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The separation of layered MFI into unilamellar nanosheets in solution confirms the general validity of soft-chemical exfoliation for zeolites and allows top-down production of films with potential applications in separation and catalysis.

Selective hydrogenation catalysts play a key role in many industrial processes, but they are primarily based on supported noble metals, such as Pt and Pd, which are usually dispersed in nanoparticles. However, the production and recovery of these noble metal nanoparticles is a very energy-consuming and expensive procedure. Accordingly, replacing these metals by other inexpensive, transition metals such as Fe and Cu without sacrificing the activity and selectivity, will necessarily reduce their production costs. Moreover, zeolites as a support provide the advantage of shape selectivity to the desired product. In this study, we develop an alternative method for preparing hydrogenation catalysts composed of metallic nanoparticles encapsulated into zeolite frameworks through reductive demetallation of Fe-zeolites or Cu/Fe-zeolites with MFI topology. Particularly, the process of reductive demetallation is described using temperature-programmed reduction (TPR) and Mossbauer spectroscopy data. The reductive demetallation of Fe-MFI, consisting of Fe extraction from the zeolite framework and formation of Fe0 nanoparticles, starts at the temperatures above 800 ℃ and finishes at 1030 ℃, when sintering occurs strongly. In contrast, introduction of second metal leads to the decrease in the reduction temperature, as process of CuFe@MFI formation finishes at 800 ℃. Both Fe@MFI and CuFe@MFI show activity in p-nitrotoluene hydrogenation to p-toluidine. Conversion of the substrate grows with increase in the Cu and Fe loading. Thus, this synthesis method of encapsulation of Fe0 nanoparticles and Fe0-Cu0 bimetallic nanoparticles into the zeolite micropores through reductive demetallation of Fe-zeolites can be used to prepare hydrogenation catalysts.

Nanoporous crystalline aluminosilicates, zeolites, are synthesised by solvothermal method producing three-dimensional (3D) crystals. An alternative, more controllable approach of zeolite synthesis - ADOR – can be used for preparation of isoreticular zeolites with tuneable porosity. Zeolites porosity allows their wide use as isomerisation catalysts due to their shape selectivity effects. Selective isomerisation of m-xylene towards p-xylene is an industrially important reaction due to a high demand for the latter as a substrate for terephthalic acid production. In this work, we investigated the influence of pore size (shape selectivity effect) on the isomerization of m-xylene using a system of isoreticular Al-containing zeolites. These materials, prepared by ADOR approach (UTL, IPC-7, IPC-2, IPC-6, and IPC-4) had different layers connectivity, and therefore various channel systems. We tracked the influence of the pore systems of ADOR zeolites (8- up to 14-ring channels) on the catalytic performance in gas-phase m-xylene isomerisation. We investigated the crystallinity and interlayer distances, phase purity, textural properties of prepared materials, their crystals morphology, and aluminium content. M-xylene isomerisation was carried out in a fixed-bed reactor at 350 °C. ADOR catalysts were compared with standard ZSM-5 zeolite. We show the dependence of zeolite porosity on the performance in isomerisation of m- to p-xylene. Smaller pore zeolites: IPC-4 (8- and 10-ring channels) and IPC-6 (8-, 10- and 12-ring channels) exhibited the lowest conversions, while the highest conversion and p-xylene yields were observed for IPC-2 (10- and 12-ring channels). Presence of extra-large, 14-ring channels (IPC-7 and UTL) resulted in the drop of selectivity due to the xylene disproportionation.

Palladium nanoparticles entrapped in porous aromatic frameworks (PAFs) or covalent organic frameworks may promote heterogeneous catalytic reactions. However, preparing such materials as active nanocatalysts usually requires additional steps for palladium entrapment and reduction. This paper reports as a new approach, a simple procedure leading to the self-entrapment of Pd nanoparticles within the PAF structure. Thus, the selected Sonogashira synthesis affords PAF-entrapped Pd nanoparticles that can catalyze the C-C Suzuki-Miyaura cross-coupling reactions. Following this new concept, PAFs were synthesized via Sonogashira cross-coupling of the tetraiodurated derivative of tetraphenyladamantane or spiro-9,9'-bifluorene with 1,6-diethynylpyrene, then characterized them using powder X-ray diffraction, diffuse reflectance infrared Fourier transform spectroscopy, X-ray photoelectron spectroscopy, high-resolution scanning transmission electron microscopy, and textural properties (i.e., adsorption-desorption isotherms). The PAF-entrapped Pd nanocatalysts showed high catalytic activity in Suzuki-Miyaura coupling reactions (demonstrated by preserving the turnover frequency values) and stability (demonstrated by palladium leaching and recycling experiments). This new approach presents a new class of PAFs with unique structural, topological, and compositional complexities as entrapped metal nanocatalysts or for other diverse applications.

Extra-large pore zeolites clear the way for the synthesis of fine chemicals and bulky compounds unable to enter the channels of medium- and large-pore zeolites.

Recently reported groundbreaking discovery of efficient delamination of zeolite MCM-56, producing colloidal suspensions of MWW monolayers dispersed in the liquid phase, created unprecedented possibilities for the synthesis of a zeolite catalyst. Based on this innovation, the concept of using MWW monolayers to prepare silica-supported zeolite nanosheet catalysts suitable for transformations of large organic molecules was explored in this work. A series of silica-MWW preparations was synthesized from colloidal suspensions of the monolayers, using both solid and colloidal silica sources. The synthesized solids were thoroughly characterized with various physicochemical methods and their catalytic performance was tested in alkylation of mesitylene with benzyl alcohol. The obtained results indicate that solids containing MWW layers dispersed on silica show promising catalytic properties. The mixed MWW:silica catalysts synthesized from dispersions of MWW monolayers and liquid silica were found to exhibit high specific catalytic activity (with TOF values of 3.4 × 10−3 to 4.8 × 10−3 s−1), despite the high content of inactive amorphous silica support (40–60%). Materials synthesized from solid fumed and precipitated silicas showed low or negligible overall activity, which could be attributed to the small incorporation of the zeolitic active phase. For one of such materials, a notable high TOF (4.8 × 10−3 s−1) was found. It was found earlier that ethanol is an effective flocculent for zeolite layers by themselves, but in the presence of solid silica its efficiency was reduced.

