Three-dimensional(3D)covalent organic frameworks(COFs)have attracted extensive attention as photocatalysts for CO_(2)reduction reactions.Introducing metal atoms is essential for enhancing activity,but previous metal s...Three-dimensional(3D)covalent organic frameworks(COFs)have attracted extensive attention as photocatalysts for CO_(2)reduction reactions.Introducing metal atoms is essential for enhancing activity,but previous metal sites in 3D COFs predominantly exhibit symmetrical coordination,making them unsuitable for CO_(2)activation.Here,we design a 3D COF with 2,2'-pyridine linked around tetra-(4-anilyl)methane(TCM-Bpy-COF),where Co^(2+)is asymmetrically coordinated by bipyridine and acetates(TCMBpy-COF-CoAc).The TCM-Bpy-COF-CoAc exhibits outstanding photocatalytic CO_(2)reduction performance under weak visible light,achieving a CO evolution rate of 26,650μmol g^(-1)h^(-1)under 5 W of lightemitting-diode(LED)lamp and high apparent quantum efficiency.The performance far exceeds that of symmetrically coordinated bipyridine-Co-bipyridine TCM-Bpy-COF and surpasses most reported COF-based photocatalysts.In-situ spectral characterizations and theoretical calculations show that asymmetric N,O-coordination around the Co^(2+)center polarizes electron density and lowers reaction energy barriers of^(*)COOH intermediates,enhancing the conversion of CO_(2)to CO.This work inspires the design of 3D COF-based photocatalysts with highly catalytic efficiency.展开更多
Using photoelectrocatalytic CO_(2) reduction reaction(CO_(2)RR)to produce valuable fuels is a fascinating way to alleviate environmental issues and energy crises.Bismuth-based(Bi-based)catalysts have attracted widespr...Using photoelectrocatalytic CO_(2) reduction reaction(CO_(2)RR)to produce valuable fuels is a fascinating way to alleviate environmental issues and energy crises.Bismuth-based(Bi-based)catalysts have attracted widespread attention for CO_(2)RR due to their high catalytic activity,selectivity,excellent stability,and low cost.However,they still need to be further improved to meet the needs of industrial applications.This review article comprehensively summarizes the recent advances in regulation strategies of Bi-based catalysts and can be divided into six categories:(1)defect engineering,(2)atomic doping engineering,(3)organic framework engineering,(4)inorganic heterojunction engineering,(5)crystal face engineering,and(6)alloying and polarization engineering.Meanwhile,the corresponding catalytic mechanisms of each regulation strategy will also be discussed in detail,aiming to enable researchers to understand the structure-property relationship of the improved Bibased catalysts fundamentally.Finally,the challenges and future opportunities of the Bi-based catalysts in the photoelectrocatalytic CO_(2)RR application field will also be featured from the perspectives of the(1)combination or synergy of multiple regulatory strategies,(2)revealing formation mechanism and realizing controllable synthesis,and(3)in situ multiscale investigation of activation pathways and uncovering the catalytic mechanisms.On the one hand,through the comparative analysis and mechanism explanation of the six major regulatory strategies,a multidimensional knowledge framework of the structure-activity relationship of Bi-based catalysts can be constructed for researchers,which not only deepens the atomic-level understanding of catalytic active sites,charge transport paths,and the adsorption behavior of intermediate products,but also provides theoretical guiding principles for the controllable design of new catalysts;on the other hand,the promising collaborative regulation strategies,controllable synthetic paths,and the in situ multiscale characterization techniques presented in this work provides a paradigm reference for shortening the research and development cycle of high-performance catalysts,conducive to facilitating the transition of photoelectrocatalytic CO_(2)RR technology from the laboratory routes to industrial application.展开更多
Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when ta...Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when tackling high-dimensional optimization challenges.To effectively address these challenges,this study introduces cooperative metaheuristics integrating dynamic dimension reduction(DR).Building upon particle swarm optimization(PSO)and differential evolution(DE),the proposed cooperative methods C-PSO and C-DE are developed.In the proposed methods,the modified principal components analysis(PCA)is utilized to reduce the dimension of design variables,thereby decreasing computational costs.The dynamic DR strategy implements periodic execution of modified PCA after a fixed number of iterations,resulting in the important dimensions being dynamically identified.Compared with the static one,the dynamic DR strategy can achieve precise identification of important dimensions,thereby enabling accelerated convergence toward optimal solutions.Furthermore,the influence of cumulative contribution rate thresholds on optimization problems with different dimensions is investigated.Metaheuristic algorithms(PSO,DE)and cooperative metaheuristics(C-PSO,C-DE)are examined by 15 benchmark functions and two engineering design problems(speed reducer and composite pressure vessel).Comparative results demonstrate that the cooperative methods achieve significantly superior performance compared to standard methods in both solution accuracy and computational efficiency.Compared to standard metaheuristic algorithms,cooperative metaheuristics achieve a reduction in computational cost of at least 40%.The cooperative metaheuristics can be effectively used to tackle both high-dimensional unconstrained and constrained optimization problems.展开更多
In the present work, we report nitrogen and phosphorus co-doped 3-D structured carbon nanotube intercalated graphene nanoribbon composite. The graphene nanoribbons are prepared via partial exfoliation of multi-walled ...In the present work, we report nitrogen and phosphorus co-doped 3-D structured carbon nanotube intercalated graphene nanoribbon composite. The graphene nanoribbons are prepared via partial exfoliation of multi-walled carbon nanotubes. In the graphene nanoribbons/CNTs composite, carbon nanotubes play a role of skeleton and support the exfoliated graphene nanoribbons to form the stereo structure. After high temperature heat-treatment with ammonium dihydrogen phosphate, the unique structure reserves both the properties of carbon nanotube and graphene, exhibiting excellent catalytic performance for the ORR with excellent onset and half-wave potential, which is similar to commercial Pt/C electrocatalysts.展开更多
