Structural Engineering of Hierarchical Magnetic/Carbon Nanocomposites via In Situ Growth for High-Efficient Electromagnetic Wave Absorption

Materials exhibiting high-performance electromagnetic wave absorption have garnered considerable scientific and technological attention,yet encounter significant challenges.Developing new materials and innovative structural design concepts is crucial for expanding the application field of electromagnetic wave absorption.Particularly,hierarchical structure engineering has emerged as a promising approach to enhance the physical and chemical properties of materials,providing immense potential for creating versatile electromagnetic wave absorption materials.Herein,an exceptional multi-dimensional hierarchical structure was meticulously devised,unleashing the full microwave attenuation capabilities through in situ growth,selfreduction,and multi-heterogeneous interface integration.The hierarchical structure features a three-dimensional carbon framework,where magnetic nanoparticles grow in situ on the carbon skeleton,creating a necklace-like structure.Furthermore,magnetic nanosheets assemble within this framework.Enhanced impedance matching was achieved by precisely adjusting component proportions,and intelligent integration of diverse interfaces bolstered dielectric polarization.The obtain Fe_(3)O_(4)-Fe nanoparticles/carbon nanofibers/Al-Fe_(3)O_(4)-Fe nanosheets composites demonstrated outstanding performance with a minimum reflection loss(RLmin)value of−59.3 dB and an effective absorption bandwidth(RL≤−10 dB)extending up to 5.6 GHz at 2.2 mm.These notable accomplishments offer fresh insights into the precision design of high-efficient electromagnetic wave absorption materials.

In situ growth of 3D walnut-like nano-architecture Mo-Ni2P@NiFeLDH/NF arrays for synergistically enhanced overall water splitting

The in situ growth of nano-array on material structure is a novel and high-efficient strategy to design catalysts,however,it still remains a challenge to fabricate unique nano-architecture electrocatalyst with prominent activity and superior durability for oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).Herein,a unique nano-architecture catalyst is successfully synthesized by using NiFe LDH nanosheets as framework to the in situ growth Mo-doped Ni2 P ultrafine nanosheets(marked as Mo-Ni2 P@NiFe LDH/NF).The unique 3 D core-shell nano-architecture is favorable for enhancing electron transfer/mass diffusion,providing abundant active sites,prompting O2/H2 gas release,and creating the synergistic effect between Mo-Ni2 P and NiFe LDH.Therefore,comparing with pure NiFe LDH/NF and MoNi2 P/NF electrodes,walnut-like Mo-Ni2 P@Ni Fe LDH/NF catalyst exhibits significantly improved electrocatalytic activities and durability towards OER(269 m V@40 m A cm^-2),HER(82 mV@10 mA cm^-2),and overall water splitting(1.46 V@10 m A cm^-2),respectively.Such electrocatalytic activity of Mo-Ni2 P@NiFe LDH/NF is comparable with that of majority reported non-precious metal catalysts and even precious catalysts(IrO2 and Pt/C).This work presents a new perspective strategy to fabricate ingeniously bifunctional electrocatalysts with well-designed structure and superior performance for clean energy conversion technologies or storage devices.

Investigation of in situ Growth of SrMoO_4 Nanoplates by Microcalorimetry

SrMoO4 nanoplates were synthesized by a facile reverse microemulsion method at room temperature.Energy evolution of this in situ growth process was monitored by means of a microcalorimeter.A sharp exothermic peak for the initial reaction and two discontinuous relatively weak exothermic peaks for the subsequent crystal growth emerged on the microcalorimetric heat flow curve.Based on the in situ thermokinetic data,the rate constants of the nucleation process and crystallization process at 298.15 K were calculated to be 4.078×10-3 and 5.033×10-4 s-1,respectively.The growth mechanism and energy evolution were investigated.

