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defects boost graphitization for highly conductive graphene films

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National Science Review 2023年第7期10卷 172-182页

作者： Qing Zhang Qinwei Wei Kun Huang Zhibo Liu Wei Ma Zehui Zhang Yanfeng Zhang Hui-Ming Cheng Wencai Ren Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China School of Materials Science and Engineering Peking University Shenzhen Institute of Advanced Technology Chinese Academy of Sciences

Fabricating highly crystalline macroscopic films with extraordinary electrical and thermal conductivities from graphene sheets is essential for applications in electronics,telecommunications and thermal management.High-temperature graphitization is the only method known to date for the crystallization of all types of carbon materials,where defects are gradually removed with increasing temperature.However,when using graphene materials as precursors,including graphene oxide,reduced graphene oxide and pristine graphene,even lengthy graphitization at 3000℃ can only produce graphene films with small grain sizes and abundant structural disorders,which limit their conductivities.Here,we show that high-temperature defects substantially accelerate the grain growth and ordering of graphene films during graphitization,enabling ideal AB stacking as well as a 100-fold,64-fold and 28-fold improvement in grain size,electrical conductivity and thermal conductivity,respectively,between 2000℃ and 3000℃.This process is realized by nitrogen doping,which retards the lattice restoration of defective graphene,retaining abundant defects such as vacancies,dislocations and grain boundaries in graphene films at a high temperature.With this approach,a highly ordered crystalline graphene film similar to highly oriented pyrolytic graphite is fabricated,with electrical and thermal conductivities(～2.0×104S cm-1;～1.7×103W m-1K-1) that are improved by about 6-and 2-fold,respectively,compared to those of the graphene films fabricated by graphene oxide.Such graphene film also exhibits a superhigh electromagnetic interference shielding effectiveness of ～90 dB at a thickness of 10 μm,outperforming all the synthetic materials of comparable thickness including MXene films.This work not only paves the way for the te chnological application of highly conductive graphene films but also provides a general strategy to efficiently improve the synthesis and properties of other carbon materials such as graphene fibers,carbon nanotube fibers,carbon fibers,polym

关键词： graphene film defects graphitization electrical and thermal conductivity thermal management and EMI shielding

空间选择性缺陷管理制备高性能碳基CsPbI_(3)钙钛矿太阳能电池

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Science Bulletin 2024年第8期69卷 1050-1060页

作者：王海亮张啟先林则东刘慧丛魏晓震宋永发律春宇李卫平朱立群王科翔崔振华王兰林常青殷鹏刚宋廷鲁白阳陈棋杨世和陈海宁 School of Materials Science and Engineering Beihang UniversityBeijing 100191China Guangdong Provincial Key Lab of Nano-Micro Materials Research School of Advanced MaterialsShenzhen Graduate SchoolPeking UniversityShenzhen 518055China Institute of Biomedical Engineering Shenzhen Bay LaboratoryShenzhen 518107China School of Chemistry Beihang UniversityBeijing 100191China Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesExperimental Center of Advanced MaterialsSchool of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China School of Internet of Things Engineering Jiangnan UniversityWuxi 214122China School of Physical Science and Technology Guangxi UniversityNanning 530004China Experimental Center of Advanced Materials School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China

defects formed at the surface,buried interface and grain boundaries(GB)of CsPbI_(3)perovskite films considerably limit photovoltaic performance.Such defects could be passivated effectively by the most prevalent post modification strategy without compromising the photoelectric properties of perovskite films,but it is still a great challenge to make this strategy comprehensive to different defects spatially distributed throughout the films.Herein,a spatially selective defect management(SSDM)strategy is developed to roundly passivate various defects at different locations within the perovskite film by a facile one-step treatment procedure using a piperazine-1,4-diium tetrafluoroborate(PZD(BF_(4))_(2))solution.The small-size PZD^(2+)cations could penetrate into the film interior and even make it all the way to the buried interface of CsPbI_(3)perovskite films,while the BF_(4)^(-)anions,with largely different properties from I^(-)anions,mainly anchor on the film surface.Consequently,virtually all the defects at the surface,buried interface and grain boundaries of CsPbI_(3)perovskite films are effectively healed,leading to significantly improved film quality,enhanced phase stability,optimized energy level alignment and promoted carrier transport.With these films,the fabricated CsPbI_(3)PSCs based on carbon electrode(C-PSCs)achieve an efficiency of18.27%,which is among the highest-reported values for inorganic C-PSCs,and stability of 500 h at 85℃with 65%efficiency maintenance.