Metal-free carbon-based materials are considered as promising oxygen reduction reaction(ORR)electrocatalysts for clean energy conversion,and their highly dense and exposed carbon active sites are crucial for efficient...Metal-free carbon-based materials are considered as promising oxygen reduction reaction(ORR)electrocatalysts for clean energy conversion,and their highly dense and exposed carbon active sites are crucial for efficient ORR.In this work,two unique quasi-three-dimensional cyclotriphosphazene-based covalent organic frameworks(Q3CTP-COFs)and their nanosheets were successfully synthesized and applied as ORR electrocatalysts.The abundant electrophilic structure in Q3CTP-COFs induces a high density of carbon active sites,and the unique bilayer stacking of[6+3]imine-linked backbone facilitates the exposure of active carbon sites and accelerates mass diffusion during ORR.In particular,bulk Q3CTP-COFs can be easily exfoliated into thin COF nanosheets(NSs)due to the weak interlayerπ-πinteractions.Q3CTP-COF NSs exhibit highly efficient ORR catalytic activity(half-wave potential of 0.72 V vs.RHE in alkaline electrolyte),which is one of the best COF-based ORR electrocatalysts reported so far.Furthermore,Q3CTP-COF NSs can serve as a promising cathode for Zn-air batteries(delivered power density of 156 mW cm-2 at 300 mA cm^(-2)).This judicious design and accurate synthesis of such COFs with highly dense and exposed active sites and their nanosheets will promote the development of metal-free carbon-based electrocatalysts.展开更多
The through silicon via （TSV） technology has proven to be the critical enabler to realize a three-dimensional （3D） gigscale system with higher performance but shorter interconnect length. However, the received dig...The through silicon via （TSV） technology has proven to be the critical enabler to realize a three-dimensional （3D） gigscale system with higher performance but shorter interconnect length. However, the received digital signal after trans- mission through a TSV channel, composed of redistribution layers （RDLs）, TSVs, and bumps, is degraded at a high data-rate due to the non-idealities of the channel. We propose the Chebyshev multisection transformers to reduce the signal reflec- tion of TSV channel when operating frequency goes up to 20 GHz, by which signal reflection coefficient （$11） and signal transmission coefficient （$21） are improved remarkably by 150% and 73.3%, respectively. Both the time delay and power dissipation are also reduced by 4% and 13.3%, respectively. The resistance-inductance-conductance-capacitance （RLGC） elements of the TSV channel are iterated from scattering （S）-parameters, and the proposed method of weakening the signal reflection is verified using high frequency simulator structure （HFSS） simulation software by Ansoft.展开更多
Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In...Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In this study,we develop a novel solvent method to prepare interconnected N,S co-doped three-dimensional（3D）carbon networks with tunable nanopores derived from an asso-ciated complex based on melamine and sodium dodecylbenzene sulfonate（SDBS）.After the intro-duction of silica templates and calcination,the catalyst exhibits 3D networks with interconnected 50-nm pores and partial graphitization.With the increase of the number of Lewis base sites caused by the N doping and change of the carbon charge and spin densities caused by the S doping,the designed N,S co-doped catalyst exhibits a similar electrochemical activity to that of the commercial 20-wt%Pt/C as an oxygen reduction reaction catalyst.In addition,in an aluminum-air battery,the proposed catalyst even outperforms the commercial 5-wt%Pt/C catalyst.Both interconnected porous structures and synergistic effects of N and S contribute to the superior catalytic perfor-mance.This study paves the way for the synthesis of various other N-doped and co-doped carbon materials as efficient catalysts in electrochemical energy applications.展开更多
The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large de...The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large deformation during the LCR process and to minimize the thickness of the slab in bending segments,the maximum theoretical reduction amount and the corresponding reduction scheme for the LCR process must be determined.With SPA-H weathering steel as a specific research steel grade,the distributions of tem-perature and deformation fields of a slab with the LCR process were analyzed using a three-dimensional thermal-mechanical finite ele-ment model.High-temperature tensile tests were designed to determine the critical strain of corner crack propagation and intermediate crack initiation with various strain rates and temperatures,and a prediction model of the critical strain for two typical cracks,combining the effects of strain rate and temperature,was proposed by incorporating the Zener-Hollomon parameter.The crack risks with different LCR schemes were calculated using the crack risk prediction model,and the maximum theoretical reduction amount for the SPA-H slab with a transverse section of 145 mm×1600 mm was 41.8 mm,with corresponding reduction amounts for Segment 0 to Segment 4 of 15.8,7.3,6.5,6.4,and 5.8 mm,respectively.展开更多
Exploiting non-precious metal catalysts with excellent oxygen reduction reaction(ORR)performance for energy devices is paramount essential for the green and sustainable society development.Herein,low-cost,high-perform...Exploiting non-precious metal catalysts with excellent oxygen reduction reaction(ORR)performance for energy devices is paramount essential for the green and sustainable society development.Herein,low-cost,high-performance biomass-derived ORR catalysts with an asymmetric Fe-N_(3)P configuration was prepared by a simple pyrolysis-etching technique,where carboxymethyl cellulose(CMC)was used as the carbon source,urea and 1,10-phenanthroline iron complex(FePhen)as additives,and Na_(3)PO_(4)as the phosphorus dopant and a pore-forming agent.The CMC-derived FeNPC catalyst displayed a large specific area(BET:1235 m^(2)g^(-1))with atomically dispersed Fe-N_(3)P active sites,which exhibited superior ORR activity and stability in alkaline solution(E_(1/2)=0.90 V vs.RHE)and Zn-air batteries(P_(max)=149 mW cm^(-2))to commercial Pt/C catalyst(E_(1/2)=0.87 V,P_(max)=118 mW cm^(-2))under similar experimental conditions.This work provides a feasible and costeffective route toward highly efficient ORR catalysts and their application to Zn-air batteries for energy conversion.展开更多
Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This ...Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).展开更多
