English

• 0.   Introduction

  Catalysis provides vital solutions to global energy, sustainability, and healthcare challenges, with both surface reactions and mass transfer serving as critical determinants of catalytic efficiency^[1-5]. Among the diverse range of emerging catalysts, hollow multi-shelled structures (HoMSs)—consisting of at least two separate shells assembled from nanoscale subunits—have attracted significant interest due to their spatiotemporal mass transfer characteristics and exceptional performance in various applications^[6-10]. Compared with single-shelled or densely packed materials, multi-shelled architectures offer multiple confined reaction zones, ample pore channels, and highly accessible active sites, thus enabling precise control over the sequential passage of light, charges, and molecules^[11-14].

  Central to HoMS construction is the concept of hierarchical assembly from the microscale to the nanoscale. Basic functional units (such as nanoparticles or nanosheets) initially form individual shells, which then assemble into multi-shelled hollow frameworks. This design yields layered confined spaces within and between shells, regulating the transport of molecules, ions, and photons according to their size and facilitating enhanced catalytic activities through selective adsorption, diffusion, and reaction^[15-17]. Moreover, judicious choice of shell composition, crystal structure, facet exposure, and morphology allows for precise tuning of adsorption sites, electronic properties, and redox behavior—key factors that drive catalytic efficiency^[18-23].

  An important milestone in HoMS synthesis is the introduction of the sequential templating approach (STA), inspired by Xie′s programmed temperature method^[24] and Li′s carbon matrix-sacrificed strategy^[25]. In 2009, our group adopted STA to synthesize MFe₂O₄-HoMSs (M=Zn, Co, Ni, Cd) via a one-step process^[26], sparking rapid growth in HoMS research. By exploiting multiple template interactions during the removal phase, STA enables the precise control of shell number, thickness, intershell spacing, facet exposure, and crystallinity. More recently, mathematical modeling of STA has uncovered the concentration-wave phenomenon, extending STA′s reach to gentler solution-based systems and broadening the range of chemical compositions and geometric configurations accessible for HoMS^[27-36]. Consequently, HoMSs have found diverse applications not only in catalysis^[37-40] but also in electromagnetic wave absorption^[41-43], lithium-ion batteries^[44-47], targeted drug delivery^[48-50], and advanced sensing^[51-56].

  Despite their expanding scope, catalytic applications remain a primary focus of HoMS research. By leveraging multi-level confined spaces and spatiotemporal mass transfer, HoMS catalysts exhibit enhanced light harvesting, charge separation, and reaction kinetics over their single-shelled counterparts. In addition, their tunable electronic and structural features permit cascade reactions, selective adsorption, improved diffusion, and sequential release, which hold great promise for applications ranging from sustainable fuel production and pollutant degradation to medical therapies.

  In this review, we underscore the importance of temporal-spatial ordering within HoMS and how it fundamentally influences catalytic activity and selectivity. We begin with an overview of spatiotemporal mass transfer in multi-shelled architectures, highlighting its role in ion insertion/extraction, electron-hole separation, and molecular adsorption/desorption. We then explore how the STA facilitates the fine-tuning of HoMS micro-/nano- and electronic structures, integrating insights from both experimental studies and theoretical simulations of formation mechanisms. Next, we present selected case studies to demonstrate how manipulating chemical composition, shell arrangement, and pore architecture can effectively optimize mass transport and catalytic efficiency. Finally, we offer a forward-looking perspective on emerging hurdles and future directions, aiming to inspire new endeavors in photocatalysis, electrocatalysis, thermal catalysis, and beyond. We hope this review will guide further research leveraging HoMS for critical energy and environmental applications, paving the way for next-generation catalytic systems.

  1.   STA for accurate synthesis of HoMS

  Synthesis determines the future. The precise synthesis and structural control of catalysts are the foundation for achieving ideal catalytic performance. In the last few decades, significant efforts have been dedicated to developing efficient synthesis methods for HoMS materials. The approaches to synthesizing hollow nanostructures have been summarized in the past^{[2, 36-37]}, including the sequential templating approach^{[22, 25, 30]}, hard and soft templating method, Ostwald ripening^[57-58], Kirkendall effect^[59-61], ion exchange^[62-63], and selective etching^[64-66], template free method^[67] and thus will not be elaborately reiterated here. Our group developed the STA for precise synthesis of HoMS in 2009^[26] and unlocked the physical essence of the STA in 2023^[28]. Additionally, it has expanded the applicable fields of STA and broadened the application areas of HoMS. In this section, we will present the research progress of STA from both experimental and theoretical perspectives, as well as demonstrate how STA can be applied to achieve precise structure control of HoMS materials through case studies.

  Based on the understanding of STA, we can precisely regulate the phase structure and shell thickness of HoMS by controlling the template removal rate (R_tr) and the shell formation rate (R_sf), which endow HoMSs with great opportunities in catalytic applications. The control of HoMS catalytic performance can be attained through composition and structure control of subunits, shells, and their assembly structure. As illustrated in Fig. 1a, the building subunits can be designed with various fundamental functional properties by adjusting their elemental composition, phase structure, morphology, and size. Subsequently, shells with tunable pore structures, compositions, thickness, morphologies, etc. are assembled with these well-designed subunits. Furthermore, multiple shells are hierarchically structured to form a HoMS with gaps between each shell. Therefore, by manipulating the composition, structure, and assembly of building subunits and shells, one can precisely regulate the structural and compositional features of HoMSs.

  1.1   STA

  A template with a high concentration of metal/nonmetal precursors is necessary for the synthesis of HoMS during STA. This template can act as a "sequential template" multiple times during the process of removing the template, forming each shell in sequence and ultimately constructing HoMS^[27]. As shown in Fig. 1a, carbonaceous microspheres (CMSs) containing hydroxyl (—OH), carbonyl (—C=O), and carboxyl (—COOH) functional groups can serve as templates for adsorbing ions with suitable surface electronegativity^[68]. This makes the CMSs tend to adsorb oxygen-rich groups such as —OH, giving the CMSs a negative charge. These negative charges facilitate CMSs to enrich metal cations through electrostatic interaction, as depicted in route (ⅰ) in Fig. 1b. Additionally, our previous research show that CMSs can also allow the penetration of various anions, as shown in route (ⅱ) in Fig. 1b. This approach has been effectively used to create a variety of hollow multi-shelled structures made of metal oxides, complexes, and other materials. Expanding on these advancements, researchers have carefully designed hollow multi-shelled structures with a wide range of compositions and structures, signaling the start of a new era in creating HoMS materials. In the STA, templates containing precursors are used iteratively as "sequential templates", allowing for the one-step formation of hollow multi-shelled structures. By controlling the composition of template materials and the precursors used, various types of HoMS materials can be synthesized, including metal oxide (Mn₃O₄^[69], NiO^[36], V₂O₅^[35], Fe₂O₃/Cr₂O₃^[70], CeO₂/TiO₂^[12], ZnO@ TiO₂^[71], etc.), heterogeneous composite structure (Co₃O₄/CNTs^[72], TiO₂/C^[9], etc.), and some specific HoMS, such as graphdiyne^[73], Sn NPs@N_xC^[74], CoP^[14] and so on. This precision-controlled synthesis requires controlling R_sf and R_tr in balance^{[1-2, 29]}, as shown in Fig. 1c-1d. Two main conditions are necessary for successfully producing HoMS through STA: a significant infiltration depth of the precursors into the templates, denoted as C_r, and close alignment between R_sf and R_tr. If R_sf is significantly lower than R_tr, the template may be removed before reaching the critical concentration required to form a stable shell, resulting in the production of dispersed nanoparticles instead. Conversely, if R_sf is much higher than R_tr, precursors are likely to accumulate around the template and slowly diminish, leading to the formation of porous microspheres. Therefore, the establishment of a clearly defined HoMS relies on the effective synchronization of these two rates.

