Sustainable aviation fuel(SAF)production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector,one of the most-difficult-to-electrify transportation sectors.Despite ongoing co...Sustainable aviation fuel(SAF)production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector,one of the most-difficult-to-electrify transportation sectors.Despite ongoing commercialization efforts using ASTM-certified pathways(e.g.,lipid conversion,Fischer-Tropsch synthesis),production capacities are still inadequate due to limited feedstock supply and high production costs.New conversion technologies that utilize lignocellulosic feedstocks are needed to meet these challenges and satisfy the rapidly growing market.Combining bio-and chemo-catalytic approaches can leverage advantages from both methods,i.e.,high product selectivity via biological conversion,and the capability to build C-C chains more efficiently via chemical catalysis.Herein,conversion routes,catalysis,and processes for such pathways are discussed,while key challenges and meaningful R&D opportunities are identified to guide future research activities in the space.Bio-and chemo-catalytic conversion primarily utilize the carbohydrate fraction of lignocellulose,leaving lignin as a waste product.This makes lignin conversion to SAF critical in order to utilize whole biomass,thereby lowering overall production costs while maximizing carbon efficiencies.Thus,lignin valorization strategies are also reviewed herein with vital research areas identified,such as facile lignin depolymerization approaches,highly integrated conversion systems,novel process configurations,and catalysts for the selective cleavage of aryl C-O bonds.The potential efficiency improvements available via integrated conversion steps,such as combined biological and chemo-catalytic routes,along with the use of different parallel pathways,are identified as key to producing all components of a cost-effective,100%SAF.展开更多
Catalytic/initiated cracking of endothermic hydrocarbon fuels is an eff ective technology for cooling a hypersonic aircraft with a high Mach number(over 5).Catalysts and initiators can promote fuel cracking at low tem...Catalytic/initiated cracking of endothermic hydrocarbon fuels is an eff ective technology for cooling a hypersonic aircraft with a high Mach number(over 5).Catalysts and initiators can promote fuel cracking at low temperatures,increase fuel conversion and the heat sink capacity,and suppress coke deposition,thereby reducing waste heat.Catalysts mainly include metal oxide catalysts,noble metal catalysts and metal nanoparticles,zeolite catalysts,nanozeolite catalysts,and coating catalysts.Moreover,initiators roughly include nitrogenous compounds,oxygenated compounds,and hyperbranched polymer initiators.In this review,we aim to summarize the catalysts and initiators for cracking endothermic hydrocarbon fuels and their mechanisms for promoting cracking.This review will facilitate the development of the synthesis and exploration of catalysts and initiators.展开更多
Shipping plays a vital role in the world economy.Around 90%of the world's trade is transported by ship in a cost-effective and reliable manner.Global shipping is responsible for 2-3%of the total global CO2 emissio...Shipping plays a vital role in the world economy.Around 90%of the world's trade is transported by ship in a cost-effective and reliable manner.Global shipping is responsible for 2-3%of the total global CO2 emissions.In addition,shipping accounts for up to 4-9%of all sulphur,and 10-15%of all nitrous oxide emissions.Without taking any measures,these emissions would more than double as seaborne trade is expected to further grow from 30 billion tone miles in 2006 to more than 100 billion in 2050.To counter these emissions the international community has developed frameworks for energy efficiency measures,as well as emission reduction targets for SOx and NOx in appointed ECAs(Emission Control Areas).Biofuels satisfy fully or partially the new emission regulations and sulfur limits without compromising the economy.The goal of this work is to study and evaluate the physicochemical properties of conventional marine distillate fuel and its blends with renewable-alternative fuels(UCOME(Used Cooking Oils Methyl Esters)and HVO(Hydrogenated Vegetable Oils)).展开更多
Sulphur and emissions related limits which are imposed on marine fuels drive the maritime industry to look on alternative fuels. The maximum sulphur content of the fuel has already decreased in the ECAs SOx （Sulphur ...Sulphur and emissions related limits which are imposed on marine fuels drive the maritime industry to look on alternative fuels. The maximum sulphur content of the fuel has already decreased in the ECAs SOx （Sulphur Emission Control Areas） from 1.5% to 1% from 1 July, 2010, and to 0.1% from 1 January, 2015. Globally, the highest permitted sulphur content of fuel will be reduced, as from 1 January, 2020 to 0.5%. Increasing demand of low sulphur fuel is anticipated, leading to a substantial mitigation of marine fuels from residual to distillate ones. Biodiesel or else FAME （Fatty Acid Methyl Esters） and mixtures of it with conventional petroleum fuels, constitute alternative energy source for the maritime industry. The International Standard EN （European Norme） ISO （International Organization for Standardization） 8217 specifies the requirements of petroleum fuels for use in marine diesel engines. According to the previous version of EN ISO 8217：2012, distillate fuels should comply with the ＂de minimis level＂ of approximately 0.1% v/v FAME. Nevertheless, with the latest revision of EN ISO 8217 standard in 2017, the incorporation of FAME up to 7% v/v is allowed in specific marine distillate grades as DF （Distillate FAME） grades. Marine distillates can also include hydrocarbons from synthetic or renewable sources, similar to the composition of petroleum distillate fuels.展开更多
This proposal aims to assess the market introduction of advanced technologies for the production of 2nd generation solid biofuels, specifically technologies for the production of briquettes and pellets from agro-indus...This proposal aims to assess the market introduction of advanced technologies for the production of 2nd generation solid biofuels, specifically technologies for the production of briquettes and pellets from agro-industrial wastes. The development of this project will evaluate the socio-environmental and techno-economical feasibility and use of 2nd generation solid biofuels in the CMR （Campinas Metropolitan Region）. The successful introduction of second generation briquettes and pellets to market depends, mainly, on two aspects： logistics in supply chains which generate waste, and the efficiency of production technologies. The study of logistics （supply chain） is based on survey data of the main productive supply chains, analysis, and modeling to optimize the facility location in the network for each case. The evaluation of the efficiency of production technology is provided by testing specially designed waste compacting devices, and comparing these results with the resulting power consumption during the production, in demonstration-scale, of a round of briquettes. The costs and consumption during the demonstration-scale production of briquettes are used for validation and correction of an optimization model. This project was approved in late 2012 with a period of two years for its implementation. Later in 2013, it was decided also to extend its implementation to the Metropolitan Region of Manaus, Amazon. Due to its recent beginning, the results shown here are only preliminary.展开更多
