MXene derivatives are notable two-dimensional nanomaterials with numerous prospective applications in the domains of energy development.MXene derivative,MBene,diversifies its focus on energy storage and harvesting due...MXene derivatives are notable two-dimensional nanomaterials with numerous prospective applications in the domains of energy development.MXene derivative,MBene,diversifies its focus on energy storage and harvesting due to its exceptional electrical conductivity,structural flexibility,and mechanical properties.This comprehensive review describes the sandwich-like structure of the synthesized MBene,derived from its multilayered parent material and its distinct chemical framework to date.The fields of focus encompass the investigation of novel MBenes,the study of phase-changing mechanisms,and the examination of hex-MBenes,ortho-MBenes,tetra-MBenes,tri-MBenes,and MXenes with identical transition metal components.A critical analysis is also provided on the electrochemical mechanism and performance of MBene in energy storage(Li/Na/Mg/Ca/Li–S batteries and supercapacitors),as well as conversion and harvesting(CO_(2) reduction,and nitrogen reduction reactions).The persistent difficulties associated with conducting experimental synthesis and establishing artificial intelligence-based forecasts are extensively deliberated alongside the potential and forthcoming prospects of MBenes.This review provides a single platform for an overview of the MBene’s potential in energy storage and harvesting.展开更多
Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction(OER)is pivotal for advancing proton exchange membrane water electrolysis(PEMWEs),yet balancing activity and stability remains a fo...Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction(OER)is pivotal for advancing proton exchange membrane water electrolysis(PEMWEs),yet balancing activity and stability remains a formidable challenge.Herein,we propose a dual-engineering strategy to stabilize Ru-based catalysts by synergizing the oxygen vacancy site-synergized mechanism-lattice oxygen mechanism(OVSM-LOM)with Ru-N bond stabilization.The engineered RuO_(2)@NCC catalyst exhibits exceptional OER performance in 0.5 M H2SO4,achieving an ultralow overpotential of 215 mV at 10 mA cm^(-2) and prolonged stability for over 327 h.The catalyst delivers 300 h of continuous operation at 1 A cm^(-2),with a negligible degradation rate of only 0.067 mV h-1,further demonstrating its potential for practical application.Oxygen vacancies unlock the OVSM-LOM pathway,bypassing the sluggish adsorbate evolution mechanism(AEM)and accelerating reaction kinetics,while the Ru-N bonds suppress Ru dissolution by anchoring low-valent Ru centers.Quasi-in situ X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),and isotopic labeling experiments confirm the lattice oxygen participation with *O formation as the rate-determining step.The Ru-N bonds reinforce the structural integrity by stabilizing low-valent Ru centers and inhibiting overoxidation.Theoretical calculations further verify that the synergistic interaction between OVs and Ru-O(N)active sites optimizes the Ru d-band center and stabilizes intermediates,while Ru-N coordination enhances structural integrity.This study establishes a novel paradigm for designing robust acidic OER catalysts through defect and coordination engineering,bridging the gap between activity and stability for sustainable energy technologies.展开更多
BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechan...BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers＇ hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.展开更多
The industrial implementation of Solar-driven photocatalysis is hampered by inefficient charge separation,poor reusability and hard retrieval of powdery catalysts.To conquer these drawbacks,a self-floating S-scheme Bi...The industrial implementation of Solar-driven photocatalysis is hampered by inefficient charge separation,poor reusability and hard retrieval of powdery catalysts.To conquer these drawbacks,a self-floating S-scheme Bi_(4)O_(5)Br_(2)/P-doped C_(3)N_(4)/carbon fiber cloth(BB/PN/CC)composed of carbon fibers(CC)as the core and Bi_(4)O_(5)Br_(2)/P-doped C_(3)N_(4)(BB/PN)nanosheets as the shell was constructed as a competent,recyclable cloth-shaped photocatalyst for safe and efficient degradation of aquacultural antibiotics.The BB/PN/CC fabric achieves an exceptional tetracycline degradation rate constant of 0.0118 min‒1,surpassing CN/CC(0.0015 min^(‒1)),BB/CC(0.0066 min^(‒1))and PN/CC(0.0023 min^(‒1))by 6.9,0.8 and 4.1 folds,respectively.Beyond its catalytic prowess,the photocatalyst’s practical superiority is evident in its effortless recovery and environmental adaptability.The superior catalytic effectiveness stems from the S-scheme configuration,which retains the maximum redox capacities of the constituent BB and PN while enabling efficient spatial detachment of photo-carriers.X-ray photoelectron spectroscopy(XPS),in-situ XPS,and electron paramagnetic resonance analyses corroborate the S-scheme mechanism,revealing electron accumulation on PN and hole retention on BB under illumination.Density functional theory calculations further confirm S-scheme interfacial charge redistribution and internal electric field formation.This study advances the design of macroscopic S-scheme heterojunction photocatalysts for sustainable water purification.展开更多
Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is character...Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is characterized by the inclination angle between the magnetic field lines and the thruster radial direction. Different inclination angles were obtained by varying the current ratio in the coils. The plume divergence angles were measured by a dual-directed probe. The results showed that the plume divergence angle increased obviously with the increase in the magnitude of the inclination angle near the channel exit. Therefore, in order to optimize the magnetic field for reducing plume divergence, the magnitude of the inclination angle should be reduced as much as possible. It suggests that the magnetic field configuration near the channel exit is another important factor that affects plume divergence.展开更多
Facing the complex variable high-temperature environment,electromagnetic wave(EMW)absorbing materials maintaining high stability and satisfying absorbing properties is essential.This study focused on the synthesis and...Facing the complex variable high-temperature environment,electromagnetic wave(EMW)absorbing materials maintaining high stability and satisfying absorbing properties is essential.This study focused on the synthesis and EMW absorbing performance evaluation of TiN/Fe_(2)N/C composite materials,which were prepared using electrostatic spinning followed by a high-temperature nitridation process.The TiN/Fe_(2)N/C fibers constructed a well-developed conductive network that generates considerable conduction loss.The heterogeneous interfaces between different components generated a significant level of interfacial polarization.Thanks to the synergistic effect of stable dielectric loss and optimized impedance matching,the TiN/Fe_(2)N/C composite materials demonstrated excellent and stable absorption performance across a wide temperature range(293-453 K).Moreover,TiN/Fe_(2)N/C-15 achieved a minimum reflection loss(RL)of−48.01 dB and an effective absorption bandwidth(EAB)of 3.64 GHz at 2.1 mm and 373 K.This work provides new insights into the development of high-efficiency and stabile EMW absorbing materials under complex variable high-temperature conditions.展开更多
An eco-friendly,new,and controllable approach for the preparation of manganese oxide(a-MnO_(2))nanorods has been introduced using hydrothermal reaction for supercapacitor application.The in-depth crystal structure ana...An eco-friendly,new,and controllable approach for the preparation of manganese oxide(a-MnO_(2))nanorods has been introduced using hydrothermal reaction for supercapacitor application.The in-depth crystal structure analysis ofα-MnO_(2) is analyzed by X-ray Rietveld refinement by using Full Prof program with the help of pseudo-Voigt profile function.The developed a-MnO_(2) electrode attains a remarkable capacitance of 577.7 F/g recorded at a current density value of 1 A/g with an excellent cycle life when is used for 10,000 repeated cycles due to the porous nanorod-morphology assisting the ease penetration of electrolyte ions into the electroactive sites.The diffusive and capacitive contributions of the electrode have been estimated by considering standard numerical packages in Python.After successfully assembling the aqueous symmetric supercapacitor(SSC)cell by utilizing the as-preparedα-MnO_(2),an excellent capacitance of 163.5 F/g and energy density of 58.1 Wh/kg at the constant current density of 0.5 A/g are obtained with an expanded potential frame of 1.6 V.Moreover,the cell has exceptionally withstood up to 10,000 cycles with an ultimate capacitance retention of 94.1%including the ability to light an LED for 18 s.Such findings recommend the developed a-MnO_(2) electrode to be a highly felicitous electrode for the field of energy storage.展开更多
One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of p...One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.展开更多
The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-b...The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.展开更多
Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(...Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.展开更多
