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Unveiling the size effect of nitrogen-doped carbon-supported copper-based catalysts on nitrate-to-ammonia electroreduction

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Nano Research 2024年第4期17卷 2438-2443页

作者： Ran Li Taotao Gao Wenxi Qiu Minghao Xie Zhaoyu Jin Panpan Li College of Materials Science and Engineering Sichuan UniversityChengdu 610065China Institute for Advanced Study Chengdu UniversityChengdu 610106China Materials Science and Engineering Program and Walker Department of Mechanical Engineering The University of Texas at AustinAustinTexas 78712USA Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China

The electrocatalytic nitrate reduction reaction(NitRR)represents a promising approach toward achieving economically and environmentally sustainable ammonia.However,it remains a challenge to regulate the size effect of electrocatalysts to optimize the catalytic activity and ammonia selectivity.Herein,the Cu-based catalysts were tailored at the atomic level to exhibit a size gradient ranging from single-atom catalysts(SACs,0.15–0.35 nm)to single-cluster catalysts(SCCs,1.0–2.8 nm)and nanoparticles(NPs,20–30 nm),with the aim of studying the size effect for the NO_(3)^(-)-to-NH_(3) reduction reaction.Especially,the Cu SCCs exhibit enhanced metal–substrate and metal–metal interactions by taking advantageous features of Cu SACs and Cu NPs.Thus,Cu SCCs achieve exceptional electrocatalytic performance for the NitRR with a maximum Faradaic efficiency of ca.96%NH_(3)and the largest yield rate of ca.1.99 mg·h^(-1)·cm^(-2) at-0.5 V vs.reversible hydrogen electrode(RHE).The theoretical calculation further reveals the size effect and coordination environment on the high catalytic activity and selectivity for the NitRR.This work provides a promising various size-controlled design strategy for aerogel-based catalysts effectively applied in various electrocatalytic reactions.

关键词： nitrate electroreduction ammonia electrosynthesis size effect single-cluster catalyst

Experimental study on the size effect on the equation of state of concretes under shock loading

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Defence Technology（防务技术） 2024年第3期33卷 160-167页

作者： Mei Li Jian Cui Yanchao Shi Baijian Tang Xin Chen Key Laboratory of Coast Civil Structural Safety of the Ministry of Education Tianjin UniversityTianjin 300072China School of Civil Engineering Suzhou University of Science and Technology1701 Binhe RoadSuzhou 215011JiangsuChina School of Civil Engineering Tianjin UniversityTianjin 300072China

Adopting the classical theory of hydrocodes,the constitutive relations of concretes are separated into an equation of state(EoS)which describes the volumetric behavior of concrete material and a strength model which depicts the shear properties of concrete.The experiments on the EoS of concrete is always challenging due to the technical difficulties and equipment limitations,especially for the specimen size effect on the EoS.Although some researchers investigate the shock properties of concretes by fly-plate impact tests,the specimens used in their tests are usually in one size.In this paper,the fly-plate impact tests on concrete specimens with different sizes are performed to investigate the size effect on the shock properties of concrete materials.The mechanical background of the size effect on the shock properties are revealed,which is related to the lateral rarefaction effect and the deviatoric stress produced in the specimen.According to the tests results,the modified EoS considering the size effect on the shock properties of concrete are proposed,which the bulk modulus of concrete is unpredicted by up to 20% if size effects are not accounted for.

关键词： Concrete Equation of state size effect Shock wave Fly-plate impact test

Revealing the size effect of Fe S2on solid-state battery performances at different operating temperatures

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Chinese Chemical Letters 2024年第6期35卷 189-194页

作者： Chaochao Wei Ru Wang Zhongkai Wu Qiyue Luo Ziling Jiang Liang Ming Jie Yang Liping Wang Chuang Yu School of Chemistry and Chemical Engineering Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China School of Materials and Energy University of Electronic Science and Technology of ChinaChengdu 611731China

