The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and ...The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and scanning electronic microscope, respectively. The as-synthesized CuO was assembled regularly from the nanosheets with thickness of 100 nm. The size of Au nanoparticles ranged from 50 to 200 nm. The hierarchical CuO gas sensors modified by different concentration of gold were fabricated. All the Au-loaded CuO gas sensors enhanced the response to ethanol and xylene while reducing the response to methanol, acetone, and formaldehyde. The results indicate that the Au nanoparticles prepared with PVP as surfactant can improve the selectivity of CuO gas sensors to ethanol gas for other common organic volatile gases. The improvement of gas sensing is mainly attributed to the different catalytic efficiency of the Au nanoparticles for different reactions. Meanwhile, the related mechanisms are discussed.展开更多
Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)...Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)3are fabricated by magnetron sputtering technology. We study the domain structure and switching field distribution in p-SAF by changing the thickness of the infrared space layer. The strongest exchange coupling field(Hex) is observed when the thickness of Ir layer(tIr) is 0.7 nm and becoming weak according to the Ruderman–Kittel–Kasuya–Yosida-type coupling at 1.05 nm,2.1 nm, 4.55 nm, and 4.9 nm in sequence. Furthermore, the domain switching process between the upper Co/Ni stack and the bottom Co/Ni stack is different because of the antiferromagnet coupling. Compared with ferromagnet coupling films, the antiferromagnet samples possess three irreversible reversal regions in the first-order reversal curve distribution.With tIrincreasing, these irreversible reversal regions become denser and smaller. The results from this study will help us understand the details of the magnetization reversal process in the p-SAF.展开更多
The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still ...The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still the most main issue.Defect engineering has become an effective method to improve cycle stability.Herein,a nitrogen-doped ε-MnO_(2)(MnO_(2)@N)has been prepared using electrochemical deposition and heat treatment under nitrogen atmosphere.As the cathode for zinc-ion batteries,the capacity retention rate of MnO_(2)@N cathode is close to 100%after 500 cycles at 0.5 A g^(-1),while the capacity retention rate for the initial MnO_(2) cathode is 62%.At 5 A g^(-1),the capacity retention rate of MnO_(2)@N cathode is 83%after 1000 cycles,which is much higher than the 27%capacity retention rate for the original MnO_(2) cathode.And it can be found that the oxygen vacancies increase after nitrogen doping,which can improve the conductivity of the MnO_(2)@N cathode.Also,there is Mn-N bond in MnO_(2)@N,which can enhance the electrochemical stability of MnO_(2)@N cathode.In addition,the electrochemical mechanism of MnO_(2)@N cathode has been explored by the CV,GCD and GITT tests.It is found that nitrogen doping promotes the intercalation of H^(+) and the corresponding capacity contribution.Compared with the original MnO_(2) cathode,the diffusion coefficient of H^(+) and Zn^(2+) in MnO_(2)@N cathode increases.Also,the reactions during the charging and discharging process are explored through the ex-situ XRD test.And this work may provide some new ideas for improving the stability of manganese-based zinc-ion batteries.展开更多
In this paper, the self-compliance bipolar resistive switching characteristic of an HfO-based memory device with Ag/HfO/Au structure for multilevel storage is investigated. By applying a positive voltage, the dual-ste...In this paper, the self-compliance bipolar resistive switching characteristic of an HfO-based memory device with Ag/HfO/Au structure for multilevel storage is investigated. By applying a positive voltage, the dual-step set processes corresponding to three stable resistance states are observed in the device. The multilevel switching characteristics can still be observed after 48 hours. In addition, the resistance values of all the three states show negligible degradation over 104 s,which may be useful for the applications in nonvolatile multilevel storage.展开更多
A series of a-Si：H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition （HW-MWECR-CVD）, subsequently exposed under simulated illumination for three hours. This p...A series of a-Si：H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition （HW-MWECR-CVD）, subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared （FTIR） spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.展开更多
