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Facile low-temperature supercritical carbonization method to prepare high-loading nickel single atom catalysts for efficient photodegradation of tetracycline

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Journal of Environmental Sciences 2024年第4期138卷 373-384页

作者： Han Qiao Lirong Zheng Shiwen Hu Gang Tang Hongri Suo Chongxuan Liu School of Environment Harbin Institute of TechnologyHarbin 150090China state Environmental Protection key laboratory of Integrated surface Water-Groundwater Pollution Control School of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China Beijing Synchrotron Radiation Facility(BSRF) Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China

Environmental photocatalysis is a promising technology for treating antibiotics in wastewater.In this study,a supercritical carbonization method was developed to synthesize a single-atom photocatalyst with a high loading of Ni(above 5 wt.%)anchored on a carbonnitrogen-silicate substrate for the efficient photodegradation of a ubiquitous environmental contaminant of tetracycline(TC).The photocatalyst was prepared from an easily obtained metal-biopolymer-inorganic supramolecular hydrogel,followed by supercritical drying and carbonization treatment.The low-temperature(300℃)supercritical ethanol treatment prevents the excessive structural degradation of hydrogel and greatly reduces the metal clustering and aggregation,which contributed to the high Ni loading.Atomic characterizations confirmed that Ni was present at isolated sites and stabilized by Ni-N and Ni-O bonds in a Ni-(N/O)_(6)-C/SiC configuration.A 5%Ni-C-Si catalyst,which performed the best among the studied catalysts,exhibited a wide visible light response with a narrow bandgap of 1.45 eV that could efficiently and repeatedly catalyze the oxidation of TC with a conversion rate of almost 100% within 40 min.The reactive species trapping experiments and electron spin resonance(ESR)tests demonstrated that the h+,and·O_(2)-were mainly responsible for TC degradation.The TC degradation mechanism and possible reaction pathways were provided also.Overall,this study proposed a novel strategy to synthesize a high metal loading singleatom photocatalyst that can efficiently remove TC with high concentrations,and this strategy might be extended for synthesis of other carbon-based single-atom catalysts with valuable properties.

关键词： Carbon-based single-atom catalyst Nickel Photocatalytic degradation Tetracycline Visible light

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Negative enthalpy alloys and local chemical ordering:a concept and route leading to synergy of strength and ductility

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National Science Review 2024年第4期11卷 172-184页

作者： Zibing An Tao Yang Caijuan Shi Shengcheng Mao Lihua Wang Ang Li Wei Li Xianmeng Xue Ming Sun Yifan Bai Yapeng He Fuzeng Ren Zhouguang Lu Ming Yan Yang Ren Chain-Tsuan Liu Ze Zhang Xiaodong Han Beijing key Lab of Microstructure and Property of Advanced Materials College of Materials Science &Engineering Beijing University of Technology Department of Materials Science and Engineering City University of Hong Kong key laboratory of Partial Acceleration physics& Technology Institute of High Energy PhysicsChinese Academy of Sciences Department of Materials Science &Engineering Southern University of Science and Technology Department of physics City University of Hong Kong state key laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University

Solid solutions are ubiquitous in metals and alloys. Local chemical ordering(LCO) is a fundamental sub-nano/nanoscale process that occurs in many solid solutions and can be used as a microstructure to optimize strength and ductility. However, the formation of LCO has not been fully elucidated, let alone how to provide efficient routes for designing LCO to achieve synergistic effects on both superb strength and ductility. Herein, we propose the formation and control of LCO in negative enthalpy alloys. With engineering negative enthalpy in solid solutions, genetic LCO components are formed in negative enthalpy refractory high-entropy alloys(RHEAs). In contrast to conventional ‘trial-and-error' approaches, the control of LCO by using engineering negative enthalpy in RHEAs is instructive and results in superior strength(1160 MPa) and uniform ductility(24.5%) under tension at ambient temperature, which are among the best reported so far. LCO can promote dislocation cross-slip, enhancing the interaction between dislocations and their accumulation at large tensile strains; sustainable strain hardening can thereby be attained to ensure high ductility of the alloy. This work paves the way for new research fields on negative enthalpy solid solutions and alloys for the synergy of strength and ductility as well as new functions.