FeS_(2) shows significant potential as cathode material for all-solid-state lithium batteries(ASSLBs)due to its high theoretical specific capacity,low cost,and environmental friendliness.However,the poor ion/electron conductivity and large volume variation effect of FeS_(2) inhibit its practical applications.Here,the influence of particle size of FeS_(2) on the corresponding sulfide-based solid-state batteries is carefully investigated by tuning FeS_(2) size.Moreover,low operating temperature is chosen to mitigate the large volume changes during cycling in the battery.S-FeS_(2) with smaller particle sizes delivers superior electrochemical performances than that of the larger L-FeS_(2) in Li_(5.5)PS_(4.5)Cl_(1.5)-based ASSLBs under different operating temperatures.S-FeS_(2) shows stable discharge capacities during 50 cycles with a current density of 0.1 m A/cm^(2)under -20℃.When the current density rises to 1.0 m A/cm^(2),it delivers an initial discharge capacity of 146.9 m Ah/g and maintains 63% of the capacity after 100 cycles.This work contributes to constructing ASSLBs enables excellent electrochemical performances under extreme operating temperatures.

关键词： FeS_(2) size effect Li_(5.5)PS_(4.5)Cl_(1.5) electrolytes Operating temperatures Electrochemical performances

240 nm AlGaN-based deep ultraviolet micro-LEDs:size effect versus edge effect

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Journal of Semiconductors 2024年第1期45卷 55-62页

作者： Shunpeng Lu Jiangxiao Bai Hongbo Li Ke Jiang Jianwei Ben Shanli Zhang Zi-Hui Zhang Xiaojuan Sun Dabing Li State Key Laboratory of Luminescence and Applications Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Key Laboratory of Electronic Materials and Devices of Tianjin School of Electronics and Information EngineeringHebei University of TechnologyTianjin 300401China

240 nm AlGaN-based micro-LEDs with different sizes are designed and fabricated.Then,the external quantum efficiency(EQE)and light extraction efficiency(LEE)are systematically investigated by comparing size and edge effects.Here,it is revealed that the peak optical output power increases by 81.83%with the size shrinking from 50.0 to 25.0μm.Thereinto,the LEE increases by 26.21%and the LEE enhancement mainly comes from the sidewall light extraction.Most notably,transversemagnetic(TM)mode light intensifies faster as the size shrinks due to the tilted mesa side-wall and Al reflector design.However,when it turns to 12.5μm sized micro-LEDs,the output power is lower than 25.0μm sized ones.The underlying mechanism is that even though protected by SiO2 passivation,the edge effect which leads to current leakage and Shockley-Read-Hall(SRH)recombination deteriorates rapidly with the size further shrinking.Moreover,the ratio of the p-contact area to mesa area is much lower,which deteriorates the p-type current spreading at the mesa edge.These findings show a role of thumb for the design of high efficiency micro-LEDs with wavelength below 250 nm,which will pave the way for wide applications of deep ultraviolet(DUV)micro-LEDs.

关键词： AlGaN deep ultraviolet micro-LEDs light extraction efficiency size effect edge effect

The Role of the size effect on the Drying of Refractory Castables—How Its Under-standing Could Narrow the Gap between Laboratory Studies and Industrial Reality

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China's Refractories 2024年第2期33卷 35-40页

作者： M.H.MOREIRA H.PENG S.Dal PONT V.C.PANDOLFELLI Materials Engineering Department Federal University of São Carlos(UFSCar)São Carlos 13565-905Brazil Materials Innovation Elkem Silicon Products DevelopmentKristiansand 4621Norway CNRS Grenoble INP3SRUniversitéGrenoble AlpesGrenoble 38000France