As energy demands continue to rise in modern society,the development of high-performance lithium-ion batteries(LIBs)has become crucial.However,traditional research methods of material science face challenges such as l...As energy demands continue to rise in modern society,the development of high-performance lithium-ion batteries(LIBs)has become crucial.However,traditional research methods of material science face challenges such as lengthy timelines and complex processes.In recent years,the integration of machine learning(ML)in LIB materials,including electrolytes,solid-state electrolytes,and electrodes,has yielded remarkable achievements.This comprehensive review explores the latest applications of ML in predicting LIB material performance,covering the core principles and recent advancements in three key inverse material design strategies:high-throughput virtual screening,global optimization,and generative models.These strategies have played a pivotal role in fostering LIB material innovations.Meanwhile,the paper briefly discusses the challenges associated with applying ML to materials research and offers insights and directions for future research.展开更多
The influence of partitioned profiling design based on a large-pitch highly loaded cascade is studied by numerical simulation.The partitioned profile is mainly composed of a pressure-side convex structure near the lea...The influence of partitioned profiling design based on a large-pitch highly loaded cascade is studied by numerical simulation.The partitioned profile is mainly composed of a pressure-side convex structure near the leading edge and a suction-side convex structure at the midstream and downstream sides of the passage.The influence of the change in the vertex axial position and peak value of the B-line on the secondary flow control is analyzed.In this paper,air(ideal gas)is selected as the flow media.The average static pressure at the outlet and the average total temperature at the inlet are kept constant.SST γ-θ is used as the turbulence model.The results show that the pressure-side convex structure suppresses the spanwise and pitchwise migration of the inlet flow by adjusting the static pressure distribution of the flow field,so the development of the pressure-side leg of the horseshoe vortex is effectively limited.The suction-side convex structure adjusts the static pressure distribution of the flow field and increases the included angle between the cross-flow and suction surface,so the accumulation of low-momentum fluid,the development of a corner vortex and the flow separation at the trailing edge of the suction-side surface are all suppressed near the endwall-suction corner.Consequently,the energy loss coefficient of the large-pitch highly loaded cascade is decreased from 0.0564 to 0.0485,representing a 25% reduction in secondary flow losses.展开更多
The rigorous operating condition of proton exchange membrane fuel cells(PEMFCs)poses a substantial hurdle for the long-term stability of Pt-based alloy catalysts;thus,the development of Pt-alloy catalysts with unique ...The rigorous operating condition of proton exchange membrane fuel cells(PEMFCs)poses a substantial hurdle for the long-term stability of Pt-based alloy catalysts;thus,the development of Pt-alloy catalysts with unique morphologies is crucial for enhancing the stability of PEMFCs.In this study,we synthesized a novel PtCu nano-dendrite(PtCuND)catalyst through a facile,one-step solvothermal process.The sub-nanometer particles and nanopores within this catalyst facilitate enhanced mass transport.In PEM single-cell tests,the PtCuND catalyst displays high activity and robust stability,achieving a mass activity of 0.65 A mgPt^(–1).Notably,after accelerated durability tests,the mass activity and the voltage at 0.8 A cm^(–2)of PtCuND exhibits only minimal decreases of 18.5%and 9 mV,respectively.The combined experimental results and theoretical calculations conclusively illustrate the optimized adsorption of oxygen species and the impact of compressive strain on the catalyst surface.The enhanced durability can be attributed to the maintained nano-dendritic morphology and the strengthened interaction within the Pt-Cu bonds.This work not only enhances the stability of PEMFCs but also provides a robust foundation for the future scaling up of catalyst production,paving the way for widespread application in sustainable energy systems.展开更多
Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel j...Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel jet structure is proposed in this paper to explore the feasibility of adopting impinging jets to improve the heat transfer performance of the collector tube with supercritical carbon dioxide(S-CO_(2))as the working fluid.The physical model is built based on several assumptions,and numerical simulations are performed under the mass flow rate of 0.25-0.75 kg/s and the average surface heat flux of 14.7-33 kW/m^(2).Firstly,performance comparisons are made between the jet and tube-in-tube structures.The results show that the average heat transfer coefficient h of the jet structure is 46.5%higher than that of the tube-in-tube structure and the corresponding average temperature differenceΔT between the wall and S-CO_(2)is 31.7%lower.Secondly,the effects of the jet hole circumferential position and diameter on heat transfer are investigated.It's found that by adjusting the circumferential position of the jet hole from 60°to 120°and matching the impingement area of the jets and the high heat flux region,h can be increased by 14.2%andΔT can be reduced by 12.4%.h is also found to be increased by 77.4%when the jet hole diameter is reduced from D=9.7 mm to D=5 mm.Furthermore,the jet structure is further modified by incorporating it with the eccentric configuration.The effect of eccentricity e is studied in detail,and results show that appropriate eccentricity results in higher h and smallerΔT due to the decreased impingement distance and the increased heat transfer.This study can guide the design and optimization of parabolic trough collectors.展开更多
