Advanced yolk-shell nanoparticles as nanoreactors for energy conversion

Yolk‐shell structured nanoparticles are of immense scientific and technological interests because of their unique architecture and myriad of applications.This review summarizes recent progresses in the use of yolk‐shell structured nanoparticles as nanoreactors for various chemical reactions.A very brief overview of synthetic strategies is provided with emphasis on recent research progress in the last five years.Catalytic applications of these yolk‐shell structured nanoreactors are then discussed by covering photocatalysis,methane reforming and electrochemical conversion.The state of the art research and perspective in future development are also highlighted.

Enhanced Catalytic Activity of Gold@Polydopamine Nanoreactors with Multi-compartment Structure Under NIR Irradiation

Photothermal conversion(PTC)nanostructures have great potential for applications in many fields,and therefore,they have attracted tremendous attention.However,the construction of a PTC nanoreactor with multi-compartment structure to achieve the combination of unique chemical properties and structural feature is still challenging due to the synthetic difficulties.Herein,we designed and synthesized a catalytically active,PTC gold(Au)@polydopamine(PDA)nanoreactor driven by infrared irradiation using assembled PS-b-P2VP nanosphere as soft template.The particles exhibit multi-compartment structure which is revealed by 3D electron tomography characterization technique.They feature permeable shells with tunable shell thickness.Full kinetics for the reduction reaction of 4-nitrophenol has been investigated using these particles as nanoreactors and compared with other reported systems.Notably,a remarkable acceleration of the catalytic reaction upon near-infrared irradiation is demonstrated,which reveals for the first time the importance of the synergistic effect of photothermal conversion and complex inner structure to the kinetics of the catalytic reduction.The ease of synthesis and fresh insights into catalysis will promote a new platform for novel nanoreactor studies.

Construction of a Cu@hollow TS-1 nanoreactor based on a hierarchical full-spectrum solar light utilization strategy for photothermal synergistic artificial photosynthesis

The artificial photosynthesis technology has been recognized as a promising solution for CO_(2) utilization.Photothermal catalysis has been proposed as a novel strategy to promote the efficiency of artificial photosynthesis by coupling both photochemistry and thermochemistry.However,strategies for maximizing the use of solar spectra with different frequencies in photothermal catalysis are urgently needed.Here,a hierarchical full-spectrum solar light utilization strategy is proposed.Based on this strategy,a Cu@hollow titanium silicalite-1 zeolite(TS-1)nanoreactor with spatially separated photo/thermal catalytic sites is designed to realize high-efficiency photothermal catalytic artificial photosynthesis.The space-time yield of alcohol products over the optimal catalyst reached 64.4μmol g−1 h−1,with the selectivity of CH3CH2OH of 69.5%.This rationally designed hierarchical utilization strategy for solar light can be summarized as follows:(1)high-energy ultraviolet light is utilized to drive the initial and difficult CO_(2) activation step on the TS-1 shell;(2)visible light can induce the localized surface plasmon resonance effect on plasmonic Cu to generate hot electrons for H2O dissociation and subsequent reaction steps;and(3)low-energy near-infrared light is converted into heat by the simulated greenhouse effect by cavities to accelerate the carrier dynamics.This work provides some scientific and experimental bases for research on novel,highly efficient photothermal catalysts for artificial photosynthesis.

Tailoring polysulfide trapping and kinetics by engineering hollow carbon bubble nanoreactors for high-energy Li-S pouch cells