Refractories have unique capabilities such as sustaining their shape and properties at extreme conditions such as the combination of high temperatures and thermal shock,contact with molten metals and slags and in some circumstances resistance to erosion from abrasive particles.Given the large processing output of the heavy industries such as the cement and steel ones which both require high temperature processes,the refractories structures span various meters and weight of several tons.As the water removal stage of hydraulic bonded castables in industrial sites takes hours(10-60 h)due to the risk of explosive spalling,efforts to mitigate it are commonly studied.This has provided theoretical understanding of the general aspects of drying and important tools,such as the thermogravimetry analysis(TGA),for the design of refractory compositions with higher explosive spalling resistance.However,the optimization of this process is still far from the industrial reality especially because the actual linings that require the drying are orders of magnitude larger than the samples considered in the laboratory tests.Therefore,this study proposed the analysis of the sample volume effect on the water removal dynamics through TGA of high alumina castables with calcium aluminate cement.Conventionalφ5 cm×5 cm cylindrical samples were assessed in a laboratory scale equipment whereas macro TGA were carried out considering 20 cm×20 cm×20 cm and 30 cm×30 cm×30 cm cubic samples.Additionally,the effect of polymeric fibers was also considered.It was found out that the different thermal gradients within the macro TGA samples resulted in an inflection on the sample’s heating rate and that the mass loss was affected by the volume considered,especially for the composition without additives.These findings highlight the requirement of carefully taking into consideration the different dimensional sizes and thermal gradients in the samples when analyzing and interpreting the laboratory studies,and especially when trying to extrapolate such resul

关键词： drying refractory castables size effect thermogravimetry analysis

size-effect on Ni electrocatalyst:The case of electrochemical benzyl alcohol oxidation

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Nano Research 2023年第1期16卷 202-208页

作者： Jian Zhong Yongli Shen Pei Zhu Shuang Yao Changhua An Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion School of Chemistry and Chemical EngineeringTianjin University of TechnologyTianjin 300384China Tianjin Key Laboratory of Advanced Functional Porous Materials Institute for New Energy Materials&Low-Carbon TechnologiesSchool of Materials Science and EngineeringTianjin University of TechnologyTianjin 300384China

The nanoparticles(NPs)of Ni with different sizes endows its distinctive physical and chemical properties,which represents a typical strategy for the development of high-performance catalysts.However,the size effect of metallic Ni-NPs on electrocatalytic performance remains ambiguous.Herein,the Ni-NPs with different sizes supported on nitrogen doped carbon(NC)has been synthesized by controlling the pyrolysis temperature,leading to the synthesis of Ni@NC-500(8.3 nm),Ni@NC-280(1.9 nm)and Ni@NC-200(1.0 nm).The electrooxidation of benzyl alcohol(BA)over these nanocatalysts shows the yield of benzoic acid was 99%,82%,55%on Ni@NC-280,Ni@NC-200 and Ni@NC-500,respectively.The experimental and theoretical simulation demonstrate that the difference in the adsorption strength of reactant molecules by Ni-NPs is responsible for their different performance,where the Ni@NC-280 exhibits an optimal adsorption configuration between Ni@NC-280 electrode and BA.This work provides a new angle for designing and synthesizing efficient electrocatalysts,which may be extended to the exploration of various promising electrocatalytic systems.

关键词： size effect electro-oxidation Ni nanoparticles benzyl alcohol

size effect enabling additive-free MXene ink with ultrahigh conductivity for screen printing of wireless electronics

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Nano Research 2023年第8期16卷 11012-11017页

作者： Shuaishuai Chen Huaqiang Fu Yunfa Si Xueyu Liu Zhe Wang Yixue Duan Zixin Zhang Hao Feng Xin Zhao Daping He State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China Hubei Engineering Research Center of RF-Microwave Technology and Application Wuhan University of TechnologyWuhan 430070China School of Science Wuhan University of TechnologyWuhan 430070China

Facile preparation of additive-free inks with both high viscosity and high conductivity is critical for scalable screen printing of wireless electronics,yet very challenging.MXene materials exhibit excellent conductivity and hydrophilicity,showing great potential in the field of additive-free inks for screen printing.Here,we demonstrate the synthesis of additive-free two-dimensional(2D)titanium carbide MXene inks,and realize screen-printed MXene wireless electronics for the first time.The viscosity of MXene ink is solely regulated by tuning the size of MXene nanosheet without any additives,hence rendering the printed MXene film extremely high conductivity of 1.67×10^(5) S/m and fine printing resolution down to 0.05 mm on various flexible substrates.Moreover,radio frequency identification(RFID)tags fabricated using the additive-free MXene ink via screen printing exhibit stable antenna reading performance and superb flexibility.This article,thus offers a new route for the efficient,low-cost and pollution-free manufacture of printable electronics based on additive-free MXene inks.