Nowadays,it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe,efficient and simple method.And these characteristics are usually related...Nowadays,it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe,efficient and simple method.And these characteristics are usually related to the vacancies and impurities in the electrode.To investigate the effect of the vacancies on the electrochemical properties of the supercapacitor cathode material,the uniform reduced CoNi2S4(r-CoNi2S4)nanosheets with sulfur vacancies have been successfully prepared by a one-step hydrothermal method.And the formation of sulfur vacancies are characterized by Raman,X-ray photoelectron spectroscopy and other means.As the electrode for supercapacitor,the r-CoNi2S4 nanosheet electrode delivers a high capacity of 1918.9 Fg-1 at a current density of 1 A g-1,superior rate capability(87.9%retention at a current density of 20 A g-1)and extraordinary cycling stability.Compared with the original CoNi2S4 nanosheet electrode(1226 F g-1at current density of 1 A g-1),the r-CoNi2S4 nanosheet electrode shows a great improvement.The asymmetric supercapacitor based on the r-CoNi2S4 positive electrode and activated carbon negative electrode exhibits a high energy density of 30.3 Wh kg-1 at a power density of 802.1 W kg-1,as well as excellent long-term cycling stability.The feasibility and great potential of the device in practical applications have been successfully proved by lightening the light emitting diodes of three different colors.展开更多
基金Project supported by the Provincial Natural Science Foundation of Gansu (No. 1606RJZA026)the Scientific and Technological Project of Chengguan District of Lanzhou (No. 2016-2-4)Institute of Sensor Technology, Gansu Academy of Science
文摘The three-dimensional hierarchical CuO and Au nanoparticles were synthesized by the hydrothermal method, respectively. The hierarchical CuO and the Au nanoparticles samples were characterized by X-ray diffraction and scanning electronic microscope, respectively. The as-synthesized CuO was assembled regularly from the nanosheets with thickness of 100 nm. The size of Au nanoparticles ranged from 50 to 200 nm. The hierarchical CuO gas sensors modified by different concentration of gold were fabricated. All the Au-loaded CuO gas sensors enhanced the response to ethanol and xylene while reducing the response to methanol, acetone, and formaldehyde. The results indicate that the Au nanoparticles prepared with PVP as surfactant can improve the selectivity of CuO gas sensors to ethanol gas for other common organic volatile gases. The improvement of gas sensing is mainly attributed to the different catalytic efficiency of the Au nanoparticles for different reactions. Meanwhile, the related mechanisms are discussed.
基金Project supported by the Natural Science Foundation of Gansu Province, China (Grant No. 22JR5RA775)the Science and Technology Program of Lanzhou, China (Grant No. 2021-1-157)+2 种基金the Guangdong Basic and Applied Basic Research Foundation, China (Grant Nos. 2020A1515110998 and 2022A1515012123)the Outstanding Youth Foundation of Gansu Academy of Science, China (Grant No. 2021YQ01)the Innovative Team Construction Project of Gansu Academy of Sciences, China (Grant No. 2020CX005-01)。
文摘Perpendicular synthetic-antiferromagnet(p-SAF) has broad applications in spin-transfer-torque magnetic random access memory and magnetic sensors. In this study, the p-SAF films consisting of (Co/Ni)3]/Ir(tIr)/[(Ni/Co)3are fabricated by magnetron sputtering technology. We study the domain structure and switching field distribution in p-SAF by changing the thickness of the infrared space layer. The strongest exchange coupling field(Hex) is observed when the thickness of Ir layer(tIr) is 0.7 nm and becoming weak according to the Ruderman–Kittel–Kasuya–Yosida-type coupling at 1.05 nm,2.1 nm, 4.55 nm, and 4.9 nm in sequence. Furthermore, the domain switching process between the upper Co/Ni stack and the bottom Co/Ni stack is different because of the antiferromagnet coupling. Compared with ferromagnet coupling films, the antiferromagnet samples possess three irreversible reversal regions in the first-order reversal curve distribution.With tIrincreasing, these irreversible reversal regions become denser and smaller. The results from this study will help us understand the details of the magnetization reversal process in the p-SAF.
基金financially supported by the National Natural Science Foundation of China (No. 61376011, 51402141, 61604086, 11975114)the Gansu Provincial Natural Science Foundation of China (No. 17JR5RA198)+1 种基金the Fundamental Research Funds for the Central Universities (No. lzujbky-2018-119, lzujbky-2018-ct08, lzujbky-2019-it23)the Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps (No. 2018AB004).
