Stabilization of Ni-containing Keggin-type polyoxometalates with variable oxidation states as novel catalysts for electrochemical water oxidation.

The development of new recyclable and inexpensive electrochemically active species for water oxidation catalysis is the most crucial step for future utilization of renewables. Particularly, transition metal complexes containing internal multiple, cooperative metal centers to couple with redox catalysts in the inorganic Keggin-type polyoxometalate (POM) framework at high potential or under extreme pH conditions would be promising candidates. However, most reported Ni-containing POMs have been highly unstable towards hydrolytic decomposition, which precludes them from application as water oxidation catalysts (WOCs).

Photo-Induced Active Lewis Acid-Base Pairs in a Metal-Organic Framework for H Activation.

The establishment of active sites as the frustrated Lewis pair (FLP) has recently attracted much attention ranging from homogeneous to heterogeneous systems in the field of catalysis. Their unquenched reactivity of Lewis acid and base pairs in close proximity that are unable to form stable adducts has been shown to activate small molecules such as dihydrogen heterolytically. Herein, we show that grafted Ru metal-organic framework-based catalysts prepared via N-containing linkers are rather catalytically inactive for H activation despite the application of elevated temperatures.

Exceptional Hydrogen Diffusion Rate over Ru Nanoparticle-Doped Polar MgO(111) Surface.

Hydrogen (H) conductivity on oxide-based materials is crucially important in fuel cells and related catalysis. Here, this work measures the diffusion rate of H generated from Ru nanoparticles loaded on polar MgO(111) facet particles under H at elevated temperatures without moisture and compares it to conventional nonpolar MgO(110) for the first time by in situ quasielastic neutron scattering (QENS). The QENS reveals an exceptional diffusion rate on the polar facet via a proton (H ) hopping mechanism, which is an order of magnitude superior to that of typical H -conducting oxides.

H -H Pairs in Partially Oxidized MAX Phases for Bifunctional Catalytic Conversion of Furfurals into Linear Ketones.

Currently, less favorable C=O hydrogenation and weak concerted acid catalysis cause unsatisfactory catalytic performance in the upgrading of biomass-derived furfurals (i.e., furfural, 5-methyl furfural, and 5-hydroxymethyl furfural) to ketones (i.

2D MOF with Compact Catalytic Sites for the One-pot Synthesis of 2,5-Dimethylfuran from Saccharides via Tandem Catalysis.

One pot synthesis of 2,5-dimethylfuran (2,5-DMF) from saccharides under mild conditions is of importance for the production of biofuel and fine chemicals. However, the synthesis requires a multitude of active sites and suffers from slow kinetics due to poor diffusion in most composite catalysts. Herein, a metal-acid functionalized 2D metal-organic framework (MOF; Pd/NUS-SO H), as an ultrathin nanosheet of 3-4 nm with Lewis acid, Brønsted acid, and metal active sites, was prepared based on the diazo method for acid modification and subsequent metal loading.

Thermal Alteration in Adsorption Sites over SAPO-34 Zeolite.

Zeolites have found tremendous applications in the chemical industry. However, the dynamic nature of their active sites under the flow of adsorbate molecules for adsorption and catalysis is unclear, especially in operando conditions, which could be different from the as-synthesized structures. In the present study, we report a structural transformation of the adsorptive active sites in SAPO-34 zeolite by using acetone as a probe molecule under various temperatures.

Induced Active Sites by Adsorbate in Zeotype Materials.

There has been a long debate on how and where active sites are created for molecular adsorption and catalysis in zeolites, which underpin many important industrial applications. It is well accepted that Lewis acidic sites (LASs) and basic sites (LBSs) as active sites in pristine zeolites are generally believed to be the extra-framework Al species and residue anion (OH) species formed at fixed crystallographic positions after their synthesis. However, the dynamic interactions of adsorbates/reactants with pristine zeotype materials to "create" sites during real conditions remain largely unexplored.

Responses of Defect-Rich Zr-Based Metal-Organic Frameworks toward NH Adsorption.

Understanding structural responses of metal-organic frameworks (MOFs) to external stimuli such as the inclusion of guest molecules and temperature/pressure has gained increasing attention in many applications, for example, manipulation and manifesto smart materials for gas storage, energy storage, controlled drug delivery, tunable mechanical properties, and molecular sensing, to name but a few. Herein, neutron and synchrotron diffractions along with Rietveld refinement and density functional theory calculations have been used to elucidate the responsive adsorption behaviors of defect-rich Zr-based MOFs upon the progressive incorporation of ammonia (NH) and variable temperature. UiO-67 and UiO-bpydc containing biphenyl dicarboxylate and bipyridine dicarboxylate linkers, respectively, were selected, and the results establish the paramount influence of the functional linkers on their NH affinity, which leads to stimulus-tailoring properties such as gate-controlled porosity by dynamic linker flipping, disorder, and structural rigidity.

Controlled Synthesis of Carbon-Supported Gold Clusters for Rational Catalyst Design.

The development of novel catalysts based on metal clusters requires a rational design principle as well as atomically precise synthetic methods. Toward this goal, we have developed a method to precisely and independently control the size, composition, and surface modification of heterogeneous gold clusters by calcination of the ligand-protected Au clusters on carbon supports. We studied the effects of these structural parameters using benzyl alcohol oxidation as a test reaction.