  Figure 1

  

  Figure 1.  (a) Varied HoMS functions through modification^[2]; (b) Adsorption of ions on CMS surface during HoMS synthesis^[29]; (c) Formation mechanism of HoMS^[27]; (d) Schematic diagram of C_r, R_sf, and R_tr on CMS

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  Subunits can undergo evolution from precursors, and the size of particles is connected to the Gibbs free energy within the system. Crystallization has a critical size (r_c), where nanocrystals smaller than r_c tend to dissolve, while those larger than r_c can continue growing steadily. As the reaction progresses, nanoparticles come together to form a shell structure, and how they assemble can impact the morphology of the HoMS. For instance, the pore size of the shell structure is closely linked to both nanoparticle size and their method of assembly. Larger nanoparticles have potential for assembling into larger pore sizes, while a tighter arrangement leads to smaller pore sizes. The crystal facet of nanoparticles is determined by the arrangement of atoms, which determines the crystal facet of HoMSs^[75]. Next, a HoMS will be formed by multiple shells. The number of shells in HoMSs prepared through STA is mainly influenced by R_tr and R_sf^[1]. When R_tr matches R_sf well, more shells are formed, while a greater difference between them results in fewer shells^[76]. The space between shells is affected by the heating rate, with a fast heating rate likely creating a larger inter-shell space and a slow heating rate bringing two proximate shells closer together. A higher precursor concentration in the template leads to thicker shell formation, and the morphology of HoMSs generally reflects that of the template. In this section, we will present case studies on the composition and structure control of HoMSs.

  2.2   Theoretical study of STA

  In 2023, our group developed a streamlined mathematical model based on the physical principles derived from experimental STA processes, illustrating the concentration changes of precursors at the template surface (Fig. 2)^[28]. As shown in Fig. 2a, this model is grounded in straightforward mathematical relationships. In experiments that employ carbonaceous microspheres (CMSs) as templates, their removal rate is predominantly governed by the furnace heating schedule. Consequently, temperature becomes the primary variable in these calculations. Using the model, we can determine σ, a temperature-dependent parameter, during template removal. As more precursor accumulates, σ progressively reaches a threshold that triggers shell formation. Once a shell has formed, both σ and the shell volume (V_shell) are reset to zero, mimicking the detachment of the newly formed shell and marking the start of the next formation cycle.

  Figure 2

  

  Figure 2.  (a) Mathematic model of the HoMS simulating formation process; (b) σ evolution during template removal in STA; (c) Correlation between concentration waves and the formation of HoMS; Formation of (d) Cu₂S HoMS and (e) CaCO₃ HoMS (scale bar: 200 nm)^[28]

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  Fig. 2b depicts the wave-like fluctuations of σ, referred to as "concentration waves" during template removal. As time and temperature increase, CMSs oxidize and their size shrinks, causing precursors to build up at the surface. This accumulation hinders oxygen diffusion and slows down the oxidation process, creating periodic surges in surface concentration. Upon reaching a critical shell thickness, the precursor layer detaches, sharply decreasing the surface concentration. This cycle repeats until all precursors are consumed or the templates are fully removed. These concentration oscillations play a key role in HoMS formation and align well with the predictions of the mathematical model. Although the model does not directly incorporate precursor reactions, σ effectively represents the concentration of surface products or intermediates, providing a robust theoretical framework for understanding HoMS creation.

  As illustrated in Fig. 2c, the concept of "concentration waves" is central to shell formation and offers valuable theoretical insight for refining synthesis methods. Moreover, the significance of these waves is not limited to pyrolysis-based approaches, indicating that generating comparable dynamics in other synthetic environments can also yield HoMS. To validate this concept, we conducted two exploratory experiments (Fig. 2d and 2e). In one case, we synthesized cubic CuS HoMS by gradually elevating the concentration of S^2- ions in solution (Fig. 2d). In another experiment (Fig. 2e), we introduced CO₂-infused ice templates into Ca²⁺ solutions to obtain CaCO₃ HoMS through controlled melting of the ice. Both trials demonstrate that inducing concentration waves within different reaction systems can successfully produce HoMS, broadening the scope of STA-based strategies beyond simple pyrolysis.

  3.   Catalytic performance control of HoMS

  In this section, we mainly discuss the catalytic capacity of HoMS materials. As commonly understood, the catalytic performance is significantly impacted by surface chemical reactions and mass transfer. The electronic structure of catalysts directly influences the surface chemical reaction process, while the micro-/nano-architectures of catalysts affects mass transfer properties. This section will explore strategies for controlling the performance of HoMS by regulating electronic structure and micro-/nano-architectures in surface reactions and mass transfer.

  3.1   Electronic structure control and its impact on performance

  For photocatalytic, electrocatalytic and thermocatalytic reactions, the improvement of electron transport efficiency helps to improve their catalytic activity. The surface electronic structure plays an important role in determining the adsorption/desorption of reactants, intermediates, or products during the catalytic reaction. The electronic structure of HoMS materials can be controlled by doping, heterojunction construction, and crystal surface engineering, which can effectively improve the electron transport capacity of HoMS materials.

  Through the STA, we can achieve control over the electronic structures of materials. Doping can effectively alter the crystal structure of materials and enhance their electron transport capabilities. Wang et al. adopted STA, obtaining the precursor through a dry spray method, and then calcined it to obtain LC HoMSs with different layer numbers (Fig. 3a)^[77]. By changing the element composition of the precursor, the authors successfully substituted Co for different proportions of Ni, causing lattice distortion and creating oxygen vacancies in the material. Among them, the one with a three-layer shell structure, where the Ni substitution ratio is 0.5 for 3S-LCN-0.5, has the best electrocatalytic oxygen evolution reaction (OER) activity. This Ni doping promotes electron transport by converting the catalyst from a low electron spin state to a high electron spin state through the Jahn-Teller effect, thereby enhancing the electrocatalytic OER activity.

  Figure 3

  

  Figure 3.  (a) Effect of La doping on the electron configuration of 3S-LC-HoMSs^[77]; (b) Related atom model atthe interface between SnS₂ and SnO₂ in atomic scale^[11]; (c) Rearrangement of Co atoms to obtain different crystal faces^[13]

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  By constructing heterojunctions, it is also possible to effectively modify the electronic structure of the catalyst. You et al. used STA, with carbonaceous microsphere as a template, to first synthesize quadruple-shelled SnO₂ HoMSs (Fig. 3b)^[11]. On this basis, they sulfurized SnO₂ HoMSs using thioacetamide to construct the SnS₂/SnO₂ heterojunction. Through the formation of lattice distortion at the interface between the two substances, the catalyst exposes more active sites. Meanwhile, the SnS₂/SnO₂ heterojunction also promotes the separation of photogenerated charge carriers, making it have the best solid-gas phase photocatalytic CO₂ reduction activity at the time, with a CO yield of 48.01 μmol·g^-1·h^-1 and a selectivity of 100%.

  Constructing the shell structure with an exposed catalytically active facet is of great significance for optimizing the adsorption/desorption process to promote catalytic reactions. By adopting a cobalt-based metal-organic framework (ZIF-67) as templates and precursors, through a topological transformation process of metal atoms in ZIF-67 by STA, the Co₃O₄ nanocrystals are assembled oriented to form the HoMS with unique shells with dominant exposure of (111) Co₃O₄ facets (Fig. 3c)^[13]. These exposed (111) Co₃O₄ facets possess high catalytic activity for CO₂ reduction. Accompanied by the strong solar light harvesting property and large exposed reaction surface of HoMS, the synthesized quadruple-shelled (111) Co₃O₄ HoMSs demonstrated a high catalytic activity for CO₂ photoreduction, which is about five and three times higher than Co₃O₄ nanoparticles and quadruple-shelled Co₃O₄ HoMSs without facet control, respectively.

