Ultrasmall Metal Nanoparticles Confined within Crystalline Nanoporous Materials: A Fascinating Class of Nanocatalysts

Bioinspired Pd-Cu Alloy Nanoparticles as Accept Agent for Dye Degradation Performances

Dye degradation is a key reaction in organic decomposition production through electron donor transferring. Palladium (Pd) is the best-known element for synthesis Pd-based catalyst, the surface status determines the scope of relative applications. Here we first prepare Pd-Cu alloy nanoparticles (NPs) by co-reduction of Cu(acac)₂ (acac = acetylacetonate) and Pd(C₅HF₆O₂)₂ in the presence of sodium borohydride (NaBH₄) and glutathione (GSH). The obtained Pd-Cu is about ~10 nm with super-hydrophilicity in aqueous mediums. The structural analysis clearly demonstrated the uniform distribution of Pd and Cu element. The colloidal solution keeps stability even during 30 days. Bimetallic Pd-Cu NPs shows biocompatibility in form of cell lines (IMEF, HACAT, and 239 T) exposed to colloidal solution (50 µg mL^-1) for 2 days. It shows the catalytic multi-performance for dye degradation such as methyl orange (MO), rhodamine B (RhB), and methylene blue (MB), respectively. The as-synthesized nanoparticles showed one of the best multiple catalytic activities in the industrially important (electro)-catalytic reduction of 4-nitrophenol (4-NP) to corresponding amines with noticeable reduced reaction time and increased rate constant without the use of any large area support. In addition, it exhibits peroxidase-like activity in the 3, 3', 5, 5'-Tetramethylbenzidine (TMB) color test and exhibit obvious difference with previous individual metal materials. By treated with high intensity focused ultrasound filed (HIFU), Pd-Cu NPs might be recrystallized and decreased the diameters than before. The enhancement in catalytic performance is observed obviously. This work expedites rational design and synthesis of the high-hierarchy alloy catalyst for biological and environment-friendly agents.

Metal-Organic Framework Accelerated One-Step Capture and Reduction of Palladium to Catalytically Active Nanoparticles

Recovery of noble metals and in situ transforming to functional materials hold great promise in the sustainability of natural resources but remain as a challenge. Herein, the variable chemical microenvironments created by the inorganic-organic hybrid composition of metal-organic frameworks (MOFs) were exploited to tune the metal-support interactions, thus establishing an integrated strategy for recovering and reducing palladium (Pd). Assisted by sonic waves and alcoholic solvent, selective capture of Pd(II) from a complicated matrix to directly afford Pd nanoparticles (NPs) in MOFs can be achieved in one step within several minutes. Mechanism investigation reveals that the Pd binding site and the energy barriers between ionic and metallic status are sensitive to chemical environments in different frameworks. Thanks to the clean, dispersive, and uniform nature of Pd NPs, Pd@MOFs synthesized from a complicated environment exhibited high catalytic activity toward 4-nitrophenol reduction and Suzuki coupling reactions.

Dramatic Enhancement of Thermoelectric Performance in PbTe by Unconventional Grain Shrinking in the Sintering Process

Nanostructure engineering is a key strategy for tailoring properties in the fields of batteries, solar cells, thermoelectrics, and so on. Limited by grain coarsening, however, the nanostructure effect gradually degrades during the materials' manufacturing and in-service period. Herein, a strategy of cleavage-fracture for grain shrinking is developed in a Pb_0.98 Sb_0.02 Te sample during sintering, and the grain size remains stable after repeated tests. Moreover, the initial grain boundary is filled by fractured slender grains and enriched by dislocations, evolving into a hierarchical grain-boundary structure. The lattice thermal conductivity (k_lat ) is greatly reduced to approach the amorphous limit. As a result, a record-high ZT value of ≈1.9 is obtained at 815 K in the n-type Pb_0.98 Sb_0.02 Te sample and a decent efficiency of 6.7% in thermoelectric device. This strategy for grain shrinking will shed light on the application of nanostructure engineering under high temperature and extreme conditions in other material systems.