关键词： negative enthalpy alloys local chemical ordering strength ductility dislocation

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Correlations of baryon and charge stopping in heavy ion collisions

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Chinese physics C 2024年第4期48卷 89-94页

作者：吕文棣李洋李子阳马荣荣唐泽波 Prithwish Tribedy Chun Yuen Tsang 许长补查王妹 state key laboratory of Particle Detection and Electronics University of Science and Technology of ChinaHefei 230026China physics Department Brookhaven National LaboratoryUptonNY 11973USA Department of physics Kent State UniversityKentOH 44242USA

Baryon numbers are theorized to be carried by valence quarks in the standard QCD picture of the baryon structure.Another theory proposed an alternative baryon number carrier,a non-perturbative Y-shaped configuration of the gluon field,called the baryon junction in the 1970s.However,neither of these theories has been verified experimentally.Recently,searching for the baryon junction by investigating the correlation of net-charge and net-baryon yields at midrapidity in heavy-ion collisions has been suggested.This paper presents studies of such correlations in collisions of various heavy ions from oxygen to uranium with the UrQMD Monte Carlo model.The UrQMD model implements valence quark transport as the primary means of charge and baryon stopping at midrapidity.Detailed studies are also conducted for isobaric ^(96)_(40)Zr+^(96)_(40)Zr and ^(96)_(44)Ru+^(96)_(44)Ru collisions.We found a universal trend of charge stopping with respect to baryon stopping and discovered that the charge stopping is always greater than the baryon stopping.This study provides a model baseline in valence quark transport for what is expected in net-charge and net-baryon yields at the midrapidity of relativistic heavy-ion collisions.

关键词： baryon junction baryon number carrier baryon stopping relativistic heavy ion collisions

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In-situ formation of nitrogen doped microporous carbon nanospheres derived from polystyrene as lubricant additives for anti-wear and friction reduction

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Friction 2024年第3期12卷 439-451页

作者： Yixin WANG Qi LU Huijie XIE Shujuan LIU Qian YE Feng ZHOU Weimin LIU state key laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China state key laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

This study presents a nitrogen-doped microporous carbon nanospheres(N@MCNs)prepared by a facile polymerization–carbonization process using low-cost styrene.The N element in situ introduces polystyrene(PS)nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent,and then carbonization obtains N@MCNs.The as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric chloride.The friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc structure.The results showed that N@MCNs exhibit superb reduction performance of friction and wear.When the addition of N@MCNs was 0.06 wt%,the friction coefficient of PAO-10 decreased from 0.188 to 0.105,and the wear volume reduced by 94.4%.The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%,respectively.The carrying capacity of load was rocketed from 100 to 400 N concurrently.Through the analysis of the lubrication mechanism,the result manifested that the prepared N@MCNs enter clearance of the friction pair,transform the sliding friction into the mixed friction of sliding and rolling,and repair the contact surface through the repair effect.Furthermore,the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides,which can avert direct contact with the matrix and improve the tribological properties.This experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing friction.This preparing method can be ulteriorly expanded to multi-element co-permeable materials.Nitrogen and boron co-doped carbon nanospheres(B,N@MCNs)were prepared by mixed carbonization of N-enriched PS and boric acid,and exhibited high load carrying capacity and good tribological properties.

关键词： lubricant additives hypercrosslinked polystyrene carbon nanospheres friction reduction anti-wear

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Dynamic response of a thermal transistor to time-varying signals

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Chinese physics B 2024年第5期33卷 13-19页

作者：阮琴丽刘文君王雷 Department of physics Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devicesand Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education)Renmin University of ChinaBeijing 100872China

Thermal transistor,the thermal analog of an electronic transistor,is one of the most important thermal devices for microscopic-scale heat manipulating.It is a three-terminal device,and the heat current flowing through two terminals can be largely controlled by the temperature of the third one.Dynamic response plays an important role in the application of electric devices and also thermal devices,which represents the devices’ability to treat fast varying inputs.In this paper,we systematically study two typical dynamic responses of a thermal transistor,i.e.,the response to a step-function input(a switching process)and the response to a square-wave input.The role of the length L of the control segment is carefully studied.It is revealed that when L is increased,the performance of the thermal transistor worsens badly.Both the relaxation time for the former process and the cutoff frequency for the latter one follow the power-law dependence on L quite well,which agrees with our analytical expectation.However,the detailed power exponents deviate from the expected values noticeably.This implies the violation of the conventional assumptions that we adopt.

