Ordered mesoporous nanofibers mimicking vascular bundles for lithium metal batteries.

Hierarchical self-assembly with long-range order above centimeters widely exists in nature. Mimicking similar structures to promote reaction kinetics of electrochemical energy devices is of immense interest, yet remains challenging. Here, we report a bottom-up self-assembly approach to constructing ordered mesoporous nanofibers with a structure resembling vascular bundles via electrospinning. The synthesis involves self-assembling polystyrene (PS) homopolymer, amphiphilic diblock copolymer, and precursors into supramolecular micelles. Elongational dynamics of viscoelastic micelle solution together with fast solvent evaporation during electrospinning cause simultaneous close packing and uniaxial stretching of micelles, consequently producing polymer nanofibers consisting of oriented micelles. The method is versatile for the fabrication of large-scale ordered mesoporous nanofibers with adjustable pore diameter and various compositions such as carbon, SiO2, TiO2 and WO3. The aligned longitudinal mesopores connected side-by-side by tiny pores offer highly exposed active sites and expedite electron/ion transport. The assembled electrodes deliver outstanding performance for lithium metal batteries.

Advancing Federated Learning through Verifiable Computations and Homomorphic Encryption.

Federated learning, as one of the three main technical routes for privacy computing, has been widely studied and applied in both academia and industry. However, malicious nodes may tamper with the algorithm execution process or submit false learning results, which directly affects the performance of federated learning. In addition, learning nodes can easily obtain the global model. In practical applications, we would like to obtain the federated learning results only by the demand side. Unfortunately, no discussion on protecting the privacy of the global model is found in the existing research. As emerging cryptographic tools, the zero-knowledge virtual machine (ZKVM) and homomorphic encryption provide new ideas for the design of federated learning frameworks. We have introduced ZKVM for the first time, creating learning nodes as local computing provers. This provides execution integrity proofs for multi-class machine learning algorithms. Meanwhile, we discuss how to generate verifiable proofs for large-scale machine learning tasks under resource constraints. In addition, we implement the fully homomorphic encryption (FHE) scheme in ZKVM. We encrypt the model weights so that the federated learning nodes always collaborate in the ciphertext space. The real results can be obtained only after the demand side decrypts them using the private key. The innovativeness of this paper is demonstrated in the following aspects: 1. We introduce the ZKVM for the first time, which achieves zero-knowledge proofs (ZKP) for machine learning tasks with multiple classes and arbitrary scales. 2. We encrypt the global model, which protects the model privacy during local computation and transmission. 3. We propose and implement a new federated learning framework. We measure the verification costs under different federated learning rounds on the IRIS dataset. Despite the impact of homomorphic encryption on computational accuracy, the framework proposed in this paper achieves a satisfactory 90% model accuracy. Our framework is highly secure and is expected to further improve the overall efficiency as cryptographic tools continue to evolve.

Potential Linkage between Heavy Metal Pollution Risk Assessment and Dissolved Organic Matter Spectra in the WWTPs-River Integrated Area-Case Study from Ashi River.

Direct sewage discharge can cause severe damage to the water environment of the river. However, the impacts of dissolved organic matter (DOM) in the discharge on the original pattern of DOM and the distribution of heavy metals (HMs) in the river are little known. How to monitor such areas in a long-term and systematic manner also needs to be urgently addressed. In this paper, we characterized the DOM of the sediments in the WWTPs (wastewater treatment plants)-river integrated zone by ultraviolet-visible absorption spectroscopy (UV-vis), three-dimensional excitation-emission matrix (3D-EEM) combined with parallel factor (PARAFAC) method. The effects of WWTP on receiving waters were investigated, and the potential link between DOM and HM pollution was explored. Hg (Igeo: 3.94 ± 0.65; EF: 44.83 ± 31.11), Cd (Igeo: 1.81 ± 0.69; EF: 8.02 ± 2.97), Cu (Igeo: 1.61 ± 0.83; EF: 6.85 ± 2.37), Zn (Igeo: 1.55 ± 0.54; EF: 7.24 ± 3.58), and Ni (Igeo: 1.46 ± 0.56; EF: 6.12 ± 1.99) in rivers were the primary risk sources of HM. The combined pollution risk indicates that the WWTPs-river integrated area is in a high pollution risk state. Moreover, α(254) has a significant correlation with pollution indicators and can be used as a proxy indicator. These results help to understand better the impact of WWTPs on receiving water bodies and the potential connection between DOM and HM pollution and provide new ideas for monitoring the water environment in highly polluted areas.

