Hydrothermally Synthesized ZnCr- and NiCr-Layered Double Hydroxides as Hydrogen Evolution Photocatalysts.

The layered double hydroxides (LDHs) of transition metals are of great interest as building blocks for the creation of composite photocatalytic materials for hydrogen production, environmental remediation and other applications. However, the synthesis of most LDHs is reported only by the conventional coprecipitation method, which makes it difficult to control the catalyst's crystallinity. In the present study, ZnCr- and NiCr-LDHs have been successfully prepared using a facile hydrothermal approach.

Highly Efficient Liquid-Phase Exfoliation of Layered Perovskite-like Titanates HLnTiO and HLnTiO (Ln = La, Nd) into Nanosheets.

Nanosheets of layered perovskite-like oxides attract researchers as building blocks for the creation of a wide range of demanded nanomaterials. However, Ruddlesden-Popper phases are difficult to separate into nanosheets quantitatively via the conventional liquid-phase exfoliation procedure in aqueous solutions of bulky organic bases. The present study has considered systematically a relatively novel and efficient approach to a high-yield preparation of concentrated suspensions of perovskite nanosheets.

Synthesis and Characterization of Inorganic-Organic Derivatives of Layered Perovskite-like Niobate HSrNbO with -Amines and -Alcohols.

A protonated and hydrated Dion-Jacobson-phase HSrNbO∙yHO was used to prepare two series of inorganic-organic derivatives containing non-covalently intercalated -alkylamines and covalently grafted -alkoxy groups of different lengths, as they are promising hybrid materials for photocatalytic applications. Preparation of the derivatives was carried out both under the conditions of standard laboratory synthesis and by solvothermal methods. For all the hybrid compounds synthesized structure, quantitative composition, a type of bonding between inorganic and organic parts as well as light absorption range were discussed using powder XRD, Raman, IR and NMR spectroscopy, TG, elemental CHN analysis, and DRS.

Photocatalytic Hydrogen Production from Aqueous Solutions of Glucose and Xylose over Layered Perovskite-like Oxides HCaNbO, HLaTiO and Their Inorganic-Organic Derivatives.

Nowadays, the efficient conversion of plant biomass components (alcohols, carbohydrates, etc.) into more energy-intensive fuels, such as hydrogen, is one of the urgent scientific and technological problems. The present study is the first one focused on the photoinduced hydrogen evolution from aqueous D-glucose and D-xylose using layered perovskite-like oxides HCaNbO, HLaTiO, and their organically modified derivatives that have previously proven themselves as highly active photocatalysts.

Physical-Chemical Exfoliation of Alkylamine Derivatives of Layered Perovskite-like Oxide HKBiTiO into Nanosheets.

In the present work, we report the results on exfoliation and coating formation of inorganic-organic hybrids based on the layered perovskite-like bismuth titanate HKBiTiO·HO that could be prepared by a simple ion exchange reaction from a Ruddlesden-Popper phase KBiTiO. The inorganic-organic hybrids were synthesized by intercalation reactions. Exfoliation into nanosheets was performed for the starting hydrated protonated titanate and for the derivatives intercalated by alkylamines to study the influence of preliminary intercalation on exfoliation efficiency.

H NMR Study of the HCaNbO Photocatalyst with Different Hydration Levels.

The photocatalytic activity of layered perovskite-like oxides in water splitting reaction is dependent on the hydration level and species located in the interlayer slab: simple or complex cations as well as hydrogen-bonded or non-hydrogen-bonded HO. To study proton localization and dynamics in the HCaNbO·HO photocatalyst with different hydration levels (hydrated-α-form, dehydrated--form, and intermediate-β-form), complementary Nuclear Magnetic Resonance (NMR) techniques were applied. H Magic Angle Spinning NMR evidences the presence of different proton containing species in the interlayer slab depending on the hydration level.

NMR Study of Intercalates and Grafted Organic Derivatives of HLaTiO.

The protonated perovskite-like titanate HLaTiO has been used to produce organic-inorganic hybrids with simple organic molecules: methylamine, methanol, monoethanolamine, and -butylamine. The optimal pathways for the preparation of such hybrids are summarized. Solid-state NMR, combined with thermal analysis, Raman, and IR spectroscopy, has been applied to determine the bonding type in the obtained organic-inorganic hybrids.

Study of alkylamine Intercalated Layered Perovskite-Like Niobates HCaNbO as Photocatalysts for Hydrogen Production From an Aqueous Solution of Methanol.