This study presents a comprehensive analysis of the current energy landscape and the imperative transition toward renewable energy.It begins with an overview of current energy sources and trends,highlighting the dispa...This study presents a comprehensive analysis of the current energy landscape and the imperative transition toward renewable energy.It begins with an overview of current energy sources and trends,highlighting the disparity between supply and increasing demand.Adverse impacts of reliance on fossil fuels such as environmental degradation,economic volatility,and health hazards underscore the urgent need for a transition.The study then explores the vast potential of renewable energy sources(RES)such as solar,wind,hydrogen,and hydro,emphasizing their feasibility in the Southern African context.The positive impacts of integrating renewables are examined,including reduced greenhouse gas emissions,enhanced energy security,and economic diversification.Through case studies of regional examples,the success and failures of transitioning efforts are analyzed,providing valuable insights into best practices and pitfalls.The study identifies significant challenges in transitioning,particularly in grid-tied and off-grid scenarios,and discusses infrastructural,financial,and regulatory obstacles.The recommendations section outlines strategic steps for achieving a feasible transition,proposing either a full transition or specific percentages of renewable energy integration to meet energy demands.In conclusion,the study emphasizes the critical importance of adopting these strategies for sustainable development and global climate goals,advocating for continuous innovation and localized solutions to maximize the benefits of renewable energy.Key findings are that the environmental and economic effects of fossil fuel usage strain economies by increasing fossil fuel subsidies.RES are abundant in the Southern African region,and some projects have already been successfully implemented,especially in South Africa.Economic growth and technological advancement are some of the benefits of fully transitioning to renewables,but lack of skilled labor,infrastructure,necessary technology,and most importantly,high capital requirements,etc.,are some challenges being faced.Hence,the need for regional cooperation,policy frameworks,and infrastructure enhancement,and investment mobilization for an accelerated transition.展开更多
With the increasing demand for high-performance and safe fuels in aerospace propulsion systems,gelled fliels have attracted increasing attention.Because of their unique structure,gelled fuels exhibit the advantages of...With the increasing demand for high-performance and safe fuels in aerospace propulsion systems,gelled fliels have attracted increasing attention.Because of their unique structure,gelled fuels exhibit the advantages of both solid and liquid fliels,such as high energy density,controllable thrust and storage safety.This review provides an overview on design,preparation and performance characterization of gelled fuels.The composition,preparation process and gelation mechanism of gelled high-energy-density fuels are described.Considering these aspects,the rheology and flow behavior of gelled fuels is summarized in terms of the shear thinning property,dynamic viscoelasticity and thixotropy.Moreover,the progress of atomization of gelled fuels is reviewed with a focus on the effect of atomizing nozzles.In addition,the experiments and theoretical models of single droplet combustion and combustor combustion are described.Finally,research directions for the development and application of gelled fuels are suggested.展开更多
1.Introduction The non-renewable fossil fuels have triggered severe energy crisis and global climate change,necessitating the development of sustainable solutions for the growing population.It is estimated that the gl...1.Introduction The non-renewable fossil fuels have triggered severe energy crisis and global climate change,necessitating the development of sustainable solutions for the growing population.It is estimated that the global annual production of biomass exceeds 180 billion tons[1].Due to its broad availability,renewability,and tunable molecular functionality,biomass is considered as a versatile and sustainable substitute to fossil fuels for the production of fuels and chemicals[2,3].展开更多
N,N,N',N'-tetraoctyl diglycolamide(TODGA)is a potential extractant for the co-extraction of lanthanides and actinides in high-level liquid waste.In this study,the radiolysis and extraction properties of TODGA ...N,N,N',N'-tetraoctyl diglycolamide(TODGA)is a potential extractant for the co-extraction of lanthanides and actinides in high-level liquid waste.In this study,the radiolysis and extraction properties of TODGA in kerosene solvents contacted with the aqueous phase of varying HNO_(3) concentrations were systematically investigated,and the complexation mechanism was analyzed in conjunction with density functional theory(DFT)calculations.After γ-irradiation,the variation of TODGA concentration was detected,and the variation trends in the relative content of radiolysis products(RPs)with sample type and absorbed dose were demonstrated.Results indicated that the breaking of the amide bond,ether bond,and C_(amide)-C_(ether)bond was the primary radiolysis routes.The aqueous-phase precipitate was studied as a potential new mode of TODGA radiolysis in ultrapure water aqueous phase.Moreover,TODGA/kerosene exhibited excellent extraction capabilities for lanthanides even after absorbing 100 kGy,and HNO_(3) can maintain a portion of TODGA's extraction capacity.The DFT method was applied to calculate and evaluate the complexing ability of TODGA and some of its RPs toward lanthanides.The results revealed that the complexing ability of TODGA for Ce(Ⅲ),Eu(Ⅲ),and Dy(Ⅲ)was enhanced successively,and the complexing ability of the RPs with intact oxygen-containing structures could not be neglected.展开更多
The breaking of the symmetric electronic distribution of single-atom catalysts is effective in improving the intrinsic activity.However,traditional modification strategies can only disrupt the electronic distribution ...The breaking of the symmetric electronic distribution of single-atom catalysts is effective in improving the intrinsic activity.However,traditional modification strategies can only disrupt the electronic distribution in one dimension,resulting in limited regulation of electronic structure.Herein,we report a multidimensional coordination strategy to significantly break the symmetrical electron distribution of the metal single site to achieve highly efficient electrochemical CO_(2) reduction reaction(CO_(2) RR).Ni singleatom sites decorated with planar P and axial Cl atoms are successfully constructed on carbon support(Ni-NPCl-C).Ni-NPCl-C affords CO Faraday efficiency over 90%in a wide potential window range from-0.5 to-1.2 V and an ultrahigh turnover frequency of 1.17×10^(5)h^(-1),much superior to its counterparts with single-dimensional coordination.Ni-NPCl-C can be further applied as a bifunctional catalyst to construct a rechargeable Zn-CO_(2) battery.Spectroscopic characterizations and theoretical calculations demonstrate that the dual adjustments with axial Cl and planar P can synergistically disrupt the electron distribution in two dimensions to increase electrons around Ni sites with the upshift of the d-band center,thereby facilitating the formation of*COOH intermediates and improving the CO_(2) RR performance.展开更多