EFFECT OF SUBSTRATE TEMPERATURE ON Y-Ba-Cu-O THIN FILMS IN SITU GROWTH BY MOCVD

Superconducting thin films of YBa2Cu3O7-x（Y-Ba-Cu-O） with Tc more than 85K have been deposited in situ by metalorganic chemical vapor deposition （MOCVD） on yttria stabilized zirconia（YSZ） substrates. The relationship of film orientation on substrate temperature and the lowest formation temperature region of superconducting phase have been obtained after changing the substrate temperature. The epitaxial relation between Y-Ba-Cu-O films and the YSZ su bstrates were discussed.

In situ growth of nano-hydroxyapatite on multilayered Ti_(3)C_(2)T_(x) MXene as a drug carrier with superior-performance

Bone defects caused by tumor resection typically require bone repair materials to fill the defect sites.The development of multifunctional bone filling materials with integrated chemotherapy,photohermal therapy,and guided bone regeneration is very necessary and urgently needed.Herein,for the first time,the construction of novel multilayered Ti_(3)C_(2)T_(x) MXene(m-MXene)/nano-hydroxyaptite(nHAp)composites(m-MXene/nHAp)for bone repair is reported.The in situ growth of nHAp on multilayered Ti_(3)C_(2)T_(x) MXene is achieved through a facile hydrothermal method without using any organic additives.Due to the syner-gistic effects of nHAp and m-MXene,the m-MXene/nHAp composites show superior drug carrier perfor-mance with ultra-high drug loading capacity and ultra-long drug sustained release time.The molecular dynamics simulation results indicate that both Ti_(3)C_(2)T_(x) MXene and HAp show many adsorption sites and high binding energy with DOX.Moreover,the m-MXene/nHAp composites possess high photothermal conversion efficiency and excellent photothermal stability.The in situ growth of nano-HAp can signifi-cantly improve the biocompatibility of the m-MXene.The as-prepared multifunctional m-MXene/nHAp composites in this work can be used as bone filling powder and have great potential in bone defect reconstruction caused by bone tumor.

In situ formation of self-antistacking FeCoO_(x) on N-doped graphene:A 3D-on-2D nanoarchitecture for long-life Zn-air batteries

Before the practical application of rechargeable Zn-air batteries(ZABs),a critical issue regarding the inherent slow reaction kinetics of the oxygen reduction(ORR)and oxygen evolution(OER)must be addressed.Here,we fabricate a cost-effective bifunctional oxygen electrocatalyst with a self-antistacking structure,where three-dimensional(3D)Fe-Co bimetallic oxide particles(FeCoO_(x))are directly grown on 2D N-doped graphene(NG).The in situ grown FeCoO_(x)particles can alleviate the NG interlaminar restacking,ensuring abundant channels for diffusion of O_(2)/OH−species,while the NG allows rapid electron flow.Benefiting from this self-antistacking 3D-on-2D structure and synergetic electrocatalysis,FeCoO_(x)@NG demonstrated excellent activity for both ORR and OER(ΔE=0.78 V),which is superior to that of the binary mixtures of Pt/C and RuO_(2)(ΔE=0.83 V).A homemade ZAB with 20%-FeCoO_(x)@NG delivers a specific capacity of 758.9 mAh g^(−1),a peak power density of 215 mW cm^(−2),and long-term cyclability for over 400 h.These research results suggest that designing a bimetallic oxide/N-doped carbon 3D-on-2D nanoarchitecture using an in situ growth strategy is an attractive and feasible solution to overcome electrocatalytic problems in ZABs.

An in situ growth method for property control of LPCVD polysilicon film

Polysilicon films deposited by low-pressure chemical vapor deposition (LPCVD) exhibit large residual stress and stress gradient, depending on the deposition condition. An in situ growth method based on multilayer concept is presented to control the property for as-deposited polysilicon. A 3-μm thick polysilicon film with nine layers structure is demonstrated under the detailed analysis of multi-layer theory and material characteristic of polysilicon. The results show that a 3-μm-thick polysilicon film with 8-MPa overall residual tensile stress and 2.125-MPa/μm stress gradient through the film thickness is fabricated successfully.