Metal Sites in Zeolites: Synthesis, Characterization, and Catalysis

Zeolites with ordered microporous systems, distinct framework topologies, good spatial nanoconfinement effects, and superior (hydro)thermal stability are an ideal scaffold for planting diverse active metal species, including single sites, clusters, and nanoparticles in the framework and framework-associated sites and extra-framework positions, thus affording the metal-in-zeolite catalysts outstanding activity, unique shape selectivity, and enhanced stability and recyclability in the processes of Brønsted acid-, Lewis acid-, and extra-framework metal-catalyzed reactions. Especially, thanks to the advances in zeolite synthesis and characterization techniques in recent years, zeolite-confined extra-framework metal catalysts (denoted as metal@zeolite composites) have experienced rapid development in heterogeneous catalysis, owing to the combination of the merits of both active metal sites and zeolite intrinsic properties. In this review, we will present the recent developments of synthesis strategies for incorporating and tailoring of active metal sites in zeolites and advanced characterization techniques for identification of the location, distribution, and coordination environment of metal species in zeolites. Furthermore, the catalytic applications of metal-in-zeolite catalysts are demonstrated, with an emphasis on the metal@zeolite composites in hydrogenation, dehydrogenation, and oxidation reactions. Finally, we point out the current challenges and future perspectives on precise synthesis, atomic level identification, and practical application of the metal-in-zeolite catalyst system.

Highly Efficient MOF-Driven Silver Subnanometer Clusters for the Catalytic Buchner Ring Expansion Reaction

The preparation of novel efficient catalysts—that could be applicable in industrially important chemical processes—has attracted great interest. Small subnanometer metal clusters can exhibit outstanding catalytic capabilities, and thus, research efforts have been devoted, recently, to synthesize novel catalysts bearing such active sites. Here, we report the gram-scale preparation of Ag₂⁰ subnanometer clusters within the channels of a highly crystalline three-dimensional anionic metal–organic framework, with the formula [Ag₂⁰]@Ag^I₂Na^I₂{Ni^II₄[Cu^II₂(Me₃mpba)₂]₃}·48H₂O [Me₃mpba^4– = N,N′-2,4,6-trimethyl-1,3-phenylenebis(oxamate)]. The resulting crystalline solid catalyst—fully characterized with the help of single-crystal X-ray diffraction—exhibits high catalytic activity for the catalytic Buchner ring expansion reaction.

The present work describes the MOF-driven preparation of well-defined ligand-free Ag₂⁰ nanoclusters, which are efficiently stabilized by the MOF channels. The small Ag₂⁰ nanoclusters, prepared in the gram scale, are used as efficient and recoverable catalysts for the Buchner ring expansion reaction. These results expand the toolkit of readily affordable Ag species for heterogeneous catalysis in organic synthesis.

Atomic Insight into the Local Structure and Microenvironment of Isolated Co-Motifs in MFI Zeolite Frameworks for Propane Dehydrogenation

Embedding metal species into zeolite frameworks can create framework-bond metal sites in a confined microenvironment. The metals sitting in the specific T sites of zeolites and their crystalline surroundings are both committed to the interaction with the reactant, participation in the activation, and transient state achievement during the whole catalytic process. Herein, we construct isolated Co-motifs into purely siliceous MFI zeolite frameworks (Co-MFI) and reveal the location and microenvironment of the isolated Co active center in the MFI zeolite framework particularly beneficial for propane dehydrogenation (PDH). The isolated Co-motif with the distorted tetrahedral structure ({(≡SiO)₂Co(HO-Si≡)₂}, two Co-O-Si bonds, and two pseudobridging hydroxyls (Co···OH-Si) is located at T₁₍₇₎ and T₃₍₉₎ sites of the MFI zeolite. DFT calculations and deuterium-labeling reactions verify that the isolated Co-motif together with the MFI microenvironment collectively promotes the PDH reaction by providing an exclusive microenvironment to preactivate C₃H₈, polarizing the oxygen in Co-O-Si bonds to accept H* ({(≡SiO)CoH^δ- (H^δ+O-Si≡)₃}), and a scaffold structure to stabilize the C₃H₇* intermediate. The Co-motif active center in Co-MFI goes through the dynamic evolutions and restoration in electronic states and coordination states in a continuous and repetitive way, which meets the requirements from the series of elementary steps in the PDH catalytic cycle and fulfills the successful catalysis like enzyme catalysis.

Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications

Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications.

Nanopores of a Covalent Organic Framework: A Customizable Vessel for Organocatalysis

Covalent organic frameworks (COFs) as crystalline polymers possess ordered nanochannels. When their channels are adorned with catalytically active functional groups, their highly insoluble and fluffy powder texture makes them apt heterogeneous catalysts that can be dispersed in a range of solvents and heated to high temperatures (80-180 °C). This would mean very high catalyst density, facile active-site access, and easy separation leading to high isolated yields. Different approaches have been devised to anchor or disperse the catalytic sites into the nanospaces offered by the COF pores. Such engineered COFs have been investigated as catalysts for many organic transformation reactions. These range from Suzuki-Miyaura coupling, Heck coupling, Knoevenagel condensation, Michael addition, alkene epoxidation, CO2 utilization, and more complex biomimetic catalysis. Such catalysts employ COF as a "passive" support that merely docks catalytically active inorganic clusters, or in other cases, the COF itself participates as an "active" support by altering the electronics of the inorganic catalytic sites through the redox activity of its framework. Even more, catalytic organic pockets or metal complexes have been directly tethered to COF walls to make them behave like single-site organocatalysts. Here, we have listed most COF-based organic transformations by categorizing them as metal-free non-noble-metal@COF and noble-metal@COF. The initial part of this review highlights the advantages of COFs as a component of a heterogeneous catalyst, while the latter part discusses all of the current literature on this topic.

Metal-Organic Framework-Based Nanoheater with Photo-Triggered Cascade Effects for On-Demand Suppression of Cellular Thermoresistance and Synergistic Cancer Therapy

Nanomedicine with stable light-heat conversion and spatiotemporally controllable drug activation is crucial for the success of photothermal therapy (PTT). Herein, a metal-organic framework (MOF)-based nanoheater with light-triggered multi-responsiveness is engineered to in-situ and on-demand sensitize cancer cells to local hyperthermia. Well-dispersed platinum nanoparticles synthesized inside nanospaces of the MOF are employed as the near-infrared (NIR)-harvesting unit with stable and high light-heat conversion performance. A conformation switchable polymer shell is constructed as a secondary light-responding unit to gate the targeted activation of a molecular inhibitor against thermoresistance. By cascade transformation of light stimuli to downstream signals, the nanoheater enables inhibitor release to go with local heating at the same time restricted in lesion sites to maximize efficacy and minimize systemic toxicity. The efficient photothermal conversion and the blockage of cellular heat-protective pathways provide a dual-mode of action which selectively sensitizes cancer cells to hyperthermia in a spatiotemporally controlled manner. With NIR as the remote switch, the MOF-based nanosystem demonstrates localized and boosted PTT efficacy against cancer both in vitro and in vivo. These results present nanosized MOFs as tailorable and versatile platforms for synergistic and precise cancer therapy.

