Metal–organic frameworks (MOFs) with high porosity and a regular porous structure have emerged as a promising electrode material for supercapacitors, but their poor electrical conductivity limits ...their utilization efficiency and capacitive performance. To increase the overall electrical conductivity as well as the efficiency of MOF particles, three-dimensional networked MOFs are developed via using preprepared conductive polypyrrole (PPy) tubes as the support for in situ growth of MOF particles. As a result, the highly conductive PPy tubes that run through the MOF particles not only increase the electron transfer between MOF particles and maintain the high effective porosity of the MOFs but also endow the MOFs with flexibility. Promoted by such elaborately designed MOF–PPy networks, the specific capacitance of MOF particles has been increased from 99.2 F g–1 for pristine zeolitic imidazolate framework (ZIF)-67 to 597.6 F g–1 for ZIF–PPy networks, indicating the importance of the design of the ZIF–PPy continuous microstructure. Furthermore, a flexible supercapacitor device based on ZIF–PPy networks shows an outstanding areal capacitance of 225.8 mF cm–2, which is far above other MOFs-based supercapacitors reported up to date, confirming the significance of in situ synthetic chemistry as well as the importance of hybrid materials on the nanoscale.
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•A novel in-situ synthesis strategy for preparation of a 0.6 wt% Ir@ZrO2@C.•A highly selective and acid-resistant catalyst for the levulinic acid hydrogenation.•Single atom feature of ...Ir revealed by AC-HAADF-STEM, XPS, IR-CO and H2-TPR.•Ultra-stability in LA-to-GVL hydrogenation under harsh and acidic conditions.•The ultra-stability arises from the well-defined structure of the Ir@ZrO2@C.
The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is a key reaction for the production of renewable chemicals and fuels, wherein acid-resistant and robust catalysts are highly desired for practical usage. Herein, an ultra-stable 0.6 wt% Ir@ZrO2@C single-atom catalyst was prepared via an in-situ synthesis approach during the assembly of UiO-66, followed by confined pyrolysis. The Ir@ZrO2@C offered not only a quantitative LA conversion and an excellent GVL selectivity (>99%), but also an unprecedented stability during recycling runs under harsh conditions (at T = 453 K, PH2 = 40 bar in pH = 3 or pH = 1 aqueous solution). By thorough spectroscopy characterizations, a well-defined structure of atomically dispersed Irδ+ atoms onto nano-tetragonal ZrO2 confined in the amorphous carbon was identified for the Ir@ZrO2@C. The strong metal-support interaction and the confinement of the amorphous carbon account for the ultra-stability of the Ir@ZrO2@C.
This work presents for the first time one-step ultrafast (precursor-free) synthesis of 1D MnFe2O4 (MFO) nanorods and soft magnetic colloidal nanoparticles (NPs) using microwave-assisted hydrothermal ...(MAH) methods, with or without citric acid (CA) as a surfactant (in situ synthesis), respectively. The mechanism of growth of spinel MFO nanostructures during the MAH synthesis was studied by varying synthesis duration (3–6 h) and temperature (180–200 °C). An increase in both the duration and temperature improved the purity of the samples, up to 97%. On the other hand, a temperature increase by 20 °C notably shortened the formation time of MFO nanorods, which have an average diameter and length of less than 20 nm and 350 nm, respectively, as observed at 200 °C after 6 h. All the fabricated MFO NPs with spherical and rod-like morphologies manifested high saturation magnetization in the range of 54–64 emu/g. The chelation of lattice metal ions by CA resulted in the formation of a stable colloid comprising 100% pure spinel MFO NPs with a size of ≤32 ± 10 nm (mean ± SD) and featuring very soft magnetic properties. This colloid was generated by the MAH synthesis at 175 °C within 30 min. Notably, an increase in synthesis duration from 30 min to 3 h diminished MFO phase purity from 100% to 52% and saturation magnetization from 43.4 ± 0.7 to 33.9 ± 2.0 emu/g for CA-functionalized MFO NPs owing to CA degradation increasing during the in situ MAH synthesis with longer duration. This study indicates good potential of ultrafast MAH synthesis for the development of 1D magnetic spinel nanostructures with controllable morphology, size, magnetic properties, and colloidal stability, thereby offering a wide range of applications within the fields of adsorption, catalysis, electronics, and biomedicine.
