Synthesis of stable and highly efficient Au@ZIF-8 for selective hydrogenation of nitrophenol.
TL;DR: It was found that the Au content plays an important role in the hydrogenation reaction and the recyclability of the Au@ZIF-8 catalysts showed excellent catalytic performance and great stability in the recycling reaction.
Abstract: A series of nanoparticles (NPs) with different Au content was successfully encapsulated into metal organic framework ZIF-8 with highly porous structure through room-temperature crystallization. X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption and transmission electron microscopy were carried out to characterize the obtained Au@ZIF-8 heterogeneous catalytic material comprehensively. Au NPs were dispersed uniformly in the ZIF-8 and the Au NP diameter was 5-6 nm. The crystal structure of ZIF-8 was unchanged when compared with that before Au loading. It was found that the Au content plays an important role in the hydrogenation reaction. The obtained Au@ZIF-8 exhibited high hydrogenation activity to nitrophenol and excellent selectivity to aminophenol. The recyclability of the Au@ZIF-8 catalysts showed excellent catalytic performance and great stability in the recycling reaction.
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06 Jul 2022
TL;DR: In this paper , an electrochemical detection system for glial fibrillary acidic protein (GFAP) using a label-free manner based on zeolitic imidazolate frameworks and reduced graphene oxide anchored with gold nanoparticles (Au@ZIF-8@rGO) was developed in urine samples.
Abstract: A novel electrochemical detection system for glial fibrillary acidic protein (GFAP) using a label-free manner based on zeolitic imidazolate frameworks and reduced graphene oxide anchored with gold nanoparticles (Au@ZIF-8@rGO) as a recognition element was developed in urine samples. The chosen immobilization technique was based on increasing more covalent bonding using hydroxyl moieties on the Au@ZIF-8@rGO. The concept of the immunosensor is to detect the signal perturbation obtained by measuring the changes in the charge transfer resistance of the electrode by using [Fe(CN)6]3–/4– measurements after binding of the protein during 45 min of incubation without complicated procedures and expensive equipment. Under the optimal conditions, the developed biosensor exhibited a wide linear concentration range of 50.0–10 000.0 fg/mL GFAP and an extremely low detection limit of 50.0 fg/mL (detectable). However, the real concentrations of GFAP protein in the human body are in the concentration range of our immunosensor, indicating that the developed immunosensor looks potentially compatible with practical applications. Moreover, the developed immunosensor has been applied to the assay of GFAP in urine samples with satisfying results, indicating the applicability of the as-fabricated biosensor. This work provides a new sensing platform for GFAP detection and dramatically expands the application of metal–organic frameworks (MOFs) in the electrochemical field.
13 citations
TL;DR: Selective capture and separation of gold from secondary resources is an urgently demand to offset the increasing depletion of gold resources, to meet the sustainable supply of precious metal resources as discussed by the authors , . . .
6 citations
TL;DR: In this article , an Ag-nanoparticles-doped porous ZnO photocatalyst was prepared by using metal-organic frameworks as a sacrificial precursor and the catalytic activity over 4-nitrophenol was determined.
Abstract: Oxide-supported Ag nanoparticles have been widely reported as a good approach to improve the stability and reduce the cost of photocatalysts. In this work, a Ag-nanoparticles-doped porous ZnO photocatalyst was prepared by using metal–organic frameworks as a sacrificial precursor and the catalytic activity over 4-nitrophenol was determined. The Ag-nanoparticles-doped porous ZnO heterostructure was evaluated by UV, XRD, and FETEM, and the catalytic rate constant was calculated by the change in absorbance value at 400 nm of 4-nitrophenol. The photocatalyst with a heterogeneous structure is visible, light-responsive, and beneficial to accelerating the catalytic rate. Under visible light irradiation, the heterostructure showed excellent catalytic activity over 4-nitrophenol due to the hot electrons induced by the localized surface plasmon resonance of Ag nanoparticles. Additionally, the catalytic rates of 4 nm/30 nm Ag nanoparticles and porous/nonporous ZnO were compared. We found that the as-prepared Ag-nanoparticles-doped porous ZnO heterostructure catalyst showed enhanced catalytic performance due to the synergetic effect of Ag nanoparticles and porous ZnO. This study provides a novel heterostructure photocatalyst with potential applications in solar energy and pollutant disposal.
3 citations
TL;DR: In this paper , p-nitrophenol (PNP) is an important pesticide intermediate, which is also a water pollutant that is extremely harmful to personal health, and it can be converted to p-aminophenol (PAP) through selective catalytic...
Abstract: p-Nitrophenol (PNP) is an important pesticide intermediate, which is also a water pollutant that is extremely harmful to personal health. It can be converted to p-aminophenol (PAP) through selective catalytic...
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TL;DR: Metal-organic frameworks are porous materials that have potential for applications such as gas storage and separation, as well as catalysis, and methods are being developed for making nanocrystals and supercrystals of MOFs for their incorporation into devices.
Abstract: Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.
10,934 citations
TL;DR: This work has shown that highly porous frameworks held together by strong metal–oxygen–carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.
Abstract: The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.
8,013 citations
TL;DR: This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorbents in rigid and flexible MOFs, and primary relationships between adsorptive properties and framework features are analyzed.
Abstract: Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).
7,186 citations
TL;DR: The state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their 'design', aiming at reaching very large pores are presented.
Abstract: This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)
5,187 citations
TL;DR: In this paper, gold catalysts were prepared by coprecipitation from an aqueous solution of HAuCl4 and the nitrates of various transition metals, including Auα-Fe2O3, AuCo3O4, and AuNiO.
2,917 citations