  3.2   Micro-/nano-architectures control and its impact on performance

  Beyond the electronic structure of the catalyst, its geometric structure also significantly influences catalytic reaction efficiency by affecting processes such as adsorption and diffusion. Multi-level nano-microstructures assembled from nanostructured units offer advantages in material transport. The multiple shell layers and cavities of HoMS provide a large reaction surface and abundant adsorption sites, facilitating efficient adsorption of substrate molecules and intermediate molecules by the catalyst. In addition, the transport of light and electrons is also an important part of the mass transfer process. In 2018, Lien et al. demonstrated that the structure of HoMS helps to trap light, enhance light absorption, and promote the progress of photocatalytic reactions^[53]. Multiple shell layers and inter-shell cavities optimize light transmission inside the catalyst by regulating light scattering, reflection, interference, etc., to enhance the material′s capture and absorption of light and improve photocatalytic efficiency. The network structure formed by multiple shell walls provides a parallel transmission path for charges, shortening the charge transfer path.

  For HoMS, changing the interlayer spacing is an effective means to change the micro-/nano-structure, which can improve the catalytic activity. By phosphating the Co₃O₄ HoMS synthesized using STA and controlling the phosphating time, Hou et al. obtained CoP with bubble-like shells (B-CoP-HoMSs), close-duplicated shells (D-CoP-HoMSs) and CoP with solid shells (CoP-HoMSs), respectively (Fig. 4a)^[14]. Specifically, the structure of D-CoP-HoMSs has unbalanced Laplace pressure, which can promote the release of bubbles and increase capillary force, accelerating the flow of liquid. Meanwhile, this structure also reduces the distance between the shell layers, increases the number of reaction sites, and improves the electrocatalytic activity for water splitting. Similarly, Zhang et al. have also achieved similar structures through a sulfation method^[78]. The WO₃ HoMS obtained by STA can be used as a template, and sulfurized with thiourea to ultimately result in WS_2-x HoMSs with an expanded interlayer. This structure effectively increases the interlayer spacing, laying the foundation for further modification.

  Figure 4

  

  Figure 4.  (a) Illustration of the formation process of CoP HoMSs with different micro-/nano-structures of shells^[14]; (b) Schematic illustration of STO catalyzed by ZnCrO_x HoMS/SAPO with high space velocity^[79]; (c) Schematic of highly efficient solar-to-vapor generation via amorphous Ta₂O₅/C HoMS^[9]; (d) Schematic illustration of the formation of Sn NPs@N_xC HoMS-DL inherited from SnO₂@PDA HoMS through in situ evolution of SnO₂ shell to Sn cores^[74]

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  By controlling the structure of the catalyst, it is possible to better control the molecular transport process and thereby enhance catalytic activity. Using carbon microspheres as templates, the STA was employed by adjusting the element composition of the precursor, and after calcination, different layered ZnCrO_x HoMS could be obtained (Fig. 4b)^[79]. Among them, the mixed catalyst composed of 5S-ZCHoMS with five layers of shell and SAPO has the best carbon-carbon coupling ability, with a selectivity of light olefins reaching 90%. This structure not only provides more sites for catalysis but also delays the transport of intermediate molecules due to the longer distance from 5S-ZCHoMS to SAPO in mass transfer, thereby reducing the occurrence of side reactions.

  By optimizing the micro-/nano-architectures of HoMS material, the absorption of light can be enhanced. Based on the good light-harvesting ability of HoMS itself, further optimization of the material itself can achieve better light energy transmission capability. By using carbon microsphere as the template, the amorphous Ta₂O₅/C composite HoMS can be obtained by changing the calcination temperature, time, and gas ratio, etc. (Fig. 4c)^[9]. Amorphous Ta₂O₅ can effectively increase the indirect bandgap structure with abundant energy states near the Fermi level of the material, enhance nonradiative relaxation, and improve the photothermal conversion efficiency. Meanwhile, this structure also causes the internal temperature of the material to rise, forming a temperature gradient, promoting the transport of water.

  In addition to the electronic structure, the micro-/nano-architectures of the material itself also affects the transport of electrons. Modifying nanoparticles within the HoMS can also effectively change the nanostructure of the catalyst, increase the number of reaction sites, and enhance catalytic activity. Using the STA method, SnO₂ HoMS was used as a template, and polydopamine was coated uniformly on its surface by vacuum stirring (Fig. 4d)^[74]. By changing the sintering time, it is possible to obtain N_xC HoMS with Sn nanoparticles. The fabricated composite can promote ion and electron diffusion owing to the conductive network formed by connected multiple shells and cores, effectively buffer the volume expansion, and maintain a stable electrode-electrolyte interface.

  4.   Breakthrough brought by temporal-spatial ordering property of HoMS

  4.1   Temporal-spatial ordering property of HoMS

  Furthermore, the presence of distinct compositions in the outer and inner shells of HoMS is essential for achieving controlled temporal-spatial mass transfer, as well as for storing and subsequently releasing substances. Wang et al. employed a 3D Cartesian coordinate system to gain a deeper understanding of the temporal-spatial organization in HoMS^[2]. As shown in Fig. 5a, we can introduce a time dimension (t) perpendicular to the triple concentric spheres within a HoMS structure. This configuration allows us to distinguish three separate spherical areas, known as S₁, S₂, and S₃, arranged outwardly, with S_o representing the external bulk space and S_i indicating the core internal space. When a photon or molecule moves from the external space to the central core S_i within the HoMS, it encounters points C (x₃, y₃, z₃, t₃)→B (x₂, y₂, z₂, t₂)→A (x₁, y₁, z₁, t₁) in sequence. The entry path follows the progression S_o→S₃→S₂→S₁→S_i, and its exit mirrors this sequence in reverse from S_i→S₁→S₂→S₃→S_o. In contrast, in simple hollow structures such as a series of adjacent porous spheres or tubes shown in Fig. 5a, molecules do not systematically move through defined sequential spaces. Furthermore, during mass transfer within a HoMS, substances pass through S₁, S₂, and S₃ meticulously, a phenomenon not seen in other configurations. This unique feature of HoMS provides precise temporal and spatial control over reaction processes. Just like molecules, different factors such as force and electron may also play a role in following temporal-spatial ordering, and may interfere with the process and the stability of catalysis.

  Figure 5

  

  Figure 5.  (a) Schematic of mass transfer through space with different structures^[2]; (b) CO₂ in series catalyzes gradual reduction to CH₄^[12]; (c) Efficient sequential harvesting of solar light by heterogeneous hollow shells with hierarchical pores^[41]

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  4.2   Breakthrough in catalytic applications brought by temporal-spatial ordering property

  In HoMS, the transmission of molecules must follow temporal-spatial ordering, which can be used as a principle to design cascaded micro-reactors. In the photocatalytic CO₂ reduction reaction, adsorbed CO (*CO) is an important intermediate, and its production can be regarded as the first step of conversion to other carbon-containing reduction products. Therefore, using the concept of cascaded micro-reactors, CO₂ can first be reduced to CO and then transferred to another catalyst surface for conversion. By using carbon microspheres as templates, different CTHoMSs with inner and outer heterogeneous structures can be obtained by taking advantage of the different diffusion rates of various substances^[12]. By adjusting the proportion of Ce in the precursor, CTHoMSs with different numbers of inner shells can be obtained. The 4S-CTHoMSs with a quadruple shell have the best sequential catalytic activity. CO₂ molecules are first concentrated and reduced to CO on the inner layer of CeO₂, and then CO molecules diffuse outward and are adsorbed by the amorphous TiO₂, which catalyzes the conversion of CO to CH₄. This structure ensures that substrate molecules are passed in a one-way manner, allowing the reaction to proceed sequentially.

