The Jahn-Teller effect of Mn^(3+)brings drastic structural changes to MnO_(2)-based materials and accelerates the destruction and deactivation of the internal structure of the materials,thus leading to severe capacity...The Jahn-Teller effect of Mn^(3+)brings drastic structural changes to MnO_(2)-based materials and accelerates the destruction and deactivation of the internal structure of the materials,thus leading to severe capacity fading and phase change of MnO_(2)-based materials in aqueous zinc ion batteries(AZIBs).Here,this study doped high valent vanadium ions into MnO_(2)(VMO-x)to inhibit manganese's Jahn-Teller effect.Through a series of characterizations,such as X-ray diffraction(XRD),Raman spectroscopy,and scanning electron microscopy(SEM),it was discovered that the introduction of vanadium ions effectively increased the interlayer spacing of MnO_(2),facilitating the transport of ions into the interlayer.Additionally,Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS)demonstrated vanadium doped could effectively adjust the electronic structure,decreasing the average oxidation state of manganese,thereby inhibiting the Jahn-Teller effect and significantly enhancing the stability of the VMO-x cathode.The theoretical calculation showed that introducing vanadium ions enhanced the interaction between the main material and Zn^(2+),optimized its electron transport capacity,and led to better electrical conductivity and reaction kinetics of the VMO-5.Benefiting from this,the VMO-5 cathode exhibited an outstanding capacity of 283 mAh/g and maintained a capacity retention rate of 79%after 2000 cycles,demonstrating excellent electrochemical performance.Furthermore,the mechanism of H^(+)/Zn^(2+)co-intercalation/deintercalation was demonstrated through mechanism analysis.Finally,the test results of the pouch cell demonstrated the excellent flexibility and safety exhibited by the VMO-5 make it have great potential in flexible devices.This work presented a novel approach to doping high valence metal ions into manganese-based electrodes for AZIBs.展开更多
Designing low-cost and high-efficiency bifunctional electrocatalysts is one of the challenges in the clean production of hydrogen energy in electrochemical water splitting.Transition metal selenides(TMSes)have been wi...Designing low-cost and high-efficiency bifunctional electrocatalysts is one of the challenges in the clean production of hydrogen energy in electrochemical water splitting.Transition metal selenides(TMSes)have been widely studied because of their low price,intrinsic metal properties,and high catalytic ac-tivity.In addition,the synergistic effect between bimetallic selenides exhibits better performance than monometallic selenides in the electrocatalytic process.Herein,we synthesized V-doped NiSe2 nanowire arrays on pretreated nickel foam by a convenient two-step hydrothermal synthesis method.In the al-kaline electrolyte,V-NiSe_(2)/NF exhibited excellent OER catalytic activity(293.6 mV@50 mA cm^(-2)).In ad-dition,the introduction of heteroatom V induces stronger electronic interactions between the structural atoms of the catalyst,altering the electronic structure and causing V-NiSe_(2)/NF to demonstrate excellent OER performance.In the long-term OER test,V-NiSe_(2)/NF was converted into NiOOH and SeO_(x)^(2-),which may be the“real”active species during catalytic reactions,and we also successfully captured the for-mation of intermediate NiOOH and selenite as active centers in the OER process through in-situ Raman.The theoretical calculation shows that the electron transfer modulates the electron structure,changes the adsorption-desorption energy of the reaction intermediates,reduces the potential barrier of the rate-limiting step,and improves the OER activity.The V doping engineering strategy and the unique nanowire array structure make TMSes exhibit excellent OER performance.This study provides a new idea for the design of TMSe catalysts with excellent electrocatalytic performance.展开更多
YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected...YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected as an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high valence element, vanadium, produces the extra free-electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of YBa2Cu3-xVxO7-v and also results in a depression of TC.展开更多
A model is presented to describe a compensation mechanism for semi-insulating 6H-SiC grown with the intentional doping of vanadium. Because we found nitrogen to be the principal shallow donor impurity in SiC by second...A model is presented to describe a compensation mechanism for semi-insulating 6H-SiC grown with the intentional doping of vanadium. Because we found nitrogen to be the principal shallow donor impurity in SiC by secondary ion mass spectroscopy （SIMS） measurements, semi-insulating properties in SiC are achieved by compensating the nitrogen donor with the vanadium deep acceptor level. The presence of different vanadium charge states V^3＋ and V^4＋ is detected by electron paramagnetic resonance and optical absorption measurements,which coincides with the results obtained by SIMS measurements. Both optical absorption and low temperature photoluminescence measurements reveal that the vanadium acceptor level is located at 0.62eV below the conduction band in 6H-SiC.展开更多