Study on characteristics of soil and nutrient losses in Sunjiagou small watershed in cold black soil area.

Investigating the impact of different factors on soil and nutrient loss and suggesting viable control measures is currently a significant concern. This study aims to examine the variations in soil erosion, as well as nitrogen and phosphorus loss, in the core area of the typical hilly diffuse Blackland erosion control. To achieve this, runoff plots with slopes of 3° and 5° were set up in the Sunjiagou sub-basin, located in the upper reaches of the Feiketu River. These plots were subjected to various soil and water conservation measures, along with different levels of vegetation cover. This study aims to analyze the soil and nutrient loss patterns and characteristics in each runoff plot during the natural rainfall events occurring between 2020 and 2022. The results show that soil and nutrient losses are highly significantly and positively correlated with rainfall intensity. The RUSLE model demonstrates a better fit for both cross ridge tillage and bare ground. The loss of nitrogen was much more significant than that of phosphorus, and nitrate nitrogen is the main form of nitrogen loss. Nitrogen loss is mainly dominated by nitrate nitrogen (NN), which is easily soluble in water and constantly migrates with runoff due to the negatively charged NN (NN accounted for 45.2% ~ 81.8% of total nitrogen (TN)). In contrast, the positively charged ammonia nitrogen (AN) is more stable in combination with the soil; large losses only occur under severe sediment erosion. Phosphorus is easily attached to sediment, and the high sediment production leads to a more serious loss of total phosphorus (PP) in the particulate state (PP accounts for 72.7% ~ 96.2% of total phosphorus (TP)). Changing longitudinal ridge tillage to cross ridge tillage and planting vegetation with better water retention and sediment fixation as plant hedges can effectively prevent the loss of soil, runoff, nitrogen, and phosphorus.

Modulating Electronic Structures of Iron Clusters through Orbital Rehybridization by Adjacent Single Copper Sites for Efficient Oxygen Reduction.

The atom-cluster interaction has recently been exploited as an effective way to increase the performance of metal-nitrogen-carbon catalysts for oxygen reduction reaction (ORR). However, the rational design of such catalysts and understanding their structure-property correlations remain a great challenge. Herein, we demonstrate that the introduction of adjacent metal (M)-N4 single atoms (SAs) could significantly improve the ORR performance of a well-screened Fe atomic cluster (AC) catalyst by combining density functional theory (DFT) calculations and experimental analysis. The DFT studies suggest that the Cu-N4 SAs act as a modulator to assist the O2 adsorption and cleavage of O-O bond on the Fe AC active center, as well as optimize the release of OH* intermediates to accelerate the whole ORR kinetic. The depositing of Fe AC with Cu-N4 SAs on nitrogen doped mesoporous carbon nanosheet are then constructed through a universal interfacial monomicelles assembly strategy. Consistent with theoretical predictions, the resultant catalyst exhibits an outstanding ORR performance with a half-wave potential of 0.92 eV in alkali and 0.80 eV in acid, as well as a high power density of 214.8 mW cm-2 in zinc air battery. This work provides a novel strategy for precisely tuning the atomically dispersed poly-metallic centers for electrocatalysis.

Potential linkage between WWTPs-river-integrated area pollution risk assessment and dissolved organic matter spectral index.