  Using this temporal-spatial ordering, we can design more possible catalysts and use them in more complex reactions. The cascade reaction offers numerous advantages, such as high efficiency and minimal waste, making it a popular choice for various chemical manufacturing processes^[80-81]. The antenna system of cyanobacteria is a source of inspiration from nature, where different antenna pigments are arranged in a specific order to efficiently collect light energy. This natural temporal-spatial ordering allows for the rapid accumulation of oxygen, essential for oxygenic life. This unique structure has potential applications in electromagnetic wave harvesting, cascade catalytic reactions, and hybrid energy storage technologies. By undergoing chemical alteration, HoMSs have the potential to attach to the target and potentially undergo self-improvement to acquire specific characteristics at a specified time. This would be extremely beneficial in the fields of chemical engineering and biochemistry.

  The light absorption performance of HoMSs can be improved by their geometric structures, as the multiple scatterings of solar light caused by multiple shells will increase the optical path of the incident light in HoMS space, leading to higher light harvesting efficiency. The separation and utilization efficiencies of photo-generated electron-hole pairs, which are influenced by the shell components, have a significant impact on photocatalytic activity. For example, heterojunctions in shells can enhance the separation of electron-hole pairs and reduce electron recombination. Additionally, composition control and geometric control of HoMSs can regulate the transfer and surface reaction of molecules. Based on the aforementioned discussions, the number of shells and the spacing between them can significantly impact the process of light harvesting^[82]. Furthermore, HoMSs with different compositions in each shell can facilitate sequential light harvesting, as demonstrated in Fig. 5c. For example, a quadruple-shelled TiO₂-Cu_xO HoMSs (4S-TCHoMSs) with a gradient of Ti/Cu molar ratio from the outermost to innermost shell^[41]. Consequently, only short-wavelength solar light that has weak penetration is absorbed by the outermost shell, while long-wavelength solar light with strong penetration is absorbed by the inner shell. Such structure and performance endow 4S-TCHoMSs with better photocatalytic water splitting ability. All these discussions demonstrate the concept of efficient sequential light harvesting of heterogeneous HoMSs.

  4.3   Increase the stability through temporal-spatial ordering of force

  In many catalytic studies, stability is a decisive factor for assessing a catalyst′s industrial viability. Although cyclic stability is often emphasized from a chemical standpoint, mechanical stability can be just as important. For HoMSs, preserving the spatiotemporally ordered architecture during catalysis is essential to maintain their unique mass-transfer benefits. As a result, accurately evaluating the mechanical properties of HoMSs becomes critically important.

  A variety of experimental techniques have been applied to investigate the mechanical performance of catalysts. Notably, in situ transmission electron microscopy (TEM) has emerged as a powerful tool for testing the mechanical behavior of micro- and nanoscale systems. In 2016, Yang et al.^[83] revealed that combining covalent in-plane strength with out-of-plane flexibility in hollow shells endows them with excellent mechanical stability, including high tensile strength and lower weight. By tracking force-displacement curves using in situ TEM, they confirmed that the empirical data aligned closely with theoretical simulations, providing strong evidence for enhanced mechanical properties. Moreover, the multi-shelled construction of HoMSs allows for effective load distribution. When an external force is applied to the outer shell, progressive deformation eventually brings the inner shells into contact, thereby sharing the mechanical stress and enhancing overall structural integrity. This feature is especially advantageous in catalytic processes, where mechanical durability can be a prerequisite under operational conditions.

  In a related development, Zhang et al. employed a modified STA to synthesize Fe single-atom-doped MoS₂ HoMS (Fe-M-HoMS)^[84]. The incorporation of Fe single atoms facilitated electron transfer, driving self-catalytic activity crucial for reversible phase transformations (from 2H to 1T, and from Na_xMoS₂ to Mo and Na₂S). Consequently, the resulting HoMS demonstrated outstanding cyclic stability and superior electrochemical performance compared to other materials. The hierarchical HoMS framework not only offers multiple channels for electrolyte penetration, leading to increased active sites and shorter ion/electron diffusion pathways, but also buffers volumetric changes during charge-discharge cycles, thus maintaining both electrochemical and mechanical stability. Through in situ TEM observations, throughout the loading-unloading process, the multi-shelled structure remained intact, and any volumetric changes that arose were fully reversible. Despite these promising advances, further mechanical testing and long-term durability assessments are necessary before HoMSs can be broadly adopted in industrial catalysis. Ongoing research focused on bolstering mechanical robustness, combined with the intrinsic spatiotemporal ordering of HoMS, will be vital to ensuring reliable performance in large-scale catalytic operations.

  5.   Conclusions

  In this review, we highlighted how the STA enables the precise synthesis of HoMS from both experimental and theoretical perspectives. By carefully regulating the choice of precursors, template-removal rate, and shell-formation conditions, researchers can rationally design and synthesize HoMSs with diverse chemical compositions, electronic structures, and micro-/nano-architectures. We also explored various strategies for tuning the electronic and structural properties of HoMS, illustrating how these modifications influence mass-transfer characteristics and catalytic performance through case studies. Despite the growing evidence of HoMS-based catalysis achieving promising results, this field is still in its early stages, offering numerous opportunities and challenges.

  First, the controllable synthesis of HoMS-based catalysts is critical for enhancing their performance and expanding their potential applications. For example, the electronic structure, including spin states, orbital configurations, and band alignments, plays a pivotal role in molecular adsorption, activation, and desorption, as well as in charge-transfer dynamics during catalytic processes. At the same time, multi-level confined micro-/nano-architectures (e.g., pore size, shell thickness, intershell spacing, shell count) significantly impact molecular and ion diffusion, along with light transmission, thereby dictating reaction kinetics. Achieving a highly integrated approach that precisely regulates both electronic features and structural design remains a formidable challenge. To meet industrial-scale demands, it is also imperative to extend such structural control to large-scale production. Continuous innovation in controlling chemical composition, electronic states, and morphological features will help establish a comprehensive database of HoMS-based catalysts for a wide range of catalytic applications.

  Second, the traditional trial-and-error method of catalyst development and optimization typically involves extensive experimentation, leading to excessive energy consumption and potential environmental hazards. In recent years, breakthroughs in artificial intelligence (AI) and big data analytics have paved the way for more eco-friendly and efficient research strategies in this domain. By drawing upon substantial experimental and theoretical datasets, AI can significantly streamline the design of HoMS-based catalysts with high precision. For instance, AI-driven approaches could facilitate self-regulating pore architectures that autonomously adapt to shifts in local microenvironments, an especially appealing feature in catalytic process engineering. Realizing these capabilities calls for deeper investigations into the interplay between chemical composition, electronic structures, and micro-/nano-architectural parameters of HoMS, which can be pursued through advanced in situ characterization tools and multi-scale simulation methods.

  Lastly, the temporal-spatial ordering intrinsic to HoMS has already demonstrated enhanced catalytic performance and holds considerable promise for tandem catalysis, sequential light harvesting, and other cutting-edge applications. A comprehensive understanding of this phenomenon, both theoretically and experimentally, is vital for unraveling structure-performance relationships and achieving substantial breakthroughs in catalytic efficiency. Furthermore, temporal-spatial ordering may confer additional mechanical advantages, complementing its catalytic benefits. As HoMS research advances, new functionalities arising from this ordered structure are likely to emerge, offering deeper insights into how these architectures govern catalytic processes. By integrating state-of-the-art experimental techniques, innovative analytical methodologies, and AI-driven design, we can more directly study and utilize spatiotemporally ordered mass transfer in HoMS. This rapidly evolving field shows significant potential for next-generation catalytic systems, particularly in energy and environmental contexts.