Deep level transient Fourier spectroscopy （DLTFS） measurements are used to characterize the deep impurity levels in n-type 4H-SiC by vanadium ions implantation. Two acceptor levels of vanadium at Ec - 0.81 and Ec - ...Deep level transient Fourier spectroscopy （DLTFS） measurements are used to characterize the deep impurity levels in n-type 4H-SiC by vanadium ions implantation. Two acceptor levels of vanadium at Ec - 0.81 and Ec - 1.02eV with the electron capture cross section of 7.0 × 10^16 and 6.0 × 10^-16 cm^2 are observed, respectively. Low-temperature photoluminescence measurements in the range of 1.4-3.4eV are also performed on the sample, which reveals the formation of two electron traps at 0.80 and 1. 16eV below the conduction band. These traps indicate that vanadium doping leads to the formation of two deep acceptor levels in 4H-SiC,with the location of 0.8±0.01 and 1. 1 ±0.08eV below the conduction band.展开更多
The exploration of cost-effective,high-performance,and stable electrocatalysts for the hydrogen evolution reaction(HER)over wide pH range(0–14)is of paramount importance for future renewable energy conversion technol...The exploration of cost-effective,high-performance,and stable electrocatalysts for the hydrogen evolution reaction(HER)over wide pH range(0–14)is of paramount importance for future renewable energy conversion technologies.Regulation of electronic structure through doping vanadium atoms is a feasible construction strategy to enhance catalytic activities,electron transfer capability,and stability of the HER electrode.Herein,V-doped NiCoP nanosheets on carbon fiber paper(CFP)(denoted as Vx-NiCoP/CFP)were constructed by doping V modulation on NiCoP nanosheets on CFP and used for pH-universal HER.Benefiting from the abundant catalytic sites and optimized hydrogen binding thermodynamics,the resultant V15-NiCoP/CFP demonstrates a significantly improved HER catalytic activity,requiring overpotentials of 46.5,52.4,and 85.3 mV to reach a current density of 10 mA·cm^(−2)in 1 mol·L^(−1) KOH,0.5 mol·L^(−1) H_(2)SO_(4),and 1 mol·L^(−1) phosphate buffer solution(PBS)electrolytes,respectively.This proposed cation-doping strategy provides a new inspiration to rationally enhance or design new-type nonprecious metal-based,highly efficient,and pH-universal electrocatalysts for various energy conversion systems.展开更多
基金supported the National Key Research and Development Program of China(No.2024YFA1409900)the National Natural Science Foundation of China(Nos.62101296 and 52303335)+2 种基金the China Postdoctoral Science Foundation(Nos.2021M702656 and 2023M730099)the Natural Science Foundation of Shaanxi Province(Nos.2021JQ-756 and 2021M702656)the Graduate Innovation Fund of the School of Mechanical Engineering,Shaanxi University of Technology(No.SLGJX202404)。
文摘The Jahn-Teller effect of Mn^(3+)brings drastic structural changes to MnO_(2)-based materials and accelerates the destruction and deactivation of the internal structure of the materials,thus leading to severe capacity fading and phase change of MnO_(2)-based materials in aqueous zinc ion batteries(AZIBs).Here,this study doped high valent vanadium ions into MnO_(2)(VMO-x)to inhibit manganese's Jahn-Teller effect.Through a series of characterizations,such as X-ray diffraction(XRD),Raman spectroscopy,and scanning electron microscopy(SEM),it was discovered that the introduction of vanadium ions effectively increased the interlayer spacing of MnO_(2),facilitating the transport of ions into the interlayer.Additionally,Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS)demonstrated vanadium doped could effectively adjust the electronic structure,decreasing the average oxidation state of manganese,thereby inhibiting the Jahn-Teller effect and significantly enhancing the stability of the VMO-x cathode.The theoretical calculation showed that introducing vanadium ions enhanced the interaction between the main material and Zn^(2+),optimized its electron transport capacity,and led to better electrical conductivity and reaction kinetics of the VMO-5.Benefiting from this,the VMO-5 cathode exhibited an outstanding capacity of 283 mAh/g and maintained a capacity retention rate of 79%after 2000 cycles,demonstrating excellent electrochemical performance.Furthermore,the mechanism of H^(+)/Zn^(2+)co-intercalation/deintercalation was demonstrated through mechanism analysis.Finally,the test results of the pouch cell demonstrated the excellent flexibility and safety exhibited by the VMO-5 make it have great potential in flexible devices.This work presented a novel approach to doping high valence metal ions into manganese-based electrodes for AZIBs.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.21902123 and 22179074)the Natural Science Basic Research Program of Shaanxi(Program No.2023-JC-ZD-22).
