Methanol conversion on borocarbonitride catalysts: Identification and quantification of active sites.

Borocarbonitrides (BCNs) have emerged as highly selective catalysts for the oxidative dehydrogenation (ODH) reaction. However, there is a lack of in-depth understanding of the catalytic mechanism over BCN catalysts due to the complexity of the surface oxygen functional groups. Here, BCN nanotubes with multiple active sites are synthesized for oxygen-assisted methanol conversion reaction.

Highly Efficient Metal-Free Nitrogen-Doped Nanocarbons with Unexpected Active Sites for Aerobic Catalytic Reactions.

Nitrogen (N)-doped nanocarbons (NDN) as metal-free catalysts have elicited considerable attention toward selective oxidation of alcohols with easily oxidizable groups to aldehydes in the past few years. However, finding a new NDN catalytic material that can meet the requirement of the feasibility on the aerobic catalytics for other complicated alcohols is a big challenge. The real active sites and the corresponding mechanisms on NDN are still unambiguous because of inevitable coexistence of diverse edge sites and N species