Mixed‑Dimensional Assembly Strategy to Construct Reduced Graphene Oxide/Carbon Foams Heterostructures for Microwave Absorption,Anti‑Corrosion and Thermal Insulation

Considering the serious electromagnetic wave(EMW)pollution problems and complex application condition,there is a pressing need to amalgamate multiple functionalities within a single substance.However,the effective integration of diverse functions into designed EMW absorption materials still faces the huge challenges.Herein,reduced graphene oxide/carbon foams(RGO/CFs)with two-dimensional/three-dimensional(2D/3D)van der Waals(vdWs)heterostructures were meticulously engineered and synthesized utilizing an efficient methodology involving freeze-drying,immersing absorption,secondary freeze-drying,followed by carbonization treatment.Thanks to their excellent linkage effect of amplified dielectric loss and optimized impedance matching,the designed 2D/3D RGO/CFs vdWs heterostructures demonstrated commendable EMW absorption performances,achieving a broad absorption bandwidth of 6.2 GHz and a reflection loss of-50.58 dB with the low matching thicknesses.Furthermore,the obtained 2D/3D RGO/CFs vdWs heterostructures also displayed the significant radar stealth properties,good corrosion resistance performances as well as outstanding thermal insulation capabilities,displaying the great potential in complex and variable environments.Accordingly,this work not only demonstrated a straightforward method for fabricating 2D/3D vdWs heterostructures,but also outlined a powerful mixeddimensional assembly strategy for engineering multifunctional foams for electromagnetic protection,aerospace and other complex conditions.

Modulating perovskite crystallization and band alignment using coplanar molecules for high-performance indoor photovoltaics

The proper bandgap and exceptional photostability enable CsPbI_(3) as a potential candidate for indoor photovoltaics(IPVs),but indoor power conversion efficiency(PCE) is impeded by serious nonradiative recombination stemming from challenges in incomplete DMAPbI_(3) conversion and lattice structure distortion.Here,the coplanar symmetric structu re of hexyl sulfide(HS) is employed to functionalize the CsPbI_(3) layer for fabricating highly efficient IPVs.The hydrogen bond between HS and DMAI promotes the conversion of DMAPbI_(3) to CsPbI_(3),while the copianar symmetric structure enhances crystalline order.Simultaneously,surface sulfidation during HS-induced growth results in the in situ formation of PbS,spontaneously creating a CsPbI_(3) N-P homojunction to enhance band alignment and carrier mobility.As a result,the CsPbI_(3)&HS devices achieve an impressive indoor PCE of 39.90%(P_(in):334.6 μW cm^(-2),P_(out):133.5 μW cm^(-2)) under LED@2968 K,1062 lux,and maintain over 90% initial PCE for 800 h at ^(3)0% air ambient humidity.

Stitching Perovskite Grains with Perhydropoly(Silazane)Anti-Template-Agent for High-Efficiency and Stable Solar Cells Fabricated in Ambient Air

All inorganic CsPbI_(3)perovskite solar cells(PSCs)have emerged as disruptive photovoltaic technology owing to their admirable photoelectric properties and the non-volatile active layer.However,the phase instability against moisture severely limits the fabrication environment for the high-efficiency devices,breaking through the confinement region to achieve scalable manufacturing has been the primary issue for future commercialization.Here,we develop a curing-anti-solvent strategy for fabricating high-quality and stable black-phase CsPbI_(3)perovskite films in ambient air by introducing an inorganic polymer perhydropolysilazane(PHPS)into methyl acetate to form anti-template agent.The cross-linked PHPS reduces moisture erosions while the hydrolyzate silanol network(–Si(OH)_(4)^(–))controls the perovskite crystal growth by forming Lewis adducts with PbI_(2)during the fabrication.The polycondensation adduct of Si–O–Si/Si–O–Pb strongly binds to CsPbI_(3)grains as a shield layer to hamper phase transition.Using the inorganic CsPbI_(3)perovskite thin-film with PHPS-modified anti-solvent processing as the light absorber,the n–i–p planar solar cell achieved an efficiency of 19.17%under standard illumination test conditions.More importantly,the devices showed excellent moisture stability,retaining about 90%of the initial efficiency after 1000 h under 30%RH.