文摘Designing low-cost and high-efficiency bifunctional electrocatalysts is one of the challenges in the clean production of hydrogen energy in electrochemical water splitting.Transition metal selenides(TMSes)have been widely studied because of their low price,intrinsic metal properties,and high catalytic ac-tivity.In addition,the synergistic effect between bimetallic selenides exhibits better performance than monometallic selenides in the electrocatalytic process.Herein,we synthesized V-doped NiSe2 nanowire arrays on pretreated nickel foam by a convenient two-step hydrothermal synthesis method.In the al-kaline electrolyte,V-NiSe_(2)/NF exhibited excellent OER catalytic activity(293.6 mV@50 mA cm^(-2)).In ad-dition,the introduction of heteroatom V induces stronger electronic interactions between the structural atoms of the catalyst,altering the electronic structure and causing V-NiSe_(2)/NF to demonstrate excellent OER performance.In the long-term OER test,V-NiSe_(2)/NF was converted into NiOOH and SeO_(x)^(2-),which may be the“real”active species during catalytic reactions,and we also successfully captured the for-mation of intermediate NiOOH and selenite as active centers in the OER process through in-situ Raman.The theoretical calculation shows that the electron transfer modulates the electron structure,changes the adsorption-desorption energy of the reaction intermediates,reduces the potential barrier of the rate-limiting step,and improves the OER activity.The V doping engineering strategy and the unique nanowire array structure make TMSes exhibit excellent OER performance.This study provides a new idea for the design of TMSe catalysts with excellent electrocatalytic performance.
基金Project supported by the National Science and Technology Committee of China and the National Natural Science Foundation of China.
文摘YBa2Cu3-xVxO7-y(x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductors have been prepared. X-ray diffraction shows that the system remains orthorhombic for all compositions studied, but for x > 0.4 V2O5 was detected as an impurity phase. Substitution of V5+ for Cu2+ occurs in the Cu(2) sites on the Cu(2)-O planes. The introduction of the high valence element, vanadium, produces the extra free-electrons. These electrons recombine with the positive carrier of the system. It makes depression of the mobility and the Hall number of YBa2Cu3-xVxO7-v and also results in a depression of TC.
文摘A model is presented to describe a compensation mechanism for semi-insulating 6H-SiC grown with the intentional doping of vanadium. Because we found nitrogen to be the principal shallow donor impurity in SiC by secondary ion mass spectroscopy （SIMS） measurements, semi-insulating properties in SiC are achieved by compensating the nitrogen donor with the vanadium deep acceptor level. The presence of different vanadium charge states V^3＋ and V^4＋ is detected by electron paramagnetic resonance and optical absorption measurements,which coincides with the results obtained by SIMS measurements. Both optical absorption and low temperature photoluminescence measurements reveal that the vanadium acceptor level is located at 0.62eV below the conduction band in 6H-SiC.
文摘Deep level transient Fourier spectroscopy （DLTFS） measurements are used to characterize the deep impurity levels in n-type 4H-SiC by vanadium ions implantation. Two acceptor levels of vanadium at Ec - 0.81 and Ec - 1.02eV with the electron capture cross section of 7.0 × 10^16 and 6.0 × 10^-16 cm^2 are observed, respectively. Low-temperature photoluminescence measurements in the range of 1.4-3.4eV are also performed on the sample, which reveals the formation of two electron traps at 0.80 and 1. 16eV below the conduction band. These traps indicate that vanadium doping leads to the formation of two deep acceptor levels in 4H-SiC,with the location of 0.8±0.01 and 1. 1 ±0.08eV below the conduction band.
基金Key Research and Development Program of Shanxi(Grant No.201803D421085)Shanxi Scholarship Council of China(Grant No.2019070)+1 种基金Shanxi Graduate Education Innovation Project(Grant No.2020BY095)State Key Laboratory of Physical Chemistry of Solid Surfaces,Xiamen University(Grant No.201912)。
文摘The exploration of cost-effective,high-performance,and stable electrocatalysts for the hydrogen evolution reaction(HER)over wide pH range(0–14)is of paramount importance for future renewable energy conversion technologies.Regulation of electronic structure through doping vanadium atoms is a feasible construction strategy to enhance catalytic activities,electron transfer capability,and stability of the HER electrode.Herein,V-doped NiCoP nanosheets on carbon fiber paper(CFP)(denoted as Vx-NiCoP/CFP)were constructed by doping V modulation on NiCoP nanosheets on CFP and used for pH-universal HER.Benefiting from the abundant catalytic sites and optimized hydrogen binding thermodynamics,the resultant V15-NiCoP/CFP demonstrates a significantly improved HER catalytic activity,requiring overpotentials of 46.5,52.4,and 85.3 mV to reach a current density of 10 mA·cm^(−2)in 1 mol·L^(−1) KOH,0.5 mol·L^(−1) H_(2)SO_(4),and 1 mol·L^(−1) phosphate buffer solution(PBS)electrolytes,respectively.This proposed cation-doping strategy provides a new inspiration to rationally enhance or design new-type nonprecious metal-based,highly efficient,and pH-universal electrocatalysts for various energy conversion systems.