Supported metal nanoparticles are widely used as heterogeneous catalysts but often deactivated due to sintering under harsh conditions, especially at high temperatures. Sintering can be prevented by confining metal species into a porous matrix, although supports rarely provide additional stabilization effects. Herein, we used silanol-rich layered zeolite, IPC-1P, to stabilize ultra-small Rh nanoparticles. By adjusting the interlayer space of the precursor through swelling, we prepared various architectures, including microporous Rh@IPC-4_C12 and disordered mesoporous Rh@IPC_C22. By in-situ scanning transmission electron microscopy, we confirmed that immobilized Rh nanoparticles are resistant to sintering at high temperatures (650 oC for 2hrs). Our density functional theory (DFT) calculations indicated that small Rh clusters strongly bind to the surface silanol quadruplets at IPC-1P layers through hydrogen transfer to the metallic particles, while high silanol density hinders migration on the surface. Ultimately, combining swelling with long-chain surfactant and utilizing metal-silanol interactions resulted in a novel, catalytically active zeolitic material termed Rh@IPC_C22.

Developing highly efficient electrocatalysts for electrochemical CO

In this study, a sonochemical route for the preparation of a new Hf-MIL-140A metal–organic framework from a mixture of UiO-66/MIL-140A is presented. The sonochemical synthesis route not only allows the phase-pure MIL-140A structure to be obtained but also induces structural defects in the MIL-140A structure. The synergic effect between the sonochemical irradiation and the presence of a highly acidic environment results in the generation of slit-like defects in the crystal structure, which increases specific surface area and pore volume. The BET-specific surface area in the case of sonochemically derived Zr-MIL-140A reaches 653.3 m(2)/g, which is 1.5 times higher than that obtained during conventional synthesis. The developed Hf-MIL-140A structure is isostructural to Zr-MIL-140A, which was confirmed by synchrotron X-ray powder diffraction (SR-XRD) and by continuous rotation electron diffraction (cRED) analysis. The obtained MOF materials have high thermal and chemical stability, which makes them promising candidates for applications such as gas adsorption, radioactive waste removal, catalysis, and drug delivery.

The application of the Assembly–Disassembly–Organization–Reassembly (ADOR) protocol to the synthesis of germanosilicate zeolites has become a major milestone in material design by enabling the prep...

Confining Au nanoparticles (NPs) in a restricted space (

Purpose Indium tin oxide (ITO) is a material belonging to the group of transparent conductive oxides, which are widely used in many fields of technology including optoelectronics and photovoltaics. However, the properties of ITO thin films depend on many factors. Therefore, the aim of the study was thorough investigation of the properties of sputtered ITO thin films of various thicknesses. Design/methodology/approach ITO coatings were deposited by magnetron sputtering in pure argon atmosphere using ceramic ITO target. Various deposition times resulted in obtaining thin films with different thickness, which had significant influence on the optoelectronic properties of deposited coatings. In this work the results of investigation of structural, surface, optical and electrical properties were presented. Findings Increase of the coating thickness caused change of the microstructure from amorphous to nanocrystalline and occurrence of grains with a size of 40 to 60 nm on their surface. Moreover, the fundamental absorption edge was red-shifted, whereas the average transmission in the visible wavelength range remained similar. Increase of the thickness caused considerable decrease of the sheet resistance and resistivity. It was found that even thin films with a thickness of 10 nm had antistatic properties. Originality/value The novelty and originality of presented work consists in, among other, determination of antistatic properties of ITO thin films with various sheet resistances that are in the range typical for dielectric and semiconducting material. To date, there are no reports on such investigations in the literature. Reported findings might be very helpful in the case of, for example, construction of transparent antireflective and antistatic multilayers.

Germanosilicate zeolites with extra-large-/multidimensional pore systems have a high potential for catalytic applications. However, their insufficient hydrothermal stability, high cost, and lack of...

Polymeric carbon/activated carbon aerogels were synthesized through sol-gel polycondensation reaction followed by the carbonization at 800 °C under Argon (Ar) atmosphere and subsequent physical activation under CO2 environment at different temperatures with different degrees of burn-off. Significant increase in BET specific surface area (SSA) from 537 to 1775 m2g−1 and pore volume from 0.24 to 0.94 cm3g−1 was observed after physical activation while the pore size remained constant (around 2 nm). Morphological characterization of the carbon and activated carbons was conducted using X-ray diffraction (XRD) and Raman spectroscopy. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to investigate the effect of thermal treatment (surface cleaning) on the chemical composition of carbon samples. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to analyse the capacitive and resistive behaviour of non-activated/activated/and surface cleaned activated carbons employed as electroactive material in a two electrode symmetrical electrochemical capacitor (EC) cell with 6 M KOH solution used as the electrolyte. CV measurements showed improved specific capacitance (SC) of 197 Fg−1 for activated carbon as compared to the SC of 136 Fg−1 when non-activated carbon was used as electroactive material at a scan rate of 5 mVs−1. Reduction in SC from 197 Fg−1 to 163 Fg−1 was witnessed after surface cleaning at elevated temperatures due to the reduction of surface oxygen function groups. The result of EIS measurements showed low internal resistance for all carbon samples indicating that the polymeric carbons possess a highly conductive three dimensional crosslinked structure. Because of their preferred properties such as controlled porosity, exceptionally high specific surface area, high conductivity and desirable capacitive behaviour, these materials have shown potential to be adopted as electrode materials in electrochemical capacitors.