  
  Acknowledgements: This work was financially supported by the National Key Research and Development Program of China (Grant No.2024YFA1509400), the National Natural Science Foundation of China (Grant No.22293043), and IPE Project for Frontier Basic Research (Grant No.QYJC-2023-08).
• 1. [1]

     MAO D, WAN J W, WANG J Y, WANG D. Sequential templating approach: A groundbreaking strategy to create hollow multishelled structures[J]. Adv. Mater., 2019, 31(38): 1802874 doi: 10.1002/adma.201802874

  2. [2]

     WANG J Y, WAN J W, YANG N L, LI Q, WANG D. Hollow multishell structures exercise temporal-spatial ordering and dynamic smart behaviour[J]. Nat. Rev. Chem., 2020, 4(3): 159-168 doi: 10.1038/s41570-020-0161-8

  3. [3]

     WANG J Y, WAN J W, WANG D. Hollow multishelled structures for promising applications: Understanding the structure-performance correlation[J]. Acc. Chem. Res., 2019, 52(8): 2169-2178 doi: 10.1021/acs.accounts.9b00112

  4. [4]

     WANG J Y, TANG H J, WANG H, YU R B, WANG D. Multi-shelled hollow micro-/nanostructures: Promising platforms for lithium-ion batteries[J]. Mater. Chem. Front., 2017, 1(3): 414-430 doi: 10.1039/C6QM00273K

  5. [5]

     ZHU M Y, TANG J J, WEI W J, LI S J. Recent progress in the syntheses and applications of multishelled hollow nanostructures[J]. Mater. Chem. Front., 2020, 4(4): 1105-1149 doi: 10.1039/C9QM00700H

  6. [6]

     ZHAO J L, YANG M, YANG N L, WANG J Y, WANG D. Hollow micro-/nanostructure reviving lithium-sulfur batteries[J]. Chem. Res. Chin. Univ., 2020, 36(3): 313-319 doi: 10.1007/s40242-020-0115-2

  7. [7]

     WANG Z, YANG N L, WANG D. When hollow multishelled structures (HoMSs) meet metal-organic frameworks (MOFs)[J]. Chem. Sci., 2020, 11(21): 5359-5368 doi: 10.1039/D0SC01284J

  8. [8]

     MAO D, WANG C, Li W, ZHOU L, LIU J, ZHENG Z J, ZHAO Y, CAO A M, WANG S T, HUANG J X, HOU F W, CHEN H Y, MAI L Q, YU R B, WANG L Z, LU Y F, YU C Z, YANG Q H, YANG Z Z, ZENG H C, ZHAO H J, TANG Z Y, ZHAO D Y, WANG D. Hollow multishelled structure: Synthesis chemistry and application[J]. Chem. Res. Chin. Univ., 2024, 40(3): 346-393 doi: 10.1007/s40242-024-4070-0

  9. [9]

     CHEN X B, YANG N L, WANG Y L, HE H Y, WANG J Y, WAN J W, JIANG H Y, XU B, WANG L M, YU R B, TONG L M, GU L, XIONG Q H, CHEN C Y, ZHANG S J, WANG D. Highly efficient photothermal conversion and water transport during solar evaporation enabled by amorphous hollow multishelled nanocomposites[J]. Adv. Mater., 2022, 34(7): 2107400 doi: 10.1002/adma.202107400

  10. [10]

      WEI Y Z, WAN J W, WANG J Y, ZHANG X, YU R B, YANG N L, WANG D. Hollow multishelled structured SrTiO₃ with La/Rh co-doping for enhanced photocatalytic water splitting under visible light[J]. Small, 2021, 17(22): 2005345 doi: 10.1002/smll.202005345

  11. [11]

      YOU F F, WAN J W, QI J, MAO D, YANG N L, ZHANG Q H, GU L, WANG D. Lattice distortion in hollow multi-shelled structures for efficient visible-light CO₂ reduction with a SnS₂/SnO₂ junction[J]. Angew. Chem.‒Int. Edit., 2020, 59(2): 721-724 doi: 10.1002/anie.201912069

  12. [12]

      WEI Y Z, YOU F F, ZHAO D C, WAN J W, GU L, WANG D. Heterogeneous hollow multi-shelled structures with amorphous-crystalline outer-shells for sequential photoreduction of CO₂[J]. Angew. Chem.‒Int. Edit., 2022, 61(49): e202212049 doi: 10.1002/anie.202212049

  13. [13]

      WANG L, WAN J W, ZHAO Y S, YANG N L, WANG D. Hollow multi-shelled structures of Co₃O₄ dodecahedron with unique crystal orientation for enhanced photocatalytic CO₂ reduction [J]. J. Am. Chem. Soc., 2019, 141(6): 2238-2241 doi: 10.1021/jacs.8b13528

  14. [14]

      HOU P, LI D, YANG N L, WAN J W, ZHANG C H, ZHANG X Q, JIANG H Y, ZHANG Q H, GU L, WANG D. Delicate control on the shell structure of hollow spheres enables tunable mass transport in water splitting[J]. Angew. Chem.‒Int. Edit., 2021, 60(13): 6926-6931 doi: 10.1002/anie.202016285

  15. [15]

      QIN M, ZHANG L M, ZHAO X R, WU H J. Defect induced polarization loss in multi-shelled spinel hollow spheres for electromagnetic wave absorption application[J]. Adv. Sci., 2021, 8(8): 2004640 doi: 10.1002/advs.202004640

  16. [16]

      WANG Z J, QI J, YANG N L, YU R B, WANG D. Core-shell nano/microstructures for heterogeneous tandem catalysis[J]. Mater. Chem. Front., 2021, 5(3): 1126-1139 doi: 10.1039/D0QM00538J

  17. [17]

      DIAZ-LOPEZ E, COMAS-VIVES A. Oxygen electronic character at the interface tunes catalytic selectivity[J]. Chem, 2020, 6(11): 2865-2868 doi: 10.1016/j.chempr.2020.10.013

  18. [18]

      QIAN J F, LIU P, XIAO Y, JIANG Y, CAO Y L, AI X P, YANG H X. TiO₂-coated multilayered SnO₂ hollow microspheres for dye-sensitized solar cells[J]. Adv. Mater., 2009, 21(36): 3663-3667 doi: 10.1002/adma.200900525

  19. [19]

      KIM J W, CHOI S H, LILLEHEI P T, CHU S H, KING G C, WATT G D. Cobalt oxide hollow nanoparticles derived by bio-templating[J]. Chem. Commun., 2005(32): 4101-4103 doi: 10.1039/b505097a

  20. [20]

      YANG M, MA J, NIU Z W, DONG X, XU H F, MENG Z K, JIN Z G, LU Y F, HU Z B, YANG Z Z. Synthesis of spheres with complex structures using hollow latex cages as templates[J]. Adv. Funct. Mater., 2005, 15(9): 1523-1528 doi: 10.1002/adfm.200500070

  21. [21]

      SU F M, WAN J W, WANG D. Hollow multi-shelled structure photoelectric materials: multiple shells bring novel properties[J]. Chem. Res. Chin. Univ., 2024, 40(3): 413-427 doi: 10.1007/s40242-024-4061-1

  22. [22]

      SU F, ZHAO X S, WANG Y, WANG L, LEE J Y. Hollow carbon spheres with a controllable shell structure[J]. J. Mater. Chem., 2006, 16(45): 4413-4419 doi: 10.1039/b609971h

  23. [23]

      XU H L, WANG W Z. Template synthesis of multishelled Cu₂O hollow spheres with a single-crystalline shell wall[J]. Angew. Chem.‒Int. Edit., 2007, 119(9): 1511-1514 doi: 10.1002/ange.200603895

  24. [24]

      WU C Z, ZHANG X D, NING B, YANG J L, XIE Y. Shape evolution of new-phased lepidocrocite VOOH from single-shelled to double-shelled hollow nanospheres on the basis of programmed reaction-temperature strategy[J]. Inorg. Chem., 2009, 48(13): 6044-6054 doi: 10.1021/ic900416v

