Construction of Grape-like Silica-Based Hierarchical Porous Interlocked Microcapsules by Colloidal Crystals Templates

Controllable Preparation of Monodisperse Mesoporous Silica from Microspheres to Microcapsules and Catalytic Loading of Au Nanoparticles

A unique structural transition from pomegranate-like monodisperse mesoporous silica microspheres (M-MSMs) with tunable mesopores to mesoporous silica microcapsules has been reported. The unique evolution occurred together with varying the cross-linking degrees (CLDs) of templates. Herein, using monodisperse sulfonated cross-linked polystyrene (S-CLPS) as templates, S-CLPS/SiO₂ composite microspheres were synthesized by the sol-gel method. Subsequently, the templates were removed by calcination to obtain the M-MSMs or microcapsules. The pore sizes of M-MSMs could be tailored from 3.2 to 7.4 nm by facilely varying the CLDs from 0.5 to 20%. Interestingly, mesoporous silica microcapsules were gradually formed when the CLDs were beyond 20%. Meanwhile, the specific surface area also could be adjusted by this strategy without hardly affecting the monodispersity, and the specific surface area increased to 391.9 m²/g. Significantly, Au@M-MSM was prepared by supporting Au nanoparticles (NPs) on M-MSM and used as nanocatalysts to reduce 4-nitrophenol (4-NP). The ultrathin shell and interconnected three-dimensional (3D) porous structure of M-MSMs can increase the mass transfer and protect the Au NPs from leakage, which reveals high recyclability and high conversion (>95%) after 10 regeneration-catalysis cycles. This approach provides a nanotechnology platform for the preparation of mesoporous silica materials with different microstructures, which will have enormous potential in practical applications involving different molecular sizes.

Synthesis of 3D-Ordered Macro/Microporous Yolk-Shelled Nanoreactor with Spatially Separated Functionalities for Cascade Reaction

Constructing three-dimensional (3D) hierarchical materials with spatial compartmentalization of multiple catalytic functionalities effectively facilitates the chemical processes' intensification, especially for bulky-molecule-involved cascade reaction. Herein, a facile and novel core-shell colloidal crystal templating strategy was developed to synthesize highly ordered arrays of integrated yolk-shelled nanoreactor consisting of monolithically interconnected ZIF-8 shell and sulfonated polystyrene yolks decorated with rhodium nanoparticles. The obtained nanoreactor achieves efficient catalytic one-pot cascade Knoevenagel condensation-hydrogenation reactions for larger molecules, by taking advantage of the superior mass diffusion properties of the hierarchical macro/microporous metal-organic framework (MOF) skeleton, robust monolith nature, and spatially separated functionalities. This work offers an important strategy for preparing MOF-based composites with a hierarchical framework, accelerating various applications of MOFs, such as electrochemical applications, photothermal conversion, and heterogeneous catalysis.

One-Step Synthesis of Hydrophobic Multicompartment Organosilica Microspheres with Highly Interconnected Macro-mesopores for the Stabilization of Liquid Marbles with Excellent Catalysis

The combination of an emulsion template with polymerization is a very convenient approach to the one-step realization of both simple control porous structures via a change in emulsion formulation and easy functionalization via the concomitant choice of an on-demand monomer. A major challenge of this approach is the inherent instability of the oil/water interface in emulsions, especially the occurrence of chemical reactions in oil or aqueous phases. This study reports the pioneering preparation of highly interconnected macro-mesopores and multicompartment (HIMC) vinyl organosilica microspheres with hydrophobicity by the one-step formation of W/O/W emulsions acting as a template. The emulsion system consists of acidified deionized water, a stabilizer, and vinyltriethoxysilane (VTEO) in which VTEO can be used to produce an organosilica skeleton of the resultant microsphere by a sol-gel process. The study demonstrated that the marvelous stability of W/O/W emulsions aids the formation of multicompartment organosilica microspheres with highly interconnected macro-mesopores by emulsion droplets rather than single-compartment (SC) microspheres. Meanwhile, the internal porous structure and surface morphology of as-prepared organosilica microspheres could be largely tuned by a simple variation of the pH value, the volume fraction of the water phase, and the stabilizer concentration in the initiating multiemulsions. Benefiting from such a well-orchestrated structure and the existence of numerous vinyl groups on the surface, HIMC organosilica microspheres exhibit very high hydrophobicity (with a water contact angle larger than 160°), which allows them to stabilize liquid marbles with excellent stability and high mechanical robustness. Because of its strong catalyst, Ag nanoparticles within HIMC organosilica microspheres enable Ag/HIMC-vinyl organosilica microsphere-based liquid marbles to be an efficient catalytic microreactor, realizing the complete degradation of MB to leuco methylene blue by NaBH₄ in 10 min. The result of this work could provide some guidance for the easy, low-cost, benign preparation of HIMC microspheres having the potential to be excellent supporter of metal nanoparticles or other functionalized compounds for applications in sensing, optoelectronics, and catalysis.

Silica-based hierarchical porous Janus microcapsules: construction and support of Au nano-particle catalyst inside

A facile and novel method was developed to fabricate silica-based hierarchical porous Janus microcapsules (HPJMs SiO₂) for catalysis.

Self-assembly of hollow spherical nanocatalysts with encapsulated Pt NPs and the effect of Ce-dipping on catalytic activity

This article reports a facile and controllable one-step method to construct Pt@hollow mesoporous SiO₂ (Pt@HMSiO₂) nanoparticles (NPs).

Microporous organic nanotube network supported acid and base catalyst system for one-pot cascade reactions

Acid/base functionalized microporous organic nanotube networks with excellent catalytic performance for one-pot cascade reactions were successfully prepared.