Surface hydrophobization of zeolite enables mass transfer matching in gas-liquid-solid three-phase hydrogenation under ambient pressure.

Attaining high hydrogenation performance under mild conditions, especially at ambient pressure, remains a considerable challenge due to the difficulty in achieving efficient mass transfer at the gas-liquid-solid three-phase interface. Here, we present a zeolite nanoreactor with joint gas-solid-liquid interfaces for boosting H2 gas and substrates to involve reactions. Specifically, the Pt active sites are encapsulated within zeolite crystals, followed by modifying the external zeolite surface with organosilanes. The silane sheath with aerophilic/hydrophobic properties can promote the diffusion of H2 and the mass transfer of reactant/product molecules. In aqueous solutions, the gaseous H2 molecules can rapidly diffuse into the zeolite channels, thereby augmenting H2 concentration surround Pt sites. Simultaneously, the silane sheath with lipophilicity nature promotes the enrichment of the aldehydes/ketones on the catalyst and facilitates the hydrophilia products of alcohol rediffusion back to the aqueous phase. By modifying the wettability of the catalyst, the hydrogenation of aldehydes/ketones can be operated in water at ambient H2 pressure, resulting in a noteworthy turnover frequency up to 92.3 h-1 and a 4.3-fold increase in reaction rate compared to the unmodified catalyst.

Cascaded p-d Orbital Hybridization Interaction in Ultrathin High-Entropy Alloy Nanowires Boosts Complete Non-CO Pathway of Methanol Oxidation Reaction.

Designing high efficiency platinum (Pt)-based catalysts for methanol oxidation reaction (MOR) with high "non-CO" pathway selectivity is strongly desired and remains a grand challenge. Herein, PtRuNiCoFeGaPbW HEA ultrathin nanowires (HEA-8 UNWs) are synthesized, featuring unique cascaded p-d orbital hybridization interaction by inducing dual p-block metals (Ga and Pb). In comparison with Pt/C, HEA-8 UNWs exhibit 15.0- and 4.2-times promotion of specific and mass activity for MOR. More importantly, electrochemical in situ FITR spectroscopy reveals that the production/adsorption of CO (CO*) intermediate is effectively avoided on HEA-8 UNWs, leading to the complete "non-CO" pathway for MOR. Theoretical calculations demonstrate the optimized electronic structure of HEA-8 UNWs can facilitates a lower energy barrier for the "non-CO" pathway in the MOR.

Interfacial Reaction-Directed Green Synthesis of CeO2-MnO2 Catalysts for Imine Production through Oxidative Coupling of Alcohols and Amines.

Direct oxidative coupling of alcohols with amines over cheap but efficient catalysts is a promising choice for imine formation. In this study, porous CeO2-MnO2 binary oxides were prepared via an interfacial reaction between Ce2(SO4)3 and KMnO4 at room temperature without any additives. The as-prepared porous CeO2-MnO2 catalyst has a higher fraction of Ce3+, Mn3+, and Mn4+ and contains larger surface area and more oxygen vacancies. During the oxidative coupling reaction of alcohol with amine to imine, the as-obtained CeO2-MnO2 catalyst is motivated by the above encouraging characteristics and exhibits superior catalytic activity (98% conversion and 97% selectivity) and can also work effectively under a wide scope of temperatures and substrates. The in-depth in situ DRIFTS and density functional theory (DFT) results demonstrate that there is a strong interaction between CeO2 and MnO2 in the CeO2-MnO2 catalyst, exhibiting especially a positive synergistic effect in the direct coupling of alcohol and amine reaction.

Implanting Atomic Dispersed Ru in PtNi Colloidal Nanocrystal Clusters for Efficient Catalytic Performance in Electro-oxidation of Liquid Fuels.

Although PtRu alloy nanocatalysts have been certified to possess excellent electrocatalytic performance and CO-poisoning tolerance toward formic acid and methanol electro-oxidation, the unaffordable usages of ruthenium (Ru) and platinum (Pt) have greatly limited their widespread adoption. Here, a facile one-pot method is reported for implanting atomic dispersed Ru in PtNi colloidal nanocrystal clusters with different Ru/Pt/Ni molar ratios, greatly reducing the dosages of Pt and Ru, and further improving the catalytic performances for the electro-oxidation of formic acid and methanol. Through simple control of the amount of Ni(acac)2 precursor, trimetallic Ru0.3 Pt70.5 Ni29.2 , Ru0.6 Pt55.9 Ni43.5 , Ru0.2 Pt77.3 Ni22.5 , and Ru0.9 Pt27.3 Ni71.8 colloidal nanocrystal clusters (CNCs) are obtained. In particular, the Ru0.3 Pt70.5 Ni29.2 CNCs exhibit excellent specific activities for formic acid and methanol electro-oxidation, that is, 14.2 and 15.3 times higher, respectively, than those of the Pt/C catalyst. Moreover, the Ru0.3 Pt70.5 Ni29.2 CNCs also possess better anti-CO-poisoning properties and diffusion ability than the other RuPtNi CNCs. The excellent formic acid and methanol electro-oxidation activities of RuPtNi CNCs are ascribed to the optimal ligand effects derived from the Pt, Ni, and atomic dispersed Ru atoms, which can improve the OH adsorption ability and further the anti-CO-poisoning capability. This research opens a new door for increasing the electro-oxidation properties of liquid fuels by using lower dosages of noble metals in Pt-based catalysts.