In this contribution, zeolites with different pore sizes and connectivity (MFI 10-10-10R, MTW 12R, Beta 12-12-12R) were prepared in bulk and hierarchical “nanosponge” form and with different composition (aluminosilicate, gallosilicate). Properties of the samples were characterized by X-ray diffraction, argon adsorption, transmission electron microscopy and adsorption of pyridine followed by FTIR spectroscopy. Catalytic performance (conversion of reactants, yields of products and turn-over frequencies) of prepared materials was investigated in the Pechmann condensation of resorcinol with ethyl acetoacetate. The lowest conversion (less than 15%) over the MFI samples suggests that its 10R channels are too narrow for the products to escape from the framework and thus the reaction proceeds mainly on the crystal surface. Conversion of reactants over MTW and Beta zeolites is higher (10%, 35%, 71% and 69% for bulk MTW, nanosponge MTW, bulk Beta and nanosponge Beta, respectively), however, undesired side-products are formed. The hierarchical form of MFI and MTW gives higher conversions and yields of products than their bulk counterparts. Interestingly, the difference between bulk and hierarchical Beta is negligible. The overall performance of aluminosilicates and gallosilicates in the reaction is comparable. Catalytic activity of the samples was determined mainly by their textural properties.

Hydrogenation of nitroarenes is a catalytic reaction of high interest owing to the importance of the resulting aromatic amines in the chemical industry. Up to date, various metal@zeolite catalysts have been reported for this transformation. Herein, Pd@Beta and Pd@MWW catalysts were synthesized by ion exchange with Pd(NH3)4(NO3)2 and characterized by XRD, nitrogen sorption, ICP-OES, electron microscopy and FTIR(CO). Structural and textural analysis proved no significant changes of the zeolites after the Pd precursor was introduced. STEM images proved the uniform distribution of metal species in zeolite crystals. Average size of Pd NPs is 2.6 nm and 1.7 nm for Beta and MWW zeolites, respectively. The resulting Pd@Beta catalyst exhibited higher catalytic activity compared to Pd@MWW in the hydrogenation of nitroarenes. The electronic/steric effects of substrates and products were also investigated for both catalysts. Nitroarenes with electron-donating groups exhibit higher initial reaction rates than nitroarenes containing electron-withdrawing groups. The nitroarenes bearing functionalized groups in the ortho-position are harder to hydrogenate than corresponding meta- and para- isomers because of the steric hindrance effect.

Performed reverse engineering analysis showed the complex dependence of the optical properties on the material composition and the microstructure properties of the (Ti,Cu)Ox gradient thin film prepared using multi-magnetron co-sputtering.

The paper presents the results of the analysis of resistive switching properties observed in (Ti-Cu)-oxide thin film with gradient distribution of elements over the thin film thickness. Thin films were prepared using the multisource reactive magnetron co-sputtering process. Programmed profile of the pulse width modulation coefficient during sputtering of the Cu target allowed to obtain the designed gradient U-shape profile of Cu concentration in the deposited thin film. Electrical measurements of Au/(Ti-Cu)Ox/TiAlV structure showed the presence of nonpinched hysteresis loops in the voltage–current plane testifying the resistive switching behavior. Additionally, the initial forming process of conducting filaments has been observed as well. Optical, x-ray, and ultraviolet photoelectron spectroscopy measurements allowed to create the scheme of the bandgap alignment of the prepared thin films with respect to the Au and TiAlV electrical contacts. Detailed structure and elemental profile investigations allowed to conclude about the presence of conducting filaments of the observed resistive switching mechanism occurring in the prepared test structure. The obtained results showed that the prepared gradient (Ti-Cu)Ox thin film could be an interesting alternative to the conventional multilayer stack construction of resistive switching devices.

Cerium oxide nanoparticles (CeNPs) possess multiple redox enzyme mimetic activities in scavenging reactive oxygen species (ROS) as a potential biomedicine. These enzymatic activities of CeNPs are closely related to their surface oxidation state. Here we have reported a synthetic method to modify CeNPs’ surface oxidation state by changing the conformation of the poly(acrylic acid) (PAA) polymers adsorbed onto the CeNP surface. The synthesized PAA–CeNPs exhibited the same core size, morphology, crystal structure, and colloidal stability, with the only variation being their surface oxidation state (Ce3+ percentage). The modification mechanism can be attributed to the polymers chemisorbed onto the metal oxide surface forming a metal complexation structure. Such adsorption further modified CeNPs’ surface oxidation state in a temperature-dependent manner. The series of PAA–CeNPs exhibited multiple redox enzyme mimetic activities (superoxide dismutase, catalase, peroxidase, and oxidase) directly related to their surface oxidation state. In vitro experiments showed no cytotoxic effect of these PAA–CeNPs on the osteoblastic cell line SAOS-2 at high loadings. Microscopic images confirmed the internalization of PAA–CeNPs in the cells. All tested PAA–CeNPs can reduce the basal and hydrogen peroxide-induced intracellular ROS level in the cells, indicating their effective intracellular ROS scavenging effect. However, we did not observe a positive correlation between the CeNP surface oxidation state and their capacities to reduce the intracellular ROS levels. We propose that CeNPs can maintain a dynamic state of Ce3+/Ce4+ during their catalytic activities, exhibiting a non-linear correlation between the CeNP surface oxidation state and their effect on regulating the intracellular ROS level.

