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Unique landslides (loess slide-flows) induced by an extreme rainstorm in 2018 on the Loess Plateau: A new geological hazard and erosion process

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International Journal of Sediment Research 2023年第2期38卷 228-239页

作者： Li luo Wen-Zhao Guo Pei Tian Yi-li Liu Shao-Kun Wang Jia-Wei Luo State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau/College of Water Resources and Architectural Engineering Northwest Agriculture and Forestry University State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of Technology Key Laboratory for Geographical Process Analysis & Simulation of Hubei Province Central China Normal University

Currently, the vegetation has recovered well in most areas of the Loess Plateau in China, and soil erosion has significantly decreased. However, the heavy rainfall event in July 2018 triggered many instances of a unique type of loess landslides(i.e., slide-flows) on the gully-slopes with vegetation recovery in the Nanxiaohegou Basin on the Loess Plateau. This rainfall event was unusual and was a persistent heavy rainfall. The accumulated rainfall from 24 June to 10 July was 232.2 mm, which comprised 42% of the mean annual rainfall. A loess slide-flow is characterized by combining two movement types of the slide and flow. The loess slide-flows first slide on the gully-slopes and then turn into long run-out earthflows moving downstream, delivering vast amounts of sediment to the river. The average landslide erosion rates were 110.8-134.9 kg/m2. These loess slide-flows generally did not occur individually but in groups,which were characterized by large numbers, high density, small scale, and shallow depth. The changes of vegetation characteristics and soil characteristics both had a significant impact on the scale of the landslides. Grass with high coverage had an adverse effect on the occurrence of shallow landslides. The adverse hydrological effects of the plant may offset the weak root reinforcement. Loess slide-flows have become a new geological hazard and erosion process on the Loess Plateau. Loess slide-flows are a prominent ecological and environmental problem after vegetation restoration, and more attention should be paid to loess slide-flows in the future.

关键词： Loess plateau Landslide Soil erosion Vegetation Rainfall

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Progress of hidden spin polarization in inversion-symmetric crystals

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Science China(Physics,Mechanics & Astronomy) 2022年第3期65卷 1-18页

作者： Shan Guan jia-Xin Xiong Zhi Wang Jun-wei luo State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China Beijing Academy of Quantum Information Sciences Beijing 100193China

Hidden spin polarization refers to that doubly degenerate bands protected by combined inversion and time-reversal symmetry in nonmagnetic inversion-symmetric crystals could have opposite non-zero local spin polarizations, which are spatially separated in two real-space sectors paired by the inversion symmetry. Since its first prediction from ab initio calculation, hidden spin polarization has inspired tremendous interest and has been observed experimentally due to its intriguing fundamental properties as well as the great potential for applications. Moving forward, the search for moment-dependent spin splitting has also been extended to antiferromagnets even without considering spin-orbit coupling. This paper systematically reviews recent works in this field with a focus on basic concepts and material realization. It also details several remaining bottlenecks and suggests possible avenues for future research.

关键词： spin-orbit coupling hidden spin polarization tight-binding model ab initio calculation

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Identification of in situ Generated Iron-Vacancy Induced Oxygen Evolution Reaction Kinetics on Cobalt Iron Oxyhydroxide

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Chinese Journal of Chemistry 2024年第4期42卷 343-350页

作者： Na Yao Juan Zhu Hongnan jia Hengjiang Cong wei luo College of Chemistry and Molecular Sciences Wuhan UniversityWuhanHubei430072 China

Developing highly efficient and low-cost electrocatalysts towards oxygen evolution reaction(OER)is essential for practical application in water electrolyzers and rechargeable metal-air batteries.Although Fe-based oxyhydroxides are regarded as state-of-the-art non-noble OER electrocatalysts,the origin of performance enhancement derived from Fe doping remains a hot topic of considerable discussion.Herein,we demonstrate that in situ generated Fe vacancies in the pristine CoFeOOH catalyst through a pre-conversion process during alkaline OER result from dynamic Fe dissolution,identifying the origin of Fe-vacancy-induced enhanced OER kinetics.Density functional theory(DFT)calculations and experimental results including X-ray absorption fine-structure spectroscopy,in situ UV-Vis spectroscopy,and in situ Raman spectroscopy reveal that the Fe vacancies could significantly promote the d-band center and valence states of adjacent Co sites,alter the active site from Fe atom to Co atom,accelerate the formation of high-valent active Co^(4+)species,and reduce the energy barrier of the potential-determining step,thereby contribute to the significantly enhanced OER performance.