Three-membered cyclic compounds are a fascinating class of compounds:they have the maximum torsional and angular strain(sp^(3)hybridization but bond angles deviate from 109°28’),and possess unique physical and c...Three-membered cyclic compounds are a fascinating class of compounds:they have the maximum torsional and angular strain(sp^(3)hybridization but bond angles deviate from 109°28’),and possess unique physical and chemical properties.A lot of effort has been devoted to their synthesis and applications in recent years.This review provides an overview of various synthesis strategies for three-membered cyclic compounds,and summarizes the proposed reaction mechanisms and key issues such as structure-property relationships through specific examples.Meanwhile,the advantages and disadvantages of different synthesis strategies were discussed,including the recently developed electrochemical synthesis methods.Finally,the prospects and challenges for further scientific research and practical applications of three-membered cyclic compounds were emphasized.The summary of three-membered cyclic compounds is beneficial for the development and utilization of novel functionalized molecules.展开更多
Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the developm...Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the development of novel chemical interface based on two-dimensional(2D)sensing materials for SAW sensors for the rapid and sensitive detection of NH_(3)gas at room temperature(RT)still remains challenging.Herein,we report a highly selective RT NH_(3)gas sensor based on sulfur-doped graphitic carbon nitride quantum dots(S@g-C_(3)N_(4)QD)coated langasite(LGS)SAW sensor with enhanced sensitivity and recovery rate under ultraviolet(UV)illumination.Fascinatingly,the sensitivity of the S@g-C_(3)N_(4)QD/LGS SAW sensor to NH_(3)(500 ppb)at RT is dramatically enhanced by~4.5-fold with a low detection limit(~85 ppb),high selectivity,excellent reproducibility,fast response/recovery time(70 s/79 s)under UV activation(365 nm)as compared to dark condition.Additionally,the proposed sensor exhibited augmented NH_(3)detection capability across the broad range of relative humidity(20%–80%).Such remarkable gas sensing performances of the as-prepared sensor to NH_(3)are attributed to the high surface area,enhanced functional groups,sulfur defects,UV photogenerated charge carriers,facile charge transfer in the S@g-C_(3)N_(4)QD sensing layer,which further helps to improve the gas molecules adsorption that causes the increase in conductivity,resulting in larger frequency responses.The gas sensing mechanism of S@g-C_(3)N_(4)QD/LGS SAW sensor is ascribed to the enhanced electroacoustic effect,which is supported by the correlation of resistive type and COMSOL Multiphysics simulation studies.We envisage that the present work paves a promising strategy to develop the next generation 2D g-C_(3)N_(4)based high responsive RT SAW gas sensors.展开更多
基金supported by the National Natural Science Foundation of China(No.52302241 and 22225801)the Major Science and Technology Programs of Henan Province(241100240200)the China Postdoctoral Science Foundation(No.2023M730940).
文摘MXene derivatives are notable two-dimensional nanomaterials with numerous prospective applications in the domains of energy development.MXene derivative,MBene,diversifies its focus on energy storage and harvesting due to its exceptional electrical conductivity,structural flexibility,and mechanical properties.This comprehensive review describes the sandwich-like structure of the synthesized MBene,derived from its multilayered parent material and its distinct chemical framework to date.The fields of focus encompass the investigation of novel MBenes,the study of phase-changing mechanisms,and the examination of hex-MBenes,ortho-MBenes,tetra-MBenes,tri-MBenes,and MXenes with identical transition metal components.A critical analysis is also provided on the electrochemical mechanism and performance of MBene in energy storage(Li/Na/Mg/Ca/Li–S batteries and supercapacitors),as well as conversion and harvesting(CO_(2) reduction,and nitrogen reduction reactions).The persistent difficulties associated with conducting experimental synthesis and establishing artificial intelligence-based forecasts are extensively deliberated alongside the potential and forthcoming prospects of MBenes.This review provides a single platform for an overview of the MBene’s potential in energy storage and harvesting.
基金support from the National Natural Science Foundation of China(Nos.12305373 and 52276220)the Guangzhou Basic Research Program(No.SL2024A04J00234).