Zeolite molecular sieves are widely used in gas separation and shape-selective catalysis, but these applications often require discriminating differences as little as 0.1 A. Molecular sieving with such size selectivity demands zeolites with highly tunable pore diameters and adsorption properties, which are technically challenging to prepare. Nevertheless, it is shown that a wide range of organic functional groups can be covalently functionalized onto the interior pore walls of the zeolites, MOR, LTL, FAU, and MFI, to systematically "tune" their effective pore diameters with respect to the size of organic groups. For organic functionalization, small and aggressive organic electrophiles are used (e.g., organo-halide and -diazonium) as grafting agents, which are accessible to the intracrystalline void space, forming a C-Ozeolite bond in a reaction with a bridging oxygen as proved by multiple analysis data. It is demonstrated that the post-functionalization can be used to tailor the molecular sieving action of a parent zeolite to give size-selective adsorbents for light olefin/paraffin separations. 4-Methoxybenzene-functionalized MOR separates ethylene from ethane with an ideal-adsorbed-solution-theory selectivity of ≈5873, whereas toluene-grafted MOR completely separates propylene/propane mixtures. Therefore, tailoring the molecular-sieving properties of zeolites by organic functionalization broadens their applications to challenging separations.

Direct exfoliation of layered zeolites into solutions of monolayers has remained unresolved since the 1990s. Recently, zeolite MCM-56 with the MWW topology (layers denoted mww) has been exfoliated directly in high yield by soft-chemical treatment with tetrabutylammonium hydroxide (TBAOH). This has enabled preparation of zeolite-based hierarchical materials and intimate composites with other active species that are unimaginable via the conventional solid-state routes. The extension to other frameworks, which provides broader benefits, diversified activity, and functionality, is not routine and requires finding suitable synthesis formulations, viz. compositions and conditions, of the layered zeolites themselves. This article reports exfoliation and characterization of layers with ferrierite-related structure, denoted bifer, having rectangular lattice constants like those of the FER and CDO zeolites, and thickness of approximately 2 nm, which is twice that of the so-called fer layer. Several techniques were combined to prove the exfoliation, supported by simulations: AFM; in-plane, in situ, and powder X-ray diffraction; TEM; and SAED. The results confirmed (i) the structure and crystallinity of the layers without unequivocal differentiation between the FER and CDO topologies and (ii) uniform thickness in solution (monodispersity), ruling out significant multilayered particles and other impurities. The bifer layers are zeolitic with Bronsted acid sites, demonstrated catalytic activity in the alkylation of mesitylene with benzyl alcohol, and intralayer pores visible in TEM. The practical benefits are demonstrated by the preparation of unprecedented intimately mixed zeolite composites with the mww, with activity greater than the sum of the components despite high content of inert silica as pillars.

The paper presents a discussion on memristive-like properties observed in metal/semiconducting-oxide/metal structure containing a semiconducting (TixCu1-x)Ox thin film with asymmetrical elemental Cu distribution over the thin film thickness. The thin film was prepared using a combinatorial multi-magnetron sputtering process. Based on current-to-voltage electrical investigations, a sharp forward-to-open rectifying behaviour was observed with a hysteresis loop in the forward bias conditions only. Detailed structure and elemental profile investigations allowed to propose explanation of observed type of resistive transition.

Zeolites with encapsulated metal nanoparticles (NPs) attract much attention due to the catalytic activity, stability and shape-selective properties of such materials in heterogeneous catalysis. One of the methods for introduction of metal NPs into the zeolite system is based on use of two dimensional (2D) layered precursors that are loaded with Pt source and consecutively transformed to three dimensional (3D) zeolites. This method can be combined with recently developed approach for zeolite synthesis; the ADOR (Assembly, Disassembly, Organization, and Reassembly) approach that is based on the 3D-2D-3D transformation of zeolites. Here, we report a synthesis of two ADOR zeolites: IPC-2 (OKO topology) and IPC-4 (PCR topology) functionalized with Pt NPs, Pt@IPC-2 and Pt@IPC-4, respectively. Pt@IPC-2 was prepared by intercalation of platinum(0)-2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetra siloxane into IPC-1P layered precursor and subsequent calcination. Pt@IPC-4 zeolite was prepared by the swelling of IPC-1P with the mixture of surfactant and Pt source. Final materials were investigated by XRD, nitrogen sorption, ICP-OES, and electron microscopy (SEM and STEM). Structural and textural analysis confirmed the successful syntheses of two ADOR zeolites. The size and distribution of Pt NPs were investigated by STEM. The platinum content was 0.34 wt% and 0.32 wt% and the average size of Pt NPs of 0.98 nm and 0.96 nm for Pt@IPC-2 and Pt@IPC-4, respectively. Pt@IPC-2 exhibited a broader range of Pt sizes due to larger pores.