关键词： CsPbI_(3) defects Spatially selective defect management Carbon electrode

defects and doping engineering towards high performance lead-free or lead-less perovskite solar cells

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Journal of Energy Chemistry 2022年第5期31卷 420-438页

作者： Wenying Cao Zhaosheng Hu Zhenhua Lin Xing Guo Jie Su Jingjing Chang Yue Hao State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology School of MicroelectronicsXidian UniversityXi’an 710071ShaanxiChina Advanced Interdisciplinary Research Center for Flexible Electronics Xidian UniversityXi’an 710071ShaanxiChina

Up to now, perovskite solar cells(PSCs) have reached a certified 25.5% efficiency. As a promising photo-electric material, the metal halide perovskite possesses many outstanding properties such as tunable bandgap, long diffusion length, high absorption coefficient and carrier mobility. In spite of these remarkable properties, defects are inevitable during the solution processing. Therefore, many efforts have been made to reduce defects in perovskite films and thus improve the performance of devices. Among them,substitution or doping engineering is one of the most studied methods. Meanwhile, due to the poor stability of the organic-inorganic hybrid perovskite and the toxicity of Pb-based perovskite materials, all inorganic perovskite and lead-less or lead-free perovskite have emerged as promising materials. Here,we focus on the defect engineering especially substitutions on different sites in an ABX_(3) structure. The particular attention is devoted towards lead-less or lead-free perovskites, and we discuss several common elements or groups used to partially replace Pb^(2+). It is noted that proper elemental doping at different sites is an important guarantee for obtaining high-performance lead-less or lead-free PSCs.

关键词： Perovskite defects Doping engineering Lead-free Lead-less Solar cells

The Impact of Pregnancy Termination before 28 Weeks of Gestation on the Overall Prevalence of Birth defects-Shaanxi Province,China,2014-2020

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China CDC weekly 2022年第43期4卷 967-973页

作者： Min Li Le Zhang Lu Gan Zhiwen Li Northwest Women’s and Children's Hospital Xi’an CityShaanxi ProvinceChina Institute of Reproductive and Child Health Peking UniversityBeijingChina Key Laboratory of Reproductive Health National Health Commission of the People’s Republic of ChinaBeijingChina

Introduction:The prevalence of birth defects(BDs)at≥28 gestational weeks in China has declined significantly in recent years.However,a few studies have implied that the prevalence is underestimated due to pregnancies with severe BDs often being terminated before 28 weeks of gestation.This study sought to contribute to this data conflict by determining the total prevalence of BDs throughout the entirety of pregnancies,depicting the epidemiological distribution of BDs in Shaanxi Province,and examining the impact of pregnancy termination before 28 weeks of gestation on overall BD prevalence.Methods:Based on data extracted from the provincial Birth defects Surveillance Network in Shaanxi Province,from 2014 to 2020,the trends of 18 frequent,major BDs at any gestational age were analysed.Results:The total prevalence of BDs throughout pregnancy in Shaanxi Province increased significantly from 2014 to 2020,partly due to the inclusion of slight congenital heart diseases.It was also shown that the prevalence of all major types of BD had been previously underestimated,particularly severe external BDs,anywhere from 10%to 100%due to the previous sole measurement of terminations after 28 gestational weeks.Neural tube defects,however,remained one of the top five BDs with the highest total prevalence.Conclusions:The exclusion of pregnancy terminationsdefects.To estimate the true population-level prevalence of BD better,the current BD surveillance system should include pregnancy terminations before 28 weeks of gestation.

关键词： termination Impact defects

Exceptional strength-ductility synergy of additively manufactured CoCrNi medium-entropy alloy achieved by lattice defects in heterogeneous microstructures

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Journal of Materials Science & Technology 2022年第32期127卷 61-70页

作者： Jianying Wang Jianpeng Zou Hailin Yang Lijun Zhang Zhilin Liu Xixi Dong Shouxun Ji State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Light Alloy Research Institute College of Mechanical and Electrical EngineeringCentral South UniversityChangsha 410083China Brunel Centre for Advanced Solidification Technology(BCAST) Brunel University LondonUxbridgeMiddlesex UB83PHUnited Kingdom

The selective laser melting(SLM)with subsequent cold rolling and annealing is used to produce high-density lattice defects and grain refinement in the CoCrNi medium-entropy alloys(MEAs).The superior comprehensive mechanical properties have been achieved in the as-SLMed CoCrNi alloy after rolling and annealing.The as-SLMed alloys delivered the yield strength of 693.4 MPa,the ultimate tensile strength of 912.7 MPa and the fracture strain of 54.4%.After rolling with 70%reduction in thickness and annealing at 700℃for 2 h.the yield strength,ultimate tensile strength and fracture strain reached 1161.6 MPa,1390.8 MPa and 31.5%,respectively.The exceptional strength-ductility synergy is mainly attributed to the refined hierarchical microstructures with coarsening grains at a level of 30μm and ultrafine grains at a level of 1μm,and the heritage of dislocation-formed sub-grains and other lattice defects.This investigation demonstrates that the SLM with subsequent rolling and annealing is beneficial to fabricate high strength and ductile MEAs with single face-centered cubic(fcc)structure.