关键词： CoFe oxyhydroxide Oxygen evolution reaction Fe vacancy Electrocatalysis Kinetics Reaction mechanisms

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Mechanism of thermoviscoelasticity driven solid-liquid interface reducing friction for polymer alloy coating

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Friction 2023年第9期11卷 1606-1623页

作者： Sheng TAN Yimin luo Junhua YANG wei WANG Xia LI Baoguang jia Zhuangzhu luo Guangan ZHANG School of Materials Sun Yat-sen UniversityShenzhen 518107China The 14th Research Institute of China Electronics Technology Group Corporation Nanjing 210039China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

High-temperature ablation is a common failure phenomenon that limits the service life of the transmission parts on heavy-duty machines used in heavy load,high temperature,high shock conditions due to in-sufficient supply of lubricating oil and grease.Traditional self-lubricating coatings prepared by inorganic,organic or organic-inorganic hybrid methods are prone to be oxidated at high temperatures to lose their friction reducing function,so that it is difficult to meet the engineering requirements of high-temperature lubrication.We design viscoelastic polymer coatings by a high-temperature self-lubricating and wear-resistant strategy.Polytetrafluoroethylene(PTFE,T_(m)=329℃)and polyphenylene sulfide(PPS,T_(g)=84℃,T_(m)=283℃)are used to prepare a PTFE/PPS polymer alloy coating.As the temperature increases from 25 to 300℃,the PTFE/PPS coating softens from glass state to viscoelastic state and viscous flow state,which is owing to the thermodynamic transformation characteristic of the PPS component.Additionally the friction coefficient(μ)decreased from 0.096 to 0.042 with the increasing of temperature from 25 to 300℃.The mechanism of mechanical deformation and surface morphology evolution for the PTFE/PPS coating under the multi-field coupling action of temperature(T),temperature–centrifugal force(T–F_(ω)),temperature–centrifugal force–shearing force(T–F_(ω)–F_(τ))were investigated.The physical model of“thermoviscoelasticity driven solid–liquid interface reducing friction”is proposed to clarify the self-lubricating mechanism determined by the high-temperature viscoelastic properties of polymers.The high-temperature adjusts the viscosity(η)of the coating,increases interface slipping and intensifies shear deformation(τ),reducing the friction coefficient.The result is expected to provide a new idea for designing anti-ablation coatings served in high temperature friction and wear conditions.

关键词： self-lubricating polymer coating viscoelastic state solid-liquid interface friction reduction hightemperature tribology

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Co-free/Co-poor high-Ni cathode for high energy,stable and low-cost lithium-ion batteries

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Rare Metals 2023年第7期42卷 2214-2225页

作者： Zhe-Dong Liu Chun-Ying Wang Jing-Chao Zhang Jia-Wei Luo Cui-Hua Zeng wei-Di Liu Rui Liu Ya-Nan Chen School of Materials Science and Engineering Shandong University of Science and TechnologyQingdao266590China School of Materials Science and Engineering Tianjin UniversityTianjin300072China Australian Institute for Bioengineering and Nanotechnology The University of QueenslandBrisbaneQLD4072Australia

Advanced cathode materials have been considered as the key to significantly improve the energy density of lithium-ion batteries(LIBs).High-Ni layer-structured cathodes,especially with Ni atomic content above 0.9(LiN1_(x)M_(1-x)O_(2),x≥0.9),exhibit high capacity to be commercially available in electric vehicles(EVs).However,the intrinsic structure instability of high-Ni materials and the negative impacts severely restrict their further applic ation.In addition,Co has various effective efforts to stabilize the layered structure.Nevertheless,due to the high cost of Co,it is required to be replaced.Therefore,modification methods on increasing the stability of high-Ni cathode with the reduction of Co content have been widely investigated.In this review,we summarized various effective research progresses and several potential modification strategies of Cofree/Co-poor layered c athodes with Ni content over 0.9.The challenges and development opportunities of high-Ni,Cofree/Co-poor cathodes are further overviewed to meet the future commercial energy demands.