Nanoparticle Exsolution on Perovskite Oxides:Insights into Mechanism,Characteristics and Novel Strategies

Supported nanoparticles have attracted considerable attention as a promising catalyst for achieving unique properties in numerous applications,including fuel cells,chemical conversion,and batteries.Nanocatalysts demonstrate high activity by expanding the number of active sites,but they also intensify deactivation issues,such as agglomeration and poisoning,simultaneously.Exsolution for bottomup synthesis of supported nanoparticles has emerged as a breakthrough technique to overcome limitations associated with conventional nanomaterials.Nanoparticles are uniformly exsolved from perovskite oxide supports and socketed into the oxide support by a one-step reduction process.Their uniformity and stability,resulting from the socketed structure,play a crucial role in the development of novel nanocatalysts.Recently,tremendous research efforts have been dedicated to further controlling exsolution particles.To effectively address exsolution at a more precise level,understanding the underlying mechanism is essential.This review presents a comprehensive overview of the exsolution mechanism,with a focus on its driving force,processes,properties,and synergetic strategies,as well as new pathways for optimizing nanocatalysts in diverse applications.

Co9Se8 Nanosheets Electrodes： Drop-Cast versus in situ Growth

Co9Se8 nanosheets are synthesized via a solvothermal reaction.Thin films of Co9Se8 nanosheets are respectively fabricated through drop-cast and in situ growth for use as the electrocatalyst in dye-sensitized solar cells （DSSCs）.Comparative studies reveal that the in situ growth Co9Se8 nanosheets film exhibits higher electrocatalytic activity for the electrocatalytic reduction of triiodide to iodide and better electrochemical stability than the drop-casted film.When applied as the counter electrode in DSSCs,the in situ growth film yields higher power conversion efficiency （8.65%） than the drop-casted film （5.87%） and even outperforms the reference Pt electrode （8.16%） under comparable conditions.

Investigation on the Initial Stage of Film Growth in Situ

The initial stage of Ag film growth on Cu(100). Ta(100) and Ta(110) single crystals as well as YBaCuO on Si single crystal covered by Pd was investigated in situ by means of LAS 600 surface analysis system with a sputtering source in sample preparation chamber. The results show that the initial state for Ag / Cu(100) film growth is typical S-K model, for Ag / Ta(100) and Ag / Ta(110)they have the same S-K characteristics, but due to the different surface energies of two crystalline planes. there is some difference for Ag / Ta (100) and Ag / Ta(110). YBCO sputterjng process is rather complex and Cu is the first element appearing in the film.

A bifunctional bone scaffold combines osteogenesis and antibacterial activity via in situ grown hydroxyapatite and silver nanoparticles

Hydroxyapatite(HA)nanoparticles and silver(Ag)nanoparticles are expected to enable desirable bioactivity and antibac-terial properties on biopolymer scaffolds.Nevertheless,interfacial adhesion between HA/Ag and the biopolymer is poor due to the large physicochemical differences between these components.In this study,poly L-lactic acid(PLLA)powder was first surface-modified with bioactive polydopamine(PDA)in an alkaline environment.Next,HA and Ag nanoparticles were grown in situ on the PDA-coated PLLA powder,which was then adhered to the porous bone scaffold using a selective laser-sintering process.Results showed that HA and Ag nanoparticles were homogenously distributed in the matrix,with enhanced mechanical properties.Simulated body fluid bioactivity tests showed that the in situ grown HA-endowed scaffold shows excellent bioactivity.In vitro tests confirmed that the scaffold exhibits favorable biocompatibility with human umbilical cord mesenchymal stem cells,as well as strong antibacterial activity against Gram-negative Escherichia coli.Furthermore,in vivo assays indicated that the scaffold promoted bone generation,with a new bone area fraction of 71.8%after 8 weeks’implantation,without inflammation.

