Iron-Based Layered Perovskite Oxyfluoride Electrocatalyst for Oxygen Evolution: Insights from Crystal Facets with Heteroanionic Coordination.

Mixed-anion compounds have recently attracted attention as solid-state materials that exhibit properties unattainable with those of their single-anion counterparts. However, the use of mixed-anion compounds to control the morphology and engineer the crystal facets of electrocatalysts has been limited because their synthesis method is still immature. This study explored the electrocatalytic properties of a Pb-Fe oxyfluoride, PbFeOF, with a layered perovskite structure for oxygen evolution reaction (OER) and compared its properties in detail with those of a bulk-type cubic three-dimensional (3D) perovskite, PbFeOF.

Revealing Active Sites and Reaction Pathways in Direct Oxidation of Methane over Fe-Containing CHA Zeolites Affected by the Al Arrangement.

Fe-containing zeolites are effective catalysts in converting the greenhouse gases CH and NO into valuable chemicals. However, the activities of Fe-containing zeolites in methane conversion and NO decomposition are frequently conflated, and the activities of different Fe species are still controversial. Herein, Fe-containing aluminosilicate CHA zeolites with Fe species at different spatial distances affected by the arrangement of framework Al atoms were synthesized in a one-pot manner in the presence or absence of Na.

Direct Oxidation of Methane to Methanol over Transition-Metal-Free Ferrierite Zeolite Catalysts.

Direct oxidation of methane to methanol was reported to be highly dependent on the transition- or noble-metal-loading catalysts in the past decades. Here, we show that the transition-metal-free aluminosilicate ferrierite (FER) zeolite effectively catalyzed methane and NO to methanol for the first time. The distorted tetracoordinated Al in the framework and pentacoordinated Al on the extra framework formed during calcination, activation, and reaction processes were confirmed as the potential active centers.

Understanding the effect of spatially separated Cu and acid sites in zeolite catalysts on oxidation of methane.

Unraveling the effect of spatially separated bifunctional sites on catalytic reactions is significant yet challenging. In this report, we investigate the role of spatial separation on the oxidation of methane in a series of Cu-exchanged aluminosilicate zeolites. Regulation of the bifunctional sites is done either through studying a physical mixture of Cu-exchanged zeolites and acidic zeolites or by systematically varying the Cu and acid density within a family of zeolite materials.

Modulation of Al Distribution in High-Silica ZSM-5 Zeolites for Enhancing Catalytic Performance.

The spatial distribution of framework Al (Al) has been one of the important factors that affect the catalytic properties of zeolites in diverse chemical reactions; however, the synthesis of high-silica zeolites with special Al distribution remains a challenge. In this study, we successfully synthesized high-silica ZSM-5 zeolites with a unique Al distribution by employing pentaerythritol (PET) as an additive in the presence of a few tetrapropylammonium hydroxide (TPAOH). The results demonstrated that the introduction of PET led to a higher proportion of Al atoms located at the sinusoidal and/or straight channels.

Photocatalytic Hydrogen Evolution Activity of Nitrogen/Fluorine-Codoped Rutile TiO.

The development of a photocatalyst capable of evolving H from water under visible light is important. Here, the photocatalytic activity of N/F-codoped rutile TiO (TiO:N,F) for H evolution was examined with respect to metal cocatalyst loading and irradiation conditions. Among the metal species examined, Pd was the best-performing cocatalyst for TiO:N,F under UV-vis irradiation (λ > 350 nm), producing H from an aqueous methanol solution.

Natural Rubber/Hexagonal Mesoporous Silica Nanocomposites as Efficient Adsorbents for the Selective Adsorption of (-)-Epigallocatechin Gallate and Caffeine from Green Tea.

(-)-Epigallocatechin gallate (EGCG) is a bioactive component of green tea that provides many health benefits. However, excessive intake of green tea may cause adverse effects of caffeine (CAF) since green tea (30-50 mg) has half the CAF content of coffee (80-100 mg). In this work, for enhancing the health benefits of green tea, natural rubber/hexagonal mesoporous silica (NR/HMS) nanocomposites with tunable textural properties were synthesized using different amine template sizes and applied as selective adsorbents to separate EGCG and CAF from green tea.

Design of an Organic Template for Synthesizing ITR Zeolites under Ge-Free Conditions.

Germanosilicate zeolites with various structures have been extensively synthesized, but the syntheses of corresponding zeolite structures in the absence of germanium species remain a challenge. One such example is an ITR zeolite structure, which is a twin of the ITH zeolite structure. Through the modification of a classic organic template for synthesizing ITH zeolites and thus designing a new organic template with high compatibility to ITR zeolite assisted by theoretical simulation, we, for the first time, show the Ge-free synthesis of an ITR structure including pure silica, aluminosilicate, and borosilicate ITR zeolites.

