Steering surface reconstruction of hybrid metal oxides for efficient oxygen evolution reaction in water splitting and zinc-air batteries

Surface reconstruction yields real active species in electrochemical oxygen evolution reaction(OER)conditions;however,rationally regulating reconstruction in a targeted manner for constructing highly active OER electrocatalysts remains a formidable challenge.Here,an electrochemical activation strategy with selective etching was utilized to guide the reconstruction process of a hybrid cobalt-molybdenum oxide(CoMoO_(4)/Co_(3)O_(4)@CC)in a favorable direction to improve the OER performance.Both in-situ Raman and multiple ex-situ characterization tools demonstrate that controlled surface reconstruction can be easily achieved through Mo etching,with the formation of a dynamically stable amorphous-crystalline heterostructure.Theoretical calculations together with experimental results reveal that the synergistic effects between amorphous CoOOH and crystalline Co_(3)O_(4) are crucial in enhancing the catalytic performance.Consequently,the reconstructed CoMoO_(4)/Co_(3)O_(4)@CC exhibits a low overpotential of 250 mV to achieve a current density of 10 mA cm^(-2) in 1 M KOH,and more importantly it can be practiced in electrolytic water splitting and rechargeable zinc-air batteries devices,achieving ultra-long stability for over 500 and 1200 h,respectively.This work provides a promising route for the construction of high-performance electrocatalysts.

基于硫酸钠溶液电解的废旧镍氢电池全金属回收

提出废旧镍氢(Ni-MH)电池全金属可持续回收的方法,分别用硫酸钠溶液电解获得的H_(2)SO_(4)和NaOH溶液作为浸出剂和沉淀试剂。电极材料在温和条件下浸出,超过99%的稀土元素在pH1.0时以双硫酸盐的形式从溶液中沉淀,进而通过与NaOH反应转化为氢氧化物。在后续浸出液的纯化过程中,Al^(3+)和Fe^(3+)在pH 5.5时沉积,Zn^(2+)和Mn^(2+)用皂化D2EHPA-煤油从浸出液中萃取出来,形成两种具有工业价值的氢氧化物副产品。Ni^(2+)和Co^(2+)在pH9.5时沉淀,总回收率为97.5%。Na_(2)SO_(4)的总回收率达97%。这种金属回收方法可带来明显的经济效益,且闭环处理过程中无固体或液体废弃物。

Bimetallic Oxyhydroxide as a High-Performance Water Oxidation Electrocatalyst under Industry-Relevant Conditions

Developing high-performing oxygen evolution reaction(OER)electrocatalysts under high-current operation conditions is critical for future commercial applications of alkaline water electrolysis for clean energy generation.Herein,we prepared a three-dimensional(3D)bimetallic oxyhydroxide hybrid grown on a Ni foam(NiFeOOH/NF)prepared by immersing Ni foam(NF)into Fe(NO_(3))_(3) solution.In this unique 3D structure,the NiFeOOH/NF hybrid was composed of crystalline Ni(OH)_(2) and amorphous FeOOH evenly grown on the NF surface.As a bimetallic oxyhydroxide electrocatalyst,the NiFeOOH/NF hybrid exhibited excellent catalytic activity,surpassing not only the other reported Ni–Fe based electrocatalysts,but also the commercial Ir/C catalyst.In situ electrochemical Raman spectroscopy demonstrated the active FeOOH and NiOOH phases involved in the OER process.Profiting from the synergy of Fe and Ni catalytic sites,the NiFeOOH/NF hybrid delivered an outstanding OER performance under challenging industrial conditions in a 10.0 mol·L^(-1) KOH electrolyte at 80℃,requiring potentials as small as 1.47 and 1.51 V to achieve the super-high catalytic current densities of 100 and 500mA∙cm^(-2),respectively.