  25. [25]

      SUN X M, LI Y D. Ga₂O₃ and GaN semiconductor hollow spheres[J]. Angew. Chem.‒Int. Edit., 2004, 43(29): 3827-3831 doi: 10.1002/anie.200353212

  26. [26]

      LI Z M, LAI X Y, WANG H, MAO D, XING C J, WANG D. General synthesis of homogeneous hollow core-shell ferrite microspheres[J]. J. Phys. Chem. C, 2009, 113(7): 2792-2797 doi: 10.1021/jp8094787

  27. [27]

      LAI X Y, LI J, KORGEL B A, DONG Z H, LI Z M, SU F B, DU J, WANG D. General synthesis and gas-sensing properties of multiple-shell metal oxide hollow microspheres[J]. Angew. Chem.‒Int. Edit., 2011, 12(50): 2738-2741

  28. [28]

      WEI Y Z, CHENG Y P, ZHAO D C, FENG Y, WEI P, WANG, J Y, GE W, WANG D. A universal formation mechanism of hollow multi-shelled structures dominated by concentration waves[J]. Angew. Chem.‒Int. Edit., 2023, 62(28): e202302621 doi: 10.1002/anie.202302621

  29. [29]

      WANG J Y, TANG H J, ZHANG L J, REN H, YU R B, JIN Q, QI J, MAO D, YANG M, WANG Y, LIU P R, ZHANG Y, WEN Y R, GU L, MA G H, SU Z G, TANG Z Y, ZHAO H J, WANG D. Multi-shelled metal oxides prepared via an anion-adsorption mechanism for lithium-ion batteries[J]. Nat. Energy, 2016, 1(5): 1-9

  30. [30]

      LI D W, ZHAO X X, YU R B, WANG B, WANG H, WANG D. Formation of multi-shelled nickel-based sulfide hollow spheres for rechargeable alkaline batteries[J]. Inorg. Chem. Front., 2018, 5(3): 535-540 doi: 10.1039/C7QI00760D

  31. [31]

      WILLIAMS B P, YOUNG A P, ANDONI I, HAN Y, LO W S, GOLDEN M, YANG J, LYU L M, KUO C H, EVANS J W, HUANG W Y, TSUNG C K. Strain-enhanced metallic intermixing in shape-controlled multilayered core-shell nanostructures: Toward shaped intermetallics[J]. Angew. Chem.‒Int. Edit., 2020, 59(26): 10574-10580 doi: 10.1002/anie.202001067

  32. [32]

      TAN D X, ZHANG J L, YAO L, TAN X N, CHENG X Y, WAN Q, HAN B X, ZHENG L R, ZHANG J. Multi-shelled CuO microboxes for carbon dioxide reduction to ethylene[J]. Nano Res., 2020, 13(3): 768-774 doi: 10.1007/s12274-020-2692-1

  33. [33]

      ZONG L B, XU J, JIANG S Y, ZHAO K, WANG Z M, LIU P R, ZHAO H J, CHEN J, XING X R, RU R B. Composite yttrium-carbonaceous spheres templated multi-shell YVO₄ hollow spheres with superior upconversion photoluminescence[J]. Adv. Mater., 2017, 29(9): 1604377 doi: 10.1002/adma.201604377

  34. [34]

      JIAO C W, WANG Z M, ZHAO X X, WANG H, WANG J, YU R B, WANG D. Triple-shelled manganese-cobalt oxide hollow dodecahedra with highly enhanced performance for rechargeable alkaline batteries[J]. Angew. Chem.‒Int. Edit., 2019, 58(4): 996-1001 doi: 10.1002/anie.201811683

  35. [35]

      ZHU Y J, YANG M, HUANG Q Y, WANG D R, YU R B, WANG J Y, ZHENG Z J, WANG D. V₂O₅ textile cathodes with high capacity and stability for flexible lithium-ion batteries[J]. Adv. Mater., 2020, 32(7): 1906205 doi: 10.1002/adma.201906205

  36. [36]

      WANG C, WANG J Y, HU W P, WANG D. Controllable synthesis of hollow multishell structured Co₃O₄ with improved rate performance and cyclic stability for supercapacitors[J]. Chem. Res. Chin. Univ., 2020, 36(1): 68-73 doi: 10.1007/s40242-019-0040-3

  37. [37]

      WANG J Y, CUI Y, WANG D. Design of hollow nanostructures for energy storage, conversion and production[J]. Adv. Mater., 2019, 31(38): 1801993 doi: 10.1002/adma.201801993

  38. [38]

      XIE G X, ZHANG J N, MA X B. Compartmentalization of multiple catalysts into outer and inner shells of hollow mesoporous nanospheres for heterogeneous multi-catalyzed/multi-component asymmetric organocascade[J]. ACS Catal., 2019, 9(10): 9081-9086 doi: 10.1021/acscatal.9b01608

  39. [39]

      ZHU W, CHEN Z, PAN Y, DAI R Y, WU Y, ZHUANG Z B, WANG D S, PENG Q, CHEN C, LI Y D. Functionalization of hollow nanomaterials for catalytic applications: Nanoreactor construction[J]. Adv. Mater., 2019, 31(38): 1800426 doi: 10.1002/adma.201800426

  40. [40]

      DENG Z S, CAO J Z, HU S C, WU S Q, XING M Y, ZHANG J L. Combing hollow shell structure and Z-scheme heterojunction construction for promoting CO₂ photoreduction[J]. J. Phys. Chem. C, 2023, 127(17): 8071-8082 doi: 10.1021/acs.jpcc.3c01375

  41. [41]

      WEI Y Z, WAN J W, YANG N L, YANG Y, MA Y W, WANG S C, WANG J Y, YU R B, GU L, WANG L H, WANG L Z, HUANG W, WANG D. Efficient sequential harvesting of solar light by heterogeneous hollow shells with hierarchical pores[J]. Natl. Sci. Rev., 2020, 7(11): 1638-1646 doi: 10.1093/nsr/nwaa059

  42. [42]

      ZHANG H B, ZHOU X D, YUAN M Y, XIONG X H, LV X W, LIU Y H, LV H L, LAI Y X, ZHANG J C, ZHANG H R, PAN D, CHE R C. Highly selective nano-interface engineering in multishelled nanocubes for enhanced broadband electromagnetic attenuation[J]. Adv. Funct. Mater., 2024, 34(17): 2313829 doi: 10.1002/adfm.202313829

  43. [43]

      QIAN X, ZHANG Y H, WU Z C, ZHANG R X, LI X H, WANG M, CHE R C. Multi-path electron transfer in 1D double-shelled Sn@Mo₂C/C tubes with enhanced dielectric loss for boosting microwave absorption performance[J]. Small, 2021, 17(30): 2100283 doi: 10.1002/smll.202100283

  44. [44]

      GAO S W, NV W, LI S, LI D M, CUI Z M, YUE G C, LIU J C, ZHAO X X, JIANG L, ZHAO Y. A multi-wall Sn/SnO₂@carbon hollow nanofiber anode material for high-rate and long-life lithium-ion batteries[J]. Angew. Chem.‒Int. Edit., 2020, 59(6): 2465-2472 doi: 10.1002/anie.201913170

  45. [45]

      WEI P, WANG H, YANG M, WANG J Y, WANG D. Relocatable hollow multishelled structure-based membrane enables dendrite-free lithium deposition for ultrastable lithium metal batteries[J]. Adv. Energy Mater., 2024, 14(22): 2400108 doi: 10.1002/aenm.202400108

  46. [46]