Direct Electrodeposition of Bimetallic Nanostructures on Co-Based MOFs for Electrochemical Sensing of Hydrogen Peroxide

Hydrogen peroxide (H₂O₂) is the most significant reactive oxygen species in biological systems. Here, we reported an electrochemical sensor for the detection of H₂O₂ on the basis of bimetallic gold-platinum nanoparticles (Au₃Pt₇ NPs) supported by Co-based metal organic frameworks (Co-MOFs). First, Au₃Pt₇ NPs, with optimal electrocatalytic activity and accessible active surface, can be deposited on the surface of the Co-MOF–modified glassy carbon electrodes (Au₃Pt₇/Co-MOFs/GCE) by one-step electrodeposition method. Then, the electrochemical results demonstrated that the two-dimensional (2D) Co-MOF nanosheets as the supporting material displayed better electrocatalytic properties than the 3D Co-MOF crystals for reduction of H₂O₂. The fabricated Au₃Pt₇/2D Co-MOF exhibited high electrocatalytic activity, and the catalytic current was linear with H₂O₂ concentration from 0.1 μM to 5 mM, and 5–60 mM with a low detection limit of 0.02 μM (S/N = 3). The remarkable electroanalytical performance of Au₃Pt₇/2D Co-MOF can be attributed to the synergistic effect of the high dispersion of the Au₃Pt₇ NPs with the marvelous electrochemical properties and the 2D Co-MOF with high-specific surface areas. Furthermore, this sensor has been utilized to detect H₂O₂ concentrations released from the human Hela cells. This work provides a new method for improving the performance of electrochemical sensors by choosing the proper support materials from diverse crystal morphology materials.

DNA-Assisted Creation of a Library of Ultrasmall Multimetal/Metal Oxide Nanoparticles Confined in Silica

Supported ultrasmall metal/metal oxide nanoparticles (UMNPs) with sizes in the range of 1-5 nm exhibit unique properties in sensing, catalysis, biomedicine, etc. However, the metal-support and metal-metal precursor interactions were not as well controlled to stabilize the metal nanoparticles on/in the supports. Herein, DNA is chosen as a template and a ligand for the silica-supported UMNPs, taking full use of its binding ability to metal ions via either electrostatic or coordination interactions. UMNPs thus are highly dispersed in silica via self-assembly of DNA and DNA-metal ion interactions with the assistance of a co-structural directing agent (CSDA). A large number of metal ions are easily retained in the mesostructured DNA-silica materials, and their growth is controlled by the channels after calcination. Based on this directing concept, a material library, consisting of 50 mono- and 54 bicomponent UMNPs confined within silica and with narrow size distribution, is created. Theoretical calculation proves the indispensability of DNA with combination of several organics in the synthesis of ultrasmall metal nanoparticles. The Pt-silica and Pt/Ni-silica chosen from the library exhibit good catalytic performance for toluene combustion. This generalizable and straightforward synthesis strategy is expected to widen the corresponding applications of supported UMNPs.

Direct assessment of confinement effect in zeolite-encapsulated subnanometric metal species

Subnanometric metal species confined inside the microporous channels/cavities of zeolites have been demonstrated as stable and efficient catalysts. The confinement interaction between the metal species and zeolite framework has been proposed to play the key role for stabilization, though the confinement interaction is elusive to be identified and measured. By combining theoretical calculations, imaging simulation and experimental measurements based on the scanning transmission electron microscopy-integrated differential phase contrast imaging technique, we have studied the location and coordination environment of isolated iridium atoms and clusters confined in zeolite. The image analysis results indicate that the local strain is intimately related to the strength of metal-zeolite interaction and a good correlation is found between the zeolite deformation energy, the charge state of the iridium species and the local absolute strain. The direct observation of confinement with subnanometric metal species encapsulated in zeolites provides insights to understand their structural features and catalytic consequences.

Zeolite-encapsulated metal nanoparticles have important catalytic properties, but their effect on the zeolite local structure has been difficult to characterize. Here the authors, using DFT calculations and scanning transmission electron microscopy, characterize the local strain due to confinement effects in metal-zeolite catalysts.

