hubei Province(Q20201201)the 111 project(D20015).
文摘The safe operating voltage and low volume variation of Li_(3)VO_(4)(LVO)make it an ideal anode material for lithium(Li)-ion batteries.However,the insufficient understanding of the inner storage mechanism hinders the design of LVO-based electrodes.Herein,we investigate,for the first time,the Li-ion storage activity in LVO via Cl doping.Moreover,N-doped C coating was simultaneously achieved in the Cl doping process,resulting in synergistically improved reaction kinetics.As a result,the as-prepared Cl-doped Li_(3)VO_(4) coated with N-doped C(Cl-LVO@NC)electrodes deliver a discharge capacity of 884.1 mAh/g after 200 cycles at 0.2 A/g,which is the highest among all of the LVO-based electrodes.The Cl-LVO@NC electrodes also exhibit high-capacity retention of 331.1 mAh/g at 8.0 A/g and full capacity recovery after 5 periods of rate testing over 400 cycles.After 5000 cycles at 4.0 A/g,the discharge capacity can be maintained at 423.2 mAh/g,which is superior to most LVO-based electrodes.The Li-ion storage activity in LVO via Cl doping and significant improvement in the high-rate Li-ion storage reported in this work can be used as references for the design of advanced LVO-based electrodes for high-power applications.
基金supported by The National Key Research and Development Program of China[Grant No.2017YFF0204706]the Fundamental Research Funds for the Central Universities[Grant No.FRF-MP-18-005 and FRF-MP-19-005].
文摘Band structure modification plays an important role in improving the thermoelectric performance of SnTe.Herein band sharpening as one of the band structure modifications is achieved by Cl doping and reduces the effective mass(from 0.168m_(e)to∼0.06me),which introduces a super high carrier mobility(over 2000 cm^(2)V^(−1)s^(−1))and in turn optimizes the electrical conductivity but deteriorates the Seebeck coefficient.However,the numerical calculation based on the two-band model reveals that the Seebeck coefficient recovers to a normal level close to that of pristine SnTe by temperature-driven band convergence.As a result,a maximum power factor of∼21μW cm^(−1)K^(−2)at 873 K is achieved in the SnTe_(0.94)Cl_(0.06)sample,approximately 30%higher than that of pristine SnTe.Furthermore,numerous micro-nano precipitates are observed in Cl-doped samples,giving rise to a drastic temperature dependence of the lattice thermal conductivity,thereby leading to an ultralow lattice thermal conductivity of∼0.31 W m^(−1)K^(−1)at 523 K in the SnTe0.88Cl0.12 sample which is close to the Born–von Kaman periodic boundary conditions for the minimum limit.Unexpectedly,the Cl doping activates an obvious bipolar effect at high temperature.In spite of the bipolar effect contributing to the total thermal conductivity,the figure of merit ZT is still improved from∼0.4 for pristine SnTe to∼0.78 for the SnTe_(0.88)Cl_(0.12)sample at 873 K due to the high power factor.
基金the National Natural Science Foundation of China(No.21776059 and 21376061)the Natural Science Foundation for Distinguished Young Scholar of Hebei Province(B2015208010)the Foundation for the Returned Overseas Chinese Scholars of Hebei Province(CL201609).
文摘In this paper,a novel ionic liquid-assisted solvothermal method to prepare Cl-doped bismuth oxycarbonate(Bi_(2)O_(2)CO_(3))is presented.The ionic liquid of[Hnmp]Cl not only enhances the solvothermal process to help the formation of Bi_(2)O_(2)CO_(3),but also provides chloride element as a dopant.XRD and XPS show that all three samples are Bi_(2)O_(2)CO_(3) with high purity.XPS,solid EPR,and TEM results prove that Cl is doped into the Bi_(2)O_(2)CO_(3) lattice and oxygen vacancies are generated.DRS results show that after Cl doping,the absorption of visible light by Bi_(2)O_(2)CO_(3) is enhanced.Surface photovoltage(SPV)and transient photocurrent tests show that as the doping amount of Cl increases,the separation efficiency of photogenerated electron-hole pairs over Bi_(2)O_(2)CO_(3) improves.The photocatalytic activity of Bi_(2)O_(2)CO_(3) is evaluated by the degradation of rhodamine B,which is increased after Cl doping.This work would broaden the application of ionic liquids in the solvothermal process and deepen the understanding of anionic ion doping in Bi_(2)O_(2)CO_(3).
基金support from the Foundation of Westlake University,Prof.
文摘The recent claim of potential room-temperature superconductivity in Pb_(10−x)Cu_(x)(PO_(4))_(6)O has attracted widespread attention.However,the signature of superconductivity is later attributed to the Cu_(2)S impurity formed during the multiple-step synthesis procedure.Here we report a simple one-step approach for synthesizing single-phase chloride analogue Cu-doped Pb10(PO_(4))_(6)Cl_(2) using PbO,PbCl_(2),CuCl_(2),and NH_(4)H_(2)PO_(4) as starting materials.Irrespective of the initial stoichiometry,Cu doping always leads to a lattice expansion in Pb10(PO_(4))_(6)Cl_(2).This indicates that Cu prefers to reside in the hexagonal channels rather than as substitutes at the Pb sites,and the chemical formula is expressed as Pb10(PO_(4))_(6)Cu_(x)Cl_(2).All the Pb10(PO_(4))_(6)Cu_(x)Cl_(2)(0≤x≤1.0)samples are found to be semiconductors with wide band gaps of 4.46–4.59 eV,and the Cu-doped ones(x=0.5 and 1.0)exhibit a paramagnetic behavior without any phase transition between 400 and 1.8 K.Our study calls for a reinvestigation of the Cu location in Pb_(10−x)Cu_(x)(PO_(4))_(6)O and supports the absence of superconductivity in this oxyapatite.