Despite great progress of lithium-sulfur(Li-S)battery performance at the laboratory-level,both key parameters and challenges at cell scales to achieve practical high energy density require high-sulfur-loading cathodes and lean electrolytes.Herein,a novel carbon foam integrated by hollow carbon bubble nanoreactors with ultrahigh pore volume of 6.9 cm3·g−1 is meticulously designed for ultrahigh sulfur content up to 96 wt.%.Tailoring polysulfide trapping and ion/electron transport kinetics during the charge-discharge process can be achieved by adjusting the wall thickness of hollow carbon bubbles.And a further in-depth understanding of electrochemical reaction mechanism for the cathode is impelled by the in-situ Raman spectroscopy.As a result,the as-prepared cathode delivers high specific capacitances of 1,269 and 695 mAh·g−1 at 0.1 and 5 C,respectively.Furthermore,Li-S pouch cells with high areal sulfur loading of 6.9 mg·cm−2 yield exceptional practical energy density of 382 Wh·kg−1 under lean electrolyte of 3.5µL·mg−1,which demonstrates the great potential for realistic high-energy Li-S batteries.

CoP@SiO2nanoreactors: A core-shell structure for efficient electrocatalytic oxygen evolution reaction

Metallic phosphides as a crucial class of metal-like compounds show high electric conductivity and electrochemical properties.It is of significant benefit to understanding the relationship between the electrocatalytic performance and phosphating degree of precursors.In this work,using Co3O4@SiO2 as precursor,core-shell structured CoP@SiO2 nanoreactors with outstanding oxygen evolution reaction performance were synthesized through a facile calcination method.The electrocatalytic performance of CoP@SiO2 modified electrode that treated with 500 mg NaH2PO2 was greatly enhanced.The obtained product displays a low overpotential of 280 mV at a current density of 10 mA/cm2 and a Tafel value 89 mV/dec in alkaline conditions.The easy available CoP@SiO2 with outstanding catalytic performance and stability possesses huge potential in future electrochemical applications.

Integrating theory with the nanoreactor concept to synthesize hollow carbon sphere-encapsulated PtNi alloys for enhanced H_(2) generation

The rational design of efficient bimetallic nanoparticle(NP)catalysts is challenging due to the lack of theoretical understanding of active components and insights into the mechanisms of a specific reaction.Here,we report the rational design of nanoreactors comprising hollow carbon sphere-confined PtNi bimetallic NPs(PtNi@HCS)as highly efficient catalysts for hydrogen generation via ammonia borane hydrolysis in water.Using both density functional theory calculations and molecular dynamics simulations,the effects of an active PtNi combination and the critical synergistic role of a hollow carbon shell on the molecule diffusion adsorption behaviors are explored.Kinetic isotope effects and theoretical calculations allow the clarification of the mechanism,with oxidative addition of an O-H bond of water to the catalyst surface being the rate-determining step.The remarkable catalytic activity of the PtNi@HCS nanoreactor was also utilized for successful tandem catalytic hydrogenation reactions,using in situ-generated H_(2) from ammonia borane with high efficiency.The concerted design,theoretical calculations,and experimental work presented here shed light on the rational elaboration of efficient nanocatalysts and contribute to the establishment of a circular carbon economy using green hydrogen.

NIR-triggered on-site NO/ROS/RNS nanoreactor:Cascade-amplified photodynamic/photothermal therapy with local and systemic immune responses activation

Photothermal and photodynamic therapies(PTT/PDT)hold promise for localized tumor treatment,yet their full potential is hampered by limitations such as the hypoxic tumor microenvironment and inadequate systemic immune activation.Addressing these challenges,we present a novel near-infrared(NIR)-triggered RNS nanoreactor(PBNO-Ce6)to amplify the photodynamic and photothermal therapy efficacy against triple-negative breast cancer(TNBC).The designed PBNOCe6 combines sodium nitroprusside-doped Prussian Blue nanoparticles with Chlorin e6 to enable on-site RNS production through NIR-induced concurrent NO release and ROS generation.This not only enhances tumor cell eradication but also potentiates local and systemic antitumor immune responses,protecting mice from tumor rechallenge.Our in vivo evaluations revealed that treatment with PBNO-Ce6 leads to a remarkable 2.7-fold increase in cytotoxic T lymphocytes and a 62%decrease in regulatory T cells in comparison to the control PB-Ce6(Prussian Blue nanoparticles loaded with Chlorin e6),marking a substantial improvement over traditional PTT/PDT.As such,the PBNO-Ce6 nanoreactor represents a transformative approach for improving outcomes in TNBC and potentially other malignancies affected by similar barriers.