关键词： phonon phononics thermal transistor dynamic response heat conduction

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Dynamic coupling of ferrihydrite transformation and associated arsenic desorption/redistribution mediated by sulfate-reducing bacteria

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Journal of Environmental Sciences 2024年第1期135卷 39-50页

作者： Wenjing Zhou Huiyan Zhu Shiwen Hu Bowei Zhang Kun Gao Zhi Dang Chongxuan Liu state Environmental Protection key laboratory of Integrated surface Water-Groundwater Pollution Control School of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China The key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters Ministry of EducationSouth China University of TechnologyGuangzhou 510006China

Sulfate-reducing bacteria play an important role in the geochemistry of iron(oxyhydr)oxide and arsenic(As)in natural environments;however,the associated reaction processes are yet to be fully understood.In this study,batch experiments coupled with geochemical,spectroscopic,microscopic,and thermodynamic analyses were conducted to investigate the dynamic coupling of ferrihydrite transformation and the associated As desorption/redistribution mediated by Desulfovibrio vulgaris(D.vulgaris).The results indicated that D.vulgaris could induce ferrihydrite transformation via S^(2-)-driven and direct reduction processes.In the absence of SO_(4)^(2-),D.vulgaris directly reduced ferrihydrite,and As desorption and re-sorption occurred simultaneously during the partial transformation of ferrihydrite to magnetite.The increase in SO_(4)^(2-)loading promoted the S^(2-)-driven reduction of ferrihydrite and accelerated the subsequent mineralogical transformation.In the low and medium SO_(4)^(2-)treatments,ferrihydrite was completely transformed to a mixture of magnetite and mackinawite,which increased the fraction of As in the residual phase and stabilized As.In the high SO_(4)^(2-)treatment,although the replacement of ferrihydrite by only mackinawite also increased the fraction of As in the residual phase,22.1%of the total As was released into the solution due to the poor adsorption affinity of As to mackinawite and the conversion of As^(5+)to As^(3+).The mechanisms of ferrihydrite reduction,mineralogy transformation,and As mobilization and redistribution mediated by sulfate-reducing bacteria are closely related to the surrounding SO_(4)^(2-)loadings.These results advance our understanding of the biogeochemical behavior of Fe,S,and As,and are helpful for the risk assessment and remediation of As contamination.

关键词： Sulfate-reducing bacteria Arsenic Ferrihydrite Transformation Redistribution

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Spin transport characteristics modulated by the GeBi interlayer in Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures

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Chinese physics B 2024年第2期33卷 471-475页

作者：李明明张磊金立川郭海中 key laboratory of Materials physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China state key laboratory of Electronic Thin Films&Integrated Devices University of Electronic Science and Technology of ChinaChengdu 610054China Institute of Quantum Materials and physics Henan Academy of SciencesZhengzhou 450046China

For the past few years,germanium-based semiconductor spintronics has attracted considerable interest due to its potential for integration into mainstream semiconductor technology.The main challenges in the development of modern semiconductor spintronics are the generation,detection,and manipulation of spin currents.Here,the transport characteristics of a spin current generated by spin pumping through a GeBi semiconductor barrier in Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures were investigated systematically.The effective spin-mixing conductance and inverse spin Hall voltage to quantitatively describe the spin transport characteristics were extracted.The spin-injection efficiency in the Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures is comparable to that of the Y_(3)Fe_(5)O_(12)/Pt bilayer,and the inverse spin Hall voltage exponential decays with the increase in the barrier thickness.Furthermore,the band gap of the GeBi layer was tuned by changing the Bi content.The spin-injection efficiency at the YIG/semiconductor interface and the spin transportation within the semiconductor barrier are related to the band gap of the GeBi layer.Our results may be used as guidelines for the fabrication of efficient spin transmission structures and may lead to further studies on the impacts of different kinds of barrier materials.

关键词： spin current Y_(3)Fe_(5)O_(12)/GeBi/Pt heterostructures spin pumping inverse spin Hall effect

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ARPES investigation of the electronic structure and its evolution in magnetic topological insulator MnBi2+2nTe4+3n family

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National Science Review 2024年第2期11卷 81-93页

作者： Runzhe Xu Lixuan Xu Zhongkai Liu Lexian Yang Yulin Chen state key laboratory of Low Dimensional Quantum physics Department of PhysicsTsinghua University School of Physical Science and Technology Shanghai Tech University and CAS-Shanghai Science Research Center Shanghai Tech laboratory for Topological physics Frontier Science Center for Quantum Information Collaborative Innovation Center of Quantum Matter Department of physics Clarendon LaboratoryUniversity of Oxford