文摘Developing efficient and durable electrocatalysts for acidic oxygen evolution reaction(OER)is pivotal for advancing proton exchange membrane water electrolysis(PEMWEs),yet balancing activity and stability remains a formidable challenge.Herein,we propose a dual-engineering strategy to stabilize Ru-based catalysts by synergizing the oxygen vacancy site-synergized mechanism-lattice oxygen mechanism(OVSM-LOM)with Ru-N bond stabilization.The engineered RuO_(2)@NCC catalyst exhibits exceptional OER performance in 0.5 M H2SO4,achieving an ultralow overpotential of 215 mV at 10 mA cm^(-2) and prolonged stability for over 327 h.The catalyst delivers 300 h of continuous operation at 1 A cm^(-2),with a negligible degradation rate of only 0.067 mV h-1,further demonstrating its potential for practical application.Oxygen vacancies unlock the OVSM-LOM pathway,bypassing the sluggish adsorbate evolution mechanism(AEM)and accelerating reaction kinetics,while the Ru-N bonds suppress Ru dissolution by anchoring low-valent Ru centers.Quasi-in situ X-ray photoelectron spectroscopy(XPS),X-ray absorption spectroscopy(XAS),and isotopic labeling experiments confirm the lattice oxygen participation with *O formation as the rate-determining step.The Ru-N bonds reinforce the structural integrity by stabilizing low-valent Ru centers and inhibiting overoxidation.Theoretical calculations further verify that the synergistic interaction between OVs and Ru-O(N)active sites optimizes the Ru d-band center and stabilizes intermediates,while Ru-N coordination enhances structural integrity.This study establishes a novel paradigm for designing robust acidic OER catalysts through defect and coordination engineering,bridging the gap between activity and stability for sustainable energy technologies.
基金Project(HIT.NSRIF.2010112)supported by the Fundamental Research Fund for the Central Universities,ChinaProjects(50902030,51021002)supported by the National Natural Science Foundation of China
文摘BNp/Al2O3-SiO2 system ceramic matrix composites with different volume fractions （10%-60%） of hexagonal BN particulates （BNp） were prepared by hot-press sintering technique. Phase components, microstructure, mechanical properties and plasma erosion resistance were also investigated. With the increase of h-BNp content, relative density and Vickers＇ hardness of the composite ceramics decrease, while the flexural strength, elastic modulus and fracture toughness increase and then decrease. The plasma erosion resistance linearly deteriorated with the increase of BNp content which is mainly determined by the density, crystal structure and atomic number of the elements.
文摘The industrial implementation of Solar-driven photocatalysis is hampered by inefficient charge separation,poor reusability and hard retrieval of powdery catalysts.To conquer these drawbacks,a self-floating S-scheme Bi_(4)O_(5)Br_(2)/P-doped C_(3)N_(4)/carbon fiber cloth(BB/PN/CC)composed of carbon fibers(CC)as the core and Bi_(4)O_(5)Br_(2)/P-doped C_(3)N_(4)(BB/PN)nanosheets as the shell was constructed as a competent,recyclable cloth-shaped photocatalyst for safe and efficient degradation of aquacultural antibiotics.The BB/PN/CC fabric achieves an exceptional tetracycline degradation rate constant of 0.0118 min‒1,surpassing CN/CC(0.0015 min^(‒1)),BB/CC(0.0066 min^(‒1))and PN/CC(0.0023 min^(‒1))by 6.9,0.8 and 4.1 folds,respectively.Beyond its catalytic prowess,the photocatalyst’s practical superiority is evident in its effortless recovery and environmental adaptability.The superior catalytic effectiveness stems from the S-scheme configuration,which retains the maximum redox capacities of the constituent BB and PN while enabling efficient spatial detachment of photo-carriers.X-ray photoelectron spectroscopy(XPS),in-situ XPS,and electron paramagnetic resonance analyses corroborate the S-scheme mechanism,revealing electron accumulation on PN and hole retention on BB under illumination.Density functional theory calculations further confirm S-scheme interfacial charge redistribution and internal electric field formation.This study advances the design of macroscopic S-scheme heterojunction photocatalysts for sustainable water purification.
基金supported by National Natural Science Foundation of China(No.50676026)the Program for Chair Professors of"Cheung Kong Scholars Program"of China in 2008
文摘Experimental investigations into the effects of the magnetic field configuration near the channel exit on the plume of Hall thrusters were conducted. The magnetic field configuration near the channel exit is characterized by the inclination angle between the magnetic field lines and the thruster radial direction. Different inclination angles were obtained by varying the current ratio in the coils. The plume divergence angles were measured by a dual-directed probe. The results showed that the plume divergence angle increased obviously with the increase in the magnitude of the inclination angle near the channel exit. Therefore, in order to optimize the magnetic field for reducing plume divergence, the magnitude of the inclination angle should be reduced as much as possible. It suggests that the magnetic field configuration near the channel exit is another important factor that affects plume divergence.