A series of hybrid niobates HCaNbO×RNH, containing -alkylamines (R = Me, Et, Pr, Bu, Hx, Oc) intercalated into the interlayer space, has been thoroughly studied concerning the photocatalytic hydrogen production from a model aqueous solution of methanol for the first time. All the hybrid photocatalysts were synthesized by the conventional ceramic technique followed by protonation and intercalation of -alkylamines. The products were characterized using XRD, Raman, IR and diffuse reflectance spectroscopy, TGA, CHN-analysis and SEM.

Synthesis of Organic-Inorganic Hybrids Based on Perovskite-like Bismuth Titanate HKBiTiO·HO and -Alkylamines.

New organic-inorganic hybrids have been synthesized by the intercalation of -alkylamines (methylamine, ethylamine, -propylamine, -butylamine, -hexylamine, and -octylamine) into the structure of the protonated and hydrated form of the perovskite-like layered titanate HKBiTiO·HO (HKBT·HO). The possibility of the synthesis of the hybrid materials was studied in a wide range of conditions. It was found that interlayer water plays a crucial role in the formation of intercalated hybrids.

Layered Titanate HNdTiO Intercalated With -Butylamine: A New Highly Efficient Hybrid Photocatalyst for Hydrogen Production From Aqueous Solutions of Alcohols.

A layered perovskite-type oxide intercalated with -butylamine is reported as an efficient photocatalyst for hydrogen production from aqueous solutions of alcohols for the first time. The hybrid photocatalyst HNdTiO×BuNH was synthesized by solid-state ceramic method followed by protonation, intercalation of methylamine and subsequent substitution by -butylamine. The product was characterized by powder XRD, TGA, STA-MS, DRS, IR, and Raman spectroscopy, CHN analysis, SEM.

Comprehensive Analysis of the Copper Exchange Implemented in Ammonia and Protonated Forms of Mordenite Using Microwave and Conventional Methods.

This article presents the results of a comprehensive study of copper-exchanged mordenite samples prepared from its ammonia and protonated forms (Si/Al = 10) using two different ion exchange methods: conventional and microwave (MW)-assisted. The protonated H-MOR-10 sample was obtained by calcination of commercial NHMOR-10; in this case, a slight degradation of the mordenite framework was observed, but the resulting defects were partially restored after the first ion-exchange procedure of protons for copper ions. The level of copper exchange in the studied materials was found to be limited to 70%.

Methylammonium Polyiodides: Remarkable Phase Diversity of the Simplest and Low-Melting Alkylammonium Polyiodide System.

Newly discovered methylammonium polyiodides (MAI) are unique precursors for innovative solvent-free technologies in perovskite photovoltaics because MAI are liquids at room temperature and demonstrate high chemical reactivity. We investigated the features of an MAI-I system and built up a first phase diagram in wide temperature and composition ranges using data from differential scanning calorimetry, single-crystal X-ray diffraction, and visual thermal analysis. The phase diagram has been found to differ drastically from that of any related systems owing to the unique propensity of methylammonium toward forming a diversity of polyiodides with complicated crystal structures, namely, MAI, MAI, MAI, and MAI, found in this system for the first time.

Osmolyte-Like Stabilizing Effects of Low GdnHCl Concentrations on d-Glucose/d-Galactose-Binding Protein.

The ability of d-glucose/d-galactose-binding protein (GGBP) to reversibly interact with its ligands, glucose and galactose, makes this protein an attractive candidate for sensing elements of glucose biosensors. This potential is largely responsible for attracting researchers to study the conformational properties of this protein. Previously, we showed that an increase in the fluorescence intensity of the fluorescent dye 6-bromoacetyl-2-dimetylaminonaphtalene (BADAN) is linked to the holo-form of the GGBP/H152C mutant in solutions containing sub-denaturing concentrations of guanidine hydrochloride (GdnHCl).

Polar Nature of (CHNH)BiI Perovskite-Like Hybrids.

High-quality single crystals of perovskite-like (CHNH)BiI hybrids have been synthesized, using a layered-solution crystal-growth technique. The large dielectric constant is strongly affected by the polar ordering of its constituents. Progressive dipolar ordering of the methylammonium cation upon cooling below 300 K gradually converts the hexagonal structure (space group P6/mmc) into a monoclinic phase (C2/c) at 160 K.