Accelerating H^(*)desorption of hollow Mo_(2)C nanoreactor via in-situ grown carbon dots for electrocatalytic hydrogen evolution

Molybdenum carbide(Mo_(2)C)is a promising non-noble metal electrocatalyst with electronic structures similar to Pt for hydrogen evolution reaction(HER).However,strong H^(*)adsorption at the Mo sites hinders the improvement of HER performance.Here,we synthesized monodisperse hollow Mo_(2)C nanoreactors,in which the carbon dots(CD)were in situ formed onto the surface of Mo_(2)C through carburization reactions.According to finite element simulation and analysis,the CD@Mo_(2)C possesses better mesoscale diffusion properties than Mo_(2)C alone.The optimized CD@Mo_(2)C nanoreactor demonstrates superior HER performance in alkaline electrolyte with a low overpotential of 57 mV at 10 mA cm^(−2),which is better than most Mo_(2)C-based electrocatalysts.Moreover,CD@Mo_(2)C exhibits excellent electrochemical stability during 240 h,confirmed by operando Raman and X-ray diffraction(XRD).Density functional theory(DFT)calculations show that carbon dots cause the d-band center of CD@Mo_(2)C to shift away from Fermi level,promoting water dissociation and the desorption of H^(*).This study provides a reasonable strategy towards high-activity Mo-based HER eletrocatalysts by modulating the strength of Mo–H bonds.

Nanoreactors derived from silica-protection-assisted metal-organic framework

The construction of highly stable and regular nanoreactors is a major challenge.In this work,we use a facile template protection method to obtain ZIF-67@SiO2(JS) and to encapsulate metal oxide nanoparticles(Co3O4) into nanoreactors(SiO2).ZIF-67 crystals provide a cobalt species;SiO2 was first used as a protective layer of ZIF-67 and then as a nanoreactor for metastable metal oxide nanoparticles.On this basis,Co3O4@SiO2 with dodecahedron morphology were synthesized by calcining JS at different tempe ratures,followed by a hydrothermal reaction to obtain Co3(OH)4Si2O5.Subsequently,CoSx and CoP-SiO2 were fabricated through sulfuration and phosphorization.The results in this work show that nanoreactors derived from metal-organic frameworks(MOFs) with a rational structure have broad development prospects.

Catalysis under shell： Improved CO oxidation reaction confined in Pt@h-BN core-shell nanoreactors

Core-shell nanostructures consisting of active metal cores and protective shells often exhibit enhanced catalytic performance, in which reactants can access a small part of the core surfaces through the pores in the shells. In this study, we show that Pt nanoparticles （NPs） can be embedded into few-layer hexagonal boron nitride （h-BN） overlayers, forming Pt@h-BN core-shell nanocatalysts. The h-BN shells not only protect the Pt NPs under harsh conditions but also allow gaseous molecules such as CO and 02 to access a large part of the Pt surfaces through a facile intercalation process. As a result, the Pt@h-BN nanostructures act as nanoreactors, and CO oxidation reactions with improved activity, selectivity, and stability occur at the core-shell interfaces. The confinement effect exerted by the h-BN shells promotes the Pt-catalyzed reactions. Our work suggests that two-dimensional shells can function as robust but flexible covers on nanocatalyst surfaces and tune the surface reactivity.