Nitrogen doped resorcinol/formaldehyde carbon aerogels with controlled nitrogen content are synthesized by controlling the resorcinol/melamine molar ratio (R/M) during the synthesis of aerogel precursors. The carbons were used as electrode materials in an electrochemical capacitor using 6 M KOH solution as electrolyte. All samples exhibited amorphous structure with low degree of graphitization. The maximum specific capacitance of 208 Fg-1 was observed after doping of the carbon with nitrogen at R/M = 80. Drop in solution and charge transfer resistances from 0.57Ω to 0.15Ω and 0.05Ω–0.04Ω was also observed respectively, with the drop in contact angles from 123° to 103° for the carbon doped with nitrogen at R/M = 80. BET results showed that the pore volume and surface area of carbon increase after N-doping, with a BET surface area of 841 m2 g−1 at R/M = 80. This R/M ratio is an optimum ratio at which incorporation of nitrogen into the carbon matrix improves the capacitive performance of cell as a result of improved porosity/wettability/conductivity/active sites of the electrode. Doping at higher nitrogen concentrations (R/M

Zeolites have become indispensable materials for chemical industry being applied as detergents, adsorbents and particularly catalysts. Over the past decades this broad research and application field has experienced rapid development. New zeolite structures were synthesized, fundamental knowledge of micro- and mesoporous materials synthesis and characterization was substantially deepened and, consequently, more economical and environmentally acceptable industrial technologies were developped. This chapter summarizes the fundamental as well as practical aspects of zeolite synthesis, the most important properties of zeolites and their implications for practical use together with the main industrial applications. In particular, the attention is focused on zeolite use as adsorbents and catalysts. Zeolite research field was broadened to related materials, including zeotypes, mesoporous molecular sieves, hierarchic systems and metal-organic-frameworks. Synthesis, properties, and application potential of these novel and exciting groups of porous molecular sieves are briefly highlighted as well. Keywords: Zeolites; Mesoporous materials; Hierarchic systems; Catalysis; Adsorption

The paper discusses the preparation of multicomponent thin films of Cu-Ti composite with desired elemental composition using the pulsed magnetron co-sputtering technology. The technological goal described in the paper was deposition the Cu-Ti composite with elemental ratio of about 50/50 at%, which is close to the eutectic point from the Cu-Ti alloy system. A large difference in the sputtering yield (about seven-fold) of Cu and Ti metals was challenging, because of the features of used power supplies. Desired concentrations of the Ti and Cu elements were obtained as a result of application of multimagnetron sputtering system, where magnetrons were equipped with the Ti or Cu targets. Additionally, pulse power supply was used together with the pulse width modulation controller. Moreover, the article presents investigations of structural and mechanical properties of deposited Cu, Ti and Cu-Ti films with elemental composition of ca. 50/50 at.%. It was found that the two component Cu0.5Ti0.5 thin films were composed of Cu4Ti3 nanocrystallites built-in an amorphous matrix. As compared to the pure Cu and Ti thin films, the prepared composite exhibited improved hardness and better elasticity reflected in lower values of the Young's modulus. The results of nanoindentation investigations showed that the Cu0.5Ti0.5 composite thin film was characterized by the hardness of 7.59 GPa.

Zeolites doped with metal nanoparticles have shown the outstanding activity in many processes involving heterogeneous catalysis. The size of metal nanoparticles plays a decisive role in the performance of zeolite catalysts. However, the precise control of the size of nanoparticles is still limited. Herein, we present the synthesis of Pt-MWW zeolites with controllable nanoparticle size using a series of surfactants with different alkyl chain lengths for swelling of layered MCM-22 P. The interlayer distances of swollen materials increases with the length of the surfactant from 1.06 nm (C12OH) to 2.89 nm (C18OH). During swelling, the Pt nanoparticles were intercalated to the interlayer space of MCM-22 P. Further calcination resulted in Pt-MWW materials showing similar morphologies, textural properties and Pt content despite the differences in the initial interlayer distances. The factor that differentiated the synthesized materials was the average diameter of metal nanoparticles. As a result, the average size of Pt nanoparticles increased from 0.85 nm (MCM-22-C12OH-Pt) to 2.04 nm (MCM-22-C18OH-Pt) which is related to the length of the hydrocarbon chain of the surfactant used for the swelling process.

In this paper a comparison of electrical and optical properties of mixed hafnium-titanium oxides is described. Thin films were deposited with the use of the magnetron co-sputtering method. For further analysis (Hf0.52Ti0.48)Ox and (Hf0.29Ti0.71)Ox coatings, which were amorphous directly after the deposition process, were chosen,. Moreover, post-process annealing was also performed in order to compare the electrical and optical properties of amorphous and nanocrystalline thin films with the same material composition. It was found that the phase transition from amorphous to orthorhombic HfTiO4 occurred in the case of (Hf0.52Ti0.48)Ox coating at 650 °C. In turn, the phase transition to TiO2-anatase was observed at the temperature of 600 °C in the case of (Hf0.29Ti0.71)Ox thin film. The leakage current for both amorphous coatings was in the range of 10−7–10−8 A/cm2. After additional annealing and phase transition, the leakage current slightly decreased for (Hf0.29Ti0.71)Ox thin film, while in the case of (Hf0.52Ti0.48)Ox sample the resistance switching effect was observed. The dielectric constant was equal to 24 and 25 for amorphous (Hf0.52Ti0.48)Ox and (Hf0.29Ti0.71)Ox films, respectively. However, after the phase transition it decreased to 15 for (Hf0.52Ti0.48)Ox and increased to 51 for (Hf0.29Ti0.71)Ox film. The results of optical studies showed that amorphous thin films were well transparent in a visible light range with an average transparency of ca. 85%. After the phase transition to HfTiO4-orthorhombic and TiO2-anatase, a slight decrease in the transparency level by 3% and a redshift of the cut-off wavelength was observed. Moreover, additional annealing caused small changes of the optical band gap energy, refractive index and extinction coefficient.

