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Regulations of active moiety in single atom catalysts for electrochemical hydrogen evolution reaction

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Nano Research 2022年第7期15卷 5792-5815页

作者： Peng Zhu xiang xiong Dingsheng Wang Department of Chemistry Tsinghua UniversityBeijing 100084China Powder Metallurgy Research Institute and State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Hydrogen production from water splitting using renewable electric energy is an interesting topic towards the carbon neutral future.Single atom catalysts(SACs)have emerged as a new frontier in the field of catalysis such as hydrogen evolution reaction(HER),owing to their intriguing properties like high activity and excellent chemical selectivity.The catalytic active moiety is often comprised of a single metal atom and its neighboring environment from the supports.Recent published reviews about electricdriven HER tend to classify these SACs by the species of active center atom,nevertheless the influence of their neighboring coordinated atoms from the supports is somehow neglected.Thus we classify the SACs for HER through the type of supports,highlighting the electronic metal–support interaction and their coordination environment from support.Then,we put forward some structural designing strategies including regulating of the central atoms,coordination environments,and metal-support interactions.Finally,the current challenges and future research perspectives of SACs for HER are briefly proposed.

关键词： single atom catalysts coordination environment electrocatalytic hydrogen evolution reaction

Oxidation behavior of boron-containing(Zr,Ti)C_(x)B_(y)solid solution ceramics at 1600℃in air

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Journal of Advanced Ceramics 2023年第10期12卷 1989-2002页

作者： Huilin Lun Yi Zeng xiang xiong Houbu Li State Key Laboratory of Performance and Structural Safety for Petroleum Tubular Goods and Equipment Materials CNPC Tubular Goods Research InstituteXi’an 710077China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Key Laboratory of Petroleum Tubular Goods and Equipment Ouality Safety for State Market Regulation CNPC Tubular Goods Research InstituteXi’an 710077China

Multicomponent boron-containing carbide coatings(i.e.,(Zr,Ti)C_(x)B_(y))on a C/C composite show good ablation resistance.However,the high-temperature oxidation behavior of this new type of boron-containing(Zr,Ti)C_(x)B_(y)solid solution ceramics has not been clarified yet.The present work fabricated(Zr,Ti)C_(x)B_(y)solid solution block ceramics by spark plasma sintering,and their oxidation behavior at 1600℃in air(N2–20-vol%O2)was investigated for the first time.The effects of boron on the oxidation resistance of(Zr,Ti)C_(x)B_(y)ceramics were examined.The results indicate that the(Zr,Ti)C_(x)B_(y)ceramics display good oxidation resistance with the parabolic rate law describing the oxidation process.After the trace solution of boron(0.5 wt%)into(Zr,Ti)Cx,the oxidation resistance of carbide ceramics is significantly enhanced,leading to a decrease of 30%in the oxidation rate constant.The formed oxide scale in the(Zr,Ti)C_(x)B_(y)ceramics is dense,and the interlayer shows stronger ability to inhibit inward diffusion of oxygen.In addition,the introduction of boron leads to more negative binding energy of(Zr,Ti)C_(x)B_(y)and improves the oxidation resistance of carbides.

关键词： ultra-high-temperature ceramics(UHTCs) (Zr,Ti)CxBy solid solution oxidation behavior oxidation resistance

Microstructural evolution and electromagnetic wave absorbing performance of single-source-precursor-synthesized SiCuCN-based ceramic nanocomposites

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Journal of Advanced Ceramics 2023年第7期12卷 1299-1316页

作者： Jincan Yang Qingbo Wen Bo Feng Yalei Wang xiang xiong State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Fundamentals Department Air Force Engineering UniversityXi'an 710051China

Copper(Cu)-containing single-source precursors(SSPs)for the preparation of SiCuCN-based ceramic nanocomposites were successfully synthesized for the first time using polysilazane(PSZ),copper(II)acetate monohydrate(CuAc),and 2-aminoethanol via nucleophilic substitution reactions at silicon(Si)centers of PSZ.The synthesis process,polymer-to-ceramic transformation,and high-temperature microstructural evolution of the prepared ceramics were characterized.Dielectric properties and electromagnetic wave(EMW)absorbing performance of the ceramics were investigated as well.The results show that the polymer-to-ceramic transformation finishes at ca.900 ℃,and Cu nanoparticles are homogeneously distributed in a SiCN matrix,forming a SiCN/Cu nanocomposite.After annealing at 1200 ℃,the Cu nanoparticles completely transform into copper silicide(CusSi).Interestingly,the thermal stability of the Cu nanoparticles can be strongly improved by increasing the free carbon content,so that a part of metallic Cu nanoparticles can be detected in the ceramics annealed even at 1300 ℃,forming a SiCN/Cu/Cu_(3)Si/C nanocomposite.Compared with SiCN,the SiCuCN-based nanocomposites exhibit strongly enhanced dielectric properties,which results in outstanding EMW absorbing performance.The minimum reflection coefficient(RC_(min))of the SiCN/Cu/Cu_(3)Si/C nanocomposites annealed at 1300 ℃ achieves-59.85 dB with a sample thickness of 1.55 mm,and the effective absorption bandwidth(EAB)broadens to 5.55 GHz at 1.45 mm.The enhanced EMW absorbing performance can be attributed to an in situ formed unique network,which was constructed with Cu and Cu_(3)Si nanoparticles connected by ring-like carbon ribbons within the SiCN matrix.