One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and ...One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and optimal ranges of the number of machines that can be used in a cascade?For the first time,the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges,and the performance of small and large tapered cascades was discussed.The particle swarm optimization algorithm(PSO)has been used to optimize tapered cascades.The results show:(1)For the first centrifuge,41 cascades(91≤n≤4897)and for the second centrifuge,49 cascades(18≤n≤3839)with small and large sizes can be used in enrichment facilities,and the best cascade for them has 530(with 23 stages)and 39(with 7 stages)centrifuges,respectively.(2)For both centrifuges,when 600≤n(number of centrifuges=n),the large cascade performance changes are relatively insignificant.(3)For both types of gas centrifuges,the annual los s of separation power in enrichment facilities is approximately 1.25%-4.82%of the total separation work required.展开更多
Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that...Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived CoN-C materials,which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions.The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80%after 25,000 s of continuous operation.It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.展开更多
Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face wit...Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed C–H activation has been employed for the functionalization of amino acids and peptides.Through domino C–H activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed C–H activation/annulation.展开更多
Succinonitrile(SN)-based polymer plastic crystal electrolytes(PPCEs)are regarded as promising candidates for lithium metal batteries but suffer from serious side reactions with Li metal.Herein,we propose a multi-dimen...Succinonitrile(SN)-based polymer plastic crystal electrolytes(PPCEs)are regarded as promising candidates for lithium metal batteries but suffer from serious side reactions with Li metal.Herein,we propose a multi-dimensional optimization strategy to alleviate the side reactions between SN and Li metal,and develop a highly stable poly-vinylethylene carbonate-based PPCE(PPCE-VEC).Moreover,we identify the intrinsic factors of multi-dimensional polymer structures on the electrolyte stability by three typical classes of polyesters.The PPCE-VEC constructed by in situ polymerization exhibits much better stability than poly-vinylene carbonate-based PPCE(PPCE-VCA)and poly-trifluoroethyl acrylate-based PPCE(PPCE-TFA),which is verified by its fewer SN-decomposition species in X-ray photoelectron spectroscopy(XPS)and outstanding full cell performance.The PPCE-VEC-enabled LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)full cell achieve 73.7%capacity retention after 1400 cycles,which outperforms PPCE-VCA-and PPCE-TFA-enabled full cells(61.9%and 46.9%).Spectral analysis and theoretical calculation reveal that the high solvation ability of the carbonyl site,flexible polymer chain,and homogeneous electrolyte phase of PPCE-VEC are favorable to maximizing competition coordination with Li^(+)to weaken the Li^(+)–SN binding and shape an anion-rich solvation structure.This optimized polymer-involved Li^(+)solvation enhances SN stability and facilitates the formation of B/F enriched solid-electrolyte interphase(SEI),thus significantly improving PPCE stability.展开更多
The demand for ^(238)Pu (nuclear battery heat source) drives the separation of its precursor,^(237)Np,from spent nuclear fuel (SNF).However,the co-existence of multi-valence states (Ⅳ/Ⅴ/Ⅵ) of Np and similar redox b...The demand for ^(238)Pu (nuclear battery heat source) drives the separation of its precursor,^(237)Np,from spent nuclear fuel (SNF).However,the co-existence of multi-valence states (Ⅳ/Ⅴ/Ⅵ) of Np and similar redox behavior with Pu(Ⅳ) hinder the effective separation of Np.N-Butyraldehyde (n-C_(3)H_(7)CHO) selectively reduces Np(Ⅵ) to Np(Ⅴ) without reducing Pu(Ⅳ).Herein,we examined the reduction mechanisms of Np(Ⅵ) and Pu(Ⅳ) by n-C3H7CHO using relativistic density functional theory.Based on the results of the potential energy profiles,the reductions of both Np(Ⅵ) and Pu(Ⅳ) by n-C_(3)H_(7)CHO are thermodynamically feasible,whereas only the former is kinetically achievable.It uncovers that n-C_(3)H_(7)CHO can only reduce Np(Ⅵ) to Np(Ⅴ) owing to kinetically controlled selective reduction.The analyses of spin density and bond distance indicate that the reduction nature for the first Np(Ⅵ)/Pu(Ⅳ) belongs to hydrogen atom transfer,whereas that for the second one involves outer-sphere electron transfer.Localized molecular orbitals (LMOs) analysis discloses the bonding evolution during the reduction process of Np(Ⅵ)/Pu(Ⅳ).This study elucidates the reason behind the kinetically controlled selective reduction of Np(Ⅵ)/Pu(Ⅳ) by nC3H7CHO at the molecular level and offers in-depth perspectives on the isolation of specific metal ions from the view of kinetic control.展开更多
Large-scale hydrogen production via water electrolysis faces a freshwater shortage.Direct seawater electrolysis offers a solution but encounters new challenges.Herein,we report a feasible strategy to both prevent meta...Large-scale hydrogen production via water electrolysis faces a freshwater shortage.Direct seawater electrolysis offers a solution but encounters new challenges.Herein,we report a feasible strategy to both prevent metal hydroxides deposition and boost the hydrogen evolution reaction by adding a chelating agent,EDTA-Na_(4),that chelates with Mg^(2+)/Ca^(2+),thus inhibiting their deposition and gathering them near the cathode surface,resulting in breaking the ordered hydrogen bond networks of interfacial water and reducing the activation energy of water dissociation.Furthermore,hydrolysis of–COO^(-) also promoted water dissociation to produce more active*H and*OH near the electrode surface that in turn serves as a diffusion medium for*OH,accelerating mass transfer and enabling seawater electrolysis to exhibit a stable performance,which operates continuously at 100 mA cm^(-2)@2.20 V and 200 mA cm^(-2)@2.58 V for 400 h in the symmetric electrolyzer and 500 mA cm^(-2)@2.29 V for over 500 h in the asymmetric electrolyzer.This study provides a new perspective to address the issues of stable and scalable direct seawater electrolysis for practical green hydrogen production.展开更多
Engineering the pore structure of biomass-derived activated carbons is critical for optimizing their performance in adsorptionbased applications.This study demonstrates for the first time that washing hydrochars in so...Engineering the pore structure of biomass-derived activated carbons is critical for optimizing their performance in adsorptionbased applications.This study demonstrates for the first time that washing hydrochars in solvents of different polarity before activation is a simple yet powerful strategy to tailor pore size distribution.Hydrochar is produced from spent coffee grounds via hydrothermal carbonization,followed by washing in various solvents and activation in KOH.This results in carbons with a very large surface area(~2700 m^(2)/g),and washing is demonstrated to significantly increase product yield.Furthermore,washing in non-polar or mixed-polarity solvents removes long-chain carboxylic acids and esters from the hydrochar,promoting the development of narrow micropores while suppressing mesopore formation.To illustrate the impact of this structural control of porous carbons,post-combustion CO_(2)capture is investigated as a case study.Narrower pore size distribution enhances CO_(2)uptake,significantly improving capacity from 2.8 mmol/g for unwashed samples to 3.8 mmol/g for acetone-washed samples.Interestingly,moderate pore size(9-12Å)is shown to be optimal for CO_(2):N2 selectivity,while smaller pores result in lower selectivity due to stronger interactions between N2 and the pore walls.These findings highlight the potential role of solvent washing in directing pore architecture of hydrochars for adsorption-based carbon capture technologies and beyond.展开更多
