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Root-like c/Sic surface structure fabricated by the thermal and electrochemical corrosion for brazing to Nb

cOMPOSITES PART B-ENGINEERING 2021年 218卷

作者： Ba, Jin Ji, Xu Wang, Bin Li, Peixin Lin, Jinghuang Qi, Junlei cao, Jian Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin 150001 Peoples R China

Root-like structure on c/Sic surface has been designed through selective corrosion to decrease the residual stress and then to optimize the microstructure when brazed to Nb. Thermal and electrochemical corrosion are conducted to diminish the Sic matrix and the interface between carbon fibers and Sic, respectively. The surface structure can be filled with brazing alloy characterized by the gradient layer of carbon fiber reinforced brazing alloy. compared with thermal corrosion, Sic particles and nano Ti5Si3 are uniformly dispersed throughout the gradient layer in electrochemical corrosion. The layer decreases the difference in property consequently to relieve the residual stress. In addition, the original reaction layer will be replaced by this layer, favorable for the increase in joining strength and fracture toughness. The brittle facture at the reaction layer in original joints can be transformed into the zig-zag path. The shear strength of joints with the thermal and electrochemical corrosion depth of 100 mu m increases to 151.6 MPa and 164.3 MPa, respectively, which is 77% and 92% higher than that of original joints.

关键词： Surface structure Fiber reinforcement c Sic composites Braze

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NbSe₂ Meets c₂N: A 2D-2D Heterostructure catalysts as Multifunctional Polysulfide Mediator in Ultra-Long-Life Lithium-Sulfur Batteries

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ADVANcED ENERGY MATERIALS 2021年第36期11卷

作者： Yang, Dawei Liang, Zhifu Zhang, chaoqi Jacas Biendicho, Jordi Botifoll, Marc chiara Spadaro, Maria chen, Qiulin Li, Mengyao Ramon, Alberto Moghaddam, Ahmad Ostovari Llorca, Jordi Wang, Jiaao Ramon Morante, Joan Arbiol, Jordi chou, Shu-Lei cabot, Andreu Catalonia Inst Energy Res IREC St Adria Besos Barcelona 08930 Spain Univ Barcelona Dept Elect & Biomed Engn Barcelona 08028 Spain CSIC Catalan Inst Nanosci & Nanotechnol ICN2 Campus UAB Barcelona 08193 Spain BIST Campus UAB Barcelona 08193 Spain Xiamen Univ Coll Mat Fujian Key Lab Mat Genome State Key Lab Phys Chem Solid Surfaces Xiamen 361005 Peoples R China South Ural State Univ 76 Lenin Ave Chelyabinsk 454080 Russia Univ Politecn Cataluna Inst Energy Technol Dept Chem Engn Barcelona 08019 Spain Univ Politecn Cataluna Barcelona Res Ctr Multiscale Sci & Engn Barcelona 08019 Spain Univ Texas Austin Dept Chem Austin TX 78712 USA Univ Texas Austin Oden Inst Computat Engn & Sci Austin TX 78712 USA ICREA Pg Lluis Companys 23 Barcelona 08010 Spain Univ Wollongong Inst Superconducting & Elect Mat Innovat Campus North Wollongong NSW 2500 Australia

The shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPS) hamper the practical application of lithium-sulfur batteries (LSBs). Toward overcoming these limitations, herein an in situ grown c2N@NbSe2 heterostructure is presented with remarkable specific surface area, as a Li-S catalyst and LiPS absorber. Density functional theory (DFT) calculations and experimental results comprehensively demonstrate that c2N@NbSe2 is characterized by a suitable electronic structure and charge rearrangement that strongly accelerates the LiPS electrocatalytic conversion. In addition, heterostructured c2N@NbSe2 strongly interacts with LiPS species, confining them at the cathode. As a result, LSBs cathodes based on c2N@NbSe2/S exhibit a high initial capacity of 1545 mAh g(-1) at 0.1 c. Even more excitingly, c2N@NbSe2/S cathodes are characterized by impressive cycling stability with only 0.012% capacity decay per cycle after 2000 cycles at 3 c. Even at a sulfur loading of 5.6 mg cm(-2), a high areal capacity of 5.65 mAh cm(-2) is delivered. These results demonstrate that c2N@NbSe2 heterostructures can act as multifunctional polysulfide mediators to chemically adsorb LiPS, accelerate Li-ion diffusion, chemically catalyze LiPS conversion, and lower the energy barrier for Li2S precipitation/decomposition, realizing the "adsorption-diffusion-conversion" of polysulfides.