Study on Performance Regulation and Mechanism of Quicklime and Biopolymer on Hemihydrate Phosphogypsum

In order to reduce the influence of impurities in hemihydrate phosphogypsum(HPG)on the environment and improve the workability of HPG,the effects of the content of quicklime and types of biopolymer(hydroxypropyl methylcellulose,xanthan gum,sodium polyacrylate(PAANa))on the compressive strength,softening coefficient and ultrasonic velocity of HPG were evaluated.When the content of quicklime was 1.5%and the content of PAA-Na was 0.2%,HPG had the best mechanical properties and workability,its water retention rate can be increased by 5.8%,and unconfined compressive strength of 3 days increased by 10.3%and 7 days increased by 13.1%.Through the analysis of scanning electron microscope and X-ray diffraction,it was found that the hydration reac-tion of HPG was more sufficient,the pores size and number decreased,the number of impurities on the crystal surface decreased obviously,and CaF2 and other substances were formed by the reaction after the addition of quicklime.After adding quicklime and PAANa,the indicators of gypsum self-leveling mortar prepared by HPG meet the requirements of the standard.

Novel Boron Nitride Polymorphs with Graphite-Diamond Hybrid Structure

Both boron nitride(BN)and carbon(C)have sp,sp^(2)and sp^(3)hybridization modes,thus resulting in a variety of BN and C polymorphs with similar structures,such as hexagonal BN(hBN)and graphite,cubic BN(cBN)and diamond.Here,five types of BN polymorph structures are proposed theoretically,inspired by the graphite-diamond hybrid structures discovered in a recent experiment.These BN polymorphs with graphite-diamond hybrid structures possess excellent mechanical properties with combined high hardness and high ductility,and also exhibit various electronic properties such as semi-conductivity,semi-metallicity,and even one-and two-dimensional conductivity,differing from known insulators hBN and cBN.The simulated diffraction patterns of these BN hybrid structures could account for the unsolved diffraction patterns of intermediate products composed of so-called“compressed hBN”and diamond-like BN,caused by phase transitions in previous experiments.Thus,this work provides a theoretical basis for the presence of these types of hybrid materials during phase transitions between graphite-like and diamond-like BN polymorphs.

DNS analysis of incipient drop impact dynamics using an accurate level set method

A series of 2D direct numerical simulations were performed with an accurate level set method for single drop impacts.The adopted ACLS method was validated to be efficient with perfect mass conservation in both normal and oblique impacts.A square-root correction for neck bases was modified in accuracy as well as scope of applications.In addition,process of jet formation and evolution was studied to reveal internal dynamics in drop impacts.It's found that pressure gradient and vortex are coexisting and completive reasons for jet topology while the inclined angle has a significant effect on them.Mechanisms of jet formation and evolution are different in the front and back necks.With the help of PDF distribution and correction calculation,a compromise in the competition is observed.This work lays a solid foundation for further studies of dynamics in gas-liquid flows.

Random-Gate-Voltage Induced Al'tshuler–Aronov–Spivak Effect in Topological Edge States

Helical edge states are the hallmark of the quantum spin Hall insulator. Recently, several experiments have observed transport signatures contributed by trivial edge states, making it difficult to distinguish between the topologically trivial and nontrivial phases. Here, we show that helical edge states can be identified by the randomgate-voltage induced Φ_(0)/2-period oscillation of the averaged electron return probability in the interferometer constructed by the edge states. The random gate voltage can highlight the Φ_(0)/2-period Al'tshuler–Aronov–Spivak oscillation proportional to sin^(2)(2πΦ/Φ_(0)) by quenching the Φ_(0)-period Aharonov–Bohm oscillation. It is found that the helical spin texture induced π Berry phase is key to such weak antilocalization behavior with zero return probability at Φ = 0. In contrast, the oscillation for the trivial edge states may exhibit either weak localization or antilocalization depending on the strength of the spin-orbit coupling, which has finite return probability at Φ = 0. Our results provide an effective way for the identification of the helical edge states. The predicted signature is stabilized by the time-reversal symmetry so that it is robust against disorder and does not require any fine adjustment of system.

