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Power loss transition of stable ZnO varistor ceramics: Role of oxygen adsorption on the stability of interface states at the grain boundary

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Journal of Advanced Ceramics 2023年第5期12卷 972-983页

作者： Zhuolin Cheng Rou Li Yiwei Long Jianying Li Shengtao Li Kangning Wu State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049China Department of Thermal and Fluid Engineering University of TwenteEnschede 7500AEthe Netherlands

Highly stable ZnO varistor ceramics with steadily decreasing power loss have been put into applications in electrical and electronic systems for overvoltage protections, even with the absence of general understandings on their aging behaviors. In this paper, we investigated their aging nature via conducting comparative direct current (DC) aging experiments both in air and in nitrogen, during which variations of electrical properties and interface properties were measured and analyzed. Notably, continuously increasing power loss with severe electrical degradation was observed for the sample aged in nitrogen. The power loss transition was discovered to be closely related to the consumption of oxygen adsorption at the grain boundary (GB), which could, however, remain constant for the sample aged in air. The interface density of states (DOS) Ni, which is crucial for pinning the potential barrier, was proved to decrease in nitrogen, but keep stable in air. Therefore, it is concluded that the oxygen adsorption at the GB is significant for the stability of interface states, which further correlates to the long-term stability of modern stable ZnO varistor ceramics.

关键词： ZnO varistor ceramics aging power loss oxygen adsorption interface states

Clarification of the oxygen adsorption properties of YBaCo_4O_7 at high temperature by thermogravimetry

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Journal of Rare Earths 2010年第1期28卷 84-87页

作者：朱保峰郝好山张勇贾建峰胡行 School of Physical Engineering and Material Physics Laboratory Zhengzhou University The 49th Research Institute of China Electronics Technology Group Corporation Department of Mathematical and Physical Sciences Henan Institute of Engineering

The oxygen adsorption/desorption properties of YBaCo4O7 at high temperature were investigated by thermogravimetry(TG) method,in which two types of oxygen adsorption were *** first type adsorbed oxygen at about 700 °C and released the adsorbed oxygen at 880 °*** the first type oxygen desorption,even the temperature and oxygen flow were kept the same,a second type oxygen adsorption at about 880 °C occurred and the adsorbed oxygen were released at above 980 °*** combination of these two types of...

关键词： YBaCo4O7 oxygen adsorption thermogravimetry rare earths

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Grain boundary-induced drastic sensing performance enhancement of Fe2O3 gas sensors for acetone

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Rare Metals 2024年第9期43卷 4412-4424页

作者： Tian-Jun Hu Yi-Fan Li Yu-Zhu Tian Ying Wang Ya-Ru Chen Jun-Ming Zhang Er-Gui Luo Jian-Feng Jia Key Laboratory of Magnetic Molecules & Magnetic Information Materials Ministry of Education School of Chemical and Material ScienceShanxi Normal University

Exploring the structure-activity relationship between the performance of gas sensors and the structure of semiconductor metal oxide （SMO） nanomaterials is crucial for understanding and designing gas-sensing materials and overcoming the application limitations of SMO-based gas *** of a single SMO microstructure provides a promising solution to address this scientific problem due to its controllable *** this study,we control the grain boundary （GB） density of Fe2O3nanomaterials using a simple solvothermal *** have similar chemical compositions and crystal phases,providing an ideal platform for studying the influence of the GB density on the gas-sensing ***-sensing tests showed that the Fe2O3-1 sensor with medium GB density and the Fe2O3-2 sensor with high GB density had higher sensitivity and selectivity than the Fe2O3-0 sensors with low GB density before reaching the optimal operating ***,when the GB density increased,the response to acetone decreased slightly,whereas the optimal operating temperature *** work highlights the unique performance of the GB density in enhancing the gas sensitivity of a single SMO.