关键词： polymer-derived ceramics(PDCs) dielectric property electromagnetic wave(EMW)absorbing copper(Cu) microstructure

Elucidating the role of preferential oxidation during ablation:Insights on the design and optimization of multicomponent ultra-high temperature ceramics

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Journal of Advanced Ceramics 2022年第12期11卷 1956-1975页

作者： Ziming YE Yi ZENG xiang xiong Qingbo WEN Huilin LUN State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China

Multicomponent ultra-high temperature ceramics(UHTCs)are promising candidates for thermal protection materials(TPMs)used in aerospace field.However,finding out desirable compositions from an enormous number of possible compositions remains challenging.Here,through elucidating the role of preferential oxidation in ablation behavior of multicomponent UHTCs via the thermodynamic analysis and experimental verification,the correlation between the composition and ablation performance of multicomponent UHTCs was revealed from the aspect of thermodynamics.We found that the metal components in UHTCs can be thermodynamically divided into preferentially oxidized component(denoted as MP),which builds up a skeleton in oxide layer,and laggingly oxidized component(denoted as ML),which fills the oxide skeleton.Meanwhile,a thermodynamically driven gradient in the concentration of MP and ML forms in the oxide layer.Based on these findings,a strategy for pre-evaluating the ablation performance of multicomponent UHTCs was developed,which provides a preliminary basis for the composition design of multicomponent UHTCs.

关键词： multicomponent ceramics ultra-high temperature ceramics(UHTCs) preferential oxidation oxidation behavior ablation resistance

A hybrid bacterium with tumor-associated macrophage polarization for enhanced photothermal-immunotherapy

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Acta Pharmaceutica Sinica B 2022年第6期12卷 2683-2694页

作者： Jingya Zhao Huabei Huang Jinyan Zhao xiang xiong Sibo Zheng Xiaoqing Wei Shaobing Zhou Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China

Remodeling the tumor microenvironment through reprogramming tumor-associated macrophages(TAMs) and increasing the immunogenicity of tumors via immunogenic cell death(ICD) have been emerging as promising anticancer immunotherapy strategies.However,the heterogeneous distribution of TAMs in tumor tissues and the heterogeneity of the tumor cells make the immune activation challenging.To overcome these dilemmas,a hybrid bacterium with tumor targeting and penetration,TAM polarization,and photo thermal conversion capabilities is developed for improving antitumor immunotherapy in vivo.The hybrid bacteria(B.b@QDs) are prepared by loading Ag;S quantum dots(QDs) on the Bifidobacterium bifidum(B.b) through electrostatic interactions.The hybrid bacteria with hypoxia targeting ability can effectively accumulate and penetrate the tumor tissues,enabling the B.b to fully contact with the TAMs and mediate their polarization toward M1 phenotype to reverse the immunosuppressive tumor microenvironment.It also enables to overcome the intratumoral heterogeneity and obtain abundant tumor-associated antigens by coupling tumor penetration of the B.b with photo thermal effect of the QDs,resulting in an enhanced immune effect.This strategy that combines B.b-triggered TAM polarization and QD-induced ICD achieved a remarkable inhibition of tumor growth in orthotopic breast cancer.

关键词： Immunotherapy Tumor-associated macrophage Immunogenic cell death Bifidobacterium Quantum dot

Si-based polymer-derived ceramics for energy conversion and storage

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Journal of Advanced Ceramics 2022年第2期11卷 197-246页

作者： Qingbo WEN Fangmu QU Zhaoju YU Magdalena GRACZYK-ZAJAC xiang xiong Ralf RIEDEL State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China College of Materials Key Laboratory of High-Performance Ceramic Fibers(Xiamen University)Ministry of EducationXiamen 361005China Technische Universität Darmstadt Institut für MaterialwissenschaftOtto-Berndt-Straβe 3D-64287DarmstadtGermany EnBW Energie Baden-Württemberg AG Durlacher Allee 9376131 KarlsruheGermany

Since the 1960s,a new class of Si-based advanced ceramics called polymer-derived ceramics(PDCs)has been widely reported because of their unique capabilities to produce various ceramic materials(e.g.,ceramic fibers,ceramic matrix composites,foams,films,and coatings)and their versatile applications.Particularly,due to their promising structural and functional properties for energy conversion and storage,the applications of PDCs in these fields have attracted much attention in recent years.This review highlights the recent progress in the PDC field with the focus on energy conversion and storage applications.Firstly,a brief introduction of the Si-based polymer-derived ceramics in terms of synthesis,processing,and microstructure characterization is provided,followed by a summary of PDCs used in energy conversion systems(mainly in gas turbine engines),including fundamentals and material issues,ceramic matrix composites,ceramic fibers,thermal and environmental barrier coatings,as well as high-temperature sensors.Subsequently,applications of PDCs in the field of energy storage are reviewed with a strong focus on anode materials for lithium and sodium ion batteries.The possible applications of the PDCs in Li–S batteries,supercapacitors,and fuel cells are discussed as well.Finally,a summary of the reported applications and perspectives for future research with PDCs are presented.