Design of a Class of New sp^(2)-sp^(3)Carbons Constructed by Graphite and Diamond Building Blocks

The sp^(2)–sp^(3)-hybridized carbon allotropes with the advantage of two hybrid structures possess rich and fascinating electronic and mechanical properties and they have received long-standing attention.We design a class of versatile sp^(2)–sp^(3)carbons composed of graphite and diamond structural units with variable sizes.This class of sp^(2)–sp^(3)carbons is energetically more favorable than graphite under high pressure,and their mechanical and dynamical stabilities are further confirmed at ambient pressure.The calculations of band structure and mechanical properties indicate that this class of sp^(2)–sp^(3)carbons not only exhibits peculiar electronic characteristics adjusted from semiconducting to metallic nature but also presents excellent mechanical characteristics,such as superhigh hardness and high ductility.These sp^(2)–sp^(3)carbons have desirable properties across a broad range of potential applications.

First-principles Simulations of Tunneling FETs Based on van der Waals MoTe2/SnS2 Heterojunctions with Gate-to-drain Overlap Design

The electronic properties and transport properties of MoTe2/SnS2 heterostructure Tunneling FETs are investigated by the density functional theory coupled with non-equilibrium Green’s function method.Two dimensional(2D)monolayer MoTe2 and SnS2 are combined to a vertical van der Waals heterojunction.A small staggered band gap is formed in the overlap region,while larger gaps remain in the underlap source and drain regions of monolayer MoTe2 and SnS2 respectively.Such a type-II heterojunction is favorable for tunneling FET.Furthermore,we suggest short stack length and large gate-to-drain overlap to enhance the on-state current suppress the leakage current respectively.The numerical results show that at a low drain to source voltage Vds=0.05V,On/Off current ratio can reach 108 and the On-state currents is over 20μA/μm for ntype devices.Our results present that van der Waals heterostructure TFETs can be potential candidate as next generation ultra-steep subthreshold and low-power electronic applications.

∼2.5 nm pores in carbon-based cathode promise better zinc-iodine batteries

The relationship mechanism between the material pore structures and cathodic iodine chemistry plays a vital role in efficient Zn-I_(2) batteries,but is unclear,retarding further advances.This work innovatively indicates a great contribution of∼2.5nm pore structure of nanocarbons to efficient iodine adsorption,rapid I^(−)↔I_(2) conversion,and polyiodide inhibition,via scrupulously designing catalysts with controllable pore sizes systematically.The I_(2)-loading within the designed nitrogen-doped nanocarbons can reach up to as high as 60.8 wt%.The batteries based on the cathode deliver impressive performances with a large capacity of 178.8 mAh/g and long-term cycling stability more than 4000 h at 5.0 C.Notably,these is no polyiodide such as I_(3)−and I_(5)−detected during the charge-discharge processes from comprehensive electrochemical cyclic voltammetry,X-ray photoelectron spectroscopy,and Raman technique.This work provides a novel knowledge-guided concept for rational pore design,promising better Zn-I_(2) batteries,which is also hoped to benefit other advanced energy technologies,such as Li-S,Li-ion,and Al-I_(2) batteries.

Study on the fast elimination of smoke particle based on electro-acoustic coupling agglomeration technology

Fire smoke,which consists large amounts of fine particles,is considered as the fatal factor in fires.In this study,a fast smoke particle elimination method based on electro-acoustic coupling agglomeration technology is proposed.First,the experimental results show that the electro-acoustic coupling agglomeration has higher smoke elimination efficiency compared to single-field.The smoke transmission is much less than 80%after 30s of single acoustic or electric field action,while the coupled field reaches 90%.Then,the effects of acoustic frequency,sound pressure level and voltage on the smoke elimination characteristics are discussed.It is found that the optimal acoustic frequency is 1.5kHz.While as the sound pressure level and voltage increase,the elimination efficiency first increases and then tends to stabilize,the critical values of the sound pressure level and voltage are 135 dB and 7kV.This indicates that there is an optimal combination of the three variables.Finally,through the theoretical analysis of particle movement and the micro-morphology of agglomerates,the particle agglomeration mechanism under the electro-acoustic coupling is analyzed.This study provides a new idea for the fast elimination of fire smoke particle.