Core-Sheath CeO_(2)/SiO_(2) Nanofibers as Nanoreactors for Stabilizing Sinter‑Resistant Pt,Enhanced Catalytic Oxidation and Water Remediation

One-dimensional(1D)oxide nanofibers have attracted much attention in recent years but are still hampered by the difficulty in the expansion to 2D or 3D dimensions.Herein,ultrathin CeO_(2)/SiO_(2)nanofibers with intriguing core-sheath structures were simply fabricated by a facile single-spinneret electrospinning method and were subsequently integrated as 2D nanofi-brous mats and 3D sponges.Introducing secondary oxide(i.e.,SiO_(2))could induce a unique fine structure and further inhibit the sintering of CeO_(2)nanocrystals,endowing the resultant dual-oxide nanofibers with high porosity,good flexibility,and enriched oxygen defects.Benefiting from the core-sheath structure and dual-oxide component,the CeO_(2)/SiO_(2)nanofibers could stabilize 2.59 nm-Pt clusters against sintering at 600℃.Once assembled into a 2D mat,the nanofibers could efficiently decrease the soot oxidation temperature by 63℃.Moreover,the core-sheath CeO_(2)/SiO_(2)nanofibers can be readily integrated with graphene nanosheets into a 3D sponge via a gas foaming protocol,showing 218.5 mg/g of adsorption capacity toward Rhodamine B molecules.This work shed lights on the versatile applications of oxide nanofibers toward clean energy ultili-zation and low-carbon development.

Controlled synthesis of Pt-loaded yolk-shell TiO_(2)@SiO_(2) nanoreactors as effective photocatalysts for hydrogen generation

Yolk-shell and hollow structures are powerful platforms for controlled release,confined nanocatalysis,and optical and electronic applications.This contribution describes a fabrication strategy for a yolk-shell nanoreactor(NR)using a post decoration approach.The widely studied yolk-shell structure of silica-coated TiO_(2)(TiO_(2)@SiO_(2))was used as a model.At first,anatase TiO_(2) spheres were prepared,and subsequently were given a continuous coating of carbonaceous and silica layers.Finally,the carbonaceous layer was removed to produce a yolk-shell structure TiO_(2)@SiO_(2).By using an in-situ photodeposition method,Pt-encased spheres(Pt-TiO_(2)@SiO_(2))were synthesized with Pt nanoparticles grown on the surface of the TiO_(2) core,which contained void spaces suitable for use as NRs.The NR showed enhanced hydrogen production with a rate of 24.56 mmol·g^(-1)·h^(-1) in the presence of a sacrificial agent under simulated sunlight.This strategy holds the potential to be extended for the synthesis of other yolk-shell photocatalytic NRs with different metal oxides.

Boosting ferroptosis and microtubule inhibition for antitumor therapy via a carrier-free supermolecule nanoreactor

Traditional microtubule inhibitors fail to significantly enhance+e effect of colorectal cancer;hence,new and efficient strategies are necessary.In+is study,a supramolecular nanoreactor(DOC@TA-Fe^(3+))based on tannic acid(TA),iron ion(Fe^(3+)),and docetaxel(DOC)wi+microtubule inhibition,reactive oxygen species(ROS)generation,and gluta+ione peroxidase 4(GPX4)inhibition,is prepared for ferroptosis/apoptosis treatment.After internalization by CT26 cells,+e DOC@TA-Fe^(3+)nanoreactor escapes from+e lysosomes to release payloads.+e subsequent Fe^(3+)/Fe^(2+)conversion mediated by TA reducibility can trigger+e Fenton reaction to enhance+e ROS concentration.Additionally,Fe^(3+)can consume gluta+ione to repress+e activity of GPX4 to induce ferroptosis.Meanwhile,+e released DOC controls microtubule dynamics to activate+e apoptosis pa+way.+e superior in vivo antitumor efficacy of DOC@TA-Fe^(3+)nanoreactor in terms of tumor grow+inhibition and improved survival is verified in CT26 tumor-bearing mouse model.+erefore,+e nanoreactor can act as an effective apoptosis and ferroptosis inducer for application in colorectal cancer+erapy.

