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Engineering hierarchical quaternary superstructure of an integrated MOF-derived electrode for boosting urea electrooxidation assisted water electrolysis

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Green Energy & Environment 2024年第4期9卷 695-701页

作者： jianjun tian Changsheng Cao Yingchun He Muhammad Imran Khan Xin-Tao Wu Qi-Long Zhu State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences(CAS)Fuzhou350002China Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou350108China University of Chinese Academy of Sciences Beijing100049China Research Institute of Sciences and Engineering(RISE) University of SharjahSharjah27272United Arab Emirates

Controllable design of the catalytic electrodes with hierarchical superstructures is expected to improve their electrochemical ***,a self-supported integrated electrode(NiCo-ZLDH/NF)with a unique hierarchical quaternary superstructure was fabricated through a self-sacrificing template strategy from the metal–organic framework(Co-ZIF-67)nanoplate arrays,which features an intriguing well-defined hierarchy when taking the unit cells of the NiCo-based layered double hydroxide(NiCo-LDH)as the primary structure,the ultrathin LDH nanoneedles as the secondary structure,the mesoscale hollow plates of the LDH nanoneedle arrays as the tertiary structure,and the macroscale three-dimensional frames of the plate arrays as the quaternary ***,the distinctive structure of NiCo-ZLDH/NF can not only accelerate both mass and charge transfer,but also expose plentiful accessible active sites with high intrinsic activity,endowing it with an excellent electrochemical performance for urea oxidation reaction(UOR).Specially,it only required the low potentials of 1.335,1.368 and 1.388 V to deliver the current densities of 10,100 and 200 mA cm^(-2),respectively,much superior to those for typical *** NiCo-ZLDH/NF as the bifunctional electrode for both anodic UOR and cathodic HER,an energy-saving electrolysis system was further explored which can greatly reduce the needed voltage of 213 mV to deliver the current density of 100 mA cm^(-2),as compared to the conventional water electrolysis system composed of *** work manifests that it is prospective to explore the hierarchically nanostructured electrodes and the innovative electrolytic technologies for high-efficiency electrocatalysis.

关键词： Hierarchical superstructures Metal–organic frameworks Layered double hydroxides Urea oxidation reaction Hydrogen evolution reaction

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Enhanced ferroelectric and improved leakage of BFO-based thin films through increasing entropy strategy

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2263-2273页

作者： Dongfei Lu Guoqiang Xi Hangren Li Jie Tu Xiuqiao Liu Xudong Liu jianjun tian Linxing Zhang Institute for Advanced Materials Technology University of Science and Technology Beijing

BiFeO3（BFO） has received considerable attention as a lead-free ferroelectric film due to its large theoretical remnant polarization. However, BFO suffers from a large leakage current, resulting in poor ferroelectric properties. Herein, the sol–gel method was used to deposit a series of BFO-based thin films on fluorine-doped tin oxide substrates, and the effects of the substitution of the elements Co, Cu,Mn（B-site） and Sm, Eu, La（A-site） on the crystal structure, ferroelectricity, and leakage current of the BFO-based thin films were investigated. Results confirmed that lattice distortion by X-ray diffraction can be attributed to the substitution of individual elements in the BFObased films. Sm and Eu substitutions contribute to the lattice distortion in a pseudo-cubic structure, while La is biased toward pseudo-tetragonal. Piezoelectric force microscopy confirmed that reversible switching of ferroelectric domains by nearly 180° can be realized through the prepared films. The ferroelectric hysteresis loops showed that the order for the polarization contribution is as follows: Cu >Co > Mn（B-site）, Sm > La > Eu（A-site）. The current density voltage curves indicated that the order for leakage contribution is as follows:Mn < Cu < Co（B-site）, La < Eu < Sm（A-site）. Scanning electron microscopy showed that the introduction of Cu elements facilitates the formation of dense grains, and the grain size distribution statistics proved that La element promotes the reduction of grain size, leading to the increase of grain boundaries and the reduction of leakage. Finally, a Bi0.985Sm0.045La0.03Fe0.96Co0.02Cu0.02O3（SmLa-CoCu） thin film with a qualitative leap in the remnant polarization from 25.5(Bi0.985Sm0.075FeO3) to 98.8 μC/cm2（SmLa-CoCu） was prepared through the synergistic action of Sm, La, Co, and Cu elements. The leakage current is also drastically reduced from 160 to 8.4 mA/cm2at a field strength of150 kV/cm. Thus, based on the increasing entropy strategy of chemical engineerin

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Controlled crystal orientation of two-dimensional Ruddlesden-Popper halide perovskite films for solar cells

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International Journal of Minerals,Metallurgy and Materials 2022年第1期29卷 49-58页

作者： Jiuyao Du Mengqi Zhang jianjun tian Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China

Metal halide perovskite solar cells have attracted considerable attention because of their high-power conversion efficiency and costeffective solution-processable fabrication;however,they exhibit poor structural ***-dimensional(2D)Ruddlesden-Popper(RP)perovskites could address the aforementioned issue and present excellent stability because of their hydrophobic organic spacer ***,the crystallographic orientation of 2D crystals should be perpendicular to the bottom substrates for charges to transport fast and be collected in solar ***,controlling the crystallographic orientation of the 2D RP perovskites prepared by the solution process is ***,we reviewed the progress of recent research regarding 2D RP perovskite films with the focus on the crystallographic orientation mechanism and orientation controlling ***,the current issues and prospects of 2D RP perovskites in the photovoltaic field were discussed to elucidate their development and application in the future.

