Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Hydrogen is an alternative fuel that can play a critical role in achieving net zero emissions, leading to global environment sustainability. An iridium-immobilized catalyst based on polyethyleneimine (PEI) was synthesized and utilized for hydrogen production via formic acid dehydrogenation (FADH). Iridium complex is cross-linked with its ligand and PEI to form the immobilized catalyst, where the iridium content could be easily varied in the range of 1-10 %. The structure of the iridium-immobilized catalyst was confirmed using solid-state NMR, DNP NMR, and FTIR spectroscopies. The iridium-immobilized catalyst with PEI showed excellent catalytic activity for FADH, exhibiting the catalyst's highest turnover frequency (TOF) value of 73 200 h-1 and a large turnover number (TON) value of over 1 130 000. The catalyst could be used for continuous hydrogen production via FADH, exhibiting high durability for over 2 000 h with TON value of 332 889 without any degradation in catalytic activity. The obtained hydrogen gas was evaluated for power generation using a standard fuel cell, as well as achieved 5 h of stable power generation.

Iridium Catalyst Immobilized on Crosslinked Polyethyleneimine for Continuous Hydrogen Production Using Formic Acid.

Invited for this month's cover is provided by researchers from National Institute of Advanced Industrial Science and Technology (AIST) in Japan. The image shows the flow type continuous hydrogen production from formic acid and power generation by fuel cell achieved by the iridium catalyst immobilized on crosslinked polyethylene imine. The Research Article itself is available at 10.1002/cssc.202301282.

In situ formic acid dehydrogenation observation using a UV-vis-diffuse-reflectance spectroscopy system.

By applying a simple method on the generated gas concentration in the center of a round cell through high-speed stirring, we succeeded in continuously monitoring catalytic formic acid dehydrogenation using a newly developed in situ/operando UV-vis-diffuse-reflectance spectroscopy system, which can exhibit a high S/N ratio and reliable spectra without any mechanical errors from gas meters.

A highly photoreflective and heat-insulating alumina film composed of stacked mesoporous layers in hierarchical structure.

An alumina film with highly photoreflective and heat-insulating properties can be simply synthesized using a sol of fibrous boehmite with an additive. The entangled fibers bring about mesopores among them and form stacked 2D nonwoven-like nanosheets. The porosity and the layered structure of alumina accompanying the heat resistivity provide the upper properties that are usually difficult to realize simultaneously.

Amphiphilic Organic-Inorganic Hybrid Zeotype Aluminosilicate like a Nanoporous Crystallized Langmuir-Blodgett Film.

A new organic-inorganic hybrid zeotype compound with amphiphilic one-dimensional nanopore and aluminosilicate composition was developed. The framework structure is composed of double aluminosilicate layers and 12-ring nanopores; a hydrophilic layer pillared by Q(2) silicon atom species and a lipophilic layer pillared by phenylene groups are alternately stacked, and 12-ring nanopores perpendicularly penetrate the layers. The framework topology looks similar to that of an AFI-type zeolite but possesses a quasi-multidimensional pore structure consisting of a 12-ring channel and intersecting small pores equivalent to 8-rings. The hybrid material with alternately laminated lipophilic and hydrophilic nanospaces can be assumed as a crystallized Langmuir-Blodgett film. It demonstrates microporous adsorption for both hydrophilic and lipophilic adsorptives, and its outer surface tightly adsorbs lysozyme whose molecular size is much larger than its micropore opening. Our results suggest the possibility of designing porous adsorbent with high amphipathicity.

Layered hybrid perovskites with micropores created by alkylammonium functional silsesquioxane interlayers.