Inorganic Nanozyme with Combined Self-Oxygenation/Degradable Capabilities for Sensitized Cancer Immunochemotherapy

Recently emerged cancer immunochemotherapy has provided enormous new possibilities to replace traditional chemotherapy in fighting tumor.However,the treatment efficacy is hampered by tumor hypoxiainduced immunosuppression in tumor microenvironment(TME).Herein,we fabricated a self-oxygenation/degradable inorganic nanozyme with a core-shell structure to relieve tumor hypoxia in cancer immunochemotherapy.By integrating the biocompatible CaO2 as the oxygen-storing component,this strategy is more effective than the earlier designed nanocarriers for delivering oxygen or H2O2,and thus provides remarkable oxygenation and long-term capability in relieving hypoxia throughout the tumor tissue.Consequently,in vivo tests validate that the delivery system can successfully relieve hypoxia and reverse the immunosuppressive TME to favor antitumor immune responses,leading to enhanced chemoimmunotherapy with cytotoxic T lymphocyte-associated antigen 4 blockade.Overall,a facile,robust and effective strategy is proposed to improve tumor oxygenation by using self-decomposable and biocompatible inorganic nanozyme reactor,which will not only provide an innovative pathway to relieve intratumoral hypoxia,but also present potential applications in other oxygen-favored cancer therapies or oxygen deficiency-originated diseases.

A MXene-Based Bionic Cascaded-Enzyme Nanoreactor for Tumor Phototherapy/Enzyme Dynamic Therapy and Hypoxia-Activated Chemotherapy

The enzyme-mediated elevation of reactive oxygen species(ROS)at the tumor sites has become an emerging strategy for regulating intracellular redox status for anticancer treatment.Herein,we proposed a camouflaged bionic cascaded-enzyme nanoreactor based on Ti_(3)C_(2)nanosheets for combined tumor enzyme dynamic therapy(EDT),phototherapy and deoxygenation-activated chemotherapy.Briefly,glucose oxidase(GOX)and chloroperoxidase(CPO)were chemically conjugated onto Ti_(3)C_(2)nanosheets,where the deoxygenation-activated drug tirapazamine(TPZ)was also loaded,and the Ti_(3)C_(2)-GOX-CPO/TPZ(TGCT)was embedded into nanosized cancer cell-derived membrane vesicles with high-expressed CD47(m_eTGCT).Due to biomimetic membrane camouflage and CD47 overexpression,m_eTGCT exhibited superior immune escape and homologous targeting capacities,which could effectively enhance the tumor preferential targeting and internalization.Once internalized into tumor cells,the cascade reaction of GOX and CPO could generate HClO for efficient EDT.Simultaneously,additional laser irradiation could accelerate the enzymic-catalytic reaction rate and increase the generation of singlet oxygen(~1O_(2)).Furthermore,local hypoxia environment with the oxygen depletion by EDT would activate deoxygenation-sensitive prodrug for additional chemotherapy.Consequently,m_eTGCT exhibits amplified synergistic therapeutic effects of tumor phototherapy,EDT and chemotherapy for efficient tumor inhibition.This intelligent cascaded-enzyme nanoreactor provides a promising approach to achieve concurrent and significant antitumor therapy.

Flexible Aluminum Nanobowls for Alternative Preparation of Individual or a Small Number of Nanoparticles

The nanoscale aluminum bowls were derived from the porous alumina and were used as the flexible nanoscale reactors for the preparation of nanoparticles. Both single source precursor and preprepared nanoparticles were induced in the nanobowls by melting the precursor/polymer films spin-coated on aluminum nanobowls for the formation of nanostructural composites in the nanobowls. We have prepared a single nanoparticle or just a small number of metal（e.g. Pt） nanoparticles or semiconductor nanoparticles（e.g. CdSe or CdSe/ZnS core-shell nanostructures） in the nanobowls.