In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields...In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.展开更多
The application of conventional manganese dioxide(MnO_(2))materials in sodium-ion supercapacitors(Na-SCs)is considerably limited by their low conductivity and structural instability.Biomimetic morphology engineering c...The application of conventional manganese dioxide(MnO_(2))materials in sodium-ion supercapacitors(Na-SCs)is considerably limited by their low conductivity and structural instability.Biomimetic morphology engineering can optimize the electrochemical performance of MnO_(2).Here,based on the metal-organic frameworks(MOFs)-derived method and electrochemical reconstruction,a coral-like MnO_(2)structure integrated with a functional nitrogen-doped carbon(NC)coating is designed for Na-SC application.The bioinspired coral-like structure captures numerous electrolyte ions and increases the Na+concentration on the electrode surface,which is beneficial for optimizing the Na+transport pathway and accelerating the electrode reaction kinetics.Moreover,the coral-like crosslinked structure effectively enhances the mechanical properties,enabling the maintenance of the structure of MnO_(2)-based electrodes during long-term operation.Furthermore,in/ex-situ characterizations are performed to elucidate the mechanism of lattice transformation during electrochemical phase reconstruction.Additionally,the theoretical calculation and simulation results reveal the ion/electron dynamics in the fabricated electrode.The prepared electrode demonstrates excellent capacitance storage ability(340.7 F g^(−1)at 0.5 A g^(−1))and cycling stability(85.1%capacitance retention after 10,000 cycles).The assembled hybrid device exhibits exceptional life-span(82.0%capacitance retention after 10,000 cycles)and exceptional energy density(36.5 Wh kg^(−1)).This study provides a reliable biomimetic morphology design strategy for MnO_(2)cathodes,paving the way for the fabrication of high-performance Na-SCs.展开更多
Multicomponent Gd_(1−x)Sm_(x)Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)double perovskites are optimized for application in terms of chemical composi-tion and morphology for the use as oxygen electrodes in solid oxide cells.Structur...Multicomponent Gd_(1−x)Sm_(x)Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)double perovskites are optimized for application in terms of chemical composi-tion and morphology for the use as oxygen electrodes in solid oxide cells.Structural studies of other physicochemical properties are con-ducted on a series of materials obtained by the sol-gel method with different ratios of Gd and Sm cations.It is documented that changing the x value,and the resulting adjustment of the average ionic radius,have a significant impact on the crystal structure,stability,as well as on the total conductivity and thermomechanical properties of the materials,with the best results obtained for the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)composition.Oxygen electrodes are prepared using the selected compound,allowing to obtain low polarization resistance values,such as 0.086Ω·cm^(2)at 800℃.Systematic studies of electrocatalytic activity are conducted using La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(_(0.2))O_(3−δ)as the electrolyte for all electrodes,and Ce_(0.8)Gd_(0.2)O_(2−δ)electrolyte for the best performing Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes.The electrochemical data are analyzed using the distribution of relaxation times method.Also,the influence of the preparation method of the electrode material is in-ve`stigated using the electrospinning technique.Finally,the performance of the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes is tested in a Ni-YSZ(yttria-stabilized zirconia)anode-supported cell with a Ce_(0.8)Gd_(0.2)O_(2−δ)buffer layer,in the fuel cell and electrolyzer operating modes.With the electrospun electrode,a power density of 462 mW·cm^(−2)is obtained at 700℃,with a current density of ca.0.2 A·cm^(−2)at 1.3 V for the electrolysis at the same temperature,indicating better performance compared to the sol-gel-based electrode.展开更多
基金supported by the Center for Bioenergy Innovation(CBI)supported by the Office of Biological and Environmental Research in the DOE Office of Science and led by Oak Ridge National Laboratory.Oak Ridge National Laboratory is managed by UT-Battelle,LLC for the US DOE under Contract Number DE-AC05-00OR22725+2 种基金authored in part by the Na-tional Renewable Energy Laboratory,operated by Alliance for Sustainable Energy,LLC,for the U.S.Department of Energy(DOE)under Contract No.DE-LC-000L054provided by the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy(EERE),and Bioenergy Technologies Office(BETO)at the Pacific Northwest National Laboratory(PNNL)under Contract No.DE-AC05-76RL01830supported by Laboratory Directed Research and Development(LDRD)funding from Argonne National Laboratory,provided by the Director,Office of Science,of the U.S.Department of Energy under Contract No.DE-AC02-06CH11357。
文摘Sustainable aviation fuel(SAF)production from biomass and biowaste streams is an attractive option for decarbonizing the aviation sector,one of the most-difficult-to-electrify transportation sectors.Despite ongoing commercialization efforts using ASTM-certified pathways(e.g.,lipid conversion,Fischer-Tropsch synthesis),production capacities are still inadequate due to limited feedstock supply and high production costs.New conversion technologies that utilize lignocellulosic feedstocks are needed to meet these challenges and satisfy the rapidly growing market.Combining bio-and chemo-catalytic approaches can leverage advantages from both methods,i.e.,high product selectivity via biological conversion,and the capability to build C-C chains more efficiently via chemical catalysis.Herein,conversion routes,catalysis,and processes for such pathways are discussed,while key challenges and meaningful R&D opportunities are identified to guide future research activities in the space.Bio-and chemo-catalytic conversion primarily utilize the carbohydrate fraction of lignocellulose,leaving lignin as a waste product.This makes lignin conversion to SAF critical in order to utilize whole biomass,thereby lowering overall production costs while maximizing carbon efficiencies.Thus,lignin valorization strategies are also reviewed herein with vital research areas identified,such as facile lignin depolymerization approaches,highly integrated conversion systems,novel process configurations,and catalysts for the selective cleavage of aryl C-O bonds.The potential efficiency improvements available via integrated conversion steps,such as combined biological and chemo-catalytic routes,along with the use of different parallel pathways,are identified as key to producing all components of a cost-effective,100%SAF.