关键词： c N-2 heterostructures lithium polysulfides lithium-sulfur batteries niobium selenides

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Long-term isothermal oxidation behavior of two industrial polycrystalline nickel base alloys in air at 700 °c-Evaluation of intergranular oxidation distribution and kinetic

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cORROSION ScIENcE 2021年 188卷

作者： Malacarne, R. Mathieu, S. Aranda, L. Vilasi, M. Desgranges, c. Knittel, S. Univ Lorraine CNRS IJL F-54000 Nancy France Safran Tech Rue Jeunes BoisCS 80112 F-78772 Magny Les Harneaux France Safran Aircraft Engines Rue Henri Auguste Desbrueres F-91000 Evry France

chromia forming Alloy 718 and AD730TM have been submitted to isothermal long-term air exposure up to 10 000 h at 700 degrees c. The resulting very low specific mass gain led to consider two alternatives to determine the oxidation kinetics. Measurements of the external layer thickness and of the intergranular oxide amount were carried out on SEM micrographs evidencing the intergranular oxidation contribute around 30% to the total specific mass change. AD730TM with a thicker external scale and a higher amount of intergranular oxide showed a twofold faster oxidation rate than Alloy718. The results demonstrated the need of even longer tests.

关键词： A Superalloys c High-temperature oxidation c Grain boundaries oxidation

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Experimental and theoretical investigation of reconstruction and active phases on honeycombed Ni3N-co3N/c in water splitting

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APPLIED cATALYSIS B-ENVIRONMENTAL 2021年 297卷

作者： Huang, chao Zhang, Biao Wu, Yuzheng Ruan, Qingdong Liu, Liangliang Su, Jianjun Tang, Yunqi Liu, Rugeng chu, Paul K. City Univ Hong Kong Dept Mat Sci & Engn Dept Phys Kowloon Tat Chee Ave Hong Kong Peoples R China City Univ Hong Kong Dept Biomed Engn Kowloon Tat Chee Ave Hong Kong Peoples R China Xiamen Univ State Key Lab Phys Chem Solid Surfaces Collaborat Innovat Ctr Chem Energy MatColl Chem Natl Engn Lab Green Chem Prod Alcohols Ethers & E Xiamen 361005 Peoples R China Harbin Engn Univ Coll Mat Sci & Chem Engn Minist Educ Key Lab Superlight Mat & Surface Technol Harbin 150001 Peoples R China

Honeycombed Ni3N-co3N decorated with carbon speckles (Ni3N-co3N/c) is prepared on nickel foam as a potent, economical, and durable water-splitting catalyst. The Ni3N-co3N/c system has excellent properties in the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), such as low overpotentials of 320/175 mV at 100 mA cm-2, small Tafel slopes of 55.2/70.2 mV dec- 1, as well as excellent stability for over 7 days. To demonstrate the commercial practicality, an overall water splitting cell composed of the bifunctional Ni3N-co3N/ c catalyst as both the anode and cathode is assembled and can be driven by a standard 1.5 V battery. Based on experimental and theoretical results obtained by in situ Raman scattering, ex situ XPS, and density-functional theory, the precise effects of the active sites and conductivity, roles of Ni3N, co3N, and c, and reaction mechanism in HER and OER, are investigated and described.

关键词： Water splitting Ni3N-co3N c Interface effect Surface reconstruction

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A Strategy for Polysulfides/Polyselenides Protection Based on co9S8@SiO2/c Host in Na-SeS2 Batteries

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ADVANcED FUNcTIONAL MATERIALS 2021年第2期31卷

作者： Yang Tingting Qi Yuruo Zhong Wei Tao Mengli Guo Bingshu Wu Yuanke Bao Shu-Juan Xu Maowen Southwest Univ Inst Clean Energy & Adv Mat Fac Mat & Energy Chongqing 400715 Peoples R China Southwest Univ Chongqing Key Lab Adv Mat & Clean Energies Techno Chongqing 400715 Peoples R China

To obtain unbroken sulfides with delicate morphology from metal-organic frameworks (MOFs), a method for in situ growth of SiO2 protective layers on the surface of MOFs is proposed. This strategy can be successfully expanded to a variety of MOFs (ZIF-67, cu-MOF, ZIF-8, and PBA). Importantly, room-temperature Na-SeS2 batteries with co9S8@SiO2/c prepared from ZIF-67 as cathode host are assembled. Due to the hollow structure that can relieve the volume expansion and the co-adsorption of sodium polysulfides/sodium polyselenides by co9S8@SiO2/c, the SeS2/co9S8@SiO2/c cathode shows excellent rate performance and coulombic efficiency. In addition, ex situ X-ray diffraction and in situ Raman results show that S-8 and Se-8 are generated after the discharge of SeS2, and Se-8 is preferentially oxidized during charging.

