查看更多>>摘要：Achieving synergistic absorption of electromagnetic waves(EMWs)in the mid-high frequency and absorption band conversion is an urgent problem.However,the present solution is usually a straightforward mixture of magnetic component-carbon component.Hereby,we optimize the magnetic properties and electrical relaxation response from a chemical synthesis perspective.Through integrated design,the contents of carbon components and multi-dimensional morphology are controlled by retaining strong magnetic properties.The morphology design and the construction of heterogeneous interfaces will boost the intense response of charge in the surrounding to enhance the polarization effect.The multi-dimensional structure and electromagnetic(EM)properties of the sample after optimized engineering have an extremely powerful absorption conversion effect on EMW energy.NiCo@C particles ultimately achieve synergistic absorption effects at low thickness(d＜3.5 mm)at middle frequencies(6-10 GHz)and high frequencies(10.5-18 GHz).Our work establishes a correlation mechanism between the physical and chemical properties of materials and EM parameters.It also provides insight into the synergistic absorption of EMWs in the mid-high frequency and absorption band conversion strategies.
查看更多>>摘要：Suppressing the formation of amorphous surface carbon and contaminants during the preparation of graphene by chemical vapor deposition remains an ongoing issue.Herein,we analyzed how substrate characteristics affect graphene quality by simulating margin extension,the nucleation process,and defect pegging configurations on mono-crystalline oriented metal substrates with the aim of enhancing graphene cleanliness.Defect formation energy and nucleation potential,which are indirect substrate-graphene interaction features,were found to appropriately evaluate graphene quality.The crystallographic orientation of the metal substrate was discovered to be critical for producing superclean graphene.A low graphene defect density and high nucleation rate on the Cu(100)facet guarantee growth of high-quality graphene,especially in terms of suppressing the formation of amorphous carbon.In addition,rapid kink growth and self-healing on the Cu(100)facet facilitate rapid graphene synthesis,which is also promoted by rapid kink splicing and margin self-repair on this facet.This study provides theoretical insight useful for the synthesis of superclean graphene.
查看更多>>摘要：Supported metal catalysts are widely used in the modern chemical industry.The electronic interaction between supports and active components is of great significance for heterogeneous catalysis.Graphdiyne(GDY),a new type of carbon allotrope with sp-hybridized carbon atoms,rr conjugate structure,and electron transmission capability,is a promising candidate as catalyst support.Recent years have witnessed the rapid progress of GDY-suppported metal catalysts for different catalysis reactions.Considering that most processes in the current chemical industry are thermocatalytic reactions,we herein give an overview about the advances and particular characteristics of GDY-supported catalysts in these reactions.The geometric structure and electronic properties of GDY are first introduced.Then,the synthesis methods for GDY-supported metal catalysts and their applications in thermocatalytic reactions are discussed,in which the effect of electronic interaction on catalytic performance is highlighted.Finally,the current challenges and future directions of GDY-supported metal catalysts for thermocatalysis are proposed.It is expected that this review will enrich our understanding of the advances of GDY as a superior support for metal catalysts in thermocatalytic reactions.
查看更多>>摘要：Electrocatalytic water splitting is an essential and effective means to produce green hydrogen energy structures,so it is necessary to develop non-precious metal catalysts to replace precious metals.Cobalt-based catalysts present effective alternatives due to the diverse valence states,adjustable electronic structures,and plentiful components.In this review,the catalytic mechanisms of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)for electrocatalytic water splitting are described.Then,the synthesis strategies of various cobalt-based catalysts are systematically summarized,followed by the relationships between the structure and performance clarified.Subsequently,the effects of d-band center and spin regulation for cobalt-based catalysts are also discussed.Furthermore,the dynamic electronic and structural devolution of cobalt-based catalysts are elucidated by combining a series of in-situ characterizations.Finally,we highlight the challenges and future developed directions of cobalt-based catalysts for electrocatalytic water splitting.
查看更多>>摘要：The development of highly efficient and durable oxygen evolution reaction(OER)catalysts for seawater electrolysis is of great importance for applications.Here,an amorphous FeMoO4 nanorod array on Ni foam is reported as a highly active OER electrocatalyst in alkaline seawater,requiring only overpotentials of 303 and 332 mV to achieve 100 and 300 mA·cm-2,respectively.Moreover,it shows strong long-term electrochemical durability for at least 50 h.
查看更多>>摘要：Nitrate(NO3),a nitrogen-containing pollutant,is prevalent in aqueous solutions,contributing to a range of environmental and health-related issues.The electrocatalytic reduction of NO3 holds promise as a sustainable approach to both eliminating NO3 and generating valuable ammonia(NH3).Nevertheless,the reduction reaction of NO3(NO3-RR),involving 8-electron transfer process,is intricate,necessitating highly efficient electrocatalysts to facilitate the conversion of NO3 to NH3.In this study,Fe-doped Co3O4 nanowire strutted three-dimensional(3D)pinewood-derived carbon(Fe-Co3O4/PC)is proposed as a high-efficiency NO3-RR electrocatalyst for NH3 production.Operating within 0.1 M NaOH containing NO3-,Fe-Co3O4/PC demonstrates exceptional performance,obtain an impressively large NH3 yield of 0.55 mmol h-1·cm-2 and an exceptionally high Faradaic efficiency of 96.5％at-0.5 V,superior to its Co3O4/PC counterpart(0.2 mmol-h-1·cm-2,73.3％).Furthermore,the study delves into the reaction mechanism of Fe-Co3O4 for NO3-RR through theoretical calculations.