Nitrogen-doping of carbon support(N-C)for platinum(Pt)nanoparticles to form Pt/N-C catalyst represents an effective strategy to promote the electrocatalysis of cathodic oxygen reduction reaction(ORR)in proton exchange...Nitrogen-doping of carbon support(N-C)for platinum(Pt)nanoparticles to form Pt/N-C catalyst represents an effective strategy to promote the electrocatalysis of cathodic oxygen reduction reaction(ORR)in proton exchange membrane fuel cells.For fundamental understanding,clearly identifying the metalsupport effect on enhancement mechanisms of ORR electrocatalysis is definitely needed.In this work,the impact of Pt-support interaction via interfacial Pt-N coordination on electrocatalytic ORR activity and stability in Pt/N-C catalyst is deeply studied through structural/compositional characterizations,electrochemical measurements and theoretical DFT-calculations/AIMD-simulations.The resulting Pt/N-C catalyst exhibits a superior electrocatalytic performance compared to the commercial Pt/C catalyst in both half-cell and H_(2)-O_(2)fuel cell.Experimental and theoretical results reveal that the interfacial Pt-N coordination enables electron transfer from N-C support to Pt nanoparticles,which can weaken the adsorption strength of oxygen intermediates on Pt surface to improve ORR activity and induce the strong Pt-support interaction to enhance electrochemical stability.展开更多
Photocatalytic conversion of CO_(2) is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development.Nowadays,polymeric carbon nitride(PCN)has gained widespread application in CO_(2)...Photocatalytic conversion of CO_(2) is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development.Nowadays,polymeric carbon nitride(PCN)has gained widespread application in CO_(2) solar reduction due to its excellent visible light response,suitable conduction band position,and good cost-effectiveness.However,the amorphous nature and low conductivity of PCN limit its photocatalytic efficiency by leading to low carrier concentrations and facile electron–hole recombination during photocatalysis.Addressing this bottleneck,in this study,potassium-doped PCN(KPCN)/copper(Ⅱ)-complexed bipyridine hydroxyquinoline carboxylic acid(Cu(Ⅱ)(bpy)(H_(2)hqc))composite catalysts were synthesized through a multistep microwave heating process.In the composite,the formation of an S-scheme junction facilitates the enrichment of more negative electrons on the conduction band of KPCN via intermolecular electron–hole recombination between Cu(Ⅱ)(bpy)(H_(2)hqc)(CuPyQc)and KPCN,thereby promoting efficient photoreduction of CO_(2) to CO.Microwave heating enhances the amidation reaction between these two components,achieving the immobilization of homogeneous molecular catalysts and forming amidation chemical bonds that serve as key channels for the S-scheme charge transfer.This work not only presents a new PCN-based catalytic system for CO_(2) reduction applications,but also offers a novel microwave-practical approach for immobilizing homogeneous catalysts.展开更多
The development of an e fficacious and easily prepared no nprecious metal electrocatalyst is crucial for the oxygen reduction reaction(ORR).This work used a dual template method to prepare the amorphous rare earth-bas...The development of an e fficacious and easily prepared no nprecious metal electrocatalyst is crucial for the oxygen reduction reaction(ORR).This work used a dual template method to prepare the amorphous rare earth-based catalyst PrO_(x)-NC,and optimized the calcination temperature and proportion.The PrO_(x)-NC-900 catalyst has high durability and activity and exhibits superior ORR performance in alkaline electrolytes with an onset potential(E_(0))of 0.96 V and a half-wave potential(E_(1/2))of 0.85 V.The research results indicate that the ORR performance of rare earth oxide composite carbon catalysts can be improved by adjusting oxygen vacancies(Ov).In addition,high specific surface area,N rich defect carbon.increased oxygen vacancies,and the synergistic effect of oxygen vacancies and N-doped carbon interfacial layer play a significant part in the enhancement of ORR.The performance of the zinc air battery assembled with PrO_(x)-NC-900 is significantly improved,and rare earth oxides and carbon frameworks originating from metal organic frameworks(MOFs)contribute to the oxygen electrocatalyst and electron transfer rate of the zinc air battery.This catalyst provides promising information for the development of rare earth metal oxide nanostructures as potential candidate materials for ORR in alkaline media.展开更多
A sp^(2) carbon-conjugated covalent organic framework (BDATN) was modified through γ-ray radiation reduction and subsequent acidification with hydrochloric acid to yield a novel functional COF (named rBDATN-HCl) for ...A sp^(2) carbon-conjugated covalent organic framework (BDATN) was modified through γ-ray radiation reduction and subsequent acidification with hydrochloric acid to yield a novel functional COF (named rBDATN-HCl) for Cr(Ⅵ) removal.The morphology and structure of rBDATN-HCl were analyzed and identified by SEM,FTIR,XRD and solid-state13C NMR.It is found that the active functional groups,such as hydroxyl and amide,were introduced into BDATN after radiation reduction and acidification.The prepared rBDATN-HCl demonstrates a photocatalytic reduction removal rate of Cr(Ⅵ) above 99%after 60min of illumination with a solid-liquid ratio of 0.5 mg/mL,showing outstanding performance,which is attributed to the increase of dispersibility and adsorption sites of r BDATN-HCl.In comparison to the cBDATN-HCl synthesized with chemical reduction,rBDATN-HCl exhibits a better photoreduction performance for Cr(Ⅵ),demonstrating the advantages of radiation preparation of rBDATN-HCl.It is expected that more functionalized sp^(2) carbon-conjugated COFs could be obtained by this radiation-induced reduction strategy.展开更多
In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-dept...In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry.Typically,the isotropy of a specific facet provides a perfect support for studying heteroatom doping.Herein,this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals.The presence of iron not only modifies the electronic structure of lithium tantalate,improving its light absorption capacity,but also functions as an active site for the nitrogen adsorption and activation.The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95μg cm^(−2)h^(−1),which is three times higher than that of undoped lithium tantalate.The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating.This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.展开更多