Multi-scale numerical simulation of fluidized beds: Model applicability assessment

In the past few decades,multi-scale numerical methods have been developed to model dense gas-solidflow in fluidized beds with different resolutions,accuracies,and efficiencies.However,ambiguity needsto be clarified in the multi-scale numerical simulation of fluidized beds:(i)the selection of the submodels,parameters,and numerical resolution;(ii)the multivariate coupling of operating conditions,bed configurations,polydispersity,and additional forces.Accordingly,a state-of-the-art review is performed to assess the applicability of multi-scale numerical methods in predicting dense gas-solid flow influidized beds at specific fluidization regimes(e.g.,bubbling fluidization region,fast fluidization regime),with a focus on the inter-particle collision models,inter-phase interaction models,collision parameters,and polydispersity effect.A mutual restriction exists between resolution and efficiency.Higherresolution methods need more computational resources and thus are suitable for smaller-scale simulations to provide a database for closure development.Lower-resolution methods require fewercomputational resources and thus underpin large-scale simulations to explore macro-scale phenomena.Model validations need to be further conducted under multiple flow conditions and comprehensivemetrics(e.g.,velocity profiles at different heights,bubbles,or cluster characteristics)for furtherimprovement of the applicability of each numerical method.

Deoxynivalenol accumulation and detoxification in cereals and its potential role in wheat-Fusarium graminearum interactions

Deoxynivalenol(DON)is a prominent mycotoxin showing significant accumulation in cereal plants during infection by the phytopathogen Fusarium graminearum.It is a virulence factor that is important in the spread of F.graminearum within cereal heads,and it causes serious yield losses and significant contamination of cereal grains.In recent decades,genetic and genomic studies have facilitated the characterization of the molecular pathways of DON biosynthesis in F.graminearum and the environmental factors that influence DON accumulation.In addition,diverse scab resistance traits related to the repression of DON accumulation in plants have been identified,and experimental studies of wheat–pathogen interactions have contributed to understanding detoxification mechanisms in host plants.The present review illustrates and summarizes the molecular networks of DON mycotoxin production in F.graminearum and the methods of DON detoxification in plants based on the current literature,which provides molecular targets for crop improvement programs.This review also comprehensively discusses recent advances and challenges related to genetic engineering-mediated cultivar improvements to strengthen scab resistance.Furthermore,ongoing advancements in genetic engineering will enable the application of these molecular targets to develop more scab-resistant wheat cultivars with DON detoxification traits.

Study of biomass gasification in an industrial-scale dual circulating fluidized bed(DCFB)using the Eulerian-Lagrangian method

Dual circulating fluidized bed(DCFB)has emerged as an efficient reactor for biomass gasification due to its unique feature of high gas-solid contact efficiency and separated reactions in two reactors,yet the understanding of complex in-furnace phenomena is still lacking.In this study,biomass gasification in an industrial-scale DCFB system was numerically studied using a multiphase particle-in-cell(MP-PIC)method featuring thermochemical sub-models(e.g.,heat transfer,heterogeneous reactions,and homogeneous reactions)under the Eulerian-Lagrangian framework.After model validation,the hydrodynamics and thermochemical characteristics(i.e.,pressure,temperature,and species)in the DCFB are comprehensively investigated.The results show that size-/density-induced segregation makes solid fuels concentrate on the bed surface.Interphase momentum exchange leads to the continuous decrease of the gas pressure axially.In the gasifier and combustor,the lower heating value(LHV)of the gas products is 5.56 MJ/Nm^(3)and 0.2 MJ/Nm^(3)and the combustible gas concentration(CGC)is 65.5%and 1.86%,respectively.The temperature in the combustor is about 100 K higher than that in the gasifier.A higher solid concentration results in a smaller value of particle heat transfer coefficient(HTC).The HTCs range from 50 to 150 W/(m^(2) K)for a solid concentration larger than 0.3 in the combustor while the HTCs range from 100 to 200 W/(m^(2 )K)in the gasifier.The Reynolds number of biomass particles is two orders of magnitude larger than that of the sand particle.The numerical results shed light on the reactor design and process optimization of biomass gasification in DCFBs.