关键词： polymer-derived ceramics(PDCs) high-temperature resistance structural properties electrochemical properties microstructure

Hydropathy modulation on Bi_(2)S_(3) for enhanced electrocatalytic CO_(2) reduction

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Rare Metals 2023年第3期42卷 806-812页

作者： Long-Sheng Zhan Yu-Chao Wang Meng-Jie Liu Xin Zhao Jiao Wu xiang xiong Yong-Peng Lei State Key Laboratory of Powder Metallurgy Powder Metallurgy Research InstituteCentral South UniversityChangsha 410083China School of Material Science and Engineering Central South University of Forestry and Technology

Electrochemical CO_(2) reduction reaction(CO_(2)RR)is a promising way to achieve carbon neutrality.However,the activity and selectivity of CO_(2)RR are limited by not only the development of earth-abundant catalysts but also the CO_(2) mass transfer during the CO_(2)RR process.Herein,Bi_(2)S3 nanorods were synthesized under a relatively mild route.Furthermore,benefitting to the modulation of the hydropathy.

关键词： process neutral selectivity

Nb_(2)CT_(x)MXene boosting PEO polymer electrolyte for all-solid-state Li-S batteries:two birds with one stone strategy to enhance Li+conductivity and polysulfide adsorptivity

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稀有金属:英文版 2023年第8期42卷 2562-2576页

作者： Si-Ming Liu Meng-Xun Chen Ying Xie Deng-Hua Liu Jin-Fei Zheng xiang xiong Heng Jiang Li-Chang Wang Heng Luo Kai Han State Key Laboratory for Powder Metallurgy College of Chemistry and Chemical EngineeringCentral South UniversityChangsha 410083China Shinghwa Advanced Material Group Co. LtdDongying 257500China School of Physics and Electronics Central South UniversityChangsha 410083China Department of Chemistry Oregon State UniversityCorvallis OR 97331-4003USA School of Geosciences and Info-Physics Central South UniversityChangsha 410083China

All-solid-state lithium-sulfur(Li-S)battery is regarded as next-generation high energy density and safety battery system.The key challenge is to develop a compatible high-performance solid-state electrolyte.Herein,a two birds with one stone strategy is proposed to simultaneously enhance Li+conductivity and polysulfide adsorptivity of poly(ethylene oxide)(PEO)-based polymer electrolyte via the integration of Nb_(2)CT_(x)MXene.Moreover,the sheet size of Nb_(2)CT_(x)MXene is crucial for the enhancement of Li^(+)conductivity and polysulfide adsorptivity,attributing to the difference in a specific surface area related to the percolation effect.By tuning the sheet size of Nb_(2)CT_(x)MXene from 500-300 nm to below 100 nm,the ionic conductivity of the PEO electrolyte is increased to2.62×10^(-4)S·cm^(-1)with improved Li+transference number of 0.37 at 600C.Furthermore,theoretical calculation and X-ray photoelectron spectroscopy(XPS)conjointly prove that poly sulfides could be effectively adsorbed by Nb2CTxnanosheets via forming Nb-S bonding to inhibit their shuttle in the PEO framework.As a result,the all-solid-state Li-S cell exhibits an initial capacity of 1149 mAh·g^(-1)at 0.5C and good cycling stability with 491 mAh·g^(-1)after 200 cycles.The results demonstrate the necessity of polysulfide inhibition and the application of Nb_(2)CT_(x)MXene in PEO-based electrolytes for all-solid-state Li-S batteries.

关键词： All-solid-state Li-S batteries Polyethylene oxide(PEO)-based electrolyte Nb_(2)CT,MXene Shuttle effect inhibition

圈层舆论生成与转换机制研究——基于电影海报粉丝群的民族志观察

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现代传播（中国传媒大学学报） 2024年第5期46卷 128-139页

作者：项国雄邓天阳江西师范大学新闻与传播学院江西师范大学文学院

社交媒体推动网络圈层群体的形成,舆论也从传统现实空间转向虚拟的网络圈层空间。个体间微观的社会冲突、群体规则遭遇的挑战、群体内的分化组合、群体间冲突引发的空间转换、冲突双方合法化的演变是圈层舆论形成的关键要素。圈层舆论... 详细信息

社交媒体推动网络圈层群体的形成,舆论也从传统现实空间转向虚拟的网络圈层空间。个体间微观的社会冲突、群体规则遭遇的挑战、群体内的分化组合、群体间冲突引发的空间转换、冲突双方合法化的演变是圈层舆论形成的关键要素。圈层舆论中群体冲突方利用规则的转换和冲突引起的空间转换成为其向大众舆论转换的核心,其兼备现实社会与网络虚拟社群空间,而关系、情感和人们的参与疲劳成为解决现实冲突的主要阻碍因素,使得调节社会秩序的功能丢失,舆论成为一种非协商的抗争手段。

关键词：圈层舆论群体规则空间转换规则转换