The direct discharge of wastewater can cause severe damage to the water environment of the surface water. However, the influence of dissolved organic matter (DOM) present in wastewater on the allocation of DOM, nitrogen (N), and phosphorus (P) in rivers remains largely unexplored. Addressing the urgent need to monitor areas affected by direct wastewater discharge in a long-term and systematic manner is crucial. In this paper, the DOM of overlying water and sediment in the WWTPs-river-integrated area was characterized by ultraviolet-visible absorption spectroscopy (UV-vis), three-dimensional excitation-emission matrix combined with parallel factor (PARAFAC) method. The effects of WWTPs on receiving waters were investigated, and the potential link between DOM and N, P pollution was explored. The pollution risk was fitted and predicted using a spectral index. The results indicate that the improved water quality index (IWQI) is more suitable for the WWTPs-river integration zone. The DOM fraction in this region is dominated by humic-like matter, which is mainly influenced by WWTPs drainage as well as microbial activities. The DOM fractions in sediment and overlying water were extremely similar, but fluorescence intensity possessed more significant spatial differences. The increase in humic-like matter facilitates the production and preservation of P and also inhibits nitrification, thus affecting the N cycle. There is a significant correlation between DOM fraction, fluorescence index, and N, P. Fluorescence index (FI) fitting of overlying water DOM predicted IWQI and trophic level index, and a(254) fitting of sediment DOM predicted nitrogen and phosphorus pollution risk (FF) with good results. These results contribute to a better understanding of the impact of WWTPs on receiving waters and the potential link between DOM and N and P pollution and provide new ideas for monitoring the water environment in highly polluted areas.

Modulating the Electronic Structure of FeCo Nanoparticles in N-Doped Mesoporous Carbon for Efficient Oxygen Reduction Reaction.

The development of highly efficient and stable oxygen reduction electrocatalysts and revealing their underlying catalytic mechanism are crucial in expanding the applications of metal-air batteries. Herein, an excellent FeCo alloy nanoparticles (NPs)-decorated N-doped mesoporous carbon electrocatalyst (FeCo/NC) for oxygen reduction reaction, prepared through the pyrolysis of a dual metal containing metal-organic framework composite scaffold is reported. Benefiting from the highly exposed bimetal active sites and the carefully designed structure, the Fe0.25 Co0.75 /NC-800 catalyst exhibits a promising electrocatalytic activity and a superior durability, better than those of the state-of-the-art catalysts. Suggested by both the X-ray absorption fine structures and the density functional theoretical calculation, the outstanding catalytic performance is originated from the synergistic effects of the bimetallic loading in NC catalysts, where the electronic modulation of the Co active sites from the nearby Fe species leads to an optimized binding strength for reaction intermediates. This work demonstrates a class of highly active nonprecious metals electrocatalysts and provides valuable insights into investigating the structure-performance relationship of transition metal-based alloy catalysts.

Gradient Hierarchically Porous Structure for Rapid Capillary-Assisted Catalysis.

Synthesis of hierarchically porous structures with uniform spatial gradient and structure reinforcement effect still remains a great challenge. Herein, we report the synthesis of zeolite@mesoporous silica core-shell nanospheres (ZeoA@MesoS) with a gradient porous structure through a micellar dynamic assembly strategy. In this case, we find that the size of composite micelles can be dynamically changed with the increase of swelling agents, which in situ act as the building blocks for the modular assembly of gradient mesostructures. The ZeoA@MesoS nanospheres are highly dispersed in solvents with uniform micropores in the inner core and a gradient tubular mesopore shell. As a nanoreactor, such hierarchically gradient porous structures enable the capillary-directed fast mass transfer from the solutions to inner active sites. As a result, the ZeoA@MesoS catalysts deliver a fabulous catalytic yield of ∼75% on the esterification of long-chain carboxylic palmitic acids and high stability even toward water interference, which can be well trapped by the ZeoA core, pushing forward the chemical equilibrium. Moreover, a very remarkable catalytic conversion on the C-H arylation reaction of large N-methylindole is achieved (∼98%) by a Pd-immobilized ZeoA@MesoS catalyst. The water tolerance feature gives a notable enhancement of 26% in catalytic yield compared to the Pd-dendritic mesoporous silica without the zeolite core.