Multifunctional cellular carbon foams derived from chitosan toward self-cleaning, thermal insulation, and highly efficient microwave absorption properties

To adapt the practical demand,designing and constructing the multifunctional microwave absorbers(MAs)is the key future direction of research and development.However,effective integrating the multiple functions into a single material remains a huge challenge.Herein,cellular carbon foams(CCFs)with different porous structures were elaborately designed and fabricated in high efficiency through a facile continuous freeze-drying and carbonization processes using a sustainable biomass chitosan as the precursor.The obtained results revealed that the thermal treated temperature and g-C_(3)N_(4) amount played a great impact on the carbonization degrees,pore sizes,and morphologies of CCFs,which led to their tunable electromagnetic(EM)parameters,improved conduction loss,and polarization loss abilities.Owing to the special cellular structure,the designed CCFs samples simultaneously displayed the strong absorption capabilities,broad absorption bandwidths,and thin matching thicknesses.Meanwhile,the as-prepared CCFs exhibited the strong hydrophobicity and good thermal insulation,endowing its attractive functions of self-cleaning and thermal insulation.Therefore,our findings not only presented a facile approach to produce different porous structures of CCFs,but also provided an effective strategy to develop multifunctional high-performance MAs on basis of three-dimensional CCFs.

Universal paradigm of ternary metacomposites with tunable epsilon-negative and epsilon-near-zero response for perfect electromagnetic shielding

CaCu_(3)Ti_(4)O_(12)(CCTO)ceramic nanocomposites incorporating graphene–carbon black(GRCB)fillers were fabricated by spark plasma sintering process.The percolative effects of conductive GRCB fillers on dielectric response of GRCB/CCTO ternary metacomposites were systematically investigated.The weakly real permittivity(ε′)-negative response(ε′~−1×10^(2))was achieved which originated from weakly low-frequency plasmonic state of free carriers within constructed GRCB networks.With enhancing three-dimensional GRCB network,the plasma frequency of metacomposites increased while the damping factor decreased.Herein,theε′-negative values of metacomposites were tuned from−10^(2) to−10^(4) orders of magnitude andε′-near-zero(ENZ)frequencies from~142 to~340 MHz which substantially benefited from the moderate carrier concentration of GRCB dual fillers.The Drude model and equivalent circuit models were adopted to demonstrate dielectric and electrical characteristics.The obtained metacomposites show strong EM shielding effect along with enhanced plasmonic oscillation and even better achieving perfect EM shielding effect in ENZ media.This work achieves the tunableε′-negative andε′-near-zero response and more importantly clarifies its regulation mechanism in ceramic-based ternary metacomposites,which opens up the possibility of designing high-performance EM shielding materials based on metacomposites.

Hierarchical engineering of CoNi@Air@C/SiO_(2)@Polypyrrole multicomponent nanocubes to improve the dielectric loss capability and magnetic-dielectric synergy

Impedance matching characteristics and loss capabilities including magnetic loss,polarization loss and conduction loss are critical factors to improve microwave absorption performances(MAPs).To elevate these aspects,herein,yolk-shell structured CoNi@Air@C/SiO_(2)@Polypyrrole(PPy)magnetic multicomponent nanocubes(MCNCs)were designed and successfully fabricated in high efficiency through a continuous co-precipitation route,classical Stöber method,thermal treatment and polymerization reaction.The obtained results indicated that the formation of SiO_(2) effectively stabilized the cubic geometrical morphology and yolk-shell structure during the high-temperature pyrolysis process.The introduction of PPy greatly boosted their polarization loss and conductive loss capabilities.Therefore,the as-prepared yolkshell structured CoNi@Air@C/SiO_(2)@PPy MCNCs presented superior MAPs compared to CoNi@Air@C/SiO_(2) MCNCs.Furthermore,by regulating the content of PPy,the obtained CoNi@Air@C/SiO_(2)@PPy MCNCs displayed tunable and excellent comprehensive MAPs in terms of strong absorption capabilities,broad frequency bandwidths and thin matching thicknesses,which could be ascribed to the unique structure and excellent magnetic-dielectric synergistic effect.Therefore,our findings provided an alternative pathway to effectively utilize the magnetic-dielectric synergy and loss capabilities for the developing yolk-shell structured magnetic MCNCs as the strong wideband microwave absorbers.