关键词： Charge transfer Gas sensors Grain boundary (GB) density oxygen adsorption Semiconductor metal oxide (SMO)

Coordinatively unsaturated cobalt single-atom nanozymes for visual pesticides detection by smartphone-based platform

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Nano Research 2024年第4期17卷 2298-2307页

作者： Fangning Liu Zhe Li Hengya Wei Peng Xu Ge Kang Shicheng Zhu Tingting Wang Ruxue He Chuanxia Chen Yizhong Lu School of Materials Science and Engineering University of JinanJinan 250022China

By adjusting the coordination environment of single-atom catalysts,the enzyme-like activity can be finely tuned for highly sensitive ***,we demonstrated that coordinatively unsaturated cobalt-nitrogen sites doped within porous carbon(SA-CoN_(3))could serve as highly efficient oxidase *** with the typical planar four-coordination structure(SA-CoN_(4)),the as-obtained single-atom Co nanozymes anchored by three nitrogen atoms are found to display much higher oxidase-like catalytic *** theoretical and experimental analysis revealed that the coordinatively unsaturated Co sites could facilitate adsorption and activation of O_(2) molecule and thus improve their oxidase-like *** on the enhanced oxidase-like activity of SA-CoN_(3),a paper/smartphone sensor for organophosphorus pesticides(OPs)was successfully constructed and used to quantify glyphosate in environmental and food samples with a low detection limit of 0.66μ*** work not only highlights the important role of coordination unsaturation of SA nanozymes for promoting oxidase-like activity,but also provides an easy and cost-effective way to conduct effective quantification of OPs in the field.

关键词： single-atom nanozymes asymmetric organophosphorus pesticides oxygen adsorption smartphone

UV illumination enhanced desorption of oxygen molecules from monolayer MoS2 surface

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Nano Research 2020年第2期13卷 358-365页

作者： Yuhang Wang Zhiquan He Jinbing Zhang Hao Liu Xubo Lai Boyang Liu Yibao Chen Fengping Wang Liuwan Zhang Department of Applied Plhysics School ofMathematics and PhysicsUniversity of Science and Techmology BejingBeijing 10083China State Key Laboratory of Low-Dimensional Quantum Physics Collaborative Innovation Center of Quantum MatterDepartment of PhysicsTsinghua UniversityBeijing 100084China

The oxygen adsorption can drastically alter the electronic properties of the two-dimensional(2D)materials,which is usually dificult to be *** this work,we report the ultraviolet(UV)ilumination induced desorption of the O2 molecules from the monolayer MoS2 surface by using the atmosphere dependent transport measurement,Kelvin probe microscopy,photoluminescence spectroscopy and X-ray photoelectron *** increasing of the conductivity,rising of the Fermi level,and red shift of the photoluminescence peaks of the MoS2 were observed after the UV ilumination in vacuum,indicating the elimination of the depletion effect from the oxygen *** parameter changes can be reversibly recovered by the subsequent O2 ***,obvious decreasing of the oxygen concentration after the UV ilumination was also observed by X-ray photoelectron *** the UV induced O2 photodesorption effect is *** photo-excited charge transfer mechanism is proposed to account for the photodesorption *** results provide a nondestructive way to clean the MoS2 surface and manipulate the performance of the MoS2 based devices.

关键词： MoS2 desorption ultraviolet(UV)ilumination oxygen adsorption carrier density

Multivalent manganese oxides with high electrocatalytic activity for oxygen reduction reaction

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Frontiers of Chemical Science and Engineering 2018年第4期12卷 790-797页

作者： Xiangfeng Peng Zhenhai Wang Zhao Wang Yunxiang Pan School of Chemical Engineering and Technology State Key Laboratory of Chemical EngineeringTianjin UniversityTianjin 300350China School of Chemistry and Chemical Engineering Hefei University of TechnologyHefei 230009China

A noble-metal-free catalyst based on both Mn O and MnO was prepared by using the dielectric barrier discharge technique at moderate temperature. The prepared catalyst shows a higher electrocatalytic activity towards the oxygen reduction reaction than the catalyst prepared by using the traditional calcination process. The enhanced activity could be due to the coexistence of manganese ions with different valences, the higher oxygen adsorption capacity, and the suppressed aggregation of the catalyst nanoparticles at moderate temperature. The present work would open a new way to prepare low-cost and noble-metal-free catalysts at moderate temperature for more efficient electrocatalysis.