The impact of heavy reduction on dendritic morphology was explored by combining experimental research and numerical simulation in metallurgy,including a detailed three-dimensional(3D)analysis and reconstruction of den...The impact of heavy reduction on dendritic morphology was explored by combining experimental research and numerical simulation in metallurgy,including a detailed three-dimensional(3D)analysis and reconstruction of dendritic solidification structures.Combining scanning electron microscopy and energy-dispersive scanning analysis and ANSYS simulation,the high-precision image processing software Mimics Research was utilized to conduct the extraction of dendritic morphologies.Reverse engineering software NX Imageware was employed for the 3D reconstruction of two-dimensional dendritic morphologies,restoring the dendritic characteristics in three-dimensional space.The results demonstrate that in a two-dimensional plane,dendrites connect with each other to form irregularly shaped“ring-like”structures.These dendrites have a thickness greater than 0.1 mm along the Z-axis direction,leading to the envelopment of molten steel by dendrites in a 3D space of at least 0.1 mm.This results in obstructed flow,confirming the“bridging”of dendrites in three-dimensional space,resulting in a tendency for central segregation.Dense and dispersed tiny dendrites,under the influence of heat flow direction,interconnect and continuously grow,gradually forming primary and secondary dendrites in three-dimensional space.After the completion of dendritic solidification and growth,these microdendrites appear dense and dispersed on the two-dimensional plane,providing the nuclei for the formation of new dendrites.When reduction occurs at a solid fraction of 0.46,there is a noticeable decrease in dendritic spacing,resulting in improved central segregation.展开更多
To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D lea...To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.展开更多
Electrocatalytic nitrate reduction reaction (NO_(3)-RR) to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution issues.We report a CuO nanoparticles in...Electrocatalytic nitrate reduction reaction (NO_(3)-RR) to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution issues.We report a CuO nanoparticles incorporated on nitrogen-doped porous carbon (CuO@NC) catalyst for NO_(3)-RR.Part of Cu(Ⅱ) is reduced to Cu(Ⅰ) during the NO_(3)-RR process to construct Cu(Ⅰ)-Cu(Ⅱ) pairs,confirmed by in situ X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.Density functional theory (DFT) calculations indicated that the formation of Cu(Ⅰ) could provide a reaction path with smaller energy barrier for NO_(3)-RR,while Cu(Ⅱ) effectively suppressed the competition of hydrogen evolution reaction (HER).As a result,CuO@NC catalyst achieved a Faradaic efficiency of 84.2% at -0.49 V versus reversible hydrogen electrode (RHE),and a NH_(3)yield rate of 17.2 mg h^(-1)mg^(-1)cat.at -0.79 V vs.RHE,higher than the HaberBosch process (<3.4 g h^(-1)g^(-1)cat.).This work may open a new avenue for effective NO_(3)-RR by modulating oxidation states.展开更多
Ultra-low emission of nitrogen oxide(NO_(x))is an irreversible trend for the development of waste-to-energy industry.But traditional approaches to remove NO_(x) face significant challenge s,such as low denitration eff...Ultra-low emission of nitrogen oxide(NO_(x))is an irreversible trend for the development of waste-to-energy industry.But traditional approaches to remove NO_(x) face significant challenge s,such as low denitration efficiency,complex denitration system,and high investment and operating cost.Here we put forward a novel polymer non-catalytic reduction(PNCR)technology that utilized a new type of polymer agent to remove NO_(x),and the proposed PNCR technology was applied to the existing waste-to-energy plant to test the denitration performance.The PNCR technology demonstrated excellent denitration performance with a NO_(x) emission concentration of<100 mg/Nm^(3) and high denitration efficiency of>75%at the temperature range of 800-900℃,which showed the application feasibility even on the complex and unstable industrial operating conditions.In addition,PNCR and hybrid polymer/selective non-catalytic reduction(PNCR/SNCR)technology possessed remarkable economic advantages including low investment fee and low operating cost of<10 CNY per ton of municipal solid waste(MSW)compared with selective catalytic reduction(SCR)technology.The excellent denitration performance of PNCR technology forebodes a broad industrial application prospect in the field of flue gas cleaning for waste-to-energy plants.展开更多
Guangdong’s carbon emissions have surpassed the world’s 11th largest emitter.It is indispensable for this province to find a robust cost-effective strategy for reducing carbon emissions.This study employed the Low E...Guangdong’s carbon emissions have surpassed the world’s 11th largest emitter.It is indispensable for this province to find a robust cost-effective strategy for reducing carbon emissions.This study employed the Low Emissions Analysis Platform model,marginal cost curves,and Monte Carlo methods to simulate the energy consumption,carbon emissions,and economic benefits of emission reduction in Guangdong Province from 2020 to 2030 under the application of various structural optimization policies and energy-saving technologies.The main findings are as follows:In 2030,Guangdong Province is projected to achieve a carbon emission reduction of 273.6 to 304.6million t CO_(2eq),with a total reduction cost ranging from 1030.9 to 1452.2 billion yuan.Increasing the share of renewable energy,which still has significant growth potential,can lead to a 1.4 times greater reduction in carbon emissions compared to the application of energy-saving technologies,despite the latter yielding 2.3 times more energy savings.The emission reduction measures with net-cost can contribute 71.4%to the total carbon reduction of the province,being much larger than those with net benefits.The power sector plays a critical role in carbon emission reduction within Guangdong Province,with its various measures exerting the most substantial impact on emission reduction quantity and cost,contributing cumulative variance contributions of 90.1%and 84.3%,respectively.It has relatively large potential for emission reduction and relatively low cost of structural adjustment.展开更多
基金financial support from the National Natural Science Foundation of China(No.22072183)the Natural Science Foundation of Hunan Province,China(No.2022JJ30690)supported in part by the High Performance Computing Center of Central South University。
文摘Three-dimensional(3D)covalent organic frameworks(COFs)have attracted extensive attention as photocatalysts for CO_(2)reduction reactions.Introducing metal atoms is essential for enhancing activity,but previous metal sites in 3D COFs predominantly exhibit symmetrical coordination,making them unsuitable for CO_(2)activation.Here,we design a 3D COF with 2,2'-pyridine linked around tetra-(4-anilyl)methane(TCM-Bpy-COF),where Co^(2+)is asymmetrically coordinated by bipyridine and acetates(TCMBpy-COF-CoAc).The TCM-Bpy-COF-CoAc exhibits outstanding photocatalytic CO_(2)reduction performance under weak visible light,achieving a CO evolution rate of 26,650μmol g^(-1)h^(-1)under 5 W of lightemitting-diode(LED)lamp and high apparent quantum efficiency.The performance far exceeds that of symmetrically coordinated bipyridine-Co-bipyridine TCM-Bpy-COF and surpasses most reported COF-based photocatalysts.In-situ spectral characterizations and theoretical calculations show that asymmetric N,O-coordination around the Co^(2+)center polarizes electron density and lowers reaction energy barriers of^(*)COOH intermediates,enhancing the conversion of CO_(2)to CO.This work inspires the design of 3D COF-based photocatalysts with highly catalytic efficiency.