关键词： co9S8@SiO2 c hollow sulfides Na-SeS2 batteries shuttle effect

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The Role of the Reactive Species Involved in the Photocatalytic Degradation of HDPE Microplastics Using c,N-TiO₂ Powders

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POLYMERS 2021年第7期13卷 999-999页

作者： Vital-Grappin, Aranza Denisse Ariza-Tarazona, Maria camila Luna-Hernandez, Valeria Montserrat Villarreal-chiu, Juan Francisco Hernandez-Lopez, Juan Manuel Siligardi, cristina cedillo-Gonzalez, Erika Iveth Univ Autonoma Nuevo Leon Fac Ciencias Quim Ave Univ S-N Ciudad Univ San Nicolas De Los Garza 66455 Nuevo Leon Mexico Univ Modena & Reggio Emilia Dept Engn Enzo Ferrari Via P Vivarelli 10-1 I-41125 Modena Italy Univ Autonoma Nuevo Leon Ctr Invest Biotecnol & Nanotecnol CIByN Fac Ciencias Quim Parque Invest & Innovac Tecnol Apodaca 66629 Nuevo Leon Mexico

Microplastics (MPs) are distributed in a wide range of aquatic and terrestrial ecosystems throughout the planet. They are known to adsorb hazardous substances and can transfer them across the trophic web. To eliminate MPs pollution in an environmentally friendly process, we propose using a photocatalytic process that can easily be implemented in wastewater treatment plants (WWTPs). As photocatalysis involves the formation of reactive species such as holes (h(+)), electrons (e(-)), hydroxyl (OH?), and superoxide ion (O-2(?-)) radicals, it is imperative to determine the role of those species in the degradation process to design an effective photocatalytic system. However, for MPs, this information is limited in the literature. Therefore, we present such reactive species' role in the degradation of high-density polyethylene (HDPE) MPs using c,N-TiO2. Tert-butanol, isopropyl alcohol (IPA), Tiron, and cu(NO3)(2) were confirmed as adequate OH?, h(+), O-2(?-) and e(-) scavengers. These results revealed for the first time that the formation of free OH? through the pathways involving the photogenerated e(-) plays an essential role in the MPs' degradation. Furthermore, the degradation behaviors observed when h(+) and O-2(?-) were removed from the reaction system suggest that these species can also perform the initiating step of degradation.

关键词： microplastics HDPE microbeads photocatalysis scavengers c N-TiO2 remediation nanotechnology plastic pollution visible light photodegradation

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Al₂O₃:c optically stimulated luminescence dosimeters (OSLDs) for ultra-high dose rate proton dosimetry

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PHYSIcS IN MEDIcINE AND BIOLOGY 2021年第8期66卷

作者： christensen, Jeppe Brage Togno, Michele Nesteruk, Konrad Pawel Psoroulas, Serena Meer, David Weber, Damien charles Lomax, Tony Yukihara, Eduardo G. Safai, Sairos Paul Scherrer Inst Dept Radiat Safety & Secur Villigen Switzerland Paul Scherrer Inst Ctr Proton Therapy Villigen Switzerland Univ Hosp Zurich Dept Radiat Oncol Zurich Switzerland Univ Hosp Bern Dept Radiat Oncol Bern Switzerland Swiss Fed Inst Technol Dept Phys Zurich Switzerland

The response of Al2O3:c optically stimulated luminescence detectors (OSLDs) was investigated in a 250 MeV pencil proton beam. The OSLD response was mapped for a wide range of average dose rates up to 9000 Gy s(-1), corresponding to a similar to 150 kGy s(-1) instantaneous dose rate in each pulse. Two setups for ultra-high dose rate (FLASH) experiments are presented, which enable OSLDs or biological samples to be irradiated in either water-filled vials or cylinders. The OSLDs were found to be dose rate independent for all dose rates, with an average deviation <1% relative to the nominal dose for average dose rates of (1-1000) Gy s(-1) when irradiated in the two setups. A third setup for irradiations in a 9000 Gy s(-1) pencil beam is presented, where OSLDs are distributed in a 3 x 4 grid. calculations of the signal averaging of the beam over the OSLDs were in agreement with the measured response at 9000 Gy s(-1). Furthermore, a new method was presented to extract the beam spot size of narrow pencil beams, which is in agreement within a standard deviation with results derived from radiochromic films. The Al2O3:c OSLDs were found applicable to support radiobiological experiments in proton beams at ultra-high dose rates.