基金supported by the National Natural Science Foundation of China(No.21978200).
文摘Catalytic/initiated cracking of endothermic hydrocarbon fuels is an eff ective technology for cooling a hypersonic aircraft with a high Mach number(over 5).Catalysts and initiators can promote fuel cracking at low temperatures,increase fuel conversion and the heat sink capacity,and suppress coke deposition,thereby reducing waste heat.Catalysts mainly include metal oxide catalysts,noble metal catalysts and metal nanoparticles,zeolite catalysts,nanozeolite catalysts,and coating catalysts.Moreover,initiators roughly include nitrogenous compounds,oxygenated compounds,and hyperbranched polymer initiators.In this review,we aim to summarize the catalysts and initiators for cracking endothermic hydrocarbon fuels and their mechanisms for promoting cracking.This review will facilitate the development of the synthesis and exploration of catalysts and initiators.
文摘Shipping plays a vital role in the world economy.Around 90%of the world's trade is transported by ship in a cost-effective and reliable manner.Global shipping is responsible for 2-3%of the total global CO2 emissions.In addition,shipping accounts for up to 4-9%of all sulphur,and 10-15%of all nitrous oxide emissions.Without taking any measures,these emissions would more than double as seaborne trade is expected to further grow from 30 billion tone miles in 2006 to more than 100 billion in 2050.To counter these emissions the international community has developed frameworks for energy efficiency measures,as well as emission reduction targets for SOx and NOx in appointed ECAs(Emission Control Areas).Biofuels satisfy fully or partially the new emission regulations and sulfur limits without compromising the economy.The goal of this work is to study and evaluate the physicochemical properties of conventional marine distillate fuel and its blends with renewable-alternative fuels(UCOME(Used Cooking Oils Methyl Esters)and HVO(Hydrogenated Vegetable Oils)).
文摘Sulphur and emissions related limits which are imposed on marine fuels drive the maritime industry to look on alternative fuels. The maximum sulphur content of the fuel has already decreased in the ECAs SOx （Sulphur Emission Control Areas） from 1.5% to 1% from 1 July, 2010, and to 0.1% from 1 January, 2015. Globally, the highest permitted sulphur content of fuel will be reduced, as from 1 January, 2020 to 0.5%. Increasing demand of low sulphur fuel is anticipated, leading to a substantial mitigation of marine fuels from residual to distillate ones. Biodiesel or else FAME （Fatty Acid Methyl Esters） and mixtures of it with conventional petroleum fuels, constitute alternative energy source for the maritime industry. The International Standard EN （European Norme） ISO （International Organization for Standardization） 8217 specifies the requirements of petroleum fuels for use in marine diesel engines. According to the previous version of EN ISO 8217：2012, distillate fuels should comply with the ＂de minimis level＂ of approximately 0.1% v/v FAME. Nevertheless, with the latest revision of EN ISO 8217 standard in 2017, the incorporation of FAME up to 7% v/v is allowed in specific marine distillate grades as DF （Distillate FAME） grades. Marine distillates can also include hydrocarbons from synthetic or renewable sources, similar to the composition of petroleum distillate fuels.
文摘This proposal aims to assess the market introduction of advanced technologies for the production of 2nd generation solid biofuels, specifically technologies for the production of briquettes and pellets from agro-industrial wastes. The development of this project will evaluate the socio-environmental and techno-economical feasibility and use of 2nd generation solid biofuels in the CMR （Campinas Metropolitan Region）. The successful introduction of second generation briquettes and pellets to market depends, mainly, on two aspects： logistics in supply chains which generate waste, and the efficiency of production technologies. The study of logistics （supply chain） is based on survey data of the main productive supply chains, analysis, and modeling to optimize the facility location in the network for each case. The evaluation of the efficiency of production technology is provided by testing specially designed waste compacting devices, and comparing these results with the resulting power consumption during the production, in demonstration-scale, of a round of briquettes. The costs and consumption during the demonstration-scale production of briquettes are used for validation and correction of an optimization model. This project was approved in late 2012 with a period of two years for its implementation. Later in 2013, it was decided also to extend its implementation to the Metropolitan Region of Manaus, Amazon. Due to its recent beginning, the results shown here are only preliminary.
文摘This study presents a comprehensive analysis of the current energy landscape and the imperative transition toward renewable energy.It begins with an overview of current energy sources and trends,highlighting the disparity between supply and increasing demand.Adverse impacts of reliance on fossil fuels such as environmental degradation,economic volatility,and health hazards underscore the urgent need for a transition.The study then explores the vast potential of renewable energy sources(RES)such as solar,wind,hydrogen,and hydro,emphasizing their feasibility in the Southern African context.The positive impacts of integrating renewables are examined,including reduced greenhouse gas emissions,enhanced energy security,and economic diversification.Through case studies of regional examples,the success and failures of transitioning efforts are analyzed,providing valuable insights into best practices and pitfalls.The study identifies significant challenges in transitioning,particularly in grid-tied and off-grid scenarios,and discusses infrastructural,financial,and regulatory obstacles.The recommendations section outlines strategic steps for achieving a feasible transition,proposing either a full transition or specific percentages of renewable energy integration to meet energy demands.In conclusion,the study emphasizes the critical importance of adopting these strategies for sustainable development and global climate goals,advocating for continuous innovation and localized solutions to maximize the benefits of renewable energy.Key findings are that the environmental and economic effects of fossil fuel usage strain economies by increasing fossil fuel subsidies.RES are abundant in the Southern African region,and some projects have already been successfully implemented,especially in South Africa.Economic growth and technological advancement are some of the benefits of fully transitioning to renewables,but lack of skilled labor,infrastructure,necessary technology,and most importantly,high capital requirements,etc.,are some challenges being faced.Hence,the need for regional cooperation,policy frameworks,and infrastructure enhancement,and investment mobilization for an accelerated transition.