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•A ZIF-8/PDMS MMM was prepared via in-situ synthesis.•ZIF-8 crystallization and PDMS polymerization were simultaneously started.•The membrane combines both the compactness of PDMS and ...diffusion of ZIF-8.•A 160% of increase in total flux of n-butanol is obtained in comparison with a pure PDMS membrane.
In pervaporation processes, membranes with high flux can relief the cost issue of industry scaling-up due to the required smaller membrane area. Herein, a novel in-situ synthesis (ISS) method was adopted to fabricate ZIF-8/polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) with outstanding permeability. ZIF-8 with high hydrophobicity, benefiting from its flexible pore structure, can provid a suitable pore structure for selectively recovering organic compounds. In the membrane preparation process, the solution C (PDMS/tetraethyl orthosilicate/Zn2+) and solution D (PDMS/dibutyltin dilaurate/2-methylimidazole) were co-processed other at the C-D interface via spin-coating. ZIF-8 crystallization occurred coupled with PDMS polymerization. An effective active layer was formed including (i) continuous and defect-free PDMS layer and (ii) a ZIF-8/PDMS layer that can add passable diffusion channels, which lifted the barrier of physical incorporation of porous materials. Defect-free MMMs based on ISS method possess unprecedented total flux of 2046.3 g/m2 h (1.6 times higher than pure PDMS membrane) and without any decline in separation factor under 20 wt% ZIF-8 loading for n-butanol pervaporation recovery. The ZIF-8/PDMS MMM prepared by ISS method showed promising in n-butanol separation.
Structurally robust nanostructures on the surface of matrix highly determine the durability of superhydrophobic surface of cellulosic materials. Traditionally, the hydrophobic inorganic-organic ...nanocomposites were physically coated on the surface of cellulose fibers, whereas the nanocomposite was easy to fall off under external force due to the weak interfacial interaction between inorganic materials and cellulose, restricting their practical application. In this work, a sort of structurally stable superhydrophobic cellulosic materials was elaborately designed by successive in situ synthesis of Zn(OH)2 nanoarchitectures and coating stearic acid (STA). The unique flower-like micro/nano structures as well as the presence of hydrophobic STA imparted the cellulosic materials with superhydrophobic behavior and the optimized water contact angle of synthesized STA@Zn(OH)2/paper nanocomposite was enhanced to 171°. Moreover, the resultant cellulosic nanocomposite also possesses excellent structural stability without STA and Zn(OH)2 fall off as well as hydrophobicity reduction after bending 100 times. Compared to bare filter paper, both tensile stress and elongation at break of optimized flower-like nanocomposite reached 14.04 MPa and 25.24% with 109.6% and 323.5% improvement, respectively. Furthermore, such superhydrophobic cellulose-based material also presented excellent anti-fouling and antibacterial performances. This work proposed a facial and efficient strategy to construct structurally stable superhydrophobic cellulose-based materials, displaying great potential application in food packaging and outdoor anti-fouling fields.
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•Structurally robust superhydrophobic cellulosic materials was fabricated.•Zn(OH)2 was in situ grown within the cellulosic fibers.•The water contact angle of optimized STA@Zn(OH)2/paper reached 171°.•Hydrophobic feature remains 91% of initial value after bending for 100 times.•STA@Zn(OH)2/paper delivered well anti-fouling performance.
•A novel square-wave micromixer is designed through introducing sidewall grooves.•Mixing is significantly improved at low Re with the proposed mixer (90% at Re = 40).•The proposed micromixer is ...successfully used as a microreactor for carboxylic acid activation.•In situ synthesis of polypeptide array demonstrates the practicability of the micromixer.
The amide condensation reaction is crucial for preparing biological probes with a polypeptide backbone. The traditional condensation reaction requires the monomer and condensing agent to be pre-mixed and activated by physical agitation mixing, which entail long time, require many reagents, and yield several by-products. In microfluidic mixing devices, the high specific surface area of microchannel enables traditional chemical reactions to be accomplished efficiently and quickly using only trace amounts of reagents in real time. This paper presents a serpentine mixing channel for the activation of amino acid monomers. A number of outward convex elliptical structures are introduced to both sides of the improved serpentine microchannel, creating a Dean vortex that increases the mixing efficiency at low Reynolds condition (90% at Re = 40). Effective monomer activation can be realized directly using a micromixing reactor and leads to less by-products as verified by ultraviolet spectroscopy and high-performance liquid chromatography analysis. The practicability of the micromixer is successfully tested by utilizing it as a microreactor for the real-time activation of amino acids for the in situ synthesis of polypeptide array at a flow rate of 300 μL/min (Re = 40). The proposed micromixer has the potential to be an excellent alternative for conventional flask reactions and integrated in automated miniaturized biochip preparation systems.