In situ synthesis of a spherical covalent organic framework as a stationary phase for capillary electrochromatography

Covalent organic frameworks(COFs)are a novel type of crystalline porous organic polymer materials recently developed.It has several advantages in chromatographic separation field,such as high thermal stability,porosity,structural regularity,and large specific surface area.Here,a novel spherical COF 1,3,5-tris(4-aminophenyl)benzene(TAPB)and 2,5-bis(2-propyn-1-yloxy)-1,4-benzenedicarboxaldehyde(BPTA)was developed as an electrochromatographic stationary phase for capillary electrochromatography separation.The COF TAPB-BPTA modified capillary column was fabricated via a facile in situ growth method at room temperature.The characterization results of scanning electron microscopy(SEM),Fourier transform infrared(FT-IR)spectroscopy,and X-ray diffraction(XRD)confirmed that COF TAPB-BPTA were successfully modified onto the capillary inner surface.The electrochromatography separation performance of the COF TAPB-BPTA modified capillary was investigated.The prepared column demonstrated outstanding separation performance toward alkylbenzenes,phenols,and chlorobenzenes compounds.Furthermore,the baseline separations of non-steroidal anti-inflammatory drugs(NSAIDs)and parabens with good efficiency and high resolution were achieved.Also,the prepared column possessed satisfactory precision of the intra-day runs(n=5),inter-day runs(n=3),and parallel columns(n=3),and the relative standard deviations(RSDs)of the retention times of tested alkylbenzenes were all less than 2.58%.Thus,this new COF-based stationary phase shows tremendous application potential in chromatographic separation field.

2D Nb_(2)CT_(x) MXene/MoS_(2) heterostructure construction for nonlinear optical absorption modulation

Two-dimensional(2D)nonlinear optical mediums with high and tunable light modulation capability can significantly stimulate the development of ultrathin,compact,and integrated optoelectronics devices and photonic elements.2D carbides and nitrides of transition metals(MXenes)are a new class of 2D materials with excellent intrinsic and strong light-matter interaction characteristics.However,the current understanding of their photo-physical properties and strategies for improving optical performance is insufficient.To address this issue,we rationally designed and in situ synthesized a 2D Nb_(2)C/MoS_(2) heterostructure that outperforms pristine Nb2C in both linear and nonlinear optical performance.Excellent agreement between experimental and theoretical results demonstrated that the Nb_(2)C/MoS_(2) inherited the preponderance of Nb_(2)C and MoS_(2) in absorption at different wavelengths,resulting in the broadband enhanced optical absorption characteristics.In addition to linear optical modulation,we also achieved stronger near infrared nonlinear optical modulation,with a nonlinear absorption coefficient of Nb_(2)C/MoS_(2) being more than two times that of the pristine Nb_(2)C.These results were supported by the band alinement model which was determined by the X-ray photoelectron spectroscopy(XPS)experiment and first-principal theory calculation.The presented facile synthesis approach and robust light modulation strategy pave the way for broadband optoelectronic devices and optical modulators.

Synthesis of AgCl/Ti_(3)C_(2)@TiO_(2)Ternary Composite Photocatalysts for Photocatalytic Oxidation of 1,4-Dihydropyridine and Tetracycline Hydrochloride

AgCl/Ti_(3)C_(2)@TiO_(2)ternary composites were prepared to form a heterojunction structure between AgCl and TiO_(2)and introduce Ti3C2 as a cocatalyst.The as-prepared AgCl/Ti_(3)C_(2)@TiO_(2)composites showed higher photocatalytic activity than pure AgCl and Ti_(3)C_(2)@TiO_(2)for photooxidation of a 1,4-dihydropyridine derivative(1,4-DHP)and tetracycline hydrochloride(TCH)under visible light irradiation(λ>400 nm).The photocatalytic activity of AgCl/Ti_(3)C_(2)@TiO_(2)composites depended on Ti_(3)C_(2)@TiO_(2)content,and the catalytic activity of the optimized samples were 6.9 times higher than that of pure AgCl for 1,4-DHP photodehydrogenation and 7.3 times higher than that of Ti_(3)C_(2)@TiO_(2)for TCH photooxidation.The increased photocatalytic activity was due to the formation of a heterojunction structure between AgCl and TiO_(2)and the introduction of Ti3C2 as a cocatalyst,which lowered the internal resistance,sped up the charge transfer,and increased the separation efficiency of photogenerated carries.Photogenerated holes and superoxide radical anions were the major active species in the photocatalytic process.