Ce-Mn coordination polymer derived hierarchical/porous structured CeO2-MnOx for enhanced catalytic properties.

Catalytic performance is largely dependent on how the structures/compositions of materials are designed. Herein, CeO2-MnOx binary oxide catalysts with a hierarchical/porous structure are prepared by a facile and efficient method, which involves the preparation of the hierarchical Ce-Mn coordination polymer (CPs) precursor, followed by a thermal treatment step. The obtained CeO2-MnOx catalysts not only well inherit the hierarchical structure of Ce-Mn CPs, but also possess porous and hollow features due to the removal of organic ligands and heterogeneous contraction during the calcination process. In addition, the effect of the Mn/Ce ratio is also studied to optimize catalytic performance. Specifically, the as-prepared CeO2-MnOx (5 : 5) catalyst exhibits excellent catalytic performance toward CO oxidation and selective catalytic reduction (SCR) of NO with NH3 at low temperatures. Based on the characterization results, we propose that the special hierarchical structure, high surface area, strong synergistic interaction between CeO2 and MnOx, and high content of active Ce3+, Mn4+ and Osurf are collectively responsible for its remarkable catalytic performance.

Tandem Catalysis of Ammonia Borane Dehydrogenation and Phenylacetylene Hydrogenation Catalyzed by CeO2 Nanotube/Pd@MIL-53(Al).

Heterogeneously catalyzed, selective hydrogenation in the liquid phase is widely used in industry for the synthesis of chemicals. However, it can be a challenge to prevent active nanoparticles (e.g., palladium) from aggregation/leaching and meanwhile achieve high conversion as well as selectivity, especially under mild conditions. To address these issues, a CeO2 nanotube/Pd@MIL-53(Al) sandwich-structured catalyst has been prepared in which the MIL-53(Al) porous shell can efficiently stabilize the palladium nanoparticles. When this catalyst was used in a tandem catalytic reaction involving the dehydrogenation of ammonia borane and the hydrogenation of phenylacetylene, remarkably, the hydrogen released from the dehydrogenation of ammonia borane boosted the catalytic process, with 100 % conversion of phenylacetylene and a selectivity of 96.2 % for styrene, even at room temperature and atmospheric pressure, within 1 min. This work therefore provides an alternative strategy for balancing the conversion and selectivity of liquid-phase hydrogenation reactions.

Surface-modified Pt1Ni1-Ni(OH)2 nanoparticles with abundant Pt-Ni(OH)2 interfaces enhance electrocatalytic properties.

Pt-Based catalysts for the methanol oxidation reaction (MOR) are highly susceptible to poisoning due to the surface adsorption of reaction intermediates such as COads. Depositing Pt nanoparticles (NPs) on Ni(OH)2 to fabricate Pt-Ni(OH)2 interfaces is considered as a promising method to improve the stability of Pt-based catalysts because Ni(OH)2 could facilitate water dissociation in alkaline electrolytes to form OH adspecies and assist in the oxidative removal of COads on adjacent Pt sites. However, this supported structure rather limited Pt-Ni(OH)2 interfaces because only a small fraction of the Pt NP surface could come into contact with Ni(OH)2. Herein, this work has addressed a simple and efficient strategy to engineer novel-structure catalysts by tuning the properties of the interface of Pt-based NPs with high-index facets (HIFs). Pt1Ni1-Ni(OH)2 nanoparticles (NPs) were synthesized through Ni(OH)2 partially covering the HIFs of monodisperse Pt1Ni1 concave nanocubes (CNCs) in situ. Pt-Ni(OH)2 interfaces were characterized and over 40% of the Pt surface active sites fall within the periphery of Ni(OH)2. Thanks to the synergy of HIFs and abundant Pt-Ni(OH)2 interfaces, Pt1Ni1-Ni(OH)2 NPs exhibited remarkable catalytic performance towards the MOR in alkaline solution.