基金supports from the National Natural Science Foundation of China(Grant Nos.12305372 and 22376217)the National Key Research&Development Program of China(Grant Nos.2022YFA1603802 and 2022YFB3504100)+1 种基金the projects of the key laboratory of advanced energy materials chemistry,ministry of education(Nankai University)key laboratory of Jiangxi Province for persistent pollutants prevention control and resource reuse(2023SSY02061)are gratefully acknowledged.
文摘Using photoelectrocatalytic CO_(2) reduction reaction(CO_(2)RR)to produce valuable fuels is a fascinating way to alleviate environmental issues and energy crises.Bismuth-based(Bi-based)catalysts have attracted widespread attention for CO_(2)RR due to their high catalytic activity,selectivity,excellent stability,and low cost.However,they still need to be further improved to meet the needs of industrial applications.This review article comprehensively summarizes the recent advances in regulation strategies of Bi-based catalysts and can be divided into six categories:(1)defect engineering,(2)atomic doping engineering,(3)organic framework engineering,(4)inorganic heterojunction engineering,(5)crystal face engineering,and(6)alloying and polarization engineering.Meanwhile,the corresponding catalytic mechanisms of each regulation strategy will also be discussed in detail,aiming to enable researchers to understand the structure-property relationship of the improved Bibased catalysts fundamentally.Finally,the challenges and future opportunities of the Bi-based catalysts in the photoelectrocatalytic CO_(2)RR application field will also be featured from the perspectives of the(1)combination or synergy of multiple regulatory strategies,(2)revealing formation mechanism and realizing controllable synthesis,and(3)in situ multiscale investigation of activation pathways and uncovering the catalytic mechanisms.On the one hand,through the comparative analysis and mechanism explanation of the six major regulatory strategies,a multidimensional knowledge framework of the structure-activity relationship of Bi-based catalysts can be constructed for researchers,which not only deepens the atomic-level understanding of catalytic active sites,charge transport paths,and the adsorption behavior of intermediate products,but also provides theoretical guiding principles for the controllable design of new catalysts;on the other hand,the promising collaborative regulation strategies,controllable synthetic paths,and the in situ multiscale characterization techniques presented in this work provides a paradigm reference for shortening the research and development cycle of high-performance catalysts,conducive to facilitating the transition of photoelectrocatalytic CO_(2)RR technology from the laboratory routes to industrial application.
基金funded by National Natural Science Foundation of China(Nos.12402142,11832013 and 11572134)Natural Science Foundation of Hubei Province(No.2024AFB235)+1 种基金Hubei Provincial Department of Education Science and Technology Research Project(No.Q20221714)the Opening Foundation of Hubei Key Laboratory of Digital Textile Equipment(Nos.DTL2023019 and DTL2022012).
文摘Owing to their global search capabilities and gradient-free operation,metaheuristic algorithms are widely applied to a wide range of optimization problems.However,their computational demands become prohibitive when tackling high-dimensional optimization challenges.To effectively address these challenges,this study introduces cooperative metaheuristics integrating dynamic dimension reduction(DR).Building upon particle swarm optimization(PSO)and differential evolution(DE),the proposed cooperative methods C-PSO and C-DE are developed.In the proposed methods,the modified principal components analysis(PCA)is utilized to reduce the dimension of design variables,thereby decreasing computational costs.The dynamic DR strategy implements periodic execution of modified PCA after a fixed number of iterations,resulting in the important dimensions being dynamically identified.Compared with the static one,the dynamic DR strategy can achieve precise identification of important dimensions,thereby enabling accelerated convergence toward optimal solutions.Furthermore,the influence of cumulative contribution rate thresholds on optimization problems with different dimensions is investigated.Metaheuristic algorithms(PSO,DE)and cooperative metaheuristics(C-PSO,C-DE)are examined by 15 benchmark functions and two engineering design problems(speed reducer and composite pressure vessel).Comparative results demonstrate that the cooperative methods achieve significantly superior performance compared to standard methods in both solution accuracy and computational efficiency.Compared to standard metaheuristic algorithms,cooperative metaheuristics achieve a reduction in computational cost of at least 40%.The cooperative metaheuristics can be effectively used to tackle both high-dimensional unconstrained and constrained optimization problems.
基金supported by the National Natural Science Foundation of China (Nos. 21306060, 21573083)the Program for New Century Excellent Talents in University of Ministry o Education of China (No. NCET-13-0237)+2 种基金the Doctoral Fund o Ministry of Education of China (No. 20130142120039)the Fundamental Research Funds for the Central University (Nos 2013TS136, 2014YQ009)the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences (No. DE-SC0012704)
文摘In the present work, we report nitrogen and phosphorus co-doped 3-D structured carbon nanotube intercalated graphene nanoribbon composite. The graphene nanoribbons are prepared via partial exfoliation of multi-walled carbon nanotubes. In the graphene nanoribbons/CNTs composite, carbon nanotubes play a role of skeleton and support the exfoliated graphene nanoribbons to form the stereo structure. After high temperature heat-treatment with ammonium dihydrogen phosphate, the unique structure reserves both the properties of carbon nanotube and graphene, exhibiting excellent catalytic performance for the ORR with excellent onset and half-wave potential, which is similar to commercial Pt/C electrocatalysts.