Tunable and improved microwave absorption of flower-like core@shell MFe_(2)O_(4)@MoS_(2)(M=Mn,Ni and Zn)nanocomposites by defect and interface engineering

Previous results revealed that the defect and/or interface had a great impact on the electromagnetic pa-rameters of materials.In order to understand the main physical mechanisms and effectively utilize these strategies,in this study,M Fe_(2)O_(4)and flower-like core@shell M Fe_(2)O_(4)@MoS_(2)(M=Mn,Ni,and Zn)sam-ples with different categories were elaborately designed and selectively produced in large scale through a simple two-step hydrothermal reaction.We conducted the systematical investigation on their microstruc-tures,electromagnetic parameters and microwave absorption performances(MAPs).The obtained results revealed that the large radius of M^(2+)cation could effectively boost the concentration of oxygen vacancy in the M Fe_(2)O_(4)and M Fe_(2)O_(4)@MoS_(2)samples,which resulted in the improvement of dielectric loss capabil-ities and MAPs.Furthermore,the introduction of MoS_(2)nanosheets greatly improved the interfacial effect and enhanced the polarization loss capabilities,which also boosted the MAPs.By taking full advantage of the defect and interface,the designed M Fe_(2)O_(4)@MoS_(2)samples displayed tunable and excellent com-prehensive MAPs including strong absorption capability,wide absorption bandwidth and thin matching thicknesses.Therefore,the clear understanding of defect and interface engineering made these strategies well elaborately designed and applicable to improving MAPs.

Anion regulating endows core@shell structured hollow carbon spheres@MoSxSe_(2−x)with tunable and boosted microwave absorption performance

Due to the good manipulation of electronic structure and defect,anion regulating should be a promising strategy to regulate the electromagnetic(EM)parameters and optimize the EM wave absorption performances(EMWAPs).In this work,we proposed a facile route for the large-scale production of core@shell structured hollow carbon spheres@MoSxSe_(2−x)(x=0.2,0.6,and 1.0)multicomponent nanocomposites(MCNCs)through a mild template method followed by hydrothermal process.The obtained results revealed that the designed hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the improved sulfur vacancy concentration by regulating the x value from 0.2 to 1.0.The obtained hollow carbon spheres@MoSxSe_(2−x)MCNCs displayed the extraordinary comprehensive EMWAPs because of the introduced abundant defects and excellent interfacial effects.Furthermore,the as-prepared hollow carbon spheres@MoSxSe_(2−x)MCNCs presented the progressively improved comprehensive EMWAPs with the x value increasing from 0.2 to 1.0,which could be explained by their boosted polarization loss abilities and impedance matching characteristics originating from the enhanced sulfur vacancy concentration.Therefore,our findings not only demonstrated that the anion regulating was a promising method to optimize EM parameters and EMWAPs,but also provided a facile route to design the transition metal dichalcogenides-based MCNCs as the much more attractive candidates for highperformance microwave absorbers.

Carbon nanotube-carbon black/CaCu_(3)Ti_(4)O_(12) ternary metacomposites with tunable negative permittivity and thermal conductivity fabricated by spark plasma sintering

Metacomposites with negative permittivity usually possess huge dielectric loss,showing potential for micro-wave attenuation devices where huge heat would generate.Herein,carbon nanotube-carbon black/CaCu_(3-)Ti_(4)O_(12)(CNT-CB/CCTO)ternary metacomposites were fabricated by spark plasma sintering.The CNT-CB dualphase filler was pre-pared through electrostatic selfassembly process in order to construct an effective 3-dimensional(3D)carbon network in CCTO matrix.The percolation threshold of CNT-CB/CCTO composites was identified at filler content of 12.52 wt%which accompanied with an essential change of conduction mechanism.The negative permittivity was derived from low-frequency plasmonic state of the 3D carbon network,described by Drude model.The problem of heat transport,generally occurring in negative permittivity materials,has been solved and optimized in obtained ternary metacomposites beneftting from the substantially high thermal conductivity(9.49-2.00 W·m^(-1)·K^(-1))and diffusivity(2.74-1.22mm^(2)·s^(-1)).This work could spark significant development of practical application of metacomposites on novel electronic devices and electromagnetic apparatus.