Confinement synthesis in porous molecule-based materials: a new opportunity for ultrafine nanostructures

A balance between activity and stability is greatly challenging in designing efficient metal nanoparticles (MNPs) for heterogeneous catalysis. Generally, reducing the size of MNPs to the atomic scale can provide high atom utilization, abundant active sites, and special electronic/band structures, for vastly enhancing their catalytic activity. Nevertheless, due to the dramatically increased surface free energy, such ultrafine nanostructures often suffer from severe aggregation and/or structural degradation during synthesis and catalysis, greatly weakening their reactivities, selectivities and stabilities. Porous molecule-based materials (PMMs), mainly including metal-organic frameworks (MOFs), covalent organic frameworks (COFs) and porous organic polymers (POPs) or cages (POCs), exhibit high specific surface areas, high porosity, and tunable molecular confined space, being promising carriers or precursors to construct ultrafine nanostructures. The confinement effects of their nano/sub-nanopores or specific binding sites can not only effectively limit the agglomeration and growth of MNPs during reduction or pyrolysis processes, but also stabilize the resultant ultrafine nanostructures and modulate their electronic structures and stereochemistry in catalysis. In this review, we highlight the latest advancements in the confinement synthesis in PMMs for constructing atomic-scale nanostructures, such as ultrafine MNPs, nanoclusters, and single atoms. Firstly, we illustrated the typical confinement methods for synthesis. Secondly, we discussed different confinement strategies, including PMM-confinement strategy and PMM-confinement pyrolysis strategy, for synthesizing ultrafine nanostructures. Finally, we put forward the challenges and new opportunities for further applications of confinement synthesis in PMMs.

A coordination cage hosting ultrafine and highly catalytically active gold nanoparticles

Ultrafine metal nanoparticles (MNPs) with size <2 nm are of great interest due to their superior catalytic capabilities. Herein, we report the size-controlled synthesis of gold nanoparticles (Au NPs) by using a thiacalixarene-based coordination cage CIAC-108 as a confined host or stabilizer. The Au NPs encapsulated within the cavity of CIAC-108 (Au@CIAC-108) show smaller size (∼1.3 nm) than the ones (∼4.7 nm) anchored on the surface of CIAC-108 (Au/CIAC-108). The cage-embedded Au NPs can be used as a homogeneous catalyst in a mixture of methanol and dichloromethane while as a heterogeneous catalyst in methanol. The homogeneous catalyst Au@CIAC-108-homo exhibits significantly enhanced catalytic activities toward nitroarene reduction and organic dye decomposition, as compared with its larger counterpart Au/CIAC-108-homo and its heterogeneous counterpart Au@CIAC-108-hetero. More importantly, the as-prepared Au@CIAC-108-homo possesses remarkable stability and durability.

The size-controlled synthesis of Au NPs was achieved by using a coordination cage CIAC-108 as a support. The Au NPs encapsulated within the cavity of CIAC-108 show smaller size (∼1.3 nm) than the ones (∼4.7 nm) anchored on the surface of CIAC-108.

Catalytically active Rh species stabilized by zirconium and hafnium on zeolites

Supported subnanometric metal species and metal nanoparticles, prepared through the impregnation method, are widely used in industrial catalysis, but suffering from the poor stability of the metal species to sintering...

Advances in Zeolite-Supported Metal Catalysts for Propane Dehydrogenation

Propylene is one of the building blocks of the modern industrial mansion, which is the feeding stock for polypropylene, acrylonitrile, and other important chemicals. Propane dehydrogenation (PDH) is one of...

A new 2D layered aluminophosphate |Hada|6[Al6(PO4)8](H2O)11 supported highly uniform Ag nanoparticles for 4-nitrophenol reduction

This work presents a new 2D aluminophosphate (ZHKU-1) with inorganic sheets containing a 4,6,12-net in AAAA-stacked sequence. Moreover, small Ag clusters supported on ZHKU-1 exhibit excellent catalytic performance in 4-nitrophenol reduction.

Migration of zeolite-encapsulated Pt and Au under reducing environments

Simulations reveal accelerated migration of Pt@zeolite by reducing adsorbates and the importance of PtCO in early stages of particle growth.

In situ synthesis of Pt nanoparticles encapsulated in Silicalite-1 zeolite via a steam-assisted dry-gel conversion method

In this work, Pt nanoparticles (NPs) were directly encapsulated into MFI-type zeolite (Pt@S-1) via a steam-assisted dry-gel conversion method. The synthesis process included the disaggregation of Pt immobilized SiO2-SH spheres...