The authors would like to thank the EPSRC (grants: EP/K025112/1; EP/K005499/1; EP/K503162/1; EP/N509759/1) for funding opportunities. R.E.M., and M.M. would like to acknowledge OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 - CUCAM. We would like to thank the ERC (Advanced Grant 787073 “ADOR”). The hydrolysis (disassembly, D) and rearrangement (organization, O) steps of the assembly-disassembly-organization-reassembly (ADOR) process for the synthesis of zeolites have been studied. Germanium–rich UTL was subjected to hydrolysis conditions in water to understand the effects of temperature (100, 92, 85, 81, 77, and 70 °C). Samples were taken periodically over an 8–37 h period and each sample was analyzed by powder X-ray diffraction. The results show that the hydrolysis step is solely dependent on the presence of liquid water, whereas the rearrangement is dependent on the temperature of the system. The kinetics have been investigated using the Avrami-Erofeev model. With increasing temperature, an increase in rate of reaction for the rearrangement step was observed and the Arrhenius equation was used to ascertain an apparent activation energy for the rearrangement from the kinetic product of the disassembly (IPC-1P) to the thermodynamic product of the rearrangement (IPC-2P). From this information a mechanism for this transformation can be postulated. Publisher PDF

The authors would like to thank the EPSRC (grants: EP/K025112/1; EP/K005499/1; EP/K503162/1; EP/N509759/1) for funding opportunities. R.E.M., J.C. and M.M. would like to acknowledge OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 - CUCAM. S.E.A. would like to thank the Royal Society and the Wolfson Foundation for a merit award. J.C. acknowledges the Czech Science Foundation (P106/12/G015). High-silica zeolites, some of the most important and widely used catalysts in industry, have potential for application across a wide range of traditional and emerging technologies. The many structural topologies of zeolites have a variety of potential uses, so a strong drive to create new zeolites exists. Here, we present a protocol, the assembly–disassembly–organization–reassembly (ADOR) process, for a relatively new method of preparing these important solids. It allows the synthesis of new high-silica zeolites (Si/Al >1,000), whose synthesis is considered infeasible with traditional (solvothermal) methods, offering new topologies that may find novel applications. We show how to identify the optimal conditions (e.g., duration of reaction, temperature, acidity) for ADOR, which is a complex process with different possible outcomes. Following the protocol will allow researchers to identify the different products that are possible from a reaction without recourse to repetitive and time-consuming trial and error. In developing the protocol, germanium-containing UTL zeolites were subjected to hydrolysis conditions using both water and hydrochloric acid as media, which provides an understanding of the effects of temperature and pH on the disassembly (D) and organization (O) steps of the process that define the potential products. Samples were taken from the ongoing reaction periodically over a minimum of 8 h, and each sample was analyzed using powder X-ray diffraction to yield a time course for the reaction at each set of conditions; selected samples were analyzed using transmission electron microscopy and solid-state NMR spectroscopy. Postprint

Here, we report the in situ formation of two novel metal organic frameworks based on copper and cobalt using tetrazole-5-carboxylate ethyl ester as the ligand synthesized by a hydrothermal route. Both MOFs show isostructural three-dimensional networks with kagome tilling topology and show high chemical stability. Despite the iso-structural nature, both systems show distinct magnetic features. For the Cu-based kag-MOF system, the co-existence of energetically competing ferromagnetic and antiferromagnetic interactions resulted in the establishment of a long-range ferromagnetic order sustainable up to 52 K. On the contrary, dominant antiferromagnetic interactions identified in the Co-based MOF material were responsible for an antiferromagnetic order evolving below 7 K. Importantly, chemically different metallic ions gave rise to distinct magnetic ordering with different strength and temperature-sustainability. No dynamic magnetic phenomena were observed, implying that the concentration of the metal ions within the structure exceeded the percolation limit favoring the formation of the long-range magnetic order in the studied systems. Both designed kagome-type MOFs were thus found to show a coexistence of high frustration and long range magnetic ordering with limited orbital quenching, resulting from the choice of the ligands and crystal arrangement. Thus, the results demonstrated the potentiality to effectively control and alter the magnetic features within the particular kagome-type MOF lattice due to the chemical nature and structural incorporation of individual metal ions. The presented approach offers a promising strategy to further fine tune the physical characteristics of the MOF-based systems equipping them with more competitive potential and extending their application portfolio to other fields.

The first direct exfoliation of zeolites in high yield expands potential for catalysts, membranes, and tailored composites., The most effective approach to practical exploitation of the layered solids that often have unique valuable properties—such as graphene, clays, and other compounds—is by dispersion into colloidal suspensions of monolayers, called liquid exfoliation. This fundamentally expected behavior can be used to deposit monolayers on supports or to reassemble into hierarchical materials to produce, by design, catalysts, nanodevices, films, drug delivery systems, and other products. Zeolites have been known as extraordinary catalysts and sorbents with three-dimensional structures but emerged as an unexpected new class of layered solids contributing previously unknown valuable features: catalytically active layers with pores inside or across. The self-evident question of layered zeolite exfoliation has remained unresolved for three decades. Here, we report the first direct exfoliation of zeolites into suspension of monolayers as proof of the concept, which enables diverse applications including membranes and hierarchical catalysts with improved access.

Heterogeneous catalysis is crucial branch of chemistry, having unprecedented impact on nearly every aspect of our life. Zeolites as crystalline microporous solids have found application in many industrial catalytic processes like fluid catalytic cracking (FCC), hydrogenations, polymerisations, or alkylations. Their main advantages are defined pore structure resulting in so-called shape/size-selectivity and presence of Bronsted acid sites due to the trivalent atoms (such as Al) in the framework. The proper design of zeolite catalysts, study of the crystal formation, their morphology, structural properties, location of active species, porosity and structural determination of new materials often requires support by advanced characterisation techniques Among them, electron microscopy and related methods are often essential for the thorough description of mentioned features. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) describe the morphology and surface of crystals of zeolite catalysts. Transmission electron microscopy (TEM), including scanning mode (STEM), supported by electron diffraction (ED) methods can give crucial information about structure, especially when conventional methods are limited for the full description of solid catalysts, like zeolites. Often those techniques are supported by energy-dispersive X-ray spectroscopy (EDS) for the elemental analysis of the samples. This chapter is an overview focused on electron microscopy and related characterisation techniques as well as their utilisation in the fields of design, synthesis, and formation of crystals, characterisation, and performance of zeolites as heterogeneous catalysts.