关键词： Medium-entropy alloys Selective laser melting Strength-ductility synergy defects Microstructure

In situ generated layered NiFe-LDH/MOF heterostructure nanosheet arrays with abundant defects for efficient alkaline and seawater oxidation

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Nano Research 2023年第7期16卷 8945-8952页

作者： Manjie Xiao Can Wu Jiawei Zhu Chengtian Zhang Yan Li Jiahui Lyu Weihao Zeng Haiwen Li Lei Chen Shichun Mu State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Foshan Xianhu Laboratory Foshan 528200China Science and Technology Institute of Advanced Technology Wuhan 430051China Hefei General Machinery Research Institute Hefei 230031China

As the main limiting step of overall water splitting,oxygen evolution reaction(OER)is urgent to be enhanced by developing efficient catalysts to promote the process of electrolytic water.Based on theoretical analysis,the Ni-metal-organic framework(Ni-MOF)and NiFe-layered double hydroxide(NiFe-LDH)(NiFe-LDH/MOF)heterostructure can optimize the energy barrier of the OER process and decrease the adsorption energy of oxygen-containing intermediates,effectively accelerating the OER kinetics.Accordingly,layered NiFe-LDH/MOF heterostructures are in situ constructed through a facile two-step reaction process,with substantial oxygen defects and lattice defects that further improve the catalytic performance.As a result,only 208 and 275 mV OER overpotentials are needed for NiFe-LDH/MOF to drive the current densities of 20 and 100 mA·cm^(-2)in 1 M KOH solutions,and even maintain catalytic stability of 100 h at 20 mA·cm^(-2).When applied to seawater oxidation,only 235 and 307 mV OER overpotentials are required to achieve the current densities of 20 and 100 mA·cm^(-2),respectively,with almost no attenuation for 100 h stability test at 20 mA·cm^(-2),all better than commercial RuO_(2).This work provides the theoretical and experimental basis and a new idea for efficiently driving fresh water and seawater cracking by heterostructure and defect coupling design toward catalysts.

关键词： oxygen evolution reaction defects seawater electrolysis catalyst

Pore defects in a nickel-based superalloy with high Ti content

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Progress in Natural Science:Materials International 2022年第4期32卷 456-462页

作者： Puying Shi Wenliang Xu Baoquan Fu Jin Liu Jianing Zhang Kaixuan Wang Xianghong Liu Western Superconducting Technologies Co. Ltd. School of Mechanical Engineering Xi'an Jiaotong University

Pores are uncommon defects in superalloy bars, which deserve to be investigated. In this work, a type of pore defect within GH4710 nickel-based superalloy was investigated by 3D X-ray imaging method combined with metallographic analysis. 3D X-ray imaging was used for locating and visualizing the defects in the alloy. The 3D Xray imaging result of the defects showed a good agreement with the defect anatomical morphologies. It was observed that the pore defect was accompanied by MC carbides, micro-crack, and non-metallic inclusions. The origin of pore defect was attributed to the shrinkage pores, inclusion and the complex precipitates. The analysis showed that the pore defects in GH4710 alloy was associated with strong micro-segregation and complex phase precipitation during solidification, induced by the high weight content of Ti and C in the alloy.

关键词： Ni-based superalloy defects 3D X-ray imaging High Ti content

Innovative treatments for congenital heart defects

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World Journal of Pediatrics 2023年第1期19卷 1-6页

作者： Antonio F.Corno Taylor S.Koerner Jorge D.Salazar McGovern Medical School Children's Heart InstituteMemorial Hermann Children's HospitalUniversity of Texas Health Science Center in Houston6410 Fannin StreetMSB 6.274HoustonTX 77030USA

The past few decades have witnessed substantial advances in the treatment of complex congenital heart defects,with most significant advances in surgical treatment strategies and improved outcomes dependent upon well-educated and calculated risk-taking innovations.In the present surgical era,doing nothing for complex congenital heart defects is unacceptable,and pioneering surgeons are willing to under-take and accept the substantial risks of innovative pediatric cardiac surgery[1].

关键词： congenital treatment defects

Assembly of 3D-printed Ti scaffold and free vascularized fibula using a customized Ti plate for the reconstruction of mandibular defects

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Bio-Design and Manufacturing 2022年第2期5卷 424-429页

作者： Chiyang Zhong Yixuan Zhao Hongyu Xing Qingguo Lai Runqi Xue Tianxiang Song Xiaopeng Tang Kaiwen Zhu Yanwei Deng Department of Oral and Maxillofacial Surgery The Second HospitalCheeloo College of MedicineShandong UniversityJinan 250033China School of Stomatology Cheeloo College of MedicineShandong UniversityJinan 250012China School of Mechanical and Electronic Engineering Shandong Jianzhu UniversityJinan 250101China Research Center of 3D Printing in Stomatology of Shandong University Jinan 250012China

Introduction Mandibular segmental defects result in significant cosmetic and functional deficiencies.Meanwhile,the reconstruction of both the contour and function of the mandible is a challenging task.At present,autologous vascularized fibula transplantation is the most common method to reconstruct a mandible with long-span defects[1].

关键词： fibula mandibular defects