      LI H L, WANG Y T, ZHANG J W, ZHU L, SHI J, CHEN B, HU Y, ZHANG H, DENG X, PENG Y. The design and synthesis of spinel one-dimensional multi-shelled nanostructures for Li-ion batteries[J]. Nanoscale, 2022, 14(20): 7692-7701 doi: 10.1039/D2NR00627H

  47. [47]

      BI R, XU N, REN H, YANG N L, SUN Y G, CAO A M, RU R B, WANG D. A hollow multi-shelled structure for charge transport and active sites in lithium-ion capacitors[J]. Angew. Chem.‒Int. Edit., 2020, 132(12): 4895-4898 doi: 10.1002/ange.201914680

  48. [48]

      ZHAO D C, YANG N L, XU L K, DU J, YANG Y, WANG D. Hollow structures as drug carriers: Recognition, response, and release[J]. Nano Res., 2022: 1-19

  49. [49]

      ZHAO D C, WEI Y Z, JIN Q, YANG N L, YANG Y, WANG D. PEG-functionalized hollow multishelled structures with on-off switch and rate-regulation for controllable antimicrobial release[J]. Angew. Chem.‒Int. Edit., 2022, 61(36): e202206807 doi: 10.1002/anie.202206807

  50. [50]

      ZHAO D C, WEI Y Z, XIONG J, GAO C S, WANG D. Response and regulation of the microenvironment based on hollow structured drug delivery systems[J]. Adv. Funct. Mater., 2023, 33(31): 2300681 doi: 10.1002/adfm.202300681

  51. [51]

      DU L Y, WANG D X, GU K K, ZHANG M Z. Construction of PdO-decorated double-shell ZnSnO₃ hollow microspheres for n-propanol detection at low temperature[J]. Inorg. Chem. Front., 2021, 8(3): 787-795 doi: 10.1039/D0QI01292K

  52. [52]

      CHEN Q, ZHANG Y H, MA S Y, WANG Y H, WANG P Y, ZHANG G H, GENGZANG D J, JIAO H Y, WANG M X, CHEN W J. Multishelled NiO/NiCo₂O₄ hollow microspheres derived from bimetal-organic frameworks as high-performance sensing material for acetone detection[J]. J. Hazard. Mater., 2021, 415: 125662 doi: 10.1016/j.jhazmat.2021.125662

  53. [53]

      LIEN D H, DONG Z H, RETAMAL J R D, WANG H P, WEI T C, WANG D, HE J H, CUI Y. Resonance-enhanced absorption in hollow nanoshell spheres with omnidirectional detection and high responsivity and speed[J]. Adv. Mater., 2018, 30(34): 1801972 doi: 10.1002/adma.201801972

  54. [54]

      SONG D D, XU X Y, HUANG X G, LI G Q, ZHAO Y S, GAO F M. Oriented design of transition-metal-oxide hollow multishelled micropolyhedron derived from bimetal-organic frameworks for the electrochemical detection of multipesticide residues[J]. J Agric. Food Chem., 2023, 71(5): 2600-2609 doi: 10.1021/acs.jafc.2c08818

  55. [55]

      XU K, KAN Z W, ZHANG F Y, QU Y, LI S Q, LIU S. Hollow multi-shelled structural SnO₂ with multiple spatial confinement for ethanol gas sensing[J]. Mater. Lett., 2023, 338: 134070 doi: 10.1016/j.matlet.2023.134070

  56. [56]

      WANG Y Z, LIU C B, QIAO L, ZENG Y, TIAN H W, ZHENG W T. Localized inside-out Ostwald ripening of hybrid double-shelled cages into SnO₂ triple-shelled hollow cubes for improved toluene detection[J]. Nanoscale, 2020, 12(3): 2011-2021 doi: 10.1039/C9NR07489A

  57. [57]

      REN H, YU R B, QI J, ZHANG L J, JIN Q, WANG D. Hollow multishelled heterostructured anatase/TiO₂(B) with superior rate capability and cycling performance[J]. Adv. Mater., 2019, 31(10): 1805754 doi: 10.1002/adma.201805754

  58. [58]

      WANG H, MAO D, QI J, ZHANG Q H, MA X H, SONG S Y, GU L, YU R B, WANG D. Hollow multishelled structure of heterogeneous Co₃O₄-CeO_2-x nanocomposite for CO catalytic oxidation[J]. Adv. Funct. Mater., 2019, 29(15): 1806588 doi: 10.1002/adfm.201806588

  59. [59]

      WANG C R, ZHANG L, AL-MAMUN M, DOU Y H, SU D W, WANG G X, ZHANG S Q, WANG D, ZHAO H J. A hollow-shell structured V₂O₅ electrode-based symmetric full Li-ion battery with highest capacity[J]. Adv. Energy Mater., 2019, 9(31): 1900909 doi: 10.1002/aenm.201900909

  60. [60]

      LI M, MAO D, WAN J W, WANG K F, ZHAI T Y, WANG D. Hollow multi-shell structured SnO₂ with enhanced performance for ultraviolet photodetectors[J]. Inorg. Chem. Front., 2019, 6(8): 1968-1972 doi: 10.1039/C9QI00490D

  61. [61]

      WEI Y Z, WANG J Y, YU R B, WAN J W, WANG D. Constructing SrTiO₃-TiO₂ heterogeneous hollow multi-shelled structures for enhanced solar water splitting[J]. Angew. Chem.‒Int. Edit., 2019, 58(5): 1422-1426 doi: 10.1002/anie.201812364

  62. [62]

      唐佳易, 姚俊杰, 张晓君, 马梁, 张婷妹, 牛峥, 陈祥祯, 赵亮, 江林, 孙迎辉. 多壳层中空FeP微球的制备及全pH范围的电催化产氢性能[J]. 高等学校化学学报, 2019, 40(11): 2340-2347TANG J Y, YAO J J, ZHANG X J, MA L, ZHANG T M, NIU Z, CHEN X Z, ZHAO L, JIANG L, SUN Y H. Multi-shell hollow FeP microspheres as efficient electrocatalyst for hydrogen evolution at all pH values[J]. Chem. J. Chinese Universities, 2019, 40(11): 2340-2347

  63. [63]

      CHEN H R, SHEN K, TAN Y P, LI Y W. Multishell hollow metal/ nitrogen/carbon dodecahedrons with precisely controlled architectures and synergistically enhanced catalytic properties[J]. ACS Nano, 2019, 13(7): 7800-7810 doi: 10.1021/acsnano.9b01953

  64. [64]

      MA X M, ZHANG X T, YANG L, WANG G, JIANG K, WU G, CUI W G, WEI Z P. Tunable construction of multi-shelled hollow carbonate nanospheres and their potential applications[J]. Nanoscale, 2016, 8(16): 8687-8695 doi: 10.1039/C6NR00866F

  65. [65]

      BIE S Y, ZHU Y Q, SU J M, JIN C, LIU S H, YANG R Z, WU J. One-pot fabrication of yolk-shell structured La_0.9Sr_0.1CoO₃ perovskite microspheres with enhanced catalytic activities for oxygen reduction and evolution reactions[J]. J. Mater. Chem. A, 2015, 3(44): 22448-22453 doi: 10.1039/C5TA05271H

  66. [66]

      ZHAO Y, WU W L, LI J X, XU Z C, GUAN L H. Encapsulating MWNTs into hollow porous carbon nanotubes: A tube-in-tube carbon nanostructure for high-performance lithium-sulfur batteries[J]. Adv. Mater., 2014, 26(30): 5113-5118 doi: 10.1002/adma.201401191

  67. [67]

      PANG R, HU X J, ZHOU S Y, SUN C H, YAN J, SUN X M, XIAO S Z, CHEN P. Preparation of multi-shelled conductive polymer hollow microspheres by using Fe₃O₄ hollow spheres as sacrificial templates[J]. Chem. Commun., 2014, 50(83): 12493-12496 doi: 10.1039/C4CC05469E