查看更多>>摘要：Photothermal carbon dioxide(CO2)methanation has attracted increasing interest in solar fuel synthesis,which employs the advantages of photocatalytic H2O splitting as a hydrogen source and photothermal catalytic CO2 reduction.This work prepared three-dimensional(3D)honeycomb N-doped carbon(NC)loaded with core-shell NiO@Ni nanoparticles generated in situ at 500 ℃(NiO@Ni/NC-500).Under the photothermal catalysis(200 ℃,1.5 W/cm2),the CH4 evolution rate of NiO@Ni/NC-500 reached 5.5 mmol/(g·h),which is much higher than that of the photocatalysis(0.8 mmol/(g·h))and the thermal catalysis(3.7 mmol/(g·h)).It is found that the generated localized surface plasmon resonance enhances the injection of hot electrons from Ni to NiO,while thermal heating accelerates the thermal motion of radicals,thus generating a strong photo-thermal synergistic effect on the reaction.The CO2 reduction to CH4 follows the*OCH pathway.This work demonstrates the synergistic effect of NiO@Ni and NC can enhance the catalytic performance of photothermal CO2 reduction reaction coupled with water splitting reaction.
查看更多>>摘要：Atomically-dispersed iron-based electrocatalysts are promising substitutes for noble metal electrocatalysts because of excellent performance in oxygen reduction reaction(ORR).Rationally modulating the local coordination environment of the Fe site and optimizing the binding energy of oxygen reduction intermediates are effective strategies to optimize ORR activity.Herein,we report a new method in which Ni is introduced to construct NiFe dual single atoms and iron nanoclusters loaded on the nitrogen-doped carbon with a highly porous structure.This design plays a synergistic role of dual single atoms and clusters,optimizes the 3d orbital and Fermi level of Fe,breaks the symmetrical structure of Fe-N4,and effectively improves the adsorption/desorption behavior of the oxygen-containing intermediates.Electrochemical tests show FeNCs/NiFeSAs-NC has an excellent intrinsic activity.Theoretical calculations show the oxygen-containing species on the Ni active site will move to the middle of NiFe(bridge site connection)after optimization and that the key step is OH desorption,with a reaction energy of 0.27 eV.The electron exchange between NiFe-N6 and Fe-cluster is very strong,further indicating the introduction of Ni species and Fe clusters has a regulatory effect on the electronic structure of Fe-N4.
查看更多>>摘要：By adjusting the coordination environment of single-atom catalysts,the enzyme-like activity can be finely tuned for highly sensitive biosensing.Herein,we demonstrated that coordinatively unsaturated cobalt-nitrogen sites doped within porous carbon(SA-CoN3)could serve as highly efficient oxidase mimic.Compared with the typical planar four-coordination structure(SA-CoN4),the as-obtained single-atom Co nanozymes anchored by three nitrogen atoms are found to display much higher oxidase-like catalytic efficiency.Combined theoretical and experimental analysis revealed that the coordinatively unsaturated Co sites could facilitate adsorption and activation of O2 molecule and thus improve their oxidase-like activity.Based on the enhanced oxidase-like activity of SA-CoN3,a paper/smartphone sensor for organophosphorus pesticides(OPs)was successfully constructed and used to quantify glyphosate in environmental and food samples with a low detection limit of 0.66 μM.This work not only highlights the important role of coordination unsaturation of SA nanozymes for promoting oxidase-like activity,but also provides an easy and cost-effective way to conduct effective quantification of OPs in the field.
查看更多>>摘要：A scalable strategy for the convenient and rapid preparation of nitrogen-doped carbon-coated iron-based alloy catalysts was developed.By controlling the type and amount of metal salts in the precursor,various types of nitrogen-doped carbon-coated alloy catalysts can be prepared in a targeted manner.Fe2Ni2@CN materials with small particle sizes and relatively homogeneous basic sites showed promising results in the N-alkylation reaction of benzyl alcohol with aniline(optimum yield:99％).It is worth noting that the catalyst can also be magnetically separated and recovered after the reaction,and its performance can be regenerated through simple calcination.Furthermore,it was confirmed by kinetic experiments that the activation of C-H at the benzyl alcohol benzylic position is the rate-determining step(RDS).According to density flooding theory calculations,Fe2Ni2@CN catalysts require less energy than other materials(Fe@CN and Ni@CN)for the RDS(dehydrogenation reaction)process.Therefore N-alkylation reactions are more easily carried out on Fe2Ni2@CN catalysts,which may be the reason for the best catalytic activity of Fe-Ni alloy materials.These carbon-coated alloy materials will show great potential in more types of heterogeneous catalysis.
NETL
NSTL
万方数据