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Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

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Carbon Energy 2024年第4期6卷 128-139页

作者： Xiang jun Pu Kunran Yang Zibing Pan Chunhua Song Yangyang Lai Renjie Li Zheng‐Long Xu Zhongxue Chen Yuliang Cao Hubei key laboratory of Electrochemical Power Sources College of Chemistry and Molecular SciencesWuhan UniversityWuhanChina key laboratory of hydraulic machinery transients Ministry of EducationSchool of Power and Mechanical EngineeringWuhan UniversityWuhanChina School of Chemistry and Chemical Engineering Jiangsu University of TechnologyChangzhouJiangsuChina Zonergy Corporation ZigongSichuanChina Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHung HomHong Kong SARChina

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P2O7 unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

关键词： extending solid‐solution range off‐stoichiometric Na_(3)Fe_(2.5)(P_(2)O_(7))_(2) sodium‐ion batteries structure-function relationship

Hole cleaning evaluation and installation spacing optimization of cuttings bed remover in extended-reach drilling

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Petroleum Science 2024年第3期21卷 2005-2022页

作者： Shuo Peng Wen-Jun Huang De-Li Gao moe key laboratory of Petroleum Engineering China University of Petroleum-Beijing State key laboratory of Petroleum Resources and Engineering China University of Petroleum-Beijing

In extended-reach or long-horizontal drilling, cuttings usually deposit at the bottom of the annulus. Once cuttings accumulate to a certain thickness, complex problems such as excessive torque and drag, tubing buckling, and pipe stuck probably occur, which results in a lot of non-productive time and remedial operations. Cuttings bed remover can efficiently destroy deposited cuttings in time through hydraulic and mechanical stirring effects. This paper aims to build a method for hole cleaning evaluation and installation spacing optimization of cuttings bed remover to improve the wellbore cleaning effect. Firstly,a Computational Fluid Dynamics approach with Eulerian—Eulerian multiphase model was utilized to investigate the mechanism of cuttings transportation, and a new type of cuttings bed remover was designed. Next, an evaluation method of hole cleaning effect of remover was established. After that, the effects of several drilling parameters on hole cleaning including flow rate of drilling fluid, rotational speed of drillpipe, rate of penetration, wellbore size, rheological property of drilling fluid, and remover eccentricity on the performance of cuttings bed remover were investigated. The results demonstrate that the new type of remover with streamline blade performs better than conventional removers. The efficiency of hole cleaning is greatly improved by increasing the rotational speed of drillpipe, flow rate of drilling fluid, remover eccentricity, and 6 rpm Fann dial reading for drilling fluid. While higher rate of penetration and large wellbore size result in worse hole cleaning. These findings can serve as an important guide for the structure optimization design of cuttings bed remover and installation spacing of removers.

关键词： Extended-reach drilling Drilling hydraulics Cuttings transport Hole cleaning Cuttings bed remover

Broadband light management in hydrogel glass for energy efficient windows

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Frontiers of Optoelectronics 2022年第3期15卷 45-53页

作者： Jia Fu Chunzao Feng Yutian Liao Mingran Mao Huidong Liu Kang Liu moe key laboratory of hydraulic machinery transients School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China Wuhan National laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

Windows are critically important components in building envelopes that have a signifcant efect on the integral energy budget.For energy saving,here we propose a novel design of hydrogel-glass which consists of a layer of hydrogel and a layer of normal glass.Compared with traditional glass,the hydrogel-glass possesses a higher level of visible light transmission,stronger near-infrared light blocking,and higher mid-infrared thermal emittance.With these properties,hydrogel-glass based windows can enhance indoor illumination and reduce the temperature,reducing energy use for both lighting and cooling.Energy savings ranging from 2.37 to 10.45 MJ/m2 per year can be achieved for typical school buildings located in diferent cities around the world according to our simulations.With broadband light management covering the visible and thermal infrared regions of the spectrum,hydrogel-glass shows great potential for application in energy-saving windows.

关键词： Hydrogel Light management Windows Energy saving Broadband

Seasonal compensation implied no weakening of the land carbon sink in the Northern Hemisphere under the 2015/2016 El Niño

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Science China Earth Sciences 2024年第1期67卷 281-294页

作者： Fangzhong SHI Xiuchen WU Xiaoyan LI Philippe CIAIS Hongyan LIU Chao YUE Yuting YANG Shulei ZHANG Shushi PENG Yi YIN Benjamin POULTER Deliang CHEN State key laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China key laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation Qinghai Normal UniversityXining 810016China Research and Development Center for Watershed Environmental Eco-Engineering Beijing Normal University(Zhuhai)Zhuhai 519085China Laboratoire des Sciences du Climat et de l’Environnement(LSCE) CEA-CNRS-UVSQUMR821291191Gif-sur-YvetteFrance College of Urban and Environmental Science MOE Laboratory for Earth Surface ProcessesPeking UniversityBeijing 100871China State key laboratory of Hydroscience and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) School of Atmospheric SciencesSun Yat-sen UniversityGuangzhou 510275China California Institute of Technology PasadenaCA 91125USA Biospheric Sciences laboratory NASA Goddard Space Flight CenterGreenbeltMaryland 20771USA Regional Climate Group Department of Earth SciencesUniversity of GothenburgGothenburg SE-40530Sweden