Constructing Structurally Ordered High-Entropy Alloy Nanoparticles on Nitrogen-Rich Mesoporous Carbon Nanosheets for High-Performance Oxygen Reduction.

Recent efforts have observed nanoscaled chemical short-range order in bulk high-entropy alloys (HEAs). Simultaneously inspired with the nanostructuring technology, HEA nanoparticles (NPs) with complete chemical order may be achieved. Herein, structurally ordered HEA (OHEA) NPs are constructed on a novel 2D nitrogen-rich mesoporous carbon sandwich framework (OHEA-mNC) by combining a ligand-assisted interfacial assembly with NH3 annealing. Characterization results show that the resultant materials possess an ultrathin 2D nanosheet structure with large mesopores (≈10 nm), where structurally ordered HEA NPs with an L12 phase are homogeneously dispersed. The atom-resolved chemical analyses explicitly determine the location of each atomic site. When being evaluated for the oxygen reduction reaction, the OHEA-mNC NPs afford a greatly enhanced catalytic performance, including a large half-wave potential (0.90 eV) and a high durability (0.01 V decay after 10 000 cycles) compared with the disordered HEA and commercial Pt/C catalysts. The excellent performance is attributed to the enhanced mass transfer rate, improved electron conductivity, and the presence of the stable chemically ordered HEA phase, as revealed by both the experimental results and theoretical calculation. This study suggests a highly feasible process to achieve structurally ordered HEA NPs with advanced mesoporous function in the electrochemical field.

A Universal Single-Atom Coating Strategy Based on Tannic Acid Chemistry for Multifunctional Heterogeneous Catalysis.

Here, we report a universal single-atom coating (SAC) strategy by taking advantage of the rich chemistry of tannic acid (TA). TA units not only self-assemble into a cross-linked porous polyphenolic framework, but also can grip on different substates via multiple binding modes. Benefiting from the diverse chelating ability of TA, a series of mono-, and bi-metallic SACs can be formed on substrates of different materials (e. g., carbon, SiO2 , TiO2 , MoS2 ), dimensions (0D-3D) and sizes (50 nm-5 cm). By contrast, uniform SAC cannot be achieved using common approaches such as pyrolysis of metal-dopamine complexes or metal-organic frameworks. As a proof-of-concept demonstration, two Co SACs immobilized on graphene and TiO2 were prepared. The former one shows six-fold higher mass activity than Pt/C toward oxygen reduction. The latter one displays outstanding photocatalytic activity owing to the high activity of the single atoms and the formation of the single-atom coating-TiO2 heterojunction.

A Robust Hierarchical MXene/Ni/Aluminosilicate Glass Composite for High-Performance Microwave Absorption.

The 2D titanium carbide MXene with both extraordinary electromagnetic attenuation and elastic properties has shown great potential as the building block for constructing mechanically robust microwave absorbing composites (MACs). However, the weak thermal stability has inhibited the successful incorporation of MXene into the inorganic MACs matrix so far. Herein, an ultralow temperature sintering strategy to fabricate a hierarchical aluminosilicate glass composite is demonstrated by using EMT zeolite as starting powder, which can not only endow the composites with high sinterability, but also facilitate the alignment of MXene in the glass matrix. Accordingly, the highly oriented MXene and mesoporous structure can effectively reduce the conduction loss in the out-of-plane direction while maintaining its large polarization loss. Meanwhile, the in situ formed Ni nanoparticles via ion exchange serve as a synergistic modulator to further improve the attenuation capability and impedance matching of composite, resulting in a low reflection loss of -59.5 dB in X band and general values below -20 dB with a low fitting thickness from 4 to 18 GHz. More attractively, such a delicate structure also gives the composite a remarkable fracture strength and contact-damage-resistance, which qualifies the mesoporous glass composite as a structural MACs with a superior comprehensive performance.

Self-organization of unimolecular micelles in beam stream for functional mesoporous metal oxide nanofibers.