关键词： two-dimensional Ruddlesden-Popper crystallographic orientation perovskite solar cells

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Efficient solution-processed InP quantum-dots light-emitting diodes enabled by suppressing hole injection loss

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Nano Research 2023年第5期16卷 7511-7517页

作者： Wenxuan Du Chunyan Cheng jianjun tian Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China

Solution-processed cadmium-based quantum dots(QDs)light-emitting diodes(QLEDs)have shown promising for high-definition display panels due to their high colour purity and low-cost fabrication,but the toxicity still is a big *** is considered as the most promising cadmium-free material to achieve high performance QLEDs,however,the performance of the InP-based QLEDs is far behind of the cadmium-based ***,we report high efficiency InP-based QLEDs with more than 20%of external quantum efficiency(EQE)by suppressing hole injection *** suppression is achieved by doping a strong Lewis acid into a Lewis base poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)to form a Lewis acid-base adduct hole-transport layer(HTL),which improves the hole mobility of the HTL,reduces the hole transfer barrier between HTL and QDs layer to increase hole transport *** eventually leads to a more balanced carrier-injection through accelerating hole-injection to match well with the rate of electron-injection,thus suppressing the hole injection loss in the *** InP-based QLED shows EQE of 20.4%,current efficiency of 25.3 cd·A^(−1),turn-on voltage of 2.0 V,luminance of 24,000 cd·m^(−2).This strategy would be a constructive approach to reduce hole loss for p-n junction optoelectronics.

关键词： InP quantum dot light-emitting diode hole-transport layer high efficiency

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CuInSe_(2)/CuInS_(2)Ⅱ型核壳结构量子点的构建及高效光电化学电池

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Science China Materials 2024年第1期67卷 134-142页

作者：黄征孟杰黄菲余彬彬王俊峰杨浴民宁甲甲郑凯波田建军 Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Chemical Physics and Nano Lund University22100LundSweden College of Physics Jilin UniversityChangchun 130012China

环保型CuInSe_(2)量子点具有高消光系数和宽光谱吸收范围,在光电化学催化应用中展现了良好的发展前景.然而,CuInSe_(2)量子点较低的载流子分离能力和严重的界面电荷复合降低了其光电化学性能,制约了其应用.因此,我们设计并合成了具有Ⅱ... 详细信息

环保型CuInSe_(2)量子点具有高消光系数和宽光谱吸收范围,在光电化学催化应用中展现了良好的发展前景.然而,CuInSe_(2)量子点较低的载流子分离能力和严重的界面电荷复合降低了其光电化学性能,制约了其应用.因此,我们设计并合成了具有Ⅱ型能带排列的CuInSe_(2)/CuInS_(2)核/壳结构量子点,以促进载流子分离、减少界面缺陷;进一步通过调节In/Cu前驱体的摩尔比,产生铜空位.光物理性质研究表明,导带电子-铜空位捕获的空穴之间的辐射复合成为主要的复合方式,有效延长了载流子寿命,促进了载流子分离.因此,基于富铜空位的CuInSe_(2)/CuInS_(2)核壳量子点的光阳极获得了~8.0 mA cm^(-2)的最大饱和光电流密度,该性能是当前报道的CISe基量子点光电化学电池中的最高值之一.本工作提供了一种通过表面或内在缺陷的调控来促进光电化学应用中的电荷载流子分离和传输的有效方法.

关键词：载流子寿命电荷载流子辐射复合光电化学电池量子点消光系数复合方式光物理性质

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高导热氮化硅陶瓷用烧结助剂的研究进展

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粉末冶金技术 2024年第1期42卷 1-13页

作者：王月隆吴昊阳贾宝瑞张一铭张智睿刘昶田建军秦明礼北京科技大学新材料技术研究院北京100083

氮化硅被认为是综合性能最好的陶瓷材料,良好的导热性和优异的力学性能使其成为大功率电子器件用陶瓷基板的主流材料,在纯电动/混合电动汽车中得到广泛应用。烧结助剂对氮化硅烧结活性、微观组织和第二相成分及含量影响较大,进而影响陶... 详细信息

氮化硅被认为是综合性能最好的陶瓷材料,良好的导热性和优异的力学性能使其成为大功率电子器件用陶瓷基板的主流材料,在纯电动/混合电动汽车中得到广泛应用。烧结助剂对氮化硅烧结活性、微观组织和第二相成分及含量影响较大,进而影响陶瓷导热性能,选择合适的烧结助剂对制备高导热氮化硅陶瓷非常重要。本文整理了目前制备高导热氮化硅陶瓷用烧结助剂研究现状,分析了烧结助剂对氮化硅陶瓷导热性及力学性能的影响,并对烧结助剂未来的研究方向和发展趋势提出了展望。