文摘With the increasing demand for high-performance and safe fuels in aerospace propulsion systems,gelled fliels have attracted increasing attention.Because of their unique structure,gelled fuels exhibit the advantages of both solid and liquid fliels,such as high energy density,controllable thrust and storage safety.This review provides an overview on design,preparation and performance characterization of gelled fuels.The composition,preparation process and gelation mechanism of gelled high-energy-density fuels are described.Considering these aspects,the rheology and flow behavior of gelled fuels is summarized in terms of the shear thinning property,dynamic viscoelasticity and thixotropy.Moreover,the progress of atomization of gelled fuels is reviewed with a focus on the effect of atomizing nozzles.In addition,the experiments and theoretical models of single droplet combustion and combustor combustion are described.Finally,research directions for the development and application of gelled fuels are suggested.
基金supported by the Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University(21TQ1400211)the National Key Research and Development Program(YFB20234004900)+2 种基金the Shanghai Municipal Science and Technology Major Projectthe State Key Laboratory of Photoelectric Conversion and Utilization of Solar Energy(Innovation Fund Project SKLPCU24OP009)the National Science Foundation of China(No.22579110)。
文摘1.Introduction The non-renewable fossil fuels have triggered severe energy crisis and global climate change,necessitating the development of sustainable solutions for the growing population.It is estimated that the global annual production of biomass exceeds 180 billion tons[1].Due to its broad availability,renewability,and tunable molecular functionality,biomass is considered as a versatile and sustainable substitute to fossil fuels for the production of fuels and chemicals[2,3].
文摘N,N,N',N'-tetraoctyl diglycolamide(TODGA)is a potential extractant for the co-extraction of lanthanides and actinides in high-level liquid waste.In this study,the radiolysis and extraction properties of TODGA in kerosene solvents contacted with the aqueous phase of varying HNO_(3) concentrations were systematically investigated,and the complexation mechanism was analyzed in conjunction with density functional theory(DFT)calculations.After γ-irradiation,the variation of TODGA concentration was detected,and the variation trends in the relative content of radiolysis products(RPs)with sample type and absorbed dose were demonstrated.Results indicated that the breaking of the amide bond,ether bond,and C_(amide)-C_(ether)bond was the primary radiolysis routes.The aqueous-phase precipitate was studied as a potential new mode of TODGA radiolysis in ultrapure water aqueous phase.Moreover,TODGA/kerosene exhibited excellent extraction capabilities for lanthanides even after absorbing 100 kGy,and HNO_(3) can maintain a portion of TODGA's extraction capacity.The DFT method was applied to calculate and evaluate the complexing ability of TODGA and some of its RPs toward lanthanides.The results revealed that the complexing ability of TODGA for Ce(Ⅲ),Eu(Ⅲ),and Dy(Ⅲ)was enhanced successively,and the complexing ability of the RPs with intact oxygen-containing structures could not be neglected.
基金supported by the National Natural Science Foundation of China(Nos.22422806,22378136,and 22138003)the Guangdong Pearl River Talents Program(Nos.2021QN02C847and 2021ZT09Z109)+4 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515011196 and 2023B1515040005)the Fundamental Research Funds for the Central Universities(Nos.2024ZYGXZR011,2025ZYGXZR025)the Science and Technology Program of Guangzhou(No.2025A04J5244)the State Key Laboratory of Pulp and Paper Engineering(No.2024ZD09)the TCL Young Talent Program。
文摘The breaking of the symmetric electronic distribution of single-atom catalysts is effective in improving the intrinsic activity.However,traditional modification strategies can only disrupt the electronic distribution in one dimension,resulting in limited regulation of electronic structure.Herein,we report a multidimensional coordination strategy to significantly break the symmetrical electron distribution of the metal single site to achieve highly efficient electrochemical CO_(2) reduction reaction(CO_(2) RR).Ni singleatom sites decorated with planar P and axial Cl atoms are successfully constructed on carbon support(Ni-NPCl-C).Ni-NPCl-C affords CO Faraday efficiency over 90%in a wide potential window range from-0.5 to-1.2 V and an ultrahigh turnover frequency of 1.17×10^(5)h^(-1),much superior to its counterparts with single-dimensional coordination.Ni-NPCl-C can be further applied as a bifunctional catalyst to construct a rechargeable Zn-CO_(2) battery.Spectroscopic characterizations and theoretical calculations demonstrate that the dual adjustments with axial Cl and planar P can synergistically disrupt the electron distribution in two dimensions to increase electrons around Ni sites with the upshift of the d-band center,thereby facilitating the formation of*COOH intermediates and improving the CO_(2) RR performance.
文摘One of the main issues in designing optimum tapered cascades for uranium enrichment for annual fuel production in a power reactor is whether to employ large(fat)or small(thin)cascades.What will be the permissible and optimal ranges of the number of machines that can be used in a cascade?For the first time,the permissible and optimal ranges of the number of gas centrifuges that can be utilized in a cascade were investigated using two types of centrifuges,and the performance of small and large tapered cascades was discussed.The particle swarm optimization algorithm(PSO)has been used to optimize tapered cascades.The results show:(1)For the first centrifuge,41 cascades(91≤n≤4897)and for the second centrifuge,49 cascades(18≤n≤3839)with small and large sizes can be used in enrichment facilities,and the best cascade for them has 530(with 23 stages)and 39(with 7 stages)centrifuges,respectively.(2)For both centrifuges,when 600≤n(number of centrifuges=n),the large cascade performance changes are relatively insignificant.(3)For both types of gas centrifuges,the annual los s of separation power in enrichment facilities is approximately 1.25%-4.82%of the total separation work required.