关键词： size effect additive-free MXene ink screen printing wireless electronics radio frequency identification(RFID)

size effect of fracture characteristics for anisotropic quasi-brittle geomaterials

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International Journal of Mining Science and Technology 2023年第2期33卷 201-213页

作者： Cunbao Li Dongchao Yang Heping Xie Li Ren Jun Wang Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization Institute of Deep Earth Sciences and Green EnergyShenzhen UniversityShenzhen 518060China Shenzhen Key Laboratory of Deep Engineering Sciences and Green Energy College of Civil and Transportation EngineeringShenzhen UniversityShenzhen 518060China MOE Laboratory of Deep Earth Science and Engineering Sichuan UniversityChengdu 610065China

Understanding the size effect exhibited by the fracture mechanism of anisotropic geomaterials is important for engineering practice. In this study, the anisotropic features of the nominal strength, apparent fracture toughness, effective fracture energy and fracture process zone(FPZ) size of geomaterials were first analyzed by systematic size effect fracture experiments. The results showed that the nominal strength and the apparent fracture toughness decreased with increasing bedding plane inclination angle.The larger the specimen size was, the smaller the nominal strength and the larger the apparent fracture toughness was. When the bedding inclination angle increased from 0° to 90°, the effective fracture energy and the effective FPZ size both first decreased and then increased within two complex variation stages that were bounded by the 45° bedding angle. Regardless of the inherent anisotropy of geomaterials,the nominal strength and apparent fracture toughness can be predicted by the energy-based size effect law, which demonstrates that geomaterials have obvious quasi-brittle characteristics. Theoretical analysis indicated that the true fracture toughness and energy dissipation can be calculated by linear elastic fracture mechanics only when the brittleness number is higher than 10;otherwise, size effect tests should be adopted to determine the fracture parameters.

关键词： size effect Inherent anisotropy Fracture toughness Fracture energy effective FPZ size Quasi-brittle geomaterials

size effect on the microstructure, phase transformation behavior, and mechanical properties of NiTi shape memory alloys fabricated by laser powder bed fusion

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Journal of Materials Science & Technology 2023年第26期157卷 200-212页

作者： Hao Jiang Xiebin Wang Rui Xi Guichuan Li Huiliang Wei Jiangwei Liu Bo Zhang Sergey Kustov Kim Vanmeensel Jan Van Humbeeck Guoqun Zhao Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan 250061China Department of Materials Engineering University of Leuven(KU Leuven)Heverlee B3001Belgium School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Energy and Power Engineering Shandong UniversityJinan 250061China Shandong Institute of Medical Device and Pharmaceutical Packaging Inspection Jinan 250101China Departament de Física Universitat de les Illes BalearsCra Valldemossa km 7.5Palma de Mallorca E07122Spain

In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation behavior,and mechanical properties of the sample with different thicknesses are studied.The results indicate a strong size effect in the LPBF-fabricated NiTi alloy.The decrease of the sample thickness results in(i)the increase of porosity,(ii)the decrease of the number of adhered NiTi powder particles at the surface,(iii)the monotonous decrease of the martensitic transformation temperatures(MTTs),and(iv)the decrease of the shape recovery temperature.The influence of sample thickness on the melt-pool behavior,and thus the microstructure and performance of NiTi alloys are discussed.It is suggested that the melt-pool is deeper and narrower in the thin samples than in the thick samples.We conclude that,apart from the LPBF process conditions,the sample dimensions have also to be considered to fabricate NiTi structures with predictable properties.

关键词： Shape memory alloy NiTi Additive manufacturing Laser powder bed fusion size effect