One-step growth of ultrathin CoSe_(2)nanobelts on N-doped MXene nanosheets for dendrite-inhibited and kinetic-accelerated lithium-sulfur chemistry

The practical application of lithium–sulfur(Li–S)batteries is inhibited by the shuttle effect of lithium polysulfides(LiPSs)and slow polysulfide redox kinetics on the S cathode as well as the uncontrollable growth of dendrites on the Li metal anode.Therefore,both cathode and anode sides must be considered when modifying LiS batteries.Herein,two-dimensional(2D)ultrathin CoSe_(2)nanobelts are in situ grown on 2D N-doped MXene nanosheets(CoSe_(2)@N-MXene)via one-step solvothermal process for the first time.Owing to its unique 2D/2D structure,CoSe_(2)@N-MXene can be processed to crumpled nanosheets by freeze-drying and flexible and freestanding films by vacuum filtration.These crumpled CoSe_(2)@NMXene nanosheets with abundant active sites and inner spaces can act as S hosts to accelerate polysulfide redox kinetics and suppress the shuttle effect of LiPSs owing to their strong adsorption ability and catalytic conversion effect with LiPSs.Meanwhile,the CoSe_(2)@N-MXene film(CoSe_(2)@NMF)can act as a current collector to promote uniform Li deposition because it contains lithiophilic CoSe_(2)and N sites.Under the systematic effect of CoSe_(2)@N-MXene on S cathode and Li metal anode,the electrochemical and safety performance of Li–S batteries are improved.CoSe_(2)@NMF also shows excellent storage performances in flexible energy storage devices.

Controlled Assembly of Luminescent Lanthanide‑Organic Frameworks via Post‑Treatment of 3D‑Printed Objects

Complex multiscale assemblies of metal-organic frameworks are essential in the construction of largescale optical platforms but often restricted by their bulk nature and conventional techniques.The integration of nanomaterials and 3D printing technologies allows the fabrication of multiscale functional architectures.Our study reports a unique method of controlled 3D assembly purely relying on the post-printing treatment of printed constructs.By immersing a 3D-printed patterned construct consisting of organic ligand in a solution of lanthanide ions,in situ growth of lanthanide metal-organic frameworks(LnMOFs)can rapidly occur,resulting in macroscopic assemblies and tunable fluorescence properties.This phenomenon,caused by coordination and chelation of lanthanide ions,also renders a sub-millimeter resolution and high shape fidelity.As a proof of concept,a type of 3D assembled LnMOFsbased optical sensing platform has demonstrated the feasibility in response to small molecules such as acetone.It is anticipated that the facile printing and design approach developed in this work can be applied to fabricate bespoke multiscale architectures of functional materials with controlled assembly,bringing a realistic and economic prospect.

Engineering Leaf-Like UiO-66-SO3H Membranes for Selective Transport of Cations

Metal–organic frameworks(MOFs)with angstrom-sized pores are promising functional nanomaterials for the fabrication of cation permselective membranes(MOF-CPMs).However,only a few research reports show successful preparation of the MOF-CPMs with good cation separation performance due to several inherent problems in MOFs,such as arduous selfassembly,poor water resistance,and tedious fabrication strategies.Besides,low cation permeation flux due to the absence of the cation permeation assisting functionalities in MOFs is another big issue,which limits their widespread use in membrane technology.Therefore,it is necessary to fabricate functional MOF-CPMs using simplistic strategies to improve cation permeation.In this context,we report a facile in situ smart growth strategy to successfully produce ultrathin(<600 nm)and leaflike UiO-66-SO3H membranes at the surface of anodic alumina oxide.The physicochemical characterizations confirm that sulfonated angstrom-sized ion transport channels exist in the as-prepared UiO-66-SO3H membranes,which accelerate the cation permeation(~3×faster than non-functionalized UiO-66 membrane)and achieve a high ion selectivity(Na^+/Mg^2+>140).The outstanding cation separation performance validates the importance of introducing sulfonic acid groups in MOF-CPMs.