The paper presents the results of the investigation of the post-process annealing effect on selected properties of copper oxide thin films deposited by magnetron sputtering. It was found that the prepared thin films were nanocrystalline with the crystallite size smaller than 20 nm. Annealing at temperatures of 200°C, 300°C and 350°C caused metallic copper oxidation to copper(I) oxide and then to copper(II) oxide. As-deposited and annealed at 200°C thin films were composed of Cu and Cu2O. Copper(I) oxide transformation into CuO started at 300°C, while the thin film annealed at 350°C consisted of a single CuO phase. Scanning electron microscopy imaging revealed that annealing of the as-deposited thin films caused gradual formation of cupric oxide nanowires. Optimum annealing temperature for nanowires growth was 350°C. X-ray photoelectron spectroscopy showed that the surface of the as-deposited thin films was oxidized to Cu2O and CuO, while in the case of annealed films it was completely oxidized to CuO. Thermal treatment also contributed to the increase in coating transparency in the infrared range. The transmission coefficient at 1500 nm of the thin film annealed at 350°C was equal to 68. The resistivity of the as-deposited copper oxide thin film was equal to 1.9•10−3 Ωcm, while the highest resistivity of the annealed thin films was equal to 32 Ωcm for the coating annealed at 200°C. A further increase in the annealing temperature resulted in a slight decrease in the resistivity value. Based on Seebeck coefficient measurements, it was found that all coatings were characterized by p-type conductivity. Additionally, sensing properties toward hydrogen were examined. The best sensor response exceeding 13 was observed for the thin film annealed at 200°C.

In the paper memristive-like properties are discussed for the thin film of semiconducting (TixCu1-x)-oxide system with gradient elements distribution. The test structure was prepared using multimagnetron co-sputtering process with separate Ti and Cu targets. Based on optical and work function measurements, a discussion about the band-gap alignment of the prepared thin film with respect to the used Au and TiAlV electrical contacts has been presented. Additionally memristive properties were analyzed using ion drift model. Performed theoretical analyses together with electrical and structural investigations allowed to propose an explanation of presence of pinched hysteresis loops observed during direct and alternating current measurements.

The incorporation of various metals into the zeolite framework creates opportunities for novel applications, especially in catalysis. The recently developed assembly-disassembly-organisation-reassembly (ADOR) strategy was used to prepare zeolites with IPC-2 (OKO) topology. The layered zeolite precursor (IPC-1P) was modified by incorporating various metals (Al, Zn, Sn, Zr, V, Fe, Hf, and Ti) using a stabilisation process. The resulting materials were characterised by X-ray powder diffraction (XRD), Ar adsorption, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and diffuse reflectance UV-Vis spectroscopy (DR-UV-Vis). The acidity of Al-containing IPC-2 materials was assessed by acetonitrile and pyridine sorption followed by FT-IR spectroscopy, showing overall concentrations of acid sites of 0.863 mmol g−1 (acetonitrile) and 0.413 mmol g−1 (pyridine). Titanium containing IPC-2 was examined by selective oxidation of methylphenyl sulfide (MPS) to the corresponding sulfoxide (MPSO). Ti-IPC-2 provided a higher conversion than TS-1 after 60 min (30% and 18% respectively) and showed higher selectivity towards MPSO (77% and 63% respectively). Sn-IPC-2 was tested by Baeyer–Villiger oxidation of norcamphor with aqueous hydrogen peroxide, showing a 3.8% norcamphor conversion and a 1.3% yield of the desired lactone (after 8 h reaction). Therefore, the results reported herein clearly show the successful incorporation of metals into the IPC-2 zeolite framework.

The paper presents results of elemental and structure investigations of (Ti,Cu)-oxide system thin films with gradient Ti and Cu elements distributions vs. thin film thickness. Thin films were prepared using multi-magnetron sputtering system equipped with separate Cu and Ti targets sputtered in reactive oxygen plasma. The elements gradient distribution was assured by programming three exemplary, different profiles of powering the magnetron equipped with Cu target: linearly increasing, V- and U-shape profile of the power. Investigations performed with the aid of transmission electron microscope integrated with X-ray energy dispersive attachment showed clearly that programmed three different exemplary magnetron powering profiles were very well reproduced in Cu and Ti elements distribution profiles. Detailed structure investigations allowed on observation of the microstructure evolution during the thin film growth and it was proven that at given deposition conditions it was strongly influenced by the amount of particular element in the selected areas of deposited coatings.