基金Funded by the National Natural Science Foundation of China Guangdong(No.22279096)。
文摘Silica nanoparticles-stabilized cobalt and nitrogen-doped carbon materials were synthesized through pyrolysis of metal-organic-framework of ZIF-67 supported by silica nanoparticles.The experimental results reveal that the introduction of the silica nanoparticles can stabilize the microstructure of the derived CoN-C materials,which in turn exhibits the promising electrocatalytic activity towards both oxygen reduction and oxygen evolution reactions.The optimized sample exhibits a better oxygen reduction activity than commercial Pt/C catalyst as confirmed by the positive shift of half-wave potential by 20 mV while it has a low overpotential of 273 mV for oxygen evolution reactions with the retained performance over 80%after 25,000 s of continuous operation.It is demonstrated that the introduction of support frame might be an effective way to improve the activity and stability of metal-organic-framework derived electrocatalyst with stabilized microstructure.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20220409)the National Natural Science Foundation of China(No.22401153)+2 种基金the FWO[Fund for Scientific Research-Flanders(Belgium)]for financial support(recipient Erik V.Van der Eycken)the Research Council of the KU Leuven(recipient Erik V.Van der Eycken)the support of the"RUDN University Strategic Academic Leadership Program"(recipient Erik V.Van der Eycken).
文摘Peptides play important roles in chemistry,medicinal chemistry and life science,due to their high efficiency and specificity,unusual biological and therapeutic properties.As naturally occurring peptides often face with their intrinsic limitations including metabolic instability and low membrane permeability,the strategies for synthesizing unnatural amino acids and peptides are explored.Among the methods for modifying amino acids and peptides,chemo-and site-selective approaches are preferred because of the ability to fine-tuning structural features.Recently,transition metal-catalyzed C–H activation has been employed for the functionalization of amino acids and peptides.Through domino C–H activation/annulation,a series of structurally complex and diverse amino acids and peptides is constructed.This review highlights recent advances in the synthesis of unnatural amino acids and peptides via transition metal-catalyzed C–H activation/annulation.
基金supported by the National Natural Science Foundation of China(22072048)the Guangdong Provincial Department of Science and Technology(2021A1515010128 and 2022A0505050013).
文摘Succinonitrile(SN)-based polymer plastic crystal electrolytes(PPCEs)are regarded as promising candidates for lithium metal batteries but suffer from serious side reactions with Li metal.Herein,we propose a multi-dimensional optimization strategy to alleviate the side reactions between SN and Li metal,and develop a highly stable poly-vinylethylene carbonate-based PPCE(PPCE-VEC).Moreover,we identify the intrinsic factors of multi-dimensional polymer structures on the electrolyte stability by three typical classes of polyesters.The PPCE-VEC constructed by in situ polymerization exhibits much better stability than poly-vinylene carbonate-based PPCE(PPCE-VCA)and poly-trifluoroethyl acrylate-based PPCE(PPCE-TFA),which is verified by its fewer SN-decomposition species in X-ray photoelectron spectroscopy(XPS)and outstanding full cell performance.The PPCE-VEC-enabled LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)full cell achieve 73.7%capacity retention after 1400 cycles,which outperforms PPCE-VCA-and PPCE-TFA-enabled full cells(61.9%and 46.9%).Spectral analysis and theoretical calculation reveal that the high solvation ability of the carbonyl site,flexible polymer chain,and homogeneous electrolyte phase of PPCE-VEC are favorable to maximizing competition coordination with Li^(+)to weaken the Li^(+)–SN binding and shape an anion-rich solvation structure.This optimized polymer-involved Li^(+)solvation enhances SN stability and facilitates the formation of B/F enriched solid-electrolyte interphase(SEI),thus significantly improving PPCE stability.
基金supported by the National Natural Science Foundation of China(Nos.22376197,U2441225,22076188).
文摘The demand for ^(238)Pu (nuclear battery heat source) drives the separation of its precursor,^(237)Np,from spent nuclear fuel (SNF).However,the co-existence of multi-valence states (Ⅳ/Ⅴ/Ⅵ) of Np and similar redox behavior with Pu(Ⅳ) hinder the effective separation of Np.N-Butyraldehyde (n-C_(3)H_(7)CHO) selectively reduces Np(Ⅵ) to Np(Ⅴ) without reducing Pu(Ⅳ).Herein,we examined the reduction mechanisms of Np(Ⅵ) and Pu(Ⅳ) by n-C3H7CHO using relativistic density functional theory.Based on the results of the potential energy profiles,the reductions of both Np(Ⅵ) and Pu(Ⅳ) by n-C_(3)H_(7)CHO are thermodynamically feasible,whereas only the former is kinetically achievable.It uncovers that n-C_(3)H_(7)CHO can only reduce Np(Ⅵ) to Np(Ⅴ) owing to kinetically controlled selective reduction.The analyses of spin density and bond distance indicate that the reduction nature for the first Np(Ⅵ)/Pu(Ⅳ) belongs to hydrogen atom transfer,whereas that for the second one involves outer-sphere electron transfer.Localized molecular orbitals (LMOs) analysis discloses the bonding evolution during the reduction process of Np(Ⅵ)/Pu(Ⅳ).This study elucidates the reason behind the kinetically controlled selective reduction of Np(Ⅵ)/Pu(Ⅳ) by nC3H7CHO at the molecular level and offers in-depth perspectives on the isolation of specific metal ions from the view of kinetic control.
基金the support from the National Key Research and Development Program of China(2023YFB4005000)the Joint Fund of Liaoning Binhai Laboratory(LBLF-2023-04)+3 种基金Dalian Science and Technology Talent Innovation Support Plan(2022RY09)Innovation Research Fund of Dalian Institute of Chemical Physics(DICP I202318)National Natural Science Foundation of China(22478384)the UK EPSRC(EP/W03784X/1)。
文摘Large-scale hydrogen production via water electrolysis faces a freshwater shortage.Direct seawater electrolysis offers a solution but encounters new challenges.Herein,we report a feasible strategy to both prevent metal hydroxides deposition and boost the hydrogen evolution reaction by adding a chelating agent,EDTA-Na_(4),that chelates with Mg^(2+)/Ca^(2+),thus inhibiting their deposition and gathering them near the cathode surface,resulting in breaking the ordered hydrogen bond networks of interfacial water and reducing the activation energy of water dissociation.Furthermore,hydrolysis of–COO^(-) also promoted water dissociation to produce more active*H and*OH near the electrode surface that in turn serves as a diffusion medium for*OH,accelerating mass transfer and enabling seawater electrolysis to exhibit a stable performance,which operates continuously at 100 mA cm^(-2)@2.20 V and 200 mA cm^(-2)@2.58 V for 400 h in the symmetric electrolyzer and 500 mA cm^(-2)@2.29 V for over 500 h in the asymmetric electrolyzer.This study provides a new perspective to address the issues of stable and scalable direct seawater electrolysis for practical green hydrogen production.