基金financially supported by the Natural Science Foundation of Henan Province Youth Fund of China(No.242300421466)the Key Scientific Research Project Plan in Universities of Henan Province,China(No.23A430037)+1 种基金the Research Project of Xuchang University,China(No.2024ZD004)the College Students’Innovation and Entrepreneurship Training Program of China(No.202410480008).
文摘Facing the complex variable high-temperature environment,electromagnetic wave(EMW)absorbing materials maintaining high stability and satisfying absorbing properties is essential.This study focused on the synthesis and EMW absorbing performance evaluation of TiN/Fe_(2)N/C composite materials,which were prepared using electrostatic spinning followed by a high-temperature nitridation process.The TiN/Fe_(2)N/C fibers constructed a well-developed conductive network that generates considerable conduction loss.The heterogeneous interfaces between different components generated a significant level of interfacial polarization.Thanks to the synergistic effect of stable dielectric loss and optimized impedance matching,the TiN/Fe_(2)N/C composite materials demonstrated excellent and stable absorption performance across a wide temperature range(293-453 K).Moreover,TiN/Fe_(2)N/C-15 achieved a minimum reflection loss(RL)of−48.01 dB and an effective absorption bandwidth(EAB)of 3.64 GHz at 2.1 mm and 373 K.This work provides new insights into the development of high-efficiency and stabile EMW absorbing materials under complex variable high-temperature conditions.
基金the CONEX-Plus programme funded by Universidad Carlos III de Madrid(UC3M)the European Commission through the Marie-Sklodowska Curie COFUND Action(Grant Agreement No 801538)+2 种基金supported by the National Research Foundation of Korea Grant funded by the Korean Government(NRF-2019R1l1A3A0106383312)Supporting Project(RSP2021/55),King Saud University,Riyadh,Saudi Arabia,for financial supportfinancial support from Taif University Researchers Supporting Project number(TURSP2020/135),Taif University,Taif,Saudi Arabia。
文摘An eco-friendly,new,and controllable approach for the preparation of manganese oxide(a-MnO_(2))nanorods has been introduced using hydrothermal reaction for supercapacitor application.The in-depth crystal structure analysis ofα-MnO_(2) is analyzed by X-ray Rietveld refinement by using Full Prof program with the help of pseudo-Voigt profile function.The developed a-MnO_(2) electrode attains a remarkable capacitance of 577.7 F/g recorded at a current density value of 1 A/g with an excellent cycle life when is used for 10,000 repeated cycles due to the porous nanorod-morphology assisting the ease penetration of electrolyte ions into the electroactive sites.The diffusive and capacitive contributions of the electrode have been estimated by considering standard numerical packages in Python.After successfully assembling the aqueous symmetric supercapacitor(SSC)cell by utilizing the as-preparedα-MnO_(2),an excellent capacitance of 163.5 F/g and energy density of 58.1 Wh/kg at the constant current density of 0.5 A/g are obtained with an expanded potential frame of 1.6 V.Moreover,the cell has exceptionally withstood up to 10,000 cycles with an ultimate capacitance retention of 94.1%including the ability to light an LED for 18 s.Such findings recommend the developed a-MnO_(2) electrode to be a highly felicitous electrode for the field of energy storage.
基金National Research Foundation of Korea(NRF),Grant/Award Number:2021R1A2C2012685Korea Institute of Energy Technology Evaluation and Planning(KETEP),Grant/Award Number:20203020030010Ministry of Trade,Industry&Energy(MOTIE,Korea),Grant/Award Number:20020400。
文摘One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (Grant Nos.2018R1A6A1A03024334,2019R1A2C1007637,2021M3I3A1082880,2021R1I1A1A01044174)the Basic Science Research Capacity Enhancement Project through Korea Basic Science Institute (Grant No.2019R1A6C1010024)。
文摘The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.
基金Supported from the Regional Leading Research Center Program(2019R1A5A8080326)through the National Research Foundation funded by the Ministry of Science and ICT of Republic of Korea.