Layered organic-inorganic hybrid perovskites that consist of metal halides and organic interlayers are a class of low-dimensional materials. Here, we report the fabrication of layered hybrid perovskites using metal halides and silsesquioxane with a cage-like structure. We used a silsesquioxane as an interlayer to produce a rigid structure and improve the functionality of perovskite layers. Propylammonium-functionalized silsesquioxane and metal halide salts (CuCl2, PdCl2, PbCl2, and MnCl2) were self-assembled to form rigid layered perovskite structures with high crystallinity. The rigid silsesquioxane structure produces micropores between the perovskite layers that can potentially be filled with different molecules to tune the dielectric constants of the interlayers. The obtained silsesquioxane-metal halide hybrid perovskites exhibit some characteristic properties of layered perovskites including magnetic ordering (CuCl4(2-) and MnCl4(2-)) and excitonic absorption/emission (PbCl4(2-)). Our results indicate that inserting silsesquioxane interlayers into hybrid perovskites retains and enhances the low-dimensional properties of the materials.

Changing water affinity from hydrophobic to hydrophilic in hydrophobic channels.

The behavior of water at hydrophobic interfaces can play a significant role in determining chemical reaction outcomes and physical properties. Carbon nanotubes and aluminophosphate materials have one-dimensional hydrophobic channels, which are entirely surrounded by hydrophobic interfaces. Unique water behavior was observed in such hydrophobic channels. In this article, changes in the water affinity in one-dimensional hydrophobic channels were assessed using water vapor adsorption isotherms at 303 K and grand canonical Monte Carlo simulations. Hydrophobic behavior of water adsorbed in channels wider than 3 nm was observed for both adsorption and desorption processes, owing to the hydrophobic environment. However, water showed hydrophilic properties in both adsorption and desorption processes in channels narrower than 1 nm. In intermediate-sized channels, the hydrophobic properties of water during the adsorption process were seen to transition to hydrophilic behavior during the desorption process. Hydrophilic properties in the narrow channels for both adsorption and desorption processes are a result of the relatively strong water-channel interactions (10-15 kJ mol(-1)). In the 2-3 nm channels, the water-channel interaction energy of 4-5 kJ mol(-1) was comparable to the thermal translational energy. The cohesive water interaction was approximately 35 kJ mol(-1), which was larger than the others. Thus, the water affinity change in the 2-3 nm channels for the adsorption and desorption processes was attributed to weak water-channel interactions and strong cohesive interactions. These results are inherently important to control the properties of water in hydrophobic environments.

The selective adsorption of tellurium in the aluminosilicate regions of AFI- and MOR-type microporous crystals.

Attempts have been made to load tellurium (Te) atoms into the one-dimensional nano-channels of microporous crystals of aluminophosphate AlPO4-5 and of aluminosilicate mordenites of the Na(+) form (Na-MOR) and the H(+)-form (H-MOR) at 673 K. The density of the atoms adsorbed was in the sequence 0 ∼ AlPO4-5 ≪ H-MOR < Na-MOR. AlPO4-5 provides a shallow potential of periodical charge fluctuation for Te atoms, from the alternate ordering of Al and P atoms through O atoms. Mordenite offers a sufficiently strong potential for Te adsorption, but the magnitude varies with the type of cation. Dipoles between framework AlO2(-) anion sites and their Na(+) counter-ions in Na-MOR provide a stronger potential than the Brønsted acid points in H-MOR. The adsorption of Te atoms in the silico-aluminophosphate SAPO-5 was between that of AlPO4-5 and H-MOR, leading us to suspect that Te atoms are selectively adsorbed in the aluminosilicate regions accompanying the Brønsted acid points distributed in the major aluminophosphate network. The aluminosilicate regions in SAPO-5 are below 500 nm in size and are distributed throughout a single crystal.

Preparation of plate-like mesoporous material from layered silicate RUB-15.

A plate-like mesoporous material was formed from the lamellar structure of layered silicate RUB-15. RUB-15 was synthesized by a hydrothermal method, as reported previously. TMA (tetramethylammonium) ions exist in the interlayer of RUB-15 were exchanged with C16 TMA (hexadecyl-trimethyl-ammonium) ions, and TEOS (tetraethylorthosilicate) was then intercalated in between the layers. After steaming, the obtained powder was calcined and characterized by XRD, N2 gas adsorption, and scanning electron microscopy (SEM). The XRD patterns and N2 adsorption-desorption isotherms of the finally obtained powders indicated the presence of mesopores in the sample. The morphology of powders was plate-like which originates from the structure of the starting material. Cross-sectional FE-SEM images of the final obtained powders revealed existence of mesopores between the layers. The morphology of the final obtained mesoporous materials was affected by their remaining layered structure due to the starting material RUB-15.