The use of linear amphiphilic block copolymers as templates is an important method for the preparation of mesoporous materials. However, the obtained assemblies are usually sensitive to synthetic conditions, which impedes the preparation of such mesoporous materials in certain environments. Herein, we report a universal strategy applying an amphiphilic multi-arm triblock copolymer in the preparation of mesoporous metal oxide nanofibers (NFs) using one metal oxide (TiO2, ZrO2, WO3, CeO2), or two (TiO2/WO3, TiO2/ZrO2, TiO2/CeO2) and three (TiO2/WO3/CuO) metal oxides as composites. The template consists of modified ß-cyclodextrin as the center of the macromolecule which is attached sequentially to a block of polystyrene, poly(acrylic acid), and poly(ethylene oxide). Under electrospinning conditions, stable unimolecular micelles are formed and effectively co-assemble with metal ions to form fibrous nanostructures. As indicated by various characterization methods, the synthesized TiO2 and its derived composite NFs maintain a straight and continuous fibrous structure after calcination, and TiO2 NFs exhibit uniform mesopores of 10.8 nm in diameter and a large Brunauer-Emmett-Teller surface area of 143.3 m2 g-1. Benefiting from the characteristic structure, still present after modification, Pt-decorated mesoporous TiO2 NFs display excellent ability in the visible-light photocatalytic degradation of tetracycline, which is superior to the commercial P25 catalyst. This study reveals a promising strategy for the preparation of fibrous mesoporous metal oxides.

Incorporating Cobalt Nanoparticles in Nitrogen-Doped Mesoporous Carbon Spheres through Composite Micelle Assembly for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have exhibited tremendous potential among the various secondary batteries benefitting from their large energy density, low expense, and enhanced security. However, the commercial use for Li-S batteries is immensely limited by the insulation of S, noticeable volume expansion from S to Li2S2/Li2S, and the undesired shuttle effect of lithium polysulfides (LiPs). Herein, a composite sulfur host has been prepared by in situ incorporations of cobalt nanoparticles (NPs) into nitrogen-doped mesoporous carbon spheres (Co/N-PCSs) through the composite micelle assembly strategy. The resultant functional Co/N-PCSs not only possess uniform spherical morphology with large open mesopores, high surface area, and pore volume but also have small Co NPs homogeneously inlaid into the pore walls of carbon frameworks. Both the experimental and theoretical calculation results demonstrate that the formed cobalt NPs can efficiently accelerate the lithium-ion diffusion reaction and greatly entrap the soluble intermediate LiPs. Benefiting from the well-designed structure, the Co/N-PCSs@S cathode with a S loading of 73.82 wt % delivers superior electrochemical performance, including long cycling stability (60% for the residual capacity at 1 A g-1 within 300 cycles) and excellent rate performance (∼512 mAh g-1 at 6 A g-1). This design strategy of implanting metal NPs in mesoporous carbon can be inspiring in energy storage applications.

Mesoporous Materials-Based Electrochemical Biosensors from Enzymatic to Nonenzymatic.

Mesoporous materials have drawn more and more attention in the field of biosensors due to their high surface areas, large pore volumes, tunable pore sizes, as well as abundant frameworks. In this review, the progress on mesoporous materials-based biosensors from enzymatic to nonenzymatic are highlighted. First, recent advances on the application of mesoporous materials as supports to stabilize enzymes in enzymatic biosensing technology are summarized. Special emphasis is placed on the effect of pore size, pore structure, and surface functional groups of the support on the immobilization efficiency of enzymes and the biosensing performance. Then, the development of a nonenzymatic strategy that uses the intrinsic property of mesoporous materials (carbon, silica, metals, and composites) to mimic the behavior of enzymes for electrochemical sensing of some biomolecules is discussed. Finally, the challenges and perspective on the future development of biosensors based on mesoporous materials are proposed.

Sub-nanometric Manganous Oxide Clusters in Nitrogen Doped Mesoporous Carbon Nanosheets for High-Performance Lithium-Sulfur Batteries.