关键词： oxygen reduction reaction manganese oxides mixed valences of manganese oxygen adsorption dielectric barrier discharge

First-principles investigation of structural and electronic properties of oxygen adsorbing phosphorene

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Progress in Natural Science:Materials International 2019年第3期29卷 316-321页

作者： Zhiqiang Wang Dianlong Zhao Shidong Yu Zikai Nie Yuwei Li Lijun Zhang Key Laboratory of Automobile Materials of MOE and School of Materials Science and Engineering Jilin University North China Institute of Aerospace Engineering

Two-dimensional （2D） phosphorene has been extensively studied for potential electronic and optoelectronic *** is easily oxidized by adsorbing oxygen in the air,exhibiting changed materials stability and *** the impact of oxygen concentrations on stability and electronic properties of oxygen adsorbing phosphorene has never been systematically *** this article,the oxygen adsorbing phosphorene at different oxygen concentrations are studied via first-principles crystal structure *** considered stoichiometries of P;O,P;O;) P;O and P;O;with both single-side and dual-side adsorption for selected case P;*** energetically stable structure of each stoichiometry is *** has been found that the band gaps show rather wide range change,strongly depending on the oxygen ***,at the higher oxygen concentration the relatively low band gaps and small carrier effective masses emerge,comparable with the pristine black *** may be associated with the appearance of bridged P-O-P bonds as oxygen concentration *** electronic properties are discussed in relation to structural features and chemical bonding.

关键词： Phosphorene oxygen adsorption Electronic structures First-principles calculations

High-resolution angle-resolved photoemission study of oxygen adsorbed Fe/MgO(001)

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Chinese Physics B 2020年第6期29卷 60-68页

作者： Mingtian Zheng Eike FSchwier Hideaki Iwasawa Kenya Shimada Graduate School of Science Hiroshima UniversityKagamiyama 1-3-1Higashi-Hiroshima 739-8526Japan Hiroshima Synchrotron Radiation Center Hiroshima UniversityKagamiyama 2-313Higashi-Hiroshima 739-0046Japan

We have investigated the electronic states of clean Fe(001) and oxygen adsorbed Fe(001)–p(1 × 1)-O films epitaxially grown on MgO(001) substrates by means of polarization-dependent angle-resolved photoemission spectroscopy(ARPES)and extensive density-functional theory(DFT) calculations. The observed Fermi surfaces and band dispersions of pure Fe near the Fermi level were modified upon oxygen adsorption. By the detailed comparison of ARPES and DFT results of the oxygen adsorbed Fe surface, we have clarified the orbital-dependent p–d hybridization in the topmost and second Fe ***, the observed energy levels and Fermi wave numbers for the oxygen adsorbed Fe surface were deviated from the DFT calculations depending on the orbital characters and momentum directions, indicating an anisotropic interplay of the electron correlation and p–d hybridization effects in the surface region.

关键词： angle-resolved photoemission iron surface oxygen adsorption density-functional theory(DFT)

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Light-switchable catalytic activity of Cu for oxygen reduction reaction

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Frontiers of Materials Science 2020年第4期14卷 481-487页

作者： Yue ZHANG Yihong YU Xiankai FU Zhisen LIU Yinglei LIU Song LI Key Lab for Anisotropy and Texture of Materials(MOE) School of Materials Science and EngineeringNortheasterm UniversityShenyang 110819China Liaoning Academy of Analytical Sciences Shenyang 110015China Research Center for Metallic Wires Northeasterm UniversityShenyang 110819China

The surface reactivity of metals is fundamentally dependent on the local electronic structure generally tailored by atomic compositions and configurations during the ***,we demonstrate that Cu,which is inert for oxygen reduction reaction(ORR)due to the fully occupied d-orbital,could be activated by applying a visible-light irradiation at ambient *** ORR current is increased to 3.3 times higher in the potential range between-0.1 and 0.4 V under the light of 400 mW·cm^-2,and the activity enhancement is proportional to the light *** with the help of the first-principle calculation,the remarkably enhanced electrocatalytic activity is expected to stem mainly from the decreased metal-adsorbate binding by *** finding provides an additional degree of freedom for controlling and manipulating the surface reactivity of metal catalysts besides materials strategy.

关键词： photochemistry surface reactivity oxygen adsorption copper