Porous polyurethane hydrogels incorporated with CMC for eliminating methylene blue from water

Here,a series of polyurethane porous hydrogels(PUF-s)loaded with different sodium carboxymethyl cellulose(CMC)were successfully prepared by one-step foaming method.The physio-chemical prop-erties and morphologies were characterized.The effects of CMC content,adsorbent dosage,temperature,pH value and other fac-tors on the adsorption of methylene blue(MB)dye in water by CMC-PUF-s were also investigated through static adsorption experi-ments.The results showed that CMC-PUF-10 had excellent adsorp-tion performance for MB solution with removal rate of 81.47%,and the maximum adsorption capacity was 27.5 mg/g.In addition,the study of adsorption kinetics and adsorption isotherms showed that the adsorption of MB by CMC-PUF was more consistent with Langmuir isotherm adsorption model and pseudo second-order kinetic model.The adsorption thermodynamics study suggested that the adsorption process of MB by CMC-PUF-10 was sponta-neous and exothermic at room temperature.The results of cyclic adsorption experiment demonstrated that the removal rate of MB reached above 70%after five cycles,indicating the foams with excellent recyclability.Finally,a low-cost,environmentally friendly and recyclable MB adsorbent was synthesized in this study.As polyurethane foam was synthesized by one-step foaming method,this adsorbent can be prepared on site in practical application and reduce the transportation cost.

A novel approach for the optimal arrangement of tube bundles in a 1000-MW condenser

1Introduction The condenser plays a vital role in the operation of a thermal power generation unit.Its primary function is to remove the heat from the steam that is exhausted from the steam turbine,thereby condensing the steam into water.Additionally,it establishes and maintains a specific degree of vacuum at the exhaust port of the steam turbine,facilitating efficient operation of the turbine(Keshvarparast et al.,2020).The vacuum degree of the condenser is affected by physical factors such as steam-side resistance and heat-transfer efficiency.

Grain boundaries induce significant decrease in lattice thermal conductivity of CdTe

Semiconductors are promising in photoelectric and thermoelectric devices, for which the thermal transport properties are of particular interest. However, they have not been fully understood, especially when crystalline imperfections are present. Here, using cadmium telluride (CdTe) as an example, we illustrate how grain boundaries (GBs) affect the thermal transport properties of semiconductors. We develop a machine-learning force field from density functional theory calculations for predicting the lattice thermal conductivity (LTC) via equilibrium molecular dynamics simulations. The LTC of crystalline CdTe decreases with the relationship of κL~1/T in the simulation temperature range of 300 – 900 K, in which the isotropic LTC decreases from 3.34 to 0.23 W/ (m⋅K) due to the enhanced anharmonicity. More important, after introducing GBs, the LTC is suppressed in all directions, especially in the direction normal to the GB planes. More severe LTC suppression occurs in CdTe with Σ9 GB than that with Σ3 GB at 300 K, decreasing by 92.8% and 61.4% along the direction normal to the GB planes compared to the isotropic LTC of the crystalline CdTe, respectively. The decreased LTC is consistent with the weaker bonding near GB planes and lower shear modulus of the defective material. The analyses of the phonon dispersion curves, vibrational density of states, and phonon participation ratio indicate that the decreased LTC mainly arises from phonon scattering at GBs. Overall, our work highlights that GBs can greatly influence the LTC of semiconductors, thus providing a promising approach for thermal property design.