关键词： Lithium-ion batteries(LIBs) Co-free/poor High-Ni Cathode materials

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Metastable face-centered cubic ruthenium-based binary alloy for efficient alkaline hydrogen oxidation electrocatalysis

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Journal of Energy Chemistry 2024年第5期92卷 207-215页

作者： Yunbo Li jianchao Yue Chaoyi Yang Hongnan jia Hengjiang Cong wei luo College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072HubeiChina

Metastable nanostructured electrocatalyst with a completely different surface environment compared to conventional phase-based electrocatalyst often shows distinctive catalytic property.Although Ru-based electrocatalysts have been widely investigated toward hydrogen oxidation reaction(HOR)under alkaline electrolytes,these studies are mostly limited to conventional hexagonal-close-packed(hcp)phase,mainly arising from the lack of sufficient synthesis strategies.In this study,we report the precise synthesis of metastable binary RuW alloy with face-centered-cubic(fcc)phase.We find that the introduction of W can serve as fcc phase seeds and reduce the formation energy of metastable fcc-RuW alloy.Impressively,fcc-RuW exhibits remarkable alkaline HOR performance and stability with the activity of 0.67 mA cm_(Ru)^(-2)which is almost five and three times higher than that of hcp-Ru and commercial Pt/C,respectively,which is attributed to the optimized binding strength of adsorbed hydroxide intermediate derived from tailored electronic structure through W doping and phase engineering.Moreover,this strategy can also be applied to synthesize other metastable fcc-RuCr and fcc-RuMo alloys with enhanced HOR performances.

关键词： Hydrogen oxidation reaction Metastable phase Face-centered cubic(fcc) Ru Phase engineering

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Nitridation-induced metal-organic framework nanosheet for enhanced water oxidation electrocatalysis

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Journal of Energy Chemistry 2022年第1期31卷 531-537,I0014页

作者： Na Yao Hongnan jia Zhengyin Fan Lu Bai wei Xie Hengjiang Cong Shengli Chen wei luo College of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072HubeiChina College of Chemistry Nankai UniversityTianjin 300071China Suzhou Institute of Wuhan University Suzhou 215123JiangsuChina

We report the synthesis of nitridation-induced NiFe-MOF through post-synthetic functionalization of terminal ligand in NiFe-MOF nanosheet.We directly identify the key factor of amino ligand in N-NiFe-MOF for boosting the OER performance through combining single X-ray crystallographic characterization and in-situ Raman tracking,as well as ex-situ spectroscopy analysis.Density functional theory(DFT)calculations and experime ntal results indicate irreversible phase rec on structio n from amino ligand oxidation prior to OER could lead to the optimized ΔG_(-O),resulting in the remarkable OER performance with an overpotential of 258 mV to obtain the current density of 100 mA cm^(-2) in 1.0 M KOH solution.Our work will provide new strategy for rational designing advanced MOF-based OER electrocatalysts.

关键词： Mt ridation-induced MOF nanosheets In-sicu oxidation OER DFT calculation

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Detection and Attribution of Changes in Summer Compound Hot and Dry Events over Northeastern China with CMIP6 Models

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Journal of Meteorological Research 2022年第1期36卷 37-48页

作者： wei LI Zhihong jiaNG Laurent ZXLI Jing-jia luo Panmao ZHAI Key Laboratory of Meteorological Disaster of Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China Laboratory of Severe Weather Fujian Institute of Meteorological SciencesFuzhou 350001China Laboratoire de Météorologie Dynamique Centre National de la Recherche ScientifiqueSorbonne UniversitéEcole Normale SupérieureEcole PolytechniqueParis 75252France State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081China