基金supported by JST,grant number JPMJFS2132JST SPRING,grant number JPMJSP2136by an external research grant from Mitsubishi Fuso Truck&Bus Corporation。
文摘Engineering the pore structure of biomass-derived activated carbons is critical for optimizing their performance in adsorptionbased applications.This study demonstrates for the first time that washing hydrochars in solvents of different polarity before activation is a simple yet powerful strategy to tailor pore size distribution.Hydrochar is produced from spent coffee grounds via hydrothermal carbonization,followed by washing in various solvents and activation in KOH.This results in carbons with a very large surface area(~2700 m^(2)/g),and washing is demonstrated to significantly increase product yield.Furthermore,washing in non-polar or mixed-polarity solvents removes long-chain carboxylic acids and esters from the hydrochar,promoting the development of narrow micropores while suppressing mesopore formation.To illustrate the impact of this structural control of porous carbons,post-combustion CO_(2)capture is investigated as a case study.Narrower pore size distribution enhances CO_(2)uptake,significantly improving capacity from 2.8 mmol/g for unwashed samples to 3.8 mmol/g for acetone-washed samples.Interestingly,moderate pore size(9-12Å)is shown to be optimal for CO_(2):N2 selectivity,while smaller pores result in lower selectivity due to stronger interactions between N2 and the pore walls.These findings highlight the potential role of solvent washing in directing pore architecture of hydrochars for adsorption-based carbon capture technologies and beyond.
基金supported in part by the National Natural Science Foundation of China(Nos.12175100 and 11975132)the Construct Program of the Key Discipline in Hunan Province+5 种基金the Research Foundation of Education Bureau of Hunan Province,China(Nos.21B0402,18A237,22A0305)the Natural Science Foundation of Hunan Province,China(No.2018JJ2321)the Innovation Group of Nuclear and Particle Physics in USCthe Shandong Province Natural Science Foundation,China(No.ZR2022JQ04)the Opening Project of Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment,University of South China(No.2019KFZ10)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20251453)。
文摘In this study,the effects of laser fields that can be achieved in the near future on cluster penetration probability and half-life are quantitatively investigated.The calculation results show that extreme laser fields can slightly change the cluster-decay half-life by affecting the penetration probability within a narrow range.Subsequently,we discuss the correlation between the change rate of the penetration probability and the tunneling path.The results indicate that for different parent nuclei emitting the same cluster,nuclei with longer tunneling paths are more easily affected by the laser fields.The shell effect on this correlation is also observed.In addition,the impact of laser fields on the penetration probability in any direction is investigated.
基金supported by the National Natural Science Foundation of China(22409065)the Guangdong Basic and Applied Basic Research Foundation(2022A1515011906)+2 种基金the China Postdoctoral Science Foundation(2023M731153)the Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technologythe Postdoctoral Fellowship Program of CPSF(GZC20230868).
文摘The application of conventional manganese dioxide(MnO_(2))materials in sodium-ion supercapacitors(Na-SCs)is considerably limited by their low conductivity and structural instability.Biomimetic morphology engineering can optimize the electrochemical performance of MnO_(2).Here,based on the metal-organic frameworks(MOFs)-derived method and electrochemical reconstruction,a coral-like MnO_(2)structure integrated with a functional nitrogen-doped carbon(NC)coating is designed for Na-SC application.The bioinspired coral-like structure captures numerous electrolyte ions and increases the Na+concentration on the electrode surface,which is beneficial for optimizing the Na+transport pathway and accelerating the electrode reaction kinetics.Moreover,the coral-like crosslinked structure effectively enhances the mechanical properties,enabling the maintenance of the structure of MnO_(2)-based electrodes during long-term operation.Furthermore,in/ex-situ characterizations are performed to elucidate the mechanism of lattice transformation during electrochemical phase reconstruction.Additionally,the theoretical calculation and simulation results reveal the ion/electron dynamics in the fabricated electrode.The prepared electrode demonstrates excellent capacitance storage ability(340.7 F g^(−1)at 0.5 A g^(−1))and cycling stability(85.1%capacitance retention after 10,000 cycles).The assembled hybrid device exhibits exceptional life-span(82.0%capacitance retention after 10,000 cycles)and exceptional energy density(36.5 Wh kg^(−1)).This study provides a reliable biomimetic morphology design strategy for MnO_(2)cathodes,paving the way for the fabrication of high-performance Na-SCs.
基金funded by the National Science Centre,Poland,on the basis of the decision number UMO-2020/37/B/ST8/02097supported by the program“Excellence Initiative-Research University”for the AGH University of Krakow(IDUB AGH,No.501.696.7996,Action 4,ID 9880).
文摘Multicomponent Gd_(1−x)Sm_(x)Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)double perovskites are optimized for application in terms of chemical composi-tion and morphology for the use as oxygen electrodes in solid oxide cells.Structural studies of other physicochemical properties are con-ducted on a series of materials obtained by the sol-gel method with different ratios of Gd and Sm cations.It is documented that changing the x value,and the resulting adjustment of the average ionic radius,have a significant impact on the crystal structure,stability,as well as on the total conductivity and thermomechanical properties of the materials,with the best results obtained for the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)composition.Oxygen electrodes are prepared using the selected compound,allowing to obtain low polarization resistance values,such as 0.086Ω·cm^(2)at 800℃.Systematic studies of electrocatalytic activity are conducted using La_(0.8)Sr_(0.2)Ga_(0.8)Mg_(_(0.2))O_(3−δ)as the electrolyte for all electrodes,and Ce_(0.8)Gd_(0.2)O_(2−δ)electrolyte for the best performing Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes.The electrochemical data are analyzed using the distribution of relaxation times method.Also,the influence of the preparation method of the electrode material is in-ve`stigated using the electrospinning technique.Finally,the performance of the Gd_(0.75)Sm_(0.2)5Ba_(0.5)Sr_(0.5)CoCuO_(5+δ)electrodes is tested in a Ni-YSZ(yttria-stabilized zirconia)anode-supported cell with a Ce_(0.8)Gd_(0.2)O_(2−δ)buffer layer,in the fuel cell and electrolyzer operating modes.With the electrospun electrode,a power density of 462 mW·cm^(−2)is obtained at 700℃,with a current density of ca.0.2 A·cm^(−2)at 1.3 V for the electrolysis at the same temperature,indicating better performance compared to the sol-gel-based electrode.