基金supported by National Key R&D Prog ram of China (2022YFB3704900 and 2021YFF0500500)National Natural Science Foundation of China (22025504, 21621001, and 22105082)+4 种基金the SINOPEC Research Institute of Petroleum Processing"111"project (BP0719036 and B17020)China Postdoctoral Science Foundation (2020TQ0118 and 2020M681034)the program for JLU Science and Technology Innovative Research Teamthe Taishan Scholars Program (No. tsqn202211124)
文摘Metal-free carbon-based materials are considered as promising oxygen reduction reaction(ORR)electrocatalysts for clean energy conversion,and their highly dense and exposed carbon active sites are crucial for efficient ORR.In this work,two unique quasi-three-dimensional cyclotriphosphazene-based covalent organic frameworks(Q3CTP-COFs)and their nanosheets were successfully synthesized and applied as ORR electrocatalysts.The abundant electrophilic structure in Q3CTP-COFs induces a high density of carbon active sites,and the unique bilayer stacking of[6+3]imine-linked backbone facilitates the exposure of active carbon sites and accelerates mass diffusion during ORR.In particular,bulk Q3CTP-COFs can be easily exfoliated into thin COF nanosheets(NSs)due to the weak interlayerπ-πinteractions.Q3CTP-COF NSs exhibit highly efficient ORR catalytic activity(half-wave potential of 0.72 V vs.RHE in alkaline electrolyte),which is one of the best COF-based ORR electrocatalysts reported so far.Furthermore,Q3CTP-COF NSs can serve as a promising cathode for Zn-air batteries(delivered power density of 156 mW cm-2 at 300 mA cm^(-2)).This judicious design and accurate synthesis of such COFs with highly dense and exposed active sites and their nanosheets will promote the development of metal-free carbon-based electrocatalysts.
基金Project supported by the National Natural Science Foundation of China(Grant No.61204044)
文摘The through silicon via （TSV） technology has proven to be the critical enabler to realize a three-dimensional （3D） gigscale system with higher performance but shorter interconnect length. However, the received digital signal after trans- mission through a TSV channel, composed of redistribution layers （RDLs）, TSVs, and bumps, is degraded at a high data-rate due to the non-idealities of the channel. We propose the Chebyshev multisection transformers to reduce the signal reflec- tion of TSV channel when operating frequency goes up to 20 GHz, by which signal reflection coefficient （$11） and signal transmission coefficient （$21） are improved remarkably by 150% and 73.3%, respectively. Both the time delay and power dissipation are also reduced by 4% and 13.3%, respectively. The resistance-inductance-conductance-capacitance （RLGC） elements of the TSV channel are iterated from scattering （S）-parameters, and the proposed method of weakening the signal reflection is verified using high frequency simulator structure （HFSS） simulation software by Ansoft.
基金supported by the National Natural Science Foundation of China (51674297)the Natural Science Foundation of Hunan Province (2016JJ2137)the Fundamental Research Funds for the Central Universities of Central South University (2015cx001)~~
文摘Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In this study,we develop a novel solvent method to prepare interconnected N,S co-doped three-dimensional（3D）carbon networks with tunable nanopores derived from an asso-ciated complex based on melamine and sodium dodecylbenzene sulfonate（SDBS）.After the intro-duction of silica templates and calcination,the catalyst exhibits 3D networks with interconnected 50-nm pores and partial graphitization.With the increase of the number of Lewis base sites caused by the N doping and change of the carbon charge and spin densities caused by the S doping,the designed N,S co-doped catalyst exhibits a similar electrochemical activity to that of the commercial 20-wt%Pt/C as an oxygen reduction reaction catalyst.In addition,in an aluminum-air battery,the proposed catalyst even outperforms the commercial 5-wt%Pt/C catalyst.Both interconnected porous structures and synergistic effects of N and S contribute to the superior catalytic perfor-mance.This study paves the way for the synthesis of various other N-doped and co-doped carbon materials as efficient catalysts in electrochemical energy applications.
基金supported by the National Natural Science Foundation of China(No.52474355)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project),China(Nos.2022JH25/10200003 and 2023JH2/101800058).
文摘The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large deformation during the LCR process and to minimize the thickness of the slab in bending segments,the maximum theoretical reduction amount and the corresponding reduction scheme for the LCR process must be determined.With SPA-H weathering steel as a specific research steel grade,the distributions of tem-perature and deformation fields of a slab with the LCR process were analyzed using a three-dimensional thermal-mechanical finite ele-ment model.High-temperature tensile tests were designed to determine the critical strain of corner crack propagation and intermediate crack initiation with various strain rates and temperatures,and a prediction model of the critical strain for two typical cracks,combining the effects of strain rate and temperature,was proposed by incorporating the Zener-Hollomon parameter.The crack risks with different LCR schemes were calculated using the crack risk prediction model,and the maximum theoretical reduction amount for the SPA-H slab with a transverse section of 145 mm×1600 mm was 41.8 mm,with corresponding reduction amounts for Segment 0 to Segment 4 of 15.8,7.3,6.5,6.4,and 5.8 mm,respectively.
基金supported by the National Natural Science Foundation of China(No.21571062)the Program for Professor of Special Appointment(Eastern Scholar)at the Shanghai Institutions of Higher Learning to JGL,and the Fundamental Research Funds for the Central Universities(No.222201717003)。
文摘Exploiting non-precious metal catalysts with excellent oxygen reduction reaction(ORR)performance for energy devices is paramount essential for the green and sustainable society development.Herein,low-cost,high-performance biomass-derived ORR catalysts with an asymmetric Fe-N_(3)P configuration was prepared by a simple pyrolysis-etching technique,where carboxymethyl cellulose(CMC)was used as the carbon source,urea and 1,10-phenanthroline iron complex(FePhen)as additives,and Na_(3)PO_(4)as the phosphorus dopant and a pore-forming agent.The CMC-derived FeNPC catalyst displayed a large specific area(BET:1235 m^(2)g^(-1))with atomically dispersed Fe-N_(3)P active sites,which exhibited superior ORR activity and stability in alkaline solution(E_(1/2)=0.90 V vs.RHE)and Zn-air batteries(P_(max)=149 mW cm^(-2))to commercial Pt/C catalyst(E_(1/2)=0.87 V,P_(max)=118 mW cm^(-2))under similar experimental conditions.This work provides a feasible and costeffective route toward highly efficient ORR catalysts and their application to Zn-air batteries for energy conversion.
基金supported by the National Natural Science Foundation of China(No.41977029).
文摘Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).