Heterogeneous parahydrogen induced polarization on Rh-containing silicalite-1 zeolites: effect of the catalyst structure on signal enhancement

Parahydrogen-induced polarization (PHIP) on Rh-containing silicalite-1 catalysts is studied using both liquid-state and in situ magic angle spinning NMR techniques and the catalyst structure effect is revealed.

OUP accepted manuscript

The rational design synthesis of zeolite catalysts with effective, environmentally benign and atom-economic routes is a major topic in the field of microporous materials, as it would avoid the high labor cost and inefficiency of traditional trial-and-error methods in developing new structures and dispel environmental concerns regarding the industrial mass production of zeolites. Catalytic applications of zeolite materials have expanded from conventional single functionalities, such as solid acids or selective oxidation catalysts to bi/multifunctionalities through combination with metals or metal oxides. This is a response to new requirements from petrochemical and fine chemical industries, such as precise control of product distribution, conversion of low-carbon resources for chemical production, and solutions to increasingly severe environmental problems related to CO₂ and NO_x. Thus, based on the systematic knowledge of zeolite chemistry and science that researchers have acquired in the past half-century and the development requirements, remarkable progress has been made in zeolite synthesis and catalysis in the past 10 years. This includes the manipulation of zeolitic monolayers derived from layered zeolites and germanosilicates to construct novel zeolite materials and effective and green zeolite syntheses as well as the synergistic interaction of zeolites and metal/metal oxides with different space distributions in the conversion of low-carbon resources. With many zeolite catalysts and catalytic processes being developed, our understanding of the close relationship between zeolite synthesis, structure and catalytic properties has deepened. Researchers are gradually approaching the goal of rationally designing zeolite catalysts with precisely controlled activity and selectivity for particular applications.

Layer-by-Layer Growth of Preferred-Oriented MOF Thin Film on Nanowire Array for High-Performance Chemiresistive Sensing

High-quality MOF thin films with high orientation and controlled thickness are extremely desired for applications. However, they have been only successfully fabricated on flat substrates. Those MOF 2D thin films are limited by low exposed area and slow mass transport. To overcome these issues, MOF 3D thin films with good crystallinity, preferred orientation, and precisely controllable thickness in nanoscale were successfully prepared in a controllable layer-by-layer manner on nanowire array substrate for the first time. The as-prepared Cu-HHTP 3D thin film is superior to corresponding 2D thin films and showed one of the highest sensitivity, lowest LOD, and fastest response among all reported chemiresistive NH₃ sensing materials at RT. This work provides a feasible approach to grow preferred-oriented 3D MOF thin film, offering new perspectives for constructing MOF-based heterostructures for advanced applications.

Advances in Catalytic Applications of Zeolite-Supported Metal Catalysts

Zeolites possessing large specific surface areas, ordered micropores, and adjustable acidity/basicity have emerged as ideal supports to immobilize metal species with small sizes and high dispersities. In recent years, the zeolite-supported metal catalysts have been widely used in diverse catalytic processes, showing excellent activity, superior thermal/hydrothermal stability, and unique shape-selectivity. In this review, a comprehensive summary of the state-of-the-art achievements in catalytic applications of zeolite-supported metal catalysts are presented for important heterogeneous catalytic processes in the last five years, mainly including 1) the hydrogenation reactions (e.g., CO/CO₂ hydrogenation, hydrogenation of unsaturated compounds, and hydrogenation of nitrogenous compounds); 2) dehydrogenation reactions (e.g., alkane dehydrogenation and dehydrogenation of chemical hydrogen storage materials); 3) oxidation reactions (e.g., CO oxidation, methane oxidation, and alkene epoxidation); and 4) other reactions (e.g., hydroisomerization reaction and selective catalytic reduction of NO_x with ammonia reaction). Finally, some current limitations and future perspectives on the challenge and opportunity for this subject are pointed out. It is believed that this review will inspire more innovative research on the synthesis and catalysis of zeolite-supported metal catalysts and promote their future developments to meet the emerging demands for practical applications.