Northeastern China has experienced a significant increase in summer compound hot and dry events(CHDEs),posing a threat to local agricultural production and sustainable development.This study investigates the detectable anthropogenic signal in the long-term trend of CHDE and quantifies the contribution of different external forcings.A probability-based index(PI)is constructed through the joint probability distribution to measure the severity of CHDE,with lower values representing more severe cases.Response of CHDE to external forcing was assessed with simulations from the Coupled Model Intercomparison Project phase 6(CMIP6).The results show a significant increase in the severity of CHDE over northeastern China during the past decades.The trend of regional averaged PI is-0.28(90%confidence interval:-0.43 to-0.13)per 54 yr and it is well reproduced in the historical forcing simulations.The attribution method of optimal fingerprinting was firstly applied to a two-signal configuration with anthropogenic forcing and natural forcing;the anthropogenic impact was robustly detected and it explains most of the observed trend of PI.Similarly,three-signal analysis further demonstrated that the anthropogenic greenhouse gases dominantly contribute to the observed change,while the anthropogenic aerosol and natural forcing have almost no contribution to the observed changes.For a compound event concurrently exceeding the 95 th percentile of surface air temperature and precipitation reversal in the current period,its likelihood exhibits little change at 1.5℃global warming,but almost doubled at 2.0℃global warming.

关键词： compound hot and dry event(CHDE) detection and attribution northeastern China future projection

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High-voltage LiCoO_(2) cathodes for high-energy-density lithiumion battery

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Rare Metals 2022年第12期41卷 3946-3956页

作者： Jing-Chao Zhang Zhe-Dong Liu Cui-Hua Zeng Jia-Wei Luo Yi-Da Deng Xiao-Ya Cui Ya-Nan Chen School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Beijing Frontier Research Center for Biological Structures Tsinghua UniversityBeijing 100084China Ministry of Education Key Laboratory of Protein Sciences Beijing Advanced Innovation Center for Structural BiologySchool of Life SciencesTsinghua UniversityBeijing 100084China

As the earliest commercial cathode material for lithium-ion batteries,lithium cobalt oxide(LiCoO_(2)) shows various advantages,including high theoretical capacity,excellent rate capability,compressed electrode density,etc.Until now,it still plays an important role in the lithium-ion battery market.Due to these advantages,further increasing the charging cutoff voltage of LiCoO_(2)to guarantee higher energy density is an irresistible development trend of LiCoO_(2)cathode materials in the future.However,using high charging cutoff voltage may induce a lot of negative effects,especially the rapid decay of cycle capacity.These are mainly caused by rapid destruction of crystal structure and aggravation of interface side reaction at high voltage during the cycle.Therefore,how to maintain a stable crystal structure of LiCoO_(2)to ensure the excellent long cycle performance at high voltage is a hot research issue in the further application of LiCoO_(2).In this review,we summarized the failure causes and extensive solutions of LiCoO_(2)at high voltage and promoted some new modification strategies.Moreover,the development trend of solving the failure problem of high-voltage LiCoO_(2)in the future such as defect engineering and high-temperature shock technique is also discussed.

关键词： Lithium-ion battery Lithium cobalt oxide(LiCoO_(2))cathode High voltage Cycle performance Crystal structure

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Recent advances in electrocatalytic generation of indole-derived radical cations and their applications in organic synthesis

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Chinese Chemical Letters 2024年第4期35卷 106-123页

作者： wei Zhou Xi Chen Lin Lu Xian-Rong Song Mu-jia luo Qiang Xiao Key Laboratory of Organic Chemistry of jiangxi Province Jiangxi Science&Technology Normal UniversityNanchang 330013China

Indole-derived radical cations, open-shell reactive species, display distinctive dual reactivity due to the carbon-centered radical and more electrophilic carbocation, which frequently appear in a variety of single electron oxidation reactions for synthesizing structurally diverse functionalized indoles and indolines. Electrocatalysis is considered as a synthetically attractive and environmentally friendly alternative for driving the single electron oxidation of indoles. Remarkable achievements in electrocatalytic indolederived radical cation-mediated indole functionalization have been realized so far. This review comprehensively summarizes the recent progresses in the applications of electrocatalytic indole radical cations,including C(sp~2)–H functionalization, dearomative 2,3-difunctionalization, and ring-opening reaction, emphasizing the vital single electron oxidation steps of indoles, the substrates scope and limitations, and the reaction mechanisms.

关键词： Electrocatalysis Indole radical cation C-H functionalizatin Dearomative 2 3-difunctionalization

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