In this paper, the structural, surface, optical, and electrical properties of tungsten oxide thin films were analyzed. Eight sets of WOx thin films were prepared using the magnetron sputtering method. In each case, the sputtering process parameters were the same, except the Ar:O2 gas mixture ratios, which were intentionally changed from 1:1 to 10:1 to obtain various properties of the deposited thin film coatings. Structural properties analyzed with the aid of X-ray diffraction measurements results showed that all thin films were amorphous. X-ray photoelectron spectroscopy measurements revealed a shift of the binding energy for the W4f7/2 peak towards lower energies for increasing Ar:O2 ratio, indicating a possible change of stoichiometry and change of the oxygen vacancy concentration. It was also determined that the O/W atomic ratio at the surface of the thin films decreased from 3.01 to 2.55 with an increase of argon content in the magnetron sputtering atmosphere. Scanning electron microscope images revealed that all thin films had a smooth, homogenous, crack-free, and featureless, confirming the structural analysis. It was shown that the sputtering process atmosphere had a significant influence on the optical and electrical properties. Analysis of the transmittance spectra revealed that an increase of Ar:O2 ratio caused a gradual decrease of the average transparency in the visible wavelength range, an increase of the fundamental absorption edge, and decrease of the optical band gap energy. Moreover, the refractive index and extinction coefficient were analyzed, showing that the change of the argon content in the sputtering atmosphere significantly influenced on those parameters. The sheet resistance and resistivity of the prepared WOx thin films decreased with the increase of Ar:O2 ratio. The electrostatic charge dissipation times were measured for each coating to assess their antistatic properties. In turn, the hardness of tungsten oxide thin films increased with the increase of Ar:O2 ratio. It was found that thin films deposited with Ar:O2 ratio above 6:1 had good ability to dissipate static charge. Performed studies showed that a proper control of the gas atmosphere during magnetron sputtering of tungsten oxide thin films leads to tailoring their optoelectronic properties and creates an opportunity to design coatings destined for application in transparent electronics.

Zeolite monolayers in solution, reported recently for the framework MWW, enable unprecedented synthetic capabilities that include preparation of molecularly intimate mixtures of different zeolite topologies. As a demonstration, MWW-MFI hybrid materials were synthesized by two methods: in-situ crystallization of MFI by adding the template and silica to solutions of MWW monolayers obtained from the zeolite MCM-56, and ex-situ by mixing the solutions of MWW layers with MFI crystals. Catalytic activity of the mixtures was similar to undiluted pure MWW despite high content of siliceous MFI, which was inert. This suggests that pure MWW layers do not provide optimal packing and accessibility of active sites and can be more efficiently utilized in combination with other components. The mixture of MCM-56 and MFI crystals was 50% less active. Practical benefits may be possible by combining frameworks with different types of activity in catalysis and sorption applications. The mixtures were characterized by the standard methods: X-ray powder diffraction, TEM and SEM imaging, gas adsorptions and FTIR, which showed properties of both the MWW and MFI features with high acid activity and porosity.

In this work, selected properties of metallic and oxide thin films based on titanium and cobalt were described. Thin-film coatings were prepared using the magnetron sputtering method. The deposition was carried out from sintered targets with different Co-content (2 at.%, 12 at.% and 50 at.%). The relation between the Ti–Co target composition and the Co-content in the metallic and oxide films was examined. There was 15–20% more cobalt in the films than in the target. Moreover, the deposition rate under neutral conditions (in Ar plasma) was even 10-times higher compared to oxidizing Ar:O2 (70:30) plasma. A comprehensive analysis of the structural properties (performed with GIXRD and SEM) revealed the amorphous nature of (Ti,Co)Ox coatings, regardless of the cobalt content in the coating. The fine-grained, homogenous microstructure was observed, where cracks and voids were identified only for films with high Co-content. Optical studies have shown that these films were well transparent (60% ÷ 80%), and the amount of cobalt in the target from which they were sputtered had a significant impact on the decrease in the transparency level, the slight shift of the absorption edge position (from 279 nm to 289 nm) as well as the decrease in their optical band gap energy (from 3.13 eV to 1.71 eV). Electrical studies have shown that in (Ti,Co)Ox thin films, a unipolar memristive-like effect can be observed. The occurrence of such effects has not been reported so far in the case of TiO2 coatings with the addition of Co.

In this paper, comparative studies of the structural, mechanical and corrosion properties of TiO2-WO3 thin films, with different contents of WO3, have been investigated. The thin films were formed using the electron beam evaporation method, on the Ti6Al4 V surface. The structural characteristics of the thin films obtained, were examined using SEM and XRD measurements. The mechanical properties of the coatings were determined by nanoidentation measurements. The corrosion properties of the thin films were determined by an analysis of the voltammetric curves. The results obtained show that the layer with the highest content of tungsten – (Ti0.41W0.59)Ox is characterized by the best mechanical and corrosion properties from all tested samples. The hardness obtained for this sample was equal to 3.20 GPa, and was similar to the value obtained for undoped TiO2 thin film. In addition, the value of corrosion current density for this sample was equal to 3.6∙10−8 A/cm2, and was similar to the value obtained for pure WO3 thin film.

In this work the properties of hafnium dioxide (HfO2), titanium dioxide (TiO2) and mixed HfO2-TiO2 thin films with various amount of titanium addition, deposited by magnetron sputtering were described. Structural, surface, optical and mechanical properties of deposited coatings were analyzed. Based on X-ray diffraction and Raman scattering measuremets it was observed that there was a significant influence of titanium concentration in mixed TiO2-HfO2 thin films on their microstructure. Increase of Ti content in prepared mixed oxides coatings caused, e.g. a decrease of average crystallite size and amorphisation of the coatings. As-deposited hafnia and titania thin films exhibited nanocrystalline structure of monoclinic phase and mixed anatase-rutile phase for HfO2 and TiO2 thin films, respectively. Atomic force microscopy investigations showed that the surface of deposited thin films was densely packed, crack-free and composed of visible grains. Surface roughness and the value of water contact angle decreased with the increase of Ti content in mixed oxides. Results of optical studies showed that all deposited thin films were well transparent in a visible light range. The effect of the change of material composition on the cut-off wavelength, refractive index and packing density was also investigated. Performed measurements of mechanical properties revealed that hardness and Young’s elastic modulus of thin films were dependent on material composition. Hardness of thin films increased with an increase of Ti content in thin films, from 4.90 GPa to 13.7 GPa for HfO2 and TiO2, respectively. The results of the scratch resistance showed that thin films with proper material composition can be used as protective coatings in optical devices.