Atomic-layer-deposition-formed sacrificial template for the construction of an MIL-53 shell to increase selectivity of hydrogenation reactions.

We developed a method for using atomic layer deposition (ALD)-formed layers of Al2O3 as a sacrificial template to generate MIL-53(Al). The MOF shell in the CeO2/Pd@MIL-53(Al) configuration not only stabilized the Pd nanoparticles, but also regulated the selectivity of the hydrogenation of unsaturated aldehydes. This work represents the first demonstration of ALD-formed layers of metal oxides serving as sacrificial templates in the design of MOF-shell-based sandwich-type structures.

Metal-Organic Framework (MOF)-Derived Carbon-Mediated Interfacial Reaction for the Synthesis of CeO2 -MnO2 Catalysts.

CeO2 -based catalysts are widely studied in catalysis fields. Developing one novel synthetic approach to increase the intimate contact between CeO2 and secondary species is of particular importance for enhancing catalytic activities. Herein, an interfacial reaction between metal-organic framework (MOF)-derived carbon and KMnO4 to synthesize CeO2 -MnO2 , in which carbon is derived from the pyrolysis of Ce-MOFs under an inert atmosphere, is described. The MOF-derived carbon is found to restrain the growth of CeO2 crystallites under a high calcination temperature and, more importantly, intimate contact within CeO2 /C is conveyed to CeO2 /MnO2 after the interfacial reaction; this is responsible for the high catalytic activity of CeO2 -MnO2 towards CO oxidation.

Poly(sodium 4-styrenesulfonate) Assisted Room-Temperature Synthesis for the Mass Production of Bismuth Oxychloride Ultrathin Nanoplates with Enhanced Photocatalytic Activity.

Bismuth oxychloride ultrathin nanoplates (BiOCl-UTNs) are highly active, but their preparation are limited to closed-vessel hydrothermal and solvothermal techniques at high temperatures (110-180 °C). Here we report a straightforward poly(sodium 4-styrenesulfonate) (PSS)-mediated route for the large-scale synthesis of BiOCl-UTNs at room-temperature. In an open vessel, 6.15 g of BiOCl-UTNs with 3-5 nm thickness, and planar dimensions of 30-50 nm were produced. The strong electrostatic interaction between PSS and [Bi2 O2 ]2+ layers inhibited the growth rate of BiOCl nanoplates along <001> direction, and Na+ ions governed the electrolyte sedimentation to produce BiOCl-UTNs. The resulting BiOCl-UTNs exhibited high photocatalytic activity for the degradation of antibiotics and organic dyes because of their large specific surface area, increased light absorption ability, and fast separation and transfer efficiency of the photoexcited charge carriers.

Ultrafine NiMoO x nanoparticles confined in mesoporous carbon for the reduction of nitroarenes: effect of the composition and accessibility of the active sites.

The design of ultrafine NiMoO x nanoparticles (NPs) confined in hierarchically porous carbon remains a great challenge due to its high calcination temperature. In addition, the composition of active sites of NiMoO x NPs for the hydrogenation reaction is still ambiguous. Herein, we report a general approach for the synthesis of ultrafine NiMoO x NPs confined in mesoporous carbon with different morphologies and compositions using the replication method with SBA-15 as a hard template. The pore structure of mesoporous carbon and the Ni/Mo composition valence-state were discovered to be the main factors in the reduction of nitroarenes. The NiMoO x /mesoporous carbon-platelet (NiMoO x /MC-PL) with short mesochannels (∼350 nm) and high surface area (∼995 m2 g-1) possessed excellent catalytic activity towards the reduction of 4-nitrophenol, whereas NiMoO x /mesoporous carbon-hexagonal-prism (NiMoO x /MC-HP), NiMoO x /mesoporous carbon-long-rod (NiMoO x /MC-LR), and NiMoO x /mesoporous carbon-spherical (NiMoO x /MC-SP) with long mesochannels and relatively less surface area exhibited poor catalytic performance. The bifunctional mechanism or electronic synergistic effects of Ni and Mo species enhanced their catalytic performance. A good balance between MoO x and metallic Ni (NiMoO x /MC-PL-450) was found to be suitable for the reduction of 4-NP.

Successive Interfacial Reaction-Directed Synthesis of CeO2@Au@CeO2-MnO2 Environmental Catalyst with Sandwich Hollow Structure.