The recurrent extreme El Niño events are commonly linked to reduced vegetation growth and the land carbon sink over many but discrete regions of the Northern Hemisphere(NH).However,we reported here a pervasive and continuous vegetation greening and no weakened land carbon sink in the maturation phase of the 2015/2016 El Niño event over the NH(mainly in the extra-tropics),based on multiple evidences from remote sensing observations,global ecosystem model simulations and atmospheric CO_(2)inversions.We discovered a significant compensation effect of the enhanced vegetation growth in spring on subsequent summer/autumn vegetation growth that sustained vegetation greening and led to a slight increase in the land carbon sink over the spring and summer of 2015(average increases of 23.34%and 0.63%in net ecosystem exchange from two independent datasets relative to a 5-years average before the El Niño event,respectively)and spring of 2016(6.82%),especially in the extra-tropics of the NH,where the water supply during the pre-growing-season(November of the previous year to March of the current year)had a positive anomaly.This seasonal compensation effect was much stronger than that in 1997 and 1998 and significantly alleviated the adverse impacts of the 2015/2016 El Niño event on vegetation growth during its maturation phase.The legacy effect of water supply during the pre-growing-season on subsequent vegetation growth lasted up to approximately six months.Our findings highlight the role of seasonal compensation effects on mediating the land carbon sink in response to episodic extreme El Niño events.

关键词： El Niño Seasonal compensation effect Vegetation greening Land carbon sink Net ecosystem exchange Legacy effect

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A highly active and stable Sr_(2)Fe_(1.5)Mo(0.5)O_(6)‑δ‑Ce_(0.8)Sm_(0.2)O_(1.95)ceramic fuel electrode for efficient hydrogen production via a steam electrolyzer without safe gas

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International Journal of Coal Science & Technology 2022年第1期9卷 217-224页

作者： Yao Wang Tong Liu key laboratory of hydraulic machinery transients Ministry of EducationSchool of Power and Mechanical EngineeringWuhan UniversityHubei 430072 WuhanChina

High temperature steam(H_(2)O)electrolysis via a solid oxide electrolysis cell is an efficient way to produce hydrogen(H_(2))because of its high energy conversion efficiency as well as simple and green process,especially when the electrolysis process is combined with integrated gasification fuel cell technology or derived by renewable energy.However,about 60%-70%of the electricity input is consumed to overcome the large oxygen potential gradient but not for electrolysis to split H_(2)O to produce H_(2)due to the addition of safe gas such as H_(2)in the fuel electrode.In this work,Sr_(2)Fe_(1.5)Mo_(0.5)O_(6)-δ-Ce_(0.8)Sm_(0.2)O_(1.95)(SFM-SDC)ceramic composite material has been developed as fuel electrode to avoid the use of safe gas,and the open circuit voltage(OCV)has been effectively lowered from 1030 to 78 mV when the feeding gas in the fuel electrode is shifted from 3%H_(2)O-97%H_(2)to 3%H_(2)O-97%N_(2),reasonably resulting in a significantly increased electrolysis efficiency.In addition,it is also demonstrated that the electrolysis current density is greatly enhanced by increasing the humidity in the fuel electrode and the working temperature.A considerable electrolysis current density of−0.54 A/cm^(2)is obtained at 800°C and 0.4 V for the symmetrical electrolyzer by exposing SFM-SDC fuel electrode to 23%H_(2)O-77%N_(2),and durability test at 800°C for 35 h demonstrates a relatively stable electrochemical performance for steam electrolysis under the same operation condition without safe gas and a constant electrolysis current density of−0.060 A/cm2.Our findings achieved in this work indicate that SFM-SDC is a highly promising fuel electrode for steam electrolysis.

关键词： Solid oxide electrolysis cell Steam electrolysis Fuel electrode Molybdenum doped strontium ferrite Safe gas

Programmable microfluidics for dynamic multiband camouflage

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Microsystems & Nanoengineering 2023年第2期9卷 275-282页

作者： Chunzao Feng Mingran Mao Xiaohui Zhang Yutian Liao Xiaohui Xiao Huidong Liu Kang Liu moe key laboratory of hydraulic machinery transients School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072 HubeiChina

Achieving multiband camouflage covering both visible and infrared regions is challenging due to the broad bandwidth and differentiated regulation demand in diverse regions.In this work,we propose a programmable microfluidic strategy that uses dye molecules in layered fluids to manipulate visible light-and infrared-semitransparent solvent to manipulate infrared light.With three primary fluid inputs,we achieve 64 chromaticity values and 8 emissivities from 0.42 to 0.90.In view of the wide tuning range,we demonstrate that the microfluidic flm can dynamically change its surface reflectance to blend into varying backgrounds in both visible and infrared images.Moreover,we fabricate the microfluidic device in a textile form and demonstrate its ability to match exactly with the colors of natural leaves of different seasons in the full hyperspectrum range.Considering the broadband modulation and ease of operation,the programmable microfluidic strategy provides a feasible approach for smart optical surfaces in long-span optical spectra.