输电塔风致响应数值模拟研究进展

输电塔是输电线路中重要的承重设施,其结构安全性直接关系到国家电网和输电线路的正常运行。目前针对输电塔风致响应主要通过现场实测、风洞试验和数值模拟等方法进行研究。随着计算机技术和数值方法的发展,对输电塔风致响应特征进行数值模拟分析开始被广泛应用并取得了大量研究成果。相关的数值模拟研究先通过建立对应的风荷载模型和结构模型,然后以有限元方法分析结构动力响应特征和研究对应的风振控制方法,因此从风荷载模型、结构模型、动力响应特征和风振控制研究等方面总结输电塔风致响应数值模拟研究进展。近地面风场的平均风和脉动风模型是构建结构风荷载的基础。针对平均风主要采用指数型和对数型风速剖面模型,而脉动风则主要根据相关的脉动风谱进行模拟。在不同极端气象条件下,风场表现出不同于良态风的风场特征,对应的平均风和脉动风模型需要进一步根据实际情况研究。构建输电塔风荷载还需要结合相关的结构参数,其中塔体结构整体挡风效应以及塔体构件之间的遮挡效应可通过流场模拟进行分析研究。对输电塔塔体结构建立有限元模型时,通常可将之视为刚架结构和桁梁混合结构,而利用桁架结构进行模拟的误差较大。输电塔所承受的荷载除了风荷载等外部环境荷载外,还应考虑输电线对塔体结构作用带来的影响,因此需建立塔线耦合体系对实际输电线路中塔体结构特征进行模拟。在构建塔线体系有限元模型过程中,可结合悬链线理论和导线水平张力对导线进行建模和找形。基于风荷载模型和结构模型可进行塔体风致响应分析,结构动力特征会对风致响应产生重要的影响,其中导线对塔体的作用使得整体体系的结构动力特征更加复杂。对于不同来流风向条件下输电塔的风荷载,我国相关规范有对应的计算系数和分配系数,而在塔线耦合体系中,风向对塔体结构风致响应的影响更显著。根据是否需要外界能量输入,结构风振控制分为主动控制、被动控制和混合控制。迄今为止,被动控制特别是调谐质量阻尼器仍然是对输电塔风振控制的主要方法,其中阻尼器的自振频率应与塔体自振频率保持一致,风振控制效果才能达到最佳,但是塔线耦合作用使得风振控制的优化更为复杂。此外,还对未来可能的研究方向进行了展望,进一步研究特殊天气风场特征、开发更可靠的有限元建模方法、深入研究塔体扭转向及沿线向响应特征、优化TMD设计参数和布置方案等都应是未来重要的研究方向。

A critical review on the application of biochar in environmental pollution remediation:Role of persistent free radicals(PFRs)

Biochar as an emerging carbonaceous material has exhibited a great potential in environmental application for its perfect adsorption ability.However,there are abundant persistent free radicals(PFRs)in biochar,so the direct and indirect PFRs-mediated removal of organic and inorganic contaminants by biochar was widely reported.In order to comprehend deeply the formation of PFRs in biochar and their interactions with contaminants,this paper reviews the formation mechanisms of PFRs in biochar and the PFRs-mediated environmental applications of biochar in recent years.Finally,future challenges in this field are also proposed.This review provides a more comprehensive understanding on the emerging applications of biochar from the viewpoint of the catalytic role of PFRs.

Dynamic temperature prediction of electronic equipment under high altitude long endurance conditions

Unmanned Aerial Vehicle（UAV） is developing towards the direction of High Altitude Long Endurance（HALE）. This will have an important influence on the stability of its airborne electronic equipment using passive thermal management. In this paper, a multi-node transient thermal model for airborne electronic equipment is set up based on the thermal network method to predict their dynamic temperature responses under high altitude and long flight time conditions. Some relevant factors are considered into this temperature prediction model including flight environment,radiation, convection, heat conduction, etc. An experimental chamber simulating a high altitude flight environment was set up to survey the dynamic thermal responses of airborne electronic equipment in a UAV. According to the experimental measurement results, the multi-node transient thermal model is verified without consideration of the effects of flight speed. Then, a modified way about outside flight speed is added into the model to improve the temperature prediction performance. Finally, the corresponding simulation code is developed based on the proposed model. It can realize the dynamic temperature prediction of airborne electronic equipment under HALE conditions.