Osmium(0) nanoclusters stabilized by zeolite framework; highly active catalyst in the aerobic oxidation of alcohols under mild conditions.

Osmium(0) nanoclusters stabilized by zeolite-Y framework were reproducibly prepared by a simple two step procedure involving the incorporation of osmium(III) cations into the zeolite matrix by ion-exchange, followed by their reduction within the cavities of zeolite with sodium borohydride in aqueous solution all at room temperature. The composition and morphology of osmium(0) nanoclusters stabilized by zeolite framework, as well as the integrity and crystallinity of the host material were investigated by using ICP-OES, XRD, XPS, SEM, TEM, HRTEM, TEM/EDX, mid-IR, far-IR spectroscopies, and N(2)-adsorption/desorption technique. The results of the multiprong analysis reveal the formation of osmium(0) nanoclusters within the cavities of zeolite-Y without causing alteration in the framework lattice, formation of mesopores, or loss in the crystallinity of the host material. More importantly, far-IR studies showed that after the reduction of Os(3+) cations by sodium borohydride the Na(+) cations reoccupy their authentic cation sites restoring the integrity of zeolite-Y. The catalytic activity of osmium(0) nanoclusters stabilized by zeolite framework was tested in the aerobic oxidation of activated, unactivated and heteroatom containing alcohols to carbonyl compounds and was found to provide high activity and selectivity even under mild conditions (80 degrees C and 1 atm O(2) or air). Moreover, they were found to be stable enough to be isolated and bottled as solid material, which can be reused as active catalyst under the identical conditions of the first run.

Dependence of electron transfer among alpha cages on the chemical compositions of zeolite LTAs including K clusters.

K atoms are loaded in diluted amount into K-form LTA zeolites whose framework compositions are Al(x)Si(24-x)O(48) (6

Zeolite LTA Nanoparticles Prepared by Laser-Induced Fracture of Zeolite Microcrystals.

Zeolite LTA nanoparticles are prepared by laser-induced fragmentation of zeolite LTA microparticles using a pulsed laser. Zeolite nanoparticle formation is attributed to absorption of the laser at impurities or defects within the zeolite microcrystal generating thermoelastic stress that mechanically fractures the microparticle into smaller nanoparticle fragments. Experimentally, it is found that nanoparticles have a wide size and morphology distribution. Large nanoparticles (>200 nm) are typically irregularly shaped crystals of zeolite LTA, whereas small nanoparticles (<50 nm) tend to be spherical, dense, and amorphous, indicative of destruction of the original LTA crystal structure. Results of the fragmentation versus laser parameters show that shorter laser wavelengths are more efficient at producing zeolite nanoparticles, which is explained based on a larger cross section for optical absorption in the zeolite crystal. Increasing the laser energy density irradiating the sample was found to be a trade-off between increasing the amount of fragmentation and increasing the amount of structural damage to the zeolite crystal. It is suggested that in the presence of strongly absorbing defects, plasma formation is induced resulting in dramatically higher temperatures. On the basis of these results it is suggested the optimal laser processing conditions are 355 nm and 10 mJ/pulse laser energy for our LTA samples.

Characterization of ESR active species on lithium chloride-modified mesoporous silica.

The surface of mesoporous silica with regular nanometer-sized pores and high surface area has been modified by metal ions or functional groups to introduce specific interactions. We found that ESR active species were formed on lithium chloride (LiCl)-modified mesoporous silica after heat treatment. The structure and the surface properties of LiCl-modified mesoporous silica were characterized by XRD, ESR, nitrogen adsorption, UV-vis-NIR, and TPD. The results suggest that the ESR active species were generated on the surface in response to heat treatment above 673 K. Moreover, it was found for the first time that LiCl-modified mesoporous silica after the heat treatment has reversible adsorption properties for hydrogen under room temperature and atmospheric pressure.