In the past 5 years,there has been significant research interest in the intrinsic magnetic topological insulator family compounds MnBi2+2nTe4+3n（where n=0,1,2…）.In particular,exfoliated thin films of MnBi2Te4have led to numerous experimental breakthroughs,such as the quantum anomalous Hall effect,axion insulator phase and high-Chern number quantum Hall effect without Landau levels.However,despite extensive efforts,the energy gap of the topological surface states due to exchange magnetic coupling,which is a key feature of the characteristic band structure of the system,remains experimentally elusive.The electronic structure measured by using angle-resolved photoemission （ARPES） shows significant deviation from ab initio prediction and scanning tunneling spectroscopy measurements,making it challenging to understand the transport results based on the electronic structure.This paper reviews the measurements of the band structure of MnBi2+2nTe4+3nmagnetic topological insulators using ARPES,focusing on the evolution of their electronic structures with temperature,surface and bulk doping and film thickness.The aim of the review is to construct a unified picture of the electronic structure of MnBi2+2nTe4+3ncompounds and explore possible control of their topological properties.

关键词： magnetic topological insulator MnBi2Te4 electronic structure angle-resolved photoemission spectroscopy

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Robust enhancement of valley polarization and quantum yield in composition grading lateral heterostructure of MoS2-WS2 monolayer

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Progress in Natural Science:Materials International 2024年第1期34卷 187-193页

作者： Mengke Kang Cheng Zhang Congpu Mu Kun Zhai Tianyu Xue Bochong Wang Fusheng Wen Yingchun Cheng Jianyong Xiang Jun-Feng Dai Anmin Nie Zhongyuan Liu Center for High Pressure Science State Key Laboratory of Metastable Materials Science and Technology Yanshan University Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen key laboratory of Quantum Science and Engineering

Valley degeneracy can be broken owing to the strong spin-orbit coupling in two-dimensional transition metal dichalcogenides（2D-TMDCs）. Valley-dependent interaction of carriers in TMDCs with different circular polarizations of light offers valley degree-of-freedom besides charge and spin to carry information. Thus, bandgap engineering of 2D-TMDCs plays a critical role in developing practical valleytronic devices. Hereby, we demonstrate a great enhancement in quantum yield as well as polarization of monolayer MoS2achieved by gradually alloying W atoms in MoS2. By appropriately setting a time offset between the evaporation of MoO3and WO3precursors during chemical vapor deposition, a compositionally graded heterostructure of MoS2-WS2monolayer can be readily grown at large scale. Raman and transmission electron microscopy measurements demonstrate that the interface possesses a steep gradient in composition, spanning from MoS2to WS2over a length ～2 μm.Compared to pure monolayer MoS2, the photoluminescence intensity at the compositionally graded interface of Mo1-xWxS2was observed to increase by a factor of 16 owing to the effective separation of photogenerated carriers by the built-in electric field. Particularly, a remarkably high polarization of 70% at 16 K is demonstrated for the compositionally graded interface of Mo1-xWxS2, which is ～1.4 times larger than that in MoS2and is attributed to the combined effect of the alloyed structure and graded bandgap. Such an engineering scheme with a graded bandgap offers new approach for the development of high-efficiency valleytronics devices.

关键词： Transition metal dichalcognide monolayer Compositionally graded in-plane heterostructure Chemical vapor deposition Valley polarization Quantum yield

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Inward particle transport driven by biased endplate in a cylindrical magnetized plasma

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Plasma Science and Technology 2024年第3期26卷 126-130页

作者：盖跃徐田超肖池阶郭志彬王晓钢何任川杨肖易张祖煜袁瑞鑫 state key laboratory of Nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871People's Republic of China Department of physics Harbin Institute of TechnologyHarbin 150001People's Republic of China

The inward particle transport is associated with the formation of peaked density profiles,which contributes to improve the fusion rate and the realization of steady-state discharge.The active control of inward particle transport is considered as one of the most critical issues of magnetic confinement fusion.Recently,it is realized preliminarily by adding a biased endplate in the Peking University Plasma Test(PPT)device.The results reveal that the inward particle flux increases with the bias voltage of the endplate.It is also found that the profile of radial electric field(Er)shear is flattened by the increased bias voltage.Radial velocity fluctuations affect the inward particle more than density fluctuations,and the frequency of the dominant mode driving inward particle flux increases with the biased voltage applied to the endplate.The experimental results in the PPT device provide a method to actively control the inward particle flux using a biased endplate and enrich the understanding of the relationship between E_(r)×B shear and turbulence transport.

关键词： inward particle transport biased endplate turbulent transport

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