Noble metal nanoparticle-based catalysts are widely used for the removal of hazardous materials. During the catalytic reactions, it is of particular importance for developing novel strategies to avoid the leaching or sintering of noble metal nanoparticles. Here, the 4-nitrophenol (4-NP) and CO, typical hazardous chemicals in industrial water and exhaust gases from vehicles, are studied for their removal using CeO2@Au@CeO2-MnO2 catalyst. The sandwich hollow structure is achieved by means of successive interfacial redox reaction without any surfactants and without involving any surface modifications. Because of the synergistic interaction between Au nanoparticles and oxides, the as-prepared environmental catalyst exhibits remarkable activity toward the 4-NP reduction. Moreover, the sandwich structure inhibits the growth of the Au nanoparticles and the as-prepared catalyst still displays high activity toward CO oxidation even when the catalyst is treated at 600 °C.

High Capacitive Storage Performance of Sulfur and Nitrogen Codoped Mesoporous Graphene.

Mesoporous graphene is synthesized based on the chemical vapor deposition methodology by using heavy MgO flakes as substrates in a fluidized-bed reactor. Subsequently, sulfur and nitrogen coincorporation into graphene frameworks is realized by the reaction between carbon atoms and thiourea molecules. The as-obtained sulfur and nitrogen codoped mesoporous graphene (SNMG) exhibits remarkable capacitive energy-storage behavior, as a result of well-developed pore channels, in terms of that in a symmetric supercapacitor and lithium-ion hybrid capacitor (LIHC). The ultrahigh durability of the SNMG/SNMG symmetric supercapacitor is demonstrated by long-term cycling, for which no capacitance decay is found after 20 000 cycles. A LIHC constructed from commercial Li4 Ti5 O12 (LTO) as the anode and SNMG as the cathode is capable of delivering much enhanced lithium-storage ability and better rate capability than that of activated carbon (AC)/LTO LIHC. Moreover, SNMG/LTO LIHC exhibits maximum energy and power densities of 86.2 Wh kg-1 and 7443 W kg-1 and maintains 87 % capacitance retention after 2000 cycles.

Design of Porous/Hollow Structured Ceria by Partial Thermal Decomposition of Ce-MOF and Selective Etching.

Metal-organic frameworks (MOFs) have been widely used to prepare corresponding porous metal oxides via thermal treatment. However, high temperature treatment always leads to obtained metal oxides with a large crystallite size, thus decreasing their specific surface area. Different from the conventional complete thermal decomposition of MOFs, herein, using Ce-MOF as a demonstration, we choose partial thermal decomposition of MOF, followed by selective etching to prepare porous/hollow structured ceria because of the poor stability of Ce-MOF under acidic conditions. Compared with the ceria derived from complete thermal decomposition of Ce-MOF, the as-prepared ceria is demonstrated to be a good support for copper oxide species during the CO oxidation catalytic reaction. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and hydrogen temperature-programmed reduction (H2-TPR) analysis revealed that the as-prepared ceria is favorable for strengthening the interaction between the ceria and loaded copper oxide species. This work is expected to open a new, simple avenue for the synthesis of metal oxides from MOFs via partial thermal decomposition.

Graphene Oxide-Assisted Synthesis of Pt-Co Alloy Nanocrystals with High-Index Facets and Enhanced Electrocatalytic Properties.

Metal nanocrystals (NCs) are grown directly on the surface of reduced graphene oxide (rGO), which can maximize the rGO-NCs contact/interaction to achieve the enhanced catalytic activity. However, it is difficult to control the size and morphology of metal NCs by in situ method due to the effects of functional groups on the surface of GO, and as a result, the metal NCs/rGO hybrids are conventionally synthesized by two-step method. Herein, one-pot synthesis of Pt-Co alloy NCs is demonstrated with concave-polyhedrons and concave-nanocubes bounded by {hkl} and {hk0} high-index facets (HIFs) distributed on rGO. GO can affect the geometry and electronic structure of Pt-Co NCs. Thanks to the synergy of the HIFs and the electronic effect of the intimate contact/interaction between Pt-Co alloy and rGO, these as-prepared Pt-Co NCs/rGO hybrids presents enhanced catalytic properties for the electrooxidation of formic acid, as well as for the oxygen reduction reaction.

Mercaptosilane-assisted synthesis of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials and their enhanced hydrogenation properties.

A novel catalyst that consists of sub-nanosized Pt particles within hierarchically porous ZSM-5/SBA-15 materials was synthesized. This catalyst exhibited high stability and a hierarchically porous structure of a micro-mesoporous composite and possessed a high density of active sites by confinement of sub-nanosized Pt particles within small-pore zeolites, showing high catalytic properties for the hydrogenation of 1,3-butadiene and cyclooctadiene at room temperature.