文摘Herein,a simple synthetic approach is employed for the atomic dispersion of Rh atoms(Rh SAs)over the surface of interconnected Mo_(2)C nanosheets intimately embedded in a three-dimensional Ni_(x)MoO_(y)nanorod arrays(Ni_(x)MoO_(y)NRs)framework;we found that the introduction of both isolated Rh SAs and Ni_(x)MoO_(y)NRs adjusts the electrocatalytic function of the host Mo_(2)C toward the direction of being an advanced and highly stable electrocatalyst for efficient hydrogen evolution at pH-universal conditions.As a result,the proposed catalyst outperforms most recently reported transition metal-based catalysts,and its performance even rivals that of commercial Pt/C,as demonstrated by its ultralow overpotentials of 31.7,109.7,and 95.4 mV at a current density of 10 mA cm^(-2),along with its small Tafel slopes of 42.4,51.2,and 46.8 mV dec^(-1)in acidic,neutral,and alkaline conditions,respectively.In addition,the catalyst shows remarkable long-term stability over all pH values with good maintenance of its catalytic activity and structural characteristics after continuous operation.
基金supported by the National Natural Science Foundation of China(Grant Nos.22225801,W2441009,22408228)。
文摘As energy demands continue to rise in modern society,the development of high-performance lithium-ion batteries(LIBs)has become crucial.However,traditional research methods of material science face challenges such as lengthy timelines and complex processes.In recent years,the integration of machine learning(ML)in LIB materials,including electrolytes,solid-state electrolytes,and electrodes,has yielded remarkable achievements.This comprehensive review explores the latest applications of ML in predicting LIB material performance,covering the core principles and recent advancements in three key inverse material design strategies:high-throughput virtual screening,global optimization,and generative models.These strategies have played a pivotal role in fostering LIB material innovations.Meanwhile,the paper briefly discusses the challenges associated with applying ML to materials research and offers insights and directions for future research.
基金the financial support provided by the National Science and Technology Major Project(J2019-Ⅳ-0008-0076,No.2019-Ⅱ-0010-0030)Natural Science Fund for Excellent Young Scholars of Heilongjiang Province(No.YQ2021E023)。
文摘The influence of partitioned profiling design based on a large-pitch highly loaded cascade is studied by numerical simulation.The partitioned profile is mainly composed of a pressure-side convex structure near the leading edge and a suction-side convex structure at the midstream and downstream sides of the passage.The influence of the change in the vertex axial position and peak value of the B-line on the secondary flow control is analyzed.In this paper,air(ideal gas)is selected as the flow media.The average static pressure at the outlet and the average total temperature at the inlet are kept constant.SST γ-θ is used as the turbulence model.The results show that the pressure-side convex structure suppresses the spanwise and pitchwise migration of the inlet flow by adjusting the static pressure distribution of the flow field,so the development of the pressure-side leg of the horseshoe vortex is effectively limited.The suction-side convex structure adjusts the static pressure distribution of the flow field and increases the included angle between the cross-flow and suction surface,so the accumulation of low-momentum fluid,the development of a corner vortex and the flow separation at the trailing edge of the suction-side surface are all suppressed near the endwall-suction corner.Consequently,the energy loss coefficient of the large-pitch highly loaded cascade is decreased from 0.0564 to 0.0485,representing a 25% reduction in secondary flow losses.
文摘The rigorous operating condition of proton exchange membrane fuel cells(PEMFCs)poses a substantial hurdle for the long-term stability of Pt-based alloy catalysts;thus,the development of Pt-alloy catalysts with unique morphologies is crucial for enhancing the stability of PEMFCs.In this study,we synthesized a novel PtCu nano-dendrite(PtCuND)catalyst through a facile,one-step solvothermal process.The sub-nanometer particles and nanopores within this catalyst facilitate enhanced mass transport.In PEM single-cell tests,the PtCuND catalyst displays high activity and robust stability,achieving a mass activity of 0.65 A mgPt^(–1).Notably,after accelerated durability tests,the mass activity and the voltage at 0.8 A cm^(–2)of PtCuND exhibits only minimal decreases of 18.5%and 9 mV,respectively.The combined experimental results and theoretical calculations conclusively illustrate the optimized adsorption of oxygen species and the impact of compressive strain on the catalyst surface.The enhanced durability can be attributed to the maintained nano-dendritic morphology and the strengthened interaction within the Pt-Cu bonds.This work not only enhances the stability of PEMFCs but also provides a robust foundation for the future scaling up of catalyst production,paving the way for widespread application in sustainable energy systems.