关键词： FLASH proton dosimetry optically stimulated luminescence Al2O3 c ultra-high dose rate

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Hybrid Metal-Boron Diatomic Site Embedded in c₂N Monolayer Promotes c-c coupling in cO₂ Electroreduction

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SMALL 2021年第42期17卷 e2104445页

作者： He, Miaomiao An, Wei Wang, Yuanqiang Men, Yong Liu, Shuang Shanghai Univ Engn Coll Chem & Chem Engn 333 Longteng Rd Shanghai 201620 Peoples R China

Double-atom catalyst (DAc) has gained much interest for its versatile tuning and synergistic effect of dual-atom active sites. Metal (M)-metal (M) diatomic sites, either homo- or heteronuclear, are typically researched. Hybrid metal-non-metal combined sites have rarely been studied and even the viability of such active sites are unknown. Herein, cO2 electroreduction (cO2RR) is explored on M@X-c2N (M = Fe, co, Ni, and cu;X = S, P, and B) which renders naturally generated M-X diatomic site. Using spin-polarized density functional theory coupled with computational hydrogen electrode model, it is demonstrated that the functionality of hybrid M-B dual-atom center is superior over that of a single- or double-M center in driving cO2RR especially c-c coupling. Among metal-boron DAcs studies, Fe@B-c2N (mu = 2 mu(B)) exhibits the lowest free energy barrier of 0.17 eV in c-c coupling whereas Ni@B-c2N (mu = 0 mu(B)) mainly produces cH4 with the lowest barrier of 0.42 eV. Hence, the electronic spin state of M can be particularly important in modulating selectivity and c-c coupling barrier in cO2RR. Fe@B-c2N is predicted as the promising catalyst for cO2RR towards c2+ products owing partially to its enhanced spin state. The findings can enrich the design strategy of electrocatalysts normally running at ambient conditions.

关键词： cO (2) electroreduction c-c coupling c N-2 double-atom catalyst density functional theory

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Damage behavior of atomic oxygen on a hafnium carbide-modified c/ Sic composite

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cOMPOSITES PART B-ENGINEERING 2021年 219卷

作者： Luan, Xingang Liu, Guanghai Tian, Min chen, Zhaoke cheng, Laifei Northwestern Polytech Univ Sci & Technol Thermostruct Composite Mat Lab Xian 710072 Peoples R China Natl Engn Res Ctr Ceram Matrix Composite Manufact Xian Peoples R China Cent South Univ State Key Lab Powder Met Changsha Peoples R China

capability of a Hfc-modified c/Sic (c/Sic-Hfc) composite against high-speed atomic oxygen (AO) atoms was evaluated in a ground-based low Earth orbit simulating system. Energy Dispersive Spectrum, Scanning Electron Microscopy, X-Ray Diffraction and Raman spectroscopy were employeed to investigate the damage behaviors of the material. The results show that Hfc was oxided by AO preferentially, while HfO2 and graphite films were its main products during AO exposure. The crystallization degree of the graphite film increased with the increasing of AO total flux. It's found that Sic areas had lower surface damage than Hfc areas, and SiO2 was its main reacting product. Ascribed to the evolution of surface craters, three-point bending strength of the specimens increased within the first 10 h exposure of AO and decreased thereafter. The damage mechanisms of AO over c/ Sic-Hfc were revealed also.

关键词： c Sic-Hfc Atomic oxygen Graphite film Damage mechanisms

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Glucose transformations over a mechanical mixture of ZnO and Ru/c catalysts: Product distribution, thermodynamics and kinetics

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cHEMIcAL ENGINEERING JOURNAL 2021年 405卷

作者： Aho, Atte Engblom, Simon Eranen, Kari Russo, Vincenzo Maki-Arvela, Paivi Kumar, Narendra Warna, Johan Salmi, Tapio Murzin, Dmitry Yu. Abo Akad Univ Johan Gadolin Proc Chem Ctr Lab Ind Chem & React Engn FI-20500 Turku Finland Univ Napoli Federico II Chem Sci IT-80126 Naples Italy

Transformations of glucose to 1,2-propylene glycol were studied over a mechanical mixture of ZnO and Ru/c catalysts in the presence of hydrogen. Different reaction conditions were evaluated by changing the reaction temperature and hydrogen pressure. In addition to the cascade mode of operation, also separate steps in the overall reaction network, such as hydrogenation of pyruvaldehyde and hydroxyacetone to 1,2-propylene glycol were investigated. Fructose as a starting material was also studied resulting in a propylene glycol yield of 37.5%. The optimal temperature for glucose transformation to propylene glycol was found to be 165 degrees c. The influence of temperature on the catalytic behavior was more prominent than the effect of hydrogen pressure. Thermodynamic analysis of glucose transformation to 1,2-propylene glycol was performed and a plausible kinetic model reflecting a complex reaction network was developed being able to describe the data in a reliable way.

关键词： Glucose Hydrogenolysis 1 2-Propylene glycol Heterogeneous catalysts ZnO Ru c Optimization of reaction conditions Kinetic modelling Thermodynamic analysis

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