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•Mg2Ni–Ce6O11 binary nanocatalyst with oxygen vacancies can be in-situ synthesized.•The peak temperature for hydrogen desorption is reduced by 115.8 °C.•The apparent activation energy ...for hydrogen desorption is reduced to 72.7 kJ/mol.•Synergistic catalysis of Mg2Ni–Ce6O11 improves hydrogen sorption properties of Mg.
To decrease the hydrogen sorption temperature and increase the hydrogen sorption rate is important for the practical application of magnesium for hydrogen storage. The binary nano-catalysts Mg2Ni and Ce6O11 with oxygen vacancy defects was in-situ synthesized on Mg surface via the hydrogen activation of Mg-Ni-CeO2. The hydrogen storage material Mg-20Ni-CeO2 can release 4.19 wt% H2 in 5 min at 320 °C, which is significantly higher than that of Mg with 10 wt% Ni (3.44 wt% H2) or 10 wt% CeO2 (0.34 wt% H2). The peak temperature and apparent activation energy for hydrogen desorption of Mg-20Ni-CeO2 are reduced by 115.8 °C and 63.89 kJ/mol respectively comparing with that without catalyst. Structural analysis suggests that Mg2Ni and Ce6O11 can be in-situ synthesized on Mg surface, which shows a synergistic catalysis for hydrogen storage. During H2 absorption, the oxygen vacancy defects on Ce6O11 surface can trap H2 molecules, while the Mg2Ni on Mg/Mg2Ni interface can promote H2 dissociation. For H2 desorption, the Mg2Ni can weaken the Mg-H bond and act as “hydrogen pump” to transfer H for H2 formation with the assistance of Ce3+/Ce4+ transformation in Ce6O11. The results of this study provide a new horizon for a novel binary catalyst design for hydrogen storage.
A 3D structured composite was designed to improve the conductivity and to ease the volume problems of Si anode during cycling for lithium-ions batteries. An in situ method via a controllable gelation ...process was explored to fabricate the 3D composite of a multilayer carbon matrix toughened by cross-linked carbon nanotubes (CNTs) and decorated with conductive Cu agents. Structurally, a bifunctional carbon shell was formed on the surface of Si to improve the conductivity but alleviate side reactions. Cu particles as conducting agents decorated in the carbon matrix are also used to further improve the conductivity. The volume issue of Si particles can be effectively released via toughening the carbon matrix through the multilayered structure and cross-linked CNTs. Moreover, the carbon matrix might prevent silicon particles from agglomeration. Consequently, the Si@C@Cu composite is expected to exhibit benign electrochemical performances with a commendable capacity of 1500 mAh g–1 (900 cycles, 1 A g–1) and a high rate performance (1035 mAh g–1, 4 A g–1). The DLi + ranging from 10–11 to 10–9 cm–2 s–1 of the Si@C@Cu anode is obtained via the GITT test, which is higher than most reported data.
High ionic conductivity solid polymer electrolyte (SPE) has long been desired for the next generation high energy and safe rechargeable lithium batteries. Among all of the SPEs, composite polymer ...electrolyte (CPE) with ceramic fillers has garnered great interest due to the enhancement of ionic conductivity. However, the high degree of polymer crystallinity, agglomeration of ceramic fillers, and weak polymer–ceramic interaction limit the further improvement of ionic conductivity. Different from the existing methods of blending preformed ceramic particles with polymers, here we introduce an in situ synthesis of ceramic filler particles in polymer electrolyte. Much stronger chemical/mechanical interactions between monodispersed 12 nm diameter SiO2 nanospheres and poly(ethylene oxide) (PEO) chains were produced by in situ hydrolysis, which significantly suppresses the crystallization of PEO and thus facilitates polymer segmental motion for ionic conduction. In addition, an improved degree of LiClO4 dissociation can also be achieved. All of these lead to good ionic conductivity (1.2 × 10–3 S cm–1 at 60 °C, 4.4 × 10–5 S cm–1 at 30 °C). At the same time, largely extended electrochemical stability window up to 5.5 V can be observed. We further demonstrated all-solid-state lithium batteries showing excellent rate capability as well as good cycling performance.
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