基金supported by the National Natural Science Foundation of China(Grant No.52376087)Hunan Provincial Natural Science Foundation of China(Grant No.2023JJ30688)。
文摘Parabolic trough collectors are essential components of solar thermal power plants,and the non-uniform heat flux on the walls may lead to low heat transfer coefficients and large wall temperature differences.A novel jet structure is proposed in this paper to explore the feasibility of adopting impinging jets to improve the heat transfer performance of the collector tube with supercritical carbon dioxide(S-CO_(2))as the working fluid.The physical model is built based on several assumptions,and numerical simulations are performed under the mass flow rate of 0.25-0.75 kg/s and the average surface heat flux of 14.7-33 kW/m^(2).Firstly,performance comparisons are made between the jet and tube-in-tube structures.The results show that the average heat transfer coefficient h of the jet structure is 46.5%higher than that of the tube-in-tube structure and the corresponding average temperature differenceΔT between the wall and S-CO_(2)is 31.7%lower.Secondly,the effects of the jet hole circumferential position and diameter on heat transfer are investigated.It's found that by adjusting the circumferential position of the jet hole from 60°to 120°and matching the impingement area of the jets and the high heat flux region,h can be increased by 14.2%andΔT can be reduced by 12.4%.h is also found to be increased by 77.4%when the jet hole diameter is reduced from D=9.7 mm to D=5 mm.Furthermore,the jet structure is further modified by incorporating it with the eccentric configuration.The effect of eccentricity e is studied in detail,and results show that appropriate eccentricity results in higher h and smallerΔT due to the decreased impingement distance and the increased heat transfer.This study can guide the design and optimization of parabolic trough collectors.
基金supported by the National Natural Science Foundation of China(Nos.U21A20307,22178359,and 22308087)CAS Project for Young Scientists in Basic Research(No.YSBR-052).
文摘Three-membered cyclic compounds are a fascinating class of compounds:they have the maximum torsional and angular strain(sp^(3)hybridization but bond angles deviate from 109°28’),and possess unique physical and chemical properties.A lot of effort has been devoted to their synthesis and applications in recent years.This review provides an overview of various synthesis strategies for three-membered cyclic compounds,and summarizes the proposed reaction mechanisms and key issues such as structure-property relationships through specific examples.Meanwhile,the advantages and disadvantages of different synthesis strategies were discussed,including the recently developed electrochemical synthesis methods.Finally,the prospects and challenges for further scientific research and practical applications of three-membered cyclic compounds were emphasized.The summary of three-membered cyclic compounds is beneficial for the development and utilization of novel functionalized molecules.
基金the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2020R1A2C2013385)Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.NRF-2020R1A6A1A03047771)Korea Institute of Planning and Evaluation for Technology in Food,Agriculture and Forestry(IPET),Korea Smart Farm Research and Development Foundation(KosFarm)through Smart Farm Innovation Technology Development Program,funded by Ministry of Agriculture,Food,and Rural Affairs(MAFRA)and Ministry of Science and ICT(MSIT),Rural Development Administration(RDA)(No.421029-4).
文摘Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the development of novel chemical interface based on two-dimensional(2D)sensing materials for SAW sensors for the rapid and sensitive detection of NH_(3)gas at room temperature(RT)still remains challenging.Herein,we report a highly selective RT NH_(3)gas sensor based on sulfur-doped graphitic carbon nitride quantum dots(S@g-C_(3)N_(4)QD)coated langasite(LGS)SAW sensor with enhanced sensitivity and recovery rate under ultraviolet(UV)illumination.Fascinatingly,the sensitivity of the S@g-C_(3)N_(4)QD/LGS SAW sensor to NH_(3)(500 ppb)at RT is dramatically enhanced by~4.5-fold with a low detection limit(~85 ppb),high selectivity,excellent reproducibility,fast response/recovery time(70 s/79 s)under UV activation(365 nm)as compared to dark condition.Additionally,the proposed sensor exhibited augmented NH_(3)detection capability across the broad range of relative humidity(20%–80%).Such remarkable gas sensing performances of the as-prepared sensor to NH_(3)are attributed to the high surface area,enhanced functional groups,sulfur defects,UV photogenerated charge carriers,facile charge transfer in the S@g-C_(3)N_(4)QD sensing layer,which further helps to improve the gas molecules adsorption that causes the increase in conductivity,resulting in larger frequency responses.The gas sensing mechanism of S@g-C_(3)N_(4)QD/LGS SAW sensor is ascribed to the enhanced electroacoustic effect,which is supported by the correlation of resistive type and COMSOL Multiphysics simulation studies.We envisage that the present work paves a promising strategy to develop the next generation 2D g-C_(3)N_(4)based high responsive RT SAW gas sensors.