Fluoride-free synthesis of high-silica CHA-type aluminosilicates by seed-assisted aging treatment for starting gel.

High-silica CHA-type aluminosilicates (Si/Al molar ratio >100) were synthesized hydrothermally in the absence of fluoride media, where the seed-assisted aging treatment played an important role on the crystallization. These aluminosilicates showed a long catalytic lifetime with high selectivity toward lower olefins in the methanol-to-olefins reaction.

A Porous Polyaromatic Solid for Vapor Adsorption of Xylene with High Efficiency, Selectivity, and Reusability.

Development of porous materials capable of capturing volatile organic compounds (VOCs), such as benzene and its derivatives, with high efficiency, selectivity, and reusability is highly demanded. Here we report unusual vapor adsorption behavior toward VOCs by a new porous solid, composed of a polyaromatic capsule bearing a spherical nanocavity with subnano-sized windows. Without prior crystallization and high-temperature vacuum drying, the porous polyaromatic solid exhibits the following five features: vapor adsorption of benzene over cyclohexane with 90 % selectivity, high affinity toward o-xylene over benzene and toluene with >80 % selectivity, ortho-selective adsorption ability (>50 %) from mixed xylene isomers, tight VOCs storage even under high temperature and vacuum conditions, and at least 5 times reusability for xylene adsorption.

Synthesis of Microporous Aluminosilicate by Direct Thermal Activation of Phenyl-Substituted Single-Source Aluminosilicate Molecular Precursors.

The construction of aluminosilicates from versatile molecular precursors (MPs) represents a promising alternative strategy to conventional processes based on monomeric molecular or polymeric Al and Si sources. However, the use of MPs often suffers from drawbacks such as the decomposition of the core structures in the presence of solvents, acids, or bases. In this work, we demonstrate a simple thermal synthesis of porous aluminosilicates from single-source spiro-7-type MPs that consist of a tetrahedral Al atom and six Si atoms functionalized with 12 phenyl (Ph) groups, (C)[Al{PhSi(OSiPhO)}] (; C = pyridinium cation (PyH), Na, K, Rb, or Cs), without using a solvent or activator.

Surface-modified, dye-sensitized niobate nanosheets enabling an efficient solar-driven Z-scheme for overall water splitting.

While dye-sensitized metal oxides are good candidates as H evolution photocatalysts for solar-driven Z-scheme water splitting, their solar-to-hydrogen (STH) energy conversion efficiencies remain low because of uncontrolled charge recombination reactions. Here, we show that modification of Ru dye-sensitized, Pt-intercalated HCaNbO nanosheets (/Pt/HCaNbO) with both amorphous AlO and poly(styrenesulfonate) (PSS) improves the STH efficiency of Z-scheme overall water splitting by a factor of ~100, when the nanosheets are used in combination with a WO-based O evolution photocatalyst and an I/I redox mediator, relative to an analogous system that uses unmodified /Pt/HCaNbO. By using the optimized photocatalyst, PSS//AlO/Pt/HCaNbO, a maximum STH of 0.

Improvement of Visible-Light H Evolution Activity of Pb Ti O F Photocatalyst by Coloading of Rh and Pd Cocatalysts.

Pb Ti O F modified with various metal cocatalysts was studied as a photocatalyst for visible-light H evolution. Although unmodified Pb Ti O F showed negligible activity, modification of its surface with Rh led to the best observed promotional effect among the Pb Ti O F samples modified with a single metal cocatalyst. The H evolution activity was further enhanced by coloading with Pd; the Rh-Pd/Pb Ti O F photocatalyst showed 3.

Selective monoallylation of anilines to -allyl anilines using reusable zirconium dioxide supported tungsten oxide solid catalyst.

The monoallylation of aniline to give -allyl aniline is a fundamental transformation process that results in various kinds of valuable building block allyl compounds, which can be used in the production of pharmaceuticals and electronic materials. For decades, sustainable syntheses have been gaining much attention, and the employment of allyl alcohol as an allyl source can follow the sustainability due to the formation of only water as a coproduct through dehydrative monoallylation. Although the use of homogeneous metal complex catalysts is a straightforward choice for the acceleration of dehydrative monoallylation, the use of soluble catalysts tends to contaminate products.

Fluorine-Assisted Low-Temperature Synthesis of GaN:ZnO-Related Solid Solutions with Visible-Light Photoresponse.

Wurtzite-structured GaZn(N,O,F) was successfully synthesized by nitridation of mixtures of a Ga-containing oxide and ZnF. The addition of ZnF lowered the nitridation temperature for the synthesis of GaZn(N,O,F) to 823 K, even when bulk ZnGaO was used as a paired precursor. This lowering of the synthesis temperature was ascribed to the enhancement of nitridation through the addition of fluorine.

Highly Efficient Photothermal Reduction of CO on PdCu Dispersed TiO Photocatalyst and Operando DRIFT Spectroscopic Analysis of Reactive Intermediates.