Magnetic-dielectric synergy and interfacial engineering to design yolk-shell structured CoNi@void@C and CoNi@void@C@MoS_(2) nanocomposites with tunable and strong wideband microwave absorption

In order to effectively utilize the magnetic-dielectric synergy and interfacial engineering,in this paper,yolk–shell structured magnetic multicomponent nanocomposites(MCNCs)including CoNi@void@C and CoNi@void@C@MoS_(2) were produced in large scale by in-situ pyrolysis of cubic CoNi Prussian blue analogs(PBAs)followed by the hydrothermal process,respectively.Because of their unique structures,excellent synergistic effect between dielectric and magnetic loss,the as-prepared CoNi@void@C and CoNi@void@C@MoS_(2) MCNCs displayed very outstanding electromagnetic wave absorption performances(EMWAPs)including strong absorption capabilities,broad absorption bandwidth and thin matching thicknesses.Furthermore,the as-prepared CoNi@void@C and CoNi@void@C@MoS_(2) MCNCs well maintained the cubic configuration of CoNi PBAs even after the thermal treatment and hydrothermal processes.The unique structure and formed carbon layers effectively prevented the corrosion of internal CoNi alloy during the formation of MoS_(2),and CoNi@void@C@MoS_(2) MCNCs with different MoS_(2) contents could be synthesized by controlling the hydrothermal temperature.The obtained results revealed that the EM parameters,dielectric and magnetic loss capabilities of CoNi@void@C@MoS_(2) MCNCs could be tuned by controlling hydrothermal temperature and filler loading,which made their outstanding EMWAPs could be achieved in different frequency regions.Taking account of simple process,low density and high chemical stability,our findings provided a new and effective pathway to develop the strong wideband microwave absorbers.

Microstructure optimization of core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites towards high-efficiency microwave absorption

In this work,we put forward a scheme to exquisitely design and selectively synthesize the core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)flower-like multicomponent nanocomposites(MCNCs)through a simple two-step hydrothermal reaction on the surfaces of MFe_(2)O_4 nanospheres with the certain amounts of Mo and Se sources.With increasing the amounts of Mo and Se sources,the obtained core@shell structured MSe_(2)/FeSe_(2)@MoSe_(2)(M=Co,Ni)MCNCs with the enhanced content of MoSe_(2)and improved flower-like geometry morphology could be produced on a large scale.The obtained results revealed that the as-prepared samples displayed improved comprehensive microwave absorption properties(CMAPs)with the increased amounts of Mo and Se sources.The as-prepared CoSe_(2)/FeSe_(2)@MoSe_(2)and NiSe_(2)/FeSe_(2)@MoSe_(2)MCNCs with the well-defined flower-like morphology could simultaneously present the outstanding CMAPs in terms of strong absorption capability,wide absorption bandwidth,and thin matching thicknesses,which mainly originated from the conduction loss and flower-like geometry morphology.Therefore,the findings not only develop the very desirable candidates for high-performance microwave absorption materials but also pave a new way for optimizing the CMAPs through tailoring morphology engineering.

Defect and interface engineering in core@shell structure hollow carbon@MoS_(2)nanocomposites for boosted microwave absorption performance

Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials.In order to effectively utilize these strategies for the improvement of microwave absorption properties(MAPs),in this study,we reported the synthesis of hollow carbon shells and hollow carbon@MoS_(2)nanocomposites by the template-etching and templateetching-hydrothermal methods,respectively.The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS_(2)could be modulated by the thickness of hollow carbon shell,which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs.Furthermore,the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS_(2)in high efficiency.And the introduction of MoS_(2)nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities,which resulted in the improvement of comprehensive MAPs.The elaborately designed hollow carbon@MoS_(2)samples displayed very outstanding MAPs including strong absorption capabilities,broad absorption bandwidth,and thin matching thicknesses.Therefore,this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.