基金supported by the National Natural Science Foundation of China(Nos.22272105 and 22002110)Natural Science Foundation of Shanghai(No.23ZR1423900)。
文摘Nitrogen-doping of carbon support(N-C)for platinum(Pt)nanoparticles to form Pt/N-C catalyst represents an effective strategy to promote the electrocatalysis of cathodic oxygen reduction reaction(ORR)in proton exchange membrane fuel cells.For fundamental understanding,clearly identifying the metalsupport effect on enhancement mechanisms of ORR electrocatalysis is definitely needed.In this work,the impact of Pt-support interaction via interfacial Pt-N coordination on electrocatalytic ORR activity and stability in Pt/N-C catalyst is deeply studied through structural/compositional characterizations,electrochemical measurements and theoretical DFT-calculations/AIMD-simulations.The resulting Pt/N-C catalyst exhibits a superior electrocatalytic performance compared to the commercial Pt/C catalyst in both half-cell and H_(2)-O_(2)fuel cell.Experimental and theoretical results reveal that the interfacial Pt-N coordination enables electron transfer from N-C support to Pt nanoparticles,which can weaken the adsorption strength of oxygen intermediates on Pt surface to improve ORR activity and induce the strong Pt-support interaction to enhance electrochemical stability.
基金supported by the National Natural Science Foundation of China(Nos.22106105 and 22201180)the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-E00015)+2 种基金Shanghai Science and Technology Innovation Program(No.21DZ1206300)the Central Local Science and Technology Development Guidance Fund(No.YDZX20213100003002)Shanghai Science and Technology Commission Program(No.20060502200).
文摘Photocatalytic conversion of CO_(2) is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development.Nowadays,polymeric carbon nitride(PCN)has gained widespread application in CO_(2) solar reduction due to its excellent visible light response,suitable conduction band position,and good cost-effectiveness.However,the amorphous nature and low conductivity of PCN limit its photocatalytic efficiency by leading to low carrier concentrations and facile electron–hole recombination during photocatalysis.Addressing this bottleneck,in this study,potassium-doped PCN(KPCN)/copper(Ⅱ)-complexed bipyridine hydroxyquinoline carboxylic acid(Cu(Ⅱ)(bpy)(H_(2)hqc))composite catalysts were synthesized through a multistep microwave heating process.In the composite,the formation of an S-scheme junction facilitates the enrichment of more negative electrons on the conduction band of KPCN via intermolecular electron–hole recombination between Cu(Ⅱ)(bpy)(H_(2)hqc)(CuPyQc)and KPCN,thereby promoting efficient photoreduction of CO_(2) to CO.Microwave heating enhances the amidation reaction between these two components,achieving the immobilization of homogeneous molecular catalysts and forming amidation chemical bonds that serve as key channels for the S-scheme charge transfer.This work not only presents a new PCN-based catalytic system for CO_(2) reduction applications,but also offers a novel microwave-practical approach for immobilizing homogeneous catalysts.
基金Project supported by the National Natural Science Foundation of China(22062019)the Natural Science Foundation of Inner Mongolia of China(2022QN02002)Science and Technology Program of Inner Mongolia Autonomous Region,China(2020PT0003)。
文摘The development of an e fficacious and easily prepared no nprecious metal electrocatalyst is crucial for the oxygen reduction reaction(ORR).This work used a dual template method to prepare the amorphous rare earth-based catalyst PrO_(x)-NC,and optimized the calcination temperature and proportion.The PrO_(x)-NC-900 catalyst has high durability and activity and exhibits superior ORR performance in alkaline electrolytes with an onset potential(E_(0))of 0.96 V and a half-wave potential(E_(1/2))of 0.85 V.The research results indicate that the ORR performance of rare earth oxide composite carbon catalysts can be improved by adjusting oxygen vacancies(Ov).In addition,high specific surface area,N rich defect carbon.increased oxygen vacancies,and the synergistic effect of oxygen vacancies and N-doped carbon interfacial layer play a significant part in the enhancement of ORR.The performance of the zinc air battery assembled with PrO_(x)-NC-900 is significantly improved,and rare earth oxides and carbon frameworks originating from metal organic frameworks(MOFs)contribute to the oxygen electrocatalyst and electron transfer rate of the zinc air battery.This catalyst provides promising information for the development of rare earth metal oxide nanostructures as potential candidate materials for ORR in alkaline media.
基金supported by the National Natural Science Foundation of China(No.U2067212)the National Science Fund for Distinguished Young Scholars(No.21925603).
文摘A sp^(2) carbon-conjugated covalent organic framework (BDATN) was modified through γ-ray radiation reduction and subsequent acidification with hydrochloric acid to yield a novel functional COF (named rBDATN-HCl) for Cr(Ⅵ) removal.The morphology and structure of rBDATN-HCl were analyzed and identified by SEM,FTIR,XRD and solid-state13C NMR.It is found that the active functional groups,such as hydroxyl and amide,were introduced into BDATN after radiation reduction and acidification.The prepared rBDATN-HCl demonstrates a photocatalytic reduction removal rate of Cr(Ⅵ) above 99%after 60min of illumination with a solid-liquid ratio of 0.5 mg/mL,showing outstanding performance,which is attributed to the increase of dispersibility and adsorption sites of r BDATN-HCl.In comparison to the cBDATN-HCl synthesized with chemical reduction,rBDATN-HCl exhibits a better photoreduction performance for Cr(Ⅵ),demonstrating the advantages of radiation preparation of rBDATN-HCl.It is expected that more functionalized sp^(2) carbon-conjugated COFs could be obtained by this radiation-induced reduction strategy.
基金supported by Natural Science Foundation of Shandong Province(Nos.ZR2022YQ42,ZR2021JQ15,ZR2021QE011,ZR2021ZD20,2022GJJLJRC-01)Innovative Team Project of Jinan(No.2021GXRC019)the National Natural Science Foundation of China(Nos.52022037,52202366).