关键词： multiband tuning visible

Non-contact optical characterization of negative pressure in hydrogel voids and microchannels

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Frontiers of Optoelectronics 2022年第1期15卷 113-120页

作者： Shihao Xu Xiaowei Liu Zehua Yu Kang Liu moe key laboratory of Hydrodynamic transients School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China Wuhan National laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

Negative pressure in water under tension,as a thermodynamic non-equilibrium state,has facilitated the emergence of inno-vative technologies on microfluidics,desalination,and thermal management.However,the lack of a simple and accurate method to measure negative pressure hinders further in-depth understanding of the properties of water in such a state.In this work,we propose a non-contact optical method to quantify the negative pressure in micron-sized water voids of a hydrogel film based on the microscale mechanical deformation of the hydrogel itself.We tested three groups of hydrogel samples with different negative pressure inside,and the obtained results fit well with the theoretical prediction.Furthermore,we demonstrated that this method can characterize the distribution of negative pressure,and can thus provide the possibility of investigation of the flow behavior of water in negative pressure.These results prove this technique to be a promising approach to characterization of water under tension and for investigation of its properties under negative pressure.

关键词： Hydrogel Negative pressure Non-contact Optical

Fracture toughness and destructive mechanism of ductile nanoporous metallic glass and its crystal-impregnated nanocomposite

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Science China(Technological Sciences) 2023年第11期66卷 3328-3342页

作者： ZHANG YuHang XU JianFei HU YiQun SU Lei DING SuHang WU WenWang XIA Re key laboratory of hydraulic machinery transients(Wuhan University) Ministry of EducationWuhan 430072China Department of Engineering Mechanics School of Naval ArchitectureOcean&Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Nanoporous metallic glasses(NPMGs)and crystalline/amorphous nanocomposites exhibit superior ductility over bulk macroscopic metallic glasses(MGs).Their fracture behaviors remain a mystery due to experimental technical limitations.In this work,the fracture behaviors of pre-cracked NPMGs and crystal-impregnated nanoporous metallic glasses(CINPMGs)are investigated through large-scale molecular dynamics simulations,and the MG and crystal phases are amorphous Cu_(50)Zr_(50)and crystalline B2CuZr,respectively.Fracture toughness is determined by simultaneously considering the surface energy and plastic dissipated energy.Our results confirm the excellent plasticity of both the pre-cracked NPMGs and CINPMGs.The progressive necking and ductile rupture of ligaments are responsible for generating NPMGs with prominent ductility and fracture toughness.Meanwhile,secondary cracking is also triggered,which can consume energy without extending the major crack,thus further improving fracture resistance.It is also found that the fracture toughness of NPMGs can be improved by increasing the solid fraction of MG,and linear relation between fracture toughness and solid fraction can be expected.Crystal impregnation effectively inhibits global failure as the crystal phase shields the individual amorphous ligaments.Homogeneous plastic flow characterized by shear bands is observed in CINPMGs,and this homogeneous global deformation is facilitated by the crystalline/amorphous interface.Besides,the fracture toughness of CINPMGs is higher than that of the constituent single phases,regardless of the volume fraction of each phase.Ashby material charts manifest that these two types of materials demonstrate promising potential in the material selection library for advanced structural design.

关键词： nanoporous metals crack fracture toughness nanocomposites metallic glasses

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Simulations of Tapered Channel in Multilayer Graphene as Reverse Osmosis Membrane for Desalination

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Journal of Wuhan University of Technology(Materials Science) 2022年第3期37卷 314-323页

作者：王天振 CHEN Bo SHAO Xingyu ZHENG Huai 胡雪蛟江海峰 key laboratory of hydraulic machinery transients(Wuhan University) Ministry of EducationSchool of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China Research Institute of Tsinghua University in Shenzhen Shenzhen 518071China

Pressure-driven reverse osmosis membrane has important application in seawater desalination.Inspired by the structure of aquaporin,we established and studied the mechanism of the structure of multilayer graphene with tapered channels as reverse osmosis.The water flux of multilayer graphene with tapered channels was about 20%higher than that of parallel graphene channel.The flow resistance model was established,and the relationship between flow resistance and opening angles was clarified.The relationship between flow resistance and outlet size was also described.By means of molecular dynamics simulation,slip coefficients of multilayer graphene with tapered channel were obtained and verified by the contact angle of water.Results show that the permeability of graphene with tapered channel is about three orders of magnitude higher than that of commercial reverse osmosis membrane and the desalination rate is 100%.Temperature difference between the two sides of the tapered channel will promote the water flux positively.

关键词： multilayer graphene molecular dynamics tapered channel opening angles reverse osmosis

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