关键词：氮化硅陶瓷烧结助剂导热性力学性能

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选区激光熔化金属增材制造综合实验教学

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中国冶金教育 2024年第4期 52-55,59页

作者：刘婷婷章林张百成陈刚田建军北京科技大学材料国家级实验教学示范中心北京100083 新材料技术研究院北京100083

为满足金属增材制造技术快速发展对于高层次应用型人才的迫切需求,根据选区激光熔化工艺流程特点,设计并开发出金属增材制造综合实验。配合数据处理至零件成形的整个工艺过程,进行规范化金属增材制造全流程实验教学,旨在加深对于金属增... 详细信息

为满足金属增材制造技术快速发展对于高层次应用型人才的迫切需求,根据选区激光熔化工艺流程特点,设计并开发出金属增材制造综合实验。配合数据处理至零件成形的整个工艺过程,进行规范化金属增材制造全流程实验教学,旨在加深对于金属增材制造技术的全面认识和理解,发挥学生的主观能动性。依据已经发布的国家标准,制定了实用的选区激光熔化实验标准化流程及操作规范,不仅是保证实验教学质量和可靠性的基础,也为学生树立标准化科研意识及增材制造创新应用型高端人才培养提供有力保障。

关键词：金属增材制造选区激光熔化实验教学国家标准

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Effects of oxygen and carbon on the magnetic properties and microstructure of Sm_2Co_(17) permanent magnets

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Rare Metals 2007年第4期26卷 299-304页

作者： tian jianjun ZHANG Shengen QU Xuanhui School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The research on the sintered Sm2Co17 permanent magnets prepared by metal injection molding is still at the exploratory stage. Carbon and oxygen are two key factors that influence the magnetic properties. In this article, the effects of oxygen and carbon on the properties and microstructure of the magnets have been studied. The results indicate that oxygen consumes the effective Sm content of the magnets and forms Sm2O3-the non-magnetism phase, which result in the deterioration of the magnetic properties. Besides, the magnetic properties decrease in evidence with increasing carbon content. The main factor that affects the magnetic properties is the deterioration of the microstructure of the magnets. The Sm（Co, Cu）5 phase decreases, whereas the cell size increases with the increase of the carbon content. When the carbon content is above 0.43 wt.%, the Sm（Co, Cu）5 phase is not enough to form a uniform cellular microstructure. Thus the magnetic properties disappear. ZrC is detected in the magnets by XRD when the carbon content is above 0.21 wt.%. ZrC also reduces the properties of the magnets.

关键词： permanent magnets oxygen carbon magnetic properties microstructure

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Flow field, sedimentation, and erosion characteristics around folded linear HDPE sheet sand fence: Numerical simulation study

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Journal of Mountain Science 2024年第1期21卷 113-130页

作者： ZHANG Kai ZHANG Hailong tian Jianjin QU jianjun ZHANG Xingxin WANG Zhenghui XIAO jianhua College of Civil Engineering Lanzhou Jiaotong UniversityLanzhou 730000China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Wind and sand hazards are serious in the Milan Gobi area of the Xinjiang section of the Korla Railway. In order to ensure the safe operation of railroads, there is a need for wind and sand protection in heavily sandy areas. The wind and sand flow in the region is notably bi-directional. To shield railroads from sand, a unique sand fence made of folded linear high-density polyethylene(HDPE) is used, aligning with the principle that the dominant wind direction is perpendicular to the fence. This study employed field observations and numerical simulations to investigate the effectiveness of these HDPE sand fences in altering flow field distribution and offering protection. It also explored how these fences affect the deposition and erosion of sand particles. Findings revealed a significant reduction in wind speed near the fence corner;the minimum horizontal wind speed on the leeward side of the first sand fence(LSF) decreased dramatically from 3 m/s to 0.64 m/s. The vortex area on the LSF markedly impacted horizontal wind speeds. Within the LSF, sand deposition was a primary occurrence. As wind speeds increased, the deposition zone shrank, whereas the positive erosion zone expanded. Close to the folded corners of the HDPE sand fence, there was a notable shift from the positive erosion zone to a deposition zone. Field tests and numerical simulations confirmed the high windproof efficiency(WE) and sand resistance efficiency(SE) in the HDPE sand fence. Folded linear HDPE sheet sand fence can effectively slow down the incoming flow and reduce the sand content, thus achieving good wind and sand protection. This study provides essential theoretical guidance for the design and improvement of wind and sand protection systems in railroad engineering.

关键词： Folded linear HDPE sheet sand fence Numerical simulation Flow field characteristics Protection benefits

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All-inorganic perovskite solar cells with efficiency>20%

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Science China Materials 2021年第10期64卷 2624-2626页

作者： Di Zhang Jifeng Yuan jianjun tian Beijing Advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China

The power conversion efficiency(PCE)of organic-inorganic hybrid metal halide perovskite solar cells(PSCs)has rocketed from around 3%to more than 25%in a decade,showing a miracle in the development history of photovoltaics^([1]).However,the hybrid perovskites still suffer from the issue of thermodynamic instability due to the volatile organic cations in ***-inorganic metal halide perovskites.

关键词： perovskite inorganic halide

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