文摘In contrast to research on active sites in nanomaterials,lithium tantalate single crystals,known for their exceptional optical properties and long-range ordered lattice structure,present a promising avenue for in-depth exploration of photocatalytic reaction systems with fewer constraints imposed by surface chemistry.Typically,the isotropy of a specific facet provides a perfect support for studying heteroatom doping.Herein,this work delves into the intrinsic catalytic sites for photocatalytic nitrogen fixation in iron-doped lithium tantalate single crystals.The presence of iron not only modifies the electronic structure of lithium tantalate,improving its light absorption capacity,but also functions as an active site for the nitrogen adsorption and activation.The photocatalytic ammonia production rate of the iron-doped lithium tantalate in pure water is maximum 26.95μg cm^(−2)h^(−1),which is three times higher than that of undoped lithium tantalate.The combination of first-principles simulations with in situ characterizations confirms that iron doping promotes the rate-determining step and changes the pathway of hydrogenation to associative alternating.This study provides a new perspective on in-depth investigation of intrinsic catalytic active sites in photocatalysis and other catalytic processes.
基金supported by Open Foundation of the State Key Laboratory of Refractories and Metallurgy(No.G201711)the National Natural Science Foundation of China(Nos.52104317 and 51874001).
文摘The impact of heavy reduction on dendritic morphology was explored by combining experimental research and numerical simulation in metallurgy,including a detailed three-dimensional(3D)analysis and reconstruction of dendritic solidification structures.Combining scanning electron microscopy and energy-dispersive scanning analysis and ANSYS simulation,the high-precision image processing software Mimics Research was utilized to conduct the extraction of dendritic morphologies.Reverse engineering software NX Imageware was employed for the 3D reconstruction of two-dimensional dendritic morphologies,restoring the dendritic characteristics in three-dimensional space.The results demonstrate that in a two-dimensional plane,dendrites connect with each other to form irregularly shaped“ring-like”structures.These dendrites have a thickness greater than 0.1 mm along the Z-axis direction,leading to the envelopment of molten steel by dendrites in a 3D space of at least 0.1 mm.This results in obstructed flow,confirming the“bridging”of dendrites in three-dimensional space,resulting in a tendency for central segregation.Dense and dispersed tiny dendrites,under the influence of heat flow direction,interconnect and continuously grow,gradually forming primary and secondary dendrites in three-dimensional space.After the completion of dendritic solidification and growth,these microdendrites appear dense and dispersed on the two-dimensional plane,providing the nuclei for the formation of new dendrites.When reduction occurs at a solid fraction of 0.46,there is a noticeable decrease in dendritic spacing,resulting in improved central segregation.
文摘To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.
基金National Natural Science Foundation of China (52371228, 52402045)fund of Key Laboratory of Advanced Materials of Ministry of Education(Advmat-2414)。
文摘Electrocatalytic nitrate reduction reaction (NO_(3)-RR) to ammonia under ambient conditions is expected to be a green process for ammonia synthesis and alleviate water pollution issues.We report a CuO nanoparticles incorporated on nitrogen-doped porous carbon (CuO@NC) catalyst for NO_(3)-RR.Part of Cu(Ⅱ) is reduced to Cu(Ⅰ) during the NO_(3)-RR process to construct Cu(Ⅰ)-Cu(Ⅱ) pairs,confirmed by in situ X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy.Density functional theory (DFT) calculations indicated that the formation of Cu(Ⅰ) could provide a reaction path with smaller energy barrier for NO_(3)-RR,while Cu(Ⅱ) effectively suppressed the competition of hydrogen evolution reaction (HER).As a result,CuO@NC catalyst achieved a Faradaic efficiency of 84.2% at -0.49 V versus reversible hydrogen electrode (RHE),and a NH_(3)yield rate of 17.2 mg h^(-1)mg^(-1)cat.at -0.79 V vs.RHE,higher than the HaberBosch process (<3.4 g h^(-1)g^(-1)cat.).This work may open a new avenue for effective NO_(3)-RR by modulating oxidation states.
基金supported by the National Natural Science Foundation of China(No.92367107)。
文摘Ultra-low emission of nitrogen oxide(NO_(x))is an irreversible trend for the development of waste-to-energy industry.But traditional approaches to remove NO_(x) face significant challenge s,such as low denitration efficiency,complex denitration system,and high investment and operating cost.Here we put forward a novel polymer non-catalytic reduction(PNCR)technology that utilized a new type of polymer agent to remove NO_(x),and the proposed PNCR technology was applied to the existing waste-to-energy plant to test the denitration performance.The PNCR technology demonstrated excellent denitration performance with a NO_(x) emission concentration of<100 mg/Nm^(3) and high denitration efficiency of>75%at the temperature range of 800-900℃,which showed the application feasibility even on the complex and unstable industrial operating conditions.In addition,PNCR and hybrid polymer/selective non-catalytic reduction(PNCR/SNCR)technology possessed remarkable economic advantages including low investment fee and low operating cost of<10 CNY per ton of municipal solid waste(MSW)compared with selective catalytic reduction(SCR)technology.The excellent denitration performance of PNCR technology forebodes a broad industrial application prospect in the field of flue gas cleaning for waste-to-energy plants.
基金supported by Hainan Provincial Natural Science Foundation of China(No.721RC525).
文摘Guangdong’s carbon emissions have surpassed the world’s 11th largest emitter.It is indispensable for this province to find a robust cost-effective strategy for reducing carbon emissions.This study employed the Low Emissions Analysis Platform model,marginal cost curves,and Monte Carlo methods to simulate the energy consumption,carbon emissions,and economic benefits of emission reduction in Guangdong Province from 2020 to 2030 under the application of various structural optimization policies and energy-saving technologies.The main findings are as follows:In 2030,Guangdong Province is projected to achieve a carbon emission reduction of 273.6 to 304.6million t CO_(2eq),with a total reduction cost ranging from 1030.9 to 1452.2 billion yuan.Increasing the share of renewable energy,which still has significant growth potential,can lead to a 1.4 times greater reduction in carbon emissions compared to the application of energy-saving technologies,despite the latter yielding 2.3 times more energy savings.The emission reduction measures with net-cost can contribute 71.4%to the total carbon reduction of the province,being much larger than those with net benefits.The power sector plays a critical role in carbon emission reduction within Guangdong Province,with its various measures exerting the most substantial impact on emission reduction quantity and cost,contributing cumulative variance contributions of 90.1%and 84.3%,respectively.It has relatively large potential for emission reduction and relatively low cost of structural adjustment.