The photocatalytic conversion of CO to fuels using solar energy presents meaningful potential in the mitigation of global warming, solar energy conversion, and fuel production. Photothermal catalysis is one promising approach to convert chemically inert CO into value-added chemicals. Herein, we report the selective hydrogenation of CO to ethanol by PdCu alloy dispersed TiO (P25) photocatalyst.

Clarification of acid site location in MSE-type zeolites by spectroscopic approaches combined with catalytic activity: comparison between UZM-35 and MCM-68.

MSE-type zeolites synthesized by different organic structure-directing agents (OSDAs), UZM-35 and MCM-68, were prepared. The location of Brønsted acid sites derived from the framework Al atoms and acidic properties were investigated based on Al MQMAS NMR and IR techniques combined with the evaluation of the catalytic activity. We have successfully found a significant difference in the location of Brønsted acid sites in the MSE-type framework; 61 and 33% of acid sites were located at the 12-ring channel for MCM-68 and UZM-35, respectively.

Transcription-induced formation of paired Al sites in high-silica CHA-type zeolite framework using Al-rich amorphous aluminosilicate.

The paired Al species pre-formed in Al-rich amorphous aluminosilicates were transcribed into high-silica CHA-type zeolite frameworks under hydrothermal conditions, which offers a new approach to creating paired Al sites in zeolite frameworks. This Al-pair-rich CHA exhibited a higher Sr uptake than the control CHA zeolite synthesized by the conventional procedure.

Organic Structure-Directing Agent-Free Synthesis of Mordenite-Type Zeolites Driven by Al-Rich Amorphous Aluminosilicates.

Mordenite (MOR)-type zeolites with a Si/Al molar ratio of up to 13 with crystallite sizes of ca. 60 nm were successfully synthesized from Al-rich aluminosilicates with a Si/Al ratio of 2 and additional SiO under seed-assisted hydrothermal conditions for 6 h or longer without any organic structure-directing agents (OSDAs). In stark contrast, under the same hydrothermal conditions for 6 h, control experiments using starting reagent(s), such as Al-poor aluminosilicate, pure SiO, tetraethyl orthosilicate, and Al(NO), all of which are typically employed for zeolite synthesis, failed to yield MOR-type zeolites.

Zeolite-supported ultra-small nickel as catalyst for selective oxidation of methane to syngas.

The development of simple catalysts with high performance in the selective oxidation of methane to syngas at low temperature has attracted much attention. Here we report a nickel-based solid catalyst for the oxidation of methane, synthesised by a facile impregnation method. Highly dispersed ultra-small NiO particles of 1.

Natural rubber as a renewable carbon source for mesoporous carbon/silica nanocomposites.

This study is the first report on the preparation of mesoporous carbon/silica (MCS) nanocomposites with tunable mesoporosity and hydrophobicity using natural rubber (NR) as a renewable and cheap carbon source. A series of mesoporous nanocomposites based on NR and hexagonal mesoporous silica (HMS) were prepared via an in situ sol-gel process and used as precursors; then, they were converted into MCS materials by controlled carbonization. The NR/HMS precursors exhibited a high dispersion of rubber phase incorporated into the mesostructured silica framework as confirmed by small-angle X-ray scattering and high-resolution transmission electron microscopy.

Rational Manipulation of Stacking Arrangements in Three-Dimensional Zeolites Built from Two-Dimensional Zeolitic Nanosheets.

Unit-cell-thin zeolitic nanosheets have emerged as fascinating materials for catalysis and separation. The controllability of nanosheet stacking is extremely challenging in the chemistry of two-dimensional zeolitic materials. To date, the organization of zeolitic nanosheets in hydrothermal synthesis has been limited by the lack of tunable control over the guest-host interactions between organic structure-directing agents (OSDAs) and zeolitic nanosheets.

A Cationic Oligomer as an Organic Template for Direct Synthesis of Aluminosilicate ITH Zeolite.

There are a large number of zeolites, such as ITH, that cannot be prepared in the aluminosilicate form. Now, the successful synthesis of aluminosilicate ITH zeolite using a simple cationic oligomer as an organic template is presented. Key to the success is that the cationic oligomer has a strong complexation ability with aluminum species combined with a structural directing ability for the ITH structure similar to that of the conventional organic template.

Metal cation-exchanged zeolites with the location, state, and size of metal species controlled.

Rh ion-exchanged MFI-type aluminosilicate zeolites with different Al distributions were prepared for controlling the location, state, and size of Rh species. The MFI-type aluminosilicate zeolite with the framework Al atoms predominantly located inside the channel intersections leads to the formation of relatively large Rh species, which were confirmed by ultraviolet-visible (UV-vis) and infrared (IR) spectroscopies. Moreover, this catalyst showed a high catalytic activity for the oxidative reforming reaction of methane.