  68. [68]

      LIAO Y L, ZHANG H W, QUE W X, ZHONG P, BAI F M, ZONG Z Y, WEN Q Y, CHEN W H. Activating the single-crystal TiO₂ nanoparticle film with exposed {001} facets[J]. ACS Appl. Mater. Inter., 2013, 5(14): 6463-6466 doi: 10.1021/am401869e

  69. [69]

      QIN B, WANG Q, YAO W Q, CAI Y F, CHEN Y H, WANG P C, ZOU Y C, ZHENG X H, CAO J, QI J L, CAI W. Heterostructured Mn₃O₄-MnS multi-shelled hollow spheres for enhanced polysulfide regulation in lithium-sulfur batteries[J]. Energy Environm. Mater., 2023, 6(6): e12475 doi: 10.1002/eem2.12475

  70. [70]

      HE R H, LI S D, LIU H Y, ZHOU L. Hetero-structured Fe-Cr-O hollow multishelled spheres for stable sodium storage[J]. Mater. Chem. Front., 2022, 6(14): 1903-1911 doi: 10.1039/D2QM00295G

  71. [71]

      PARVIN N, MERUM D, MANDAL T K, JOO S W. Tunable synthesis of bimetallic hybrid multishelled hollow structure for high-performance aqueous alkaline batteries[J]. J. Energy Storage, 2023, 71: 108195 doi: 10.1016/j.est.2023.108195

  72. [72]

      HOU X Y, ZHOU G, AI D D, XI R H, YUAN Y X, KANG J L, CHEN H, TIAN J M, WANG J T. Hollow multi-shelled spherical Co₃O₄/CNTs composite as a superior anode material for lithium-ion batteries[J]. J. Alloys Compd, 2023, 967: 171649 doi: 10.1016/j.jallcom.2023.171649

  73. [73]

      ZHAN S H, CHEN X B, XU B, WANG L, TONG L M, YU R B, YANG N L, WANG D. Hollow multishelled structured graphdiyne realized radioactive water safe-discharging[J]. Nano Today, 2022, 47: 101626 doi: 10.1016/j.nantod.2022.101626

  74. [74]

      LI B, WANG J Y, BI R Y, YANG N L, WAN J W, JIANG H Y, GU L, DU J, CAO A M, GAO W, WANG D. Accurately localizing multiple nanoparticles in a multishelled matrix through shell-to-core evolution for maximizing energy-storage capability[J]. Adv. Mater., 2022, 34(18): 2200206 doi: 10.1002/adma.202200206

  75. [75]

      YANG H G, ZENG H C. Preparation of hollow anatase TiO₂ nanospheres via Ostwald ripening[J]. J. Phys. Chem. B, 2004, 108(11): 3492-3495 doi: 10.1021/jp0377782

  76. [76]

      LIU B, ZENG H C. Symmetric and asymmetric Ostwald ripening in the fabrication of homogeneous core-shell semiconductors[J]. Small, 2005, 1(5): 566-571 doi: 10.1002/smll.200500020

  77. [77]

      WANG H, QI J, YANG N L, CUI W, WANG J Y, LI Q H, ZHANG Q H, YU X Q, GU L, LI J, YU R B, HUANG K K, SONG S Y, FENG S H, WANG D. Dual-defects adjusted crystal-field splitting of LaCo_1-xNi_xO_3-δ hollow multishelled structures for efficient oxygen evolution[J]. Angew. Chem.‒Int. Edit., 2020, 59(44): 19691-19695 doi: 10.1002/anie.202007077

  78. [78]

      ZHANG X, BI R Y, WANG J Y, ZHENG M, WANG J, YU R B, WANG D. Delicate Co-control of shell structure and sulfur vacancies in interlayer-expanded tungsten disulfide hollow sphere for fast and stable sodium storage[J]. Adv. Mater., 2023, 35(7): 2209354 doi: 10.1002/adma.202209354

  79. [79]

      WANG Z J, WEI Y Z, QI J, WANG J W, WANG Z M, YU R B, WANG D. Mass transfer modulation by hollow multi-shelled structures for high space-time yield synthesis of light olefins from syngas[J]. Adv. Funct. Mater., 2024, 34(27): 2316547 doi: 10.1002/adfm.202316547

  80. [80]

      ZHANG H G, ZHU Q S, ZHANG Y, WANG Y, ZHAO L, YU B. One-pot synthesis and hierarchical assembly of hollow Cu₂O microspheres with nanocrystals-composed porous multishell and their gas-sensing properties[J]. Adv. Funct. Mater., 2007, 17(15): 2766-2771 doi: 10.1002/adfm.200601146

  81. [81]

      LI B T, HUANG J, WANG X J. Copper-cobalt bimetallic oxides-doped alumina hollow spheres: A highly efficient catalyst for epoxidation of styrene[J]. Chem. Res. Chin. Univ., 2019, 35(1): 125-132 doi: 10.1007/s40242-018-8158-2

  82. [82]

      REN H, SUN J J, YU R B, YANG M, GU L, LIU P R, ZHAO H J, KISAILUS D, WANG D. Controllable synthesis of mesostructures from TiO₂ hollow to porous nanospheres with superior rate performance for lithium ion batteries[J]. Chem. Sci., 2016, 7(1): 793-798 doi: 10.1039/C5SC03203B

  83. [83]

      YANG W Z, YANG J, DONG Y Z, MAO S M, GAO Z Z, YUE Z F, DILLON S J, XU H X, XU B X. Probing buckling and post-buckling deformation of hollow amorphous carbon nanospheres: In-situ experiment and theoretical analysis[J]. Carbon, 2018, 137: 411-418 doi: 10.1016/j.carbon.2018.05.047

  84. [84]

      ZHANG H, ZHANG S C, GUO B Y, YU L J, MA L L, HOU B X, LIU H Y, ZHANG S H, WANG J Y, SONG J J, TANG Y F, ZHAO X X. MoS₂ hollow multishelled nanospheres doped Fe single atoms capable of fast phase transformation for fast-charging Na-ion batteries[J]. Angew. Chem.‒Int. Edit., 2024, 63(17): e202400285 doi: 10.1002/anie.202400285

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  Figure 1  (a) Varied HoMS functions through modification^[2]; (b) Adsorption of ions on CMS surface during HoMS synthesis^[29]; (c) Formation mechanism of HoMS^[27]; (d) Schematic diagram of C_r, R_sf, and R_tr on CMS

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  Figure 2  (a) Mathematic model of the HoMS simulating formation process; (b) σ evolution during template removal in STA; (c) Correlation between concentration waves and the formation of HoMS; Formation of (d) Cu₂S HoMS and (e) CaCO₃ HoMS (scale bar: 200 nm)^[28]

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  Figure 3  (a) Effect of La doping on the electron configuration of 3S-LC-HoMSs^[77]; (b) Related atom model atthe interface between SnS₂ and SnO₂ in atomic scale^[11]; (c) Rearrangement of Co atoms to obtain different crystal faces^[13]

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  Figure 4  (a) Illustration of the formation process of CoP HoMSs with different micro-/nano-structures of shells^[14]; (b) Schematic illustration of STO catalyzed by ZnCrO_x HoMS/SAPO with high space velocity^[79]; (c) Schematic of highly efficient solar-to-vapor generation via amorphous Ta₂O₅/C HoMS^[9]; (d) Schematic illustration of the formation of Sn NPs@N_xC HoMS-DL inherited from SnO₂@PDA HoMS through in situ evolution of SnO₂ shell to Sn cores^[74]

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  Figure 5  (a) Schematic of mass transfer through space with different structures^[2]; (b) CO₂ in series catalyzes gradual reduction to CH₄^[12]; (c) Efficient sequential harvesting of solar light by heterogeneous hollow shells with hierarchical pores^[41]

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