文摘The research and exploration of manganese-based aqueous zinc-ion batteries have been controversial of cycle stability and mechanism investigation,thus improving the stability and exploring storage mechanism are still the most main issue.Defect engineering has become an effective method to improve cycle stability.Herein,a nitrogen-doped ε-MnO_(2)(MnO_(2)@N)has been prepared using electrochemical deposition and heat treatment under nitrogen atmosphere.As the cathode for zinc-ion batteries,the capacity retention rate of MnO_(2)@N cathode is close to 100%after 500 cycles at 0.5 A g^(-1),while the capacity retention rate for the initial MnO_(2) cathode is 62%.At 5 A g^(-1),the capacity retention rate of MnO_(2)@N cathode is 83%after 1000 cycles,which is much higher than the 27%capacity retention rate for the original MnO_(2) cathode.And it can be found that the oxygen vacancies increase after nitrogen doping,which can improve the conductivity of the MnO_(2)@N cathode.Also,there is Mn-N bond in MnO_(2)@N,which can enhance the electrochemical stability of MnO_(2)@N cathode.In addition,the electrochemical mechanism of MnO_(2)@N cathode has been explored by the CV,GCD and GITT tests.It is found that nitrogen doping promotes the intercalation of H^(+) and the corresponding capacity contribution.Compared with the original MnO_(2) cathode,the diffusion coefficient of H^(+) and Zn^(2+) in MnO_(2)@N cathode increases.Also,the reactions during the charging and discharging process are explored through the ex-situ XRD test.And this work may provide some new ideas for improving the stability of manganese-based zinc-ion batteries.
基金supported by the National Natural Science Foundation of China(Grant Nos.61664001,61574070,and 61306148)the Application Research and Development Plan of Gansu Academy of Sciences,China(Grant Nos.2015JK-11 and 2015JK-01)
文摘In this paper, the self-compliance bipolar resistive switching characteristic of an HfO-based memory device with Ag/HfO/Au structure for multilevel storage is investigated. By applying a positive voltage, the dual-step set processes corresponding to three stable resistance states are observed in the device. The multilevel switching characteristics can still be observed after 48 hours. In addition, the resistance values of all the three states show negligible degradation over 104 s,which may be useful for the applications in nonvolatile multilevel storage.
文摘A series of a-Si：H films are deposited by hot wire assisted microwave electron cyclotron resonant chemical vapour deposition （HW-MWECR-CVD）, subsequently exposed under simulated illumination for three hours. This paper studies the microstructure change during illumination by Fourier Transformation Infrared （FTIR） spectra. There are two typical transformation tendencies of microstructure after illumination. It proposes a model of light induced structural change based on the experimental results. It is found that all samples follow the same mechanism during illumination, and intrinsic structure of samples affect the total H content.
基金supported by the National Natural Science Foundation of China(61376011 and 51402141)Gansu Provincial Natural Science Foundation(17JR5RA198)+1 种基金the Fundamental Research Funds for the Central Universities(lzujbky-2018-119 and lzujbky-2018-ct08)Shenzhen Science and Technology Innovation Committee(JCYJ20170818155813437)。
文摘Nowadays,it is a matter of great concern to design electrode materials with excellent electrochemical performance for supercapacitors by a safe,efficient and simple method.And these characteristics are usually related to the vacancies and impurities in the electrode.To investigate the effect of the vacancies on the electrochemical properties of the supercapacitor cathode material,the uniform reduced CoNi2S4(r-CoNi2S4)nanosheets with sulfur vacancies have been successfully prepared by a one-step hydrothermal method.And the formation of sulfur vacancies are characterized by Raman,X-ray photoelectron spectroscopy and other means.As the electrode for supercapacitor,the r-CoNi2S4 nanosheet electrode delivers a high capacity of 1918.9 Fg-1 at a current density of 1 A g-1,superior rate capability(87.9%retention at a current density of 20 A g-1)and extraordinary cycling stability.Compared with the original CoNi2S4 nanosheet electrode(1226 F g-1at current density of 1 A g-1),the r-CoNi2S4 nanosheet electrode shows a great improvement.The asymmetric supercapacitor based on the r-CoNi2S4 positive electrode and activated carbon negative electrode exhibits a high energy density of 30.3 Wh kg-1 at a power density of 802.1 W kg-1,as well as excellent long-term cycling stability.The feasibility and great potential of the device in practical applications have been successfully proved by lightening the light emitting diodes of three different colors.