In-situ Growth of Carbon Nanosheets Intercalated with TiO_(2) for Improving Electrochemical Performance and Stability of Lithium-ion Batteries

In situ growth of carbon nanomaterials on active substance is a very favorable strategy for the preparation of electrode in lithium-ion batteries with excellent electrochemical performance and high stability.Small-sized TiO_(2) nanoparticles intercalated into carbon nanosheets(CNS@TiO_(2)SNP-600)were successfully synthesized via in-situ polymerization-carbonization method,utilizing layered H_(2)Ti_(4)O_(9)(HTO)as template and benzidine as carbon source.The morphology and size of TiO_(2) are greatly influenced by carbonization temperature.The coin cell with the CNS@TiO_(2)SNP-600 electrode demonstrates a discharge specific capacity of 430.4 mAh·g^(-1) at a current density of 0.1 A·g^(-1),and the capacity retention rate is 88.1%after 100 cycles;and it also displays a high discharge specific capacity of 101.8 mAh·g^(-1) at a high current density of 12.8 A·g^(-1).The excellent electrochemical performances can be ascribed to the capacitance effect originated from the intercalated structure of in-situ grown CNS and TiO_(2) nanoparticles.We believe this type of materials can be widely used in the lithium-ion batteries and other related green chemical fields.

Facile growth of homogeneous Ni（OH）2 coating on carbon nanosheets for high-performance asymmetric supercapacitor applications

The growth of a Ni（OH）2 coating on conductive carbon substrates is an efficient way to address issues related to their poor conductivity in electrochemical capacitor applications. However, the direct growth of nickel hydroxide coatings on a carbon substrate is challenging, because the surfaces of these systems are not compatible and a preoxidation treatment of the conductive carbon substrate is usually required. Herein, we present a facile preoxidation-free approach to fabricate a uniform Ni（OH）2 coating on carbon nanosheets （CNs） by an ion-exchange reaction to achieve the in situ transformation of a MgO/C composite to a Ni（OH）2/C one. The obtained Ni（OH）2/CNs hybrids possess nanosheet morphology, a large surface area （278 m2/g）, and homogeneous elemental distributions. When employed as supercapacitors in a three-electrode configuration, the Ni（OH）JCNs hybrid achieves a large capacitance of 2,218 F/g at a current density of 1.0 A/g. Moreover, asymmetric supercapacitors fabricated with the Ni（OH）2/CNs hybrid exhibit superior supercapacitive performances, with a large capacity of 198 F/g, and high energy density of 56.7 Wh/kg at a power density of 4.0 kW/kg. They show excellent cycling stability with 93% capacity retention after 10,000 cycles, making the Ni（OH）2/CNs hybrid a promising candidate for practical applications in supercapacitor devices.

A generalized one-step in situ formation of metal sulfide/reduced graphene oxide nanosheets toward high-performance supercapacitors

Metal sulfides are promising candidates for supercapacitors,but their slow reaction kinetics hinders their electrochemical performance.Large electrochemical surface area and combination with conductive carbon are potential methods to improve their capacitive performance.However,seeking for a generalized and simple approach to prepare two-dimensional composites of metal sulfide and conductive carbon for supercapacitors is challengeable.Herein,a generalized and facile one-step pyrolysis method was designed for in situ growth of cobalt nickel sulfides(CoNi2S4)on reduced graphene oxide(rGO)nanosheets(CoNi2S4/rGO)under mild conditions.The as-prepared CoNi2S4/rGO materials possess the nanoparticles-on-nanosheets structure,which is effective to provide a myriad of active sites and optimized electron/ion diffusion pathway.Benefiting from those advantages,the resultant CoNi2S4/rGO electrodes exhibit impressed specific capacitances of 1526 and 988 F g^−1 at 2 and 20 A g^−1,respectively.The supercapacitors based on CoNi2S4/rGO showcase an operation potential window of 1.6 V,and energy density of 54.8 W h kg^−1 at the power density of 798 W kg^−1.The capacitance retention of the supercapacitor is about 93.7%after 8000 cycles at 3 A g^−1.Moreover,a series of metal sulfide/rGO hybrids are obtained by this generalized strategy,which could be extended to construct electrode materials for various energy devices.