A confined growth strategy to construct 3DOM SiO_(2) nanoreactor insitu embedded Co_(3)O_(4) nanoparticles catalyst for the catalytic combustion of VOCs:Superior H_(2)O and SO_(2) resistance

SO_(2)poisoning is a common problem in the catalytic combustion of volatile organic compounds(VOCs).In this work,we took three-dimensionally ordered macroporous and mesoporous(3DOM)SiO_(2)as the nanoreactor to protect active sites from SO_(2)erosion in the catalytic combustion of benzene.Simultaneously,the confined growth of metal active nanoparticles in the multi-stage pore is also full of challenges.And we successfully confined Co_(3)O_(4)nanoparticles(NPs)in macroporous and mesoporous channels.Interestingly,the precursors’growth in the pore was controlled and nanoreactors with different pore sizes were prepared by adjusting the loading amount and preparation methods.It is discovered that the Co_(3)O_(4)NPs confined in 3DOM SiO_(2)nanoreactor showed superior sulfur and water resistance.Density functional theory(DFT)calculations verified that the Co-Si catalyst had high SO_(2)adsorption energy(-0.48 eV),which illustrated that SO_(2)was hard to attach to the surface of the Co-Si catalyst.The SiO_(2)nanoreactor had low SO_(2)adsorption energy(-5.15 eV),which indicated that SO_(2)was easily absorbed on SiO_(2)nanoreactor.This illustrated that the SiO_(2)nanoreactor could protect effectively active sites from SO_(2)erosion.

Spherical Polyelectrolyte Brush Nanoreactor:Preparation of Hollow TiO_(2) Nanospheres and Characterization by Small Angle X-Ray Scattering

Titanium dioxide(TiO_(2))hollow nanoparticles present significant potential for photocatalytic applications while their straightforward preparation with precise structure control is still challenging.This work reports the approach to preparing tunable hollow TiO_(2) nanospheres by utilization of spherical polyelectrolyte brushes(SPB)as nanoreactors and templates.During the preparation,the evolution of the structure was characterized by small angle X-ray scattering(SAXS),and in combination with dynamic light scattering and transmission electron microscopy.The formation of TiO_(2) shell within the brush(SPB@TiO_(2))is confirmed by the significant increase of the electron density,and its internal structure has been analyzed by fitting SAXS data,which can be influenced by Titanium precursors and ammonia concentration.After calcining SPB@TiO_(2) in a muffle furnace,hollow TiO_(2) nanospheres are produced,and their transition to the anatase crystal form is triggered,as confirmed by X-ray diffraction analysis.Utilizing the advantages of their hollow structure,these TiO_(2) nanospheres exhibit exceptional catalytic degradation efficiency of methylene blue(MB),tetracycline(TC),and 2,4-dichlorophenoxyacetic acid(2,4-D),and also demonstrate excellent recyclability.

Polyoxometalates coupled covalent organic frameworks as highly active photothermal nanoreactor for CO_(2)cycloaddition

Covalent organic frameworks(COFs)-based nanoreactors have attracted broad interest in many fields due to their voidconfinement effects.However,the inherent drawback of conventional nanoreactors is the lack of internal active sites,which limits their widespread utilization.Herein,we report the construction of hierarchical COF(EB-TFP)nanoreactor with pre-synthesized polyoxometalates(POM,[PV_(2)W_(10)O_(40)]^(5–)(PV_(2)W_(10)))clusters encapsulated inside of COF(POM@COF).PV_(2)W_(10)@EB-TFP anchors nucleophilic-group(Br–ions)and PV_(2)W_(10)anion cluster within the COF framework via electrostatic interactions,which not only simplifies the reaction system but also enhances catalytic efficiency.The reaction performance of the PV_(2)W_(10)@EB-TFP nanoreactor can be tuned to achieve excellent catalytic activity in CO_(2)cycloaddition reaction(CCR)for~97.63%conversion and~100%selectivity under visible light irradiation.A mechanistic study based on density functional theory(DFT)calculations and insitu characterization was also carried out.In summary,we have reported a method for achieving the uniform dispersion of POM single clusters into COF nanoreactor,demonstrating the potential of POM@COF nanoreactor for synergistic photothermal catalytic CO_(2)cycloaddition.