Photo-induced synthesis of ternary Pt/rGO/COF photocatalyst with Pt nanoparticles precisely anchored on rGO for efficient visible-light-driven H2 evolution

Covalent organic frameworks (COFs) have been recognized as a new type of promising visible-light-driven photocatalysts for H₂ evolution, while it still is a key point to facilitate the separation and transfer of photoinduced charges for further enhancing their activities. In this work, we fabricated a new type of ternary Pt/rGO/COF photocatalysts with Pt cocatalyst precisely anchored on rGO serving as electron collector for largely enhanced H₂ evolution. A series of ternary hybrid materials were obtained via one-pot photoreduction of Pt⁴⁺ and GO under visible-light irradiation in a solution the same as photocatalytic H₂ evolution reaction and simultaneous self-assembling of rGO/COF heterostructure. No need isolation, the synthetic system could be further used for photocatalytic H₂ evolution reaction and the results show the H₂ evolution rate of Pt/rGO(20%)/TpPa-1-COF hybrid material is 19.59 mmol·g^-1·h^-1, 6.51 times higher than that of Pt/TpPa-1-COF. The essential role of the exclusively distributed Pt nanoparticles on rGO to the high H₂ evolution activity was confirmed by various comparisons of activity for the samples with diverse Pt distribution.

Quantitative Coassembly for Precise Synthesis of Mesoporous Nanospheres with Pore Structure-Dependent Catalytic Performance

Precise synthesis of porous materials is essential for their applications. Self-assembly is a widely used strategy for synthesizing porous materials, but quantitative control of the assembly process still remains a great challenge. Here, a quantitative coassembly approach is developed for synthesizing resin/silica composite and its derived porous spheres. The assembly behaviors of the carbon and silica precursors are regulated without surfactants and the growth kinetics of the composite spheres are quantitatively controlled. This assembly approach enables the precise control of the size and pore structures of the derived carbon spheres. These carbon spheres provide a good platform to explore the structure-performance relationships of porous materials, and demonstrate their pore structure-dependent performance in catalytic water decontamination. This work provides a simple and robust approach for precise synthesis of porous spheres and brings insights into function-oriented design of porous materials.

Mussel-inspired nanozyme catalyzed conductive and self-setting hydrogel for adhesive and antibacterial bioelectronics

Adhesive hydrogels have broad applications ranging from tissue engineering to bioelectronics; however, fabricating adhesive hydrogels with multiple functions remains a challenge. In this study, a mussel-inspired tannic acid chelated-Ag (TA-Ag) nanozyme with peroxidase (POD)-like activity was designed by the in situ reduction of ultrasmall Ag nanoparticles (NPs) with TA. The ultrasmall TA-Ag nanozyme exhibited high catalytic activity to induce hydrogel self-setting without external aid. The nanozyme retained abundant phenolic hydroxyl groups and maintained the dynamic redox balance of phenol-quinone, providing the hydrogels with long-term and repeatable adhesiveness, similar to the adhesion of mussels. The phenolic hydroxyl groups also afforded uniform distribution of the nanozyme in the hydrogel network, thereby improving its mechanical properties and conductivity. Furthermore, the nanozyme endowed the hydrogel with antibacterial activity through synergistic effects of the reactive oxygen species generated via POD-like catalytic reactions and the intrinsic bactericidal activity of Ag. Owing to these advantages, the ultrasmall TA-Ag nanozyme-catalyzed hydrogel could be effectively used as an adhesive, antibacterial, and implantable bioelectrode to detect bio-signals, and as a wound dressing to accelerate tissue regeneration while preventing infection. Therefore, this study provides a promising approach for the fabrication of adhesive hydrogel bioelectronics with multiple functions via mussel-inspired nanozyme catalysis.