The greatest challenge for lithium-sulfur (Li-S) batteries application is the development of cathode hosts to address the low conductivity, huge volume change, and shuttling effect of sulfur or lithium polysulfides (LiPs). Herein, we demonstrate a composite host to circumvent these problems by confining sub-nanometric manganous oxide clusters (MOCs) in nitrogen doped mesoporous carbon nanosheets. The atomic structure of MOCs is well-characterized and optimized via the extended X-ray absorption fine structure analysis and density functional theory (DFT) calculations. Benefiting from the unique design, the assembled Li-S battery displays remarkable electrochemical performances including a high reversible capacity (990 mAh g-1 after 100 cycles at 0.2 A g-1) and a superior cycle life (60% retention over 250 cycles at 2 A g-1). Both the experimental results and DFT calculations demonstrate that the well-dispersed MOCs could significantly promote the chemisorption of LiPs, thus greatly improving the capacity and rate performance.

Liquid-Phase Assisted Engineering of Highly Strong SiC Composite Reinforced by Multiwalled Carbon Nanotubes.

Despite the ultrahigh intrinsic strength of multiwalled carbon nanotube (MWCNT), the strengthening effect on ceramic matrix composite remains far from expectation mainly due to the weak load transfer between the reinforcement and ceramic matrix. With the assistance of the in situ pullout test, it is revealed that the liquid-phase sintering (LPS) can serve as a novel strategy to achieve effective load transfer in MWCNT reinforced ceramic matrix composites. The YAlO3 formed liquid phase during spark plasma sintering of SiC composite greatly facilitates radical elastic deformation of MWCNT, leading to highly increased interfacial shear strength (IFSS) as well as interlayer shear resistance (ISR) of nested walls. The liquid phase with superior wettability can even penetrate into the defects of MWCNT, which further increases the ISR of MWCNT. Moreover, the first-principles calculation indicates that the oxygen terminated YAlO3 phase displays much stronger bonding compared with SiC matrix, which is also responsible for the large IFSS in the composite. As a result, as high as 30% improvement of bending strength is achieved in the composite with only 3 wt% MWCNT in comparison to the monolithic ceramic, manifesting the unprecedented strengthening effect of MWCNT assisted by LPS.

Confined interfacial micelle aggregating assembly of ordered macro-mesoporous tungsten oxides for H2S sensing.

Porous tungsten oxides (WO3) have been implemented in various application fields including catalysis, energy storage and conversion, and gas sensing. However, the construction of hierarchically ordered porous WO3 nanostructures with highly crystalline frameworks remains a great challenge. Herein, a confined interfacial micelle aggregating assembly approach has been developed for the synthesis of ordered macro-mesoporous WO3 (OMMW) nanostructures using three-dimensional SiO2 photonic crystals (PCs) as nanoreactors for the confined assembly of tungsten precursor and poly(ethylene oxide)-block-polystyrene (PEO-b-PS) template. After the heat treatment and etching processes, the obtained OMMW could achieve hierarchically ordered porous nanostructures with close-packed spherical mesopores (∼34.1 nm), interconnected macro-cavities (∼420 nm), high accessible surface areas (∼78 m2 g-1), and highly crystalline frameworks owing to the protection of dual templates. When OMMW nanostructures were assembled into gas sensors for the detection of H2S, the resulting sensors exhibited excellent comprehensive sensing performance, including a rapid response-recovery kinetics, in addition to high selectivity and long-term stability, which are significantly better than the previously reported WO3-based sensors. This study paves a promising way toward the development of hierarchically ordered porous semiconductors with large and interconnected porous channels for sensing applications.

Hierarchical Branched Mesoporous TiO2-SnO2 Nanocomposites with Well-Defined n-n Heterojunctions for Highly Efficient Ethanol Sensing.

The direct assembly of functional nanoparticles into a highly crystalline mesoporous semiconductor with oriented configurations is challenging but of significance. Herein, an evaporation induced oriented co-assembly strategy is reported to incorporate SnO2 nanocrystals (NCs) into a 3D branched mesoporous TiO2 framework by using poly(ethylene oxide)-block-polystyrene (PEO-b-PS) as the template, SnO2 NCs as the direct tin source, and titanium butoxide (TBOT) as the titania precursor. Owing to the combined properties of ultrasmall particle size (3-5 nm), excellent dispersibility and presence of abundant hydroxyl groups, SnO2 NCs can easily interact with PEO block of the template through hydrogen bonding and co-assemble with hydrolyzed TBOT to form a novel hierarchical branched mesoporous structure (SHMT). After calcination, the obtained composites exhibit a unique 3D flower-like structure, which consists of numerous mesoporous rutile TiO2 branches with uniform cylindrical mesopores (≈9 nm). More importantly, the SnO2 NCs are homogeneously distributed in the mesoporous TiO2 matrix, forming numerous n-n heterojunctions. Due to the unique textual structures, the SHMT-based gas sensors show excellent gas sensing performance with fast response/recovery dynamics, high sensitivity, and selectivity toward ethanol.

Spherical Mesoporous Materials from Single to Multilevel Architectures.

Mesoporous materials with various structures have attracted considerable attention due to their distinctive properties such as large pore sizes, high surface areas, tunable pore structures, and controllable framework compositions. Among them, spherical mesoporous materials (SMMs) are of great interest owing to the unique spherical shape, which show the closed packing nature and lowest surface energy. The open mesopores and short channels of SMMs not only increase the density of high accessible active sites but also facilitate the mass diffusion with short length. These characteristics are particularly useful for applications in catalysis, adsorption, energy storage and conversion, biomedicine, and so on. In addition, the creation of a spherical shape is conformable to the law of natural selection because objects in nature tend to minimize energy, while the sphere is one of the most perfect matter structures. Therefore, the design and synthesis of SMMs are very important from both fundamental and technological viewpoints. Compared to the simple single-level, SMMs with more complex multilevel structures inevitably bring unusual mechanical, electrical, and optical properties, which are highly desired for practical applications. For example, the construction of core-shell structured SMMs has inspired great attention as they can combine multiple components into one functional unit, exhibiting ameliorated or new physicochemical properties, which cannot be obtained from the isolated one. The presence of a hollow cavity in the yolk-shell structure allows sufficient exposure of the core while maintaining the protective ability of the shell, which is conducive to retaining the distance-dependent properties of the core. Multishelled hollow structures consisting of two or more mesoporous shells are expected to show superior activities in various applications compared to their bulk counterparts because more active interfaces and unique compartmentation environments can be provided. Therefore, SMMs from single to multilevel structure represent a class of advanced nanostructured materials with unique structures and fascinating properties. In this Account, we highlight the progresses on the synthesis and applications of SMMs from single to multilevel architectures. The synthetic strategies have been summarized and categorized into (i) the modified Stöber method, (ii) the hydrothermal strategy, (iii) the biphase stratification approach, (iv) the nanoemulsion assembly method, (v) the evaporation induced aggregating assembly (EIAA) method, and (vi) the confined self-assembly strategy. Special emphasis is placed on the synthetic principles and underlying mechanisms for precise control of SMMs over the particle sizes, pore sizes, pore structures and functionalities as well as different levels of architectures. Moreover, the implementation performances in catalysis, drug delivery, and energy related fields have been highlighted. Finally, the opportunities and challenges for the future development of SMMs in terms of synthesis and applications are proposed.

A review on heterogeneous sonocatalyst for treatment of organic pollutants in aqueous phase based on catalytic mechanism.

Heterogeneous sonocatalysis, as an emerging advanced oxidation process (AOP), has shown immense potential in water treatment and been widely demonstrated to remove persistent organic compounds in the past decade. The present article aims to provide a comprehensive review on the development of a heterogeneous catalyst for enhancing the ultrasonic degradation rate of organic pollutants from a viewpoint of sonocatalytic mechanism. The rational design and fundamentals for preparing sonocatalysts are presented in the context of facilitating the heterogeneous nucleation and photo-thermal-catalytic effects as well as considering the mechanical stability and separation capacity of the heterogeneous catalyst. In addition, some new trends, ongoing challenges and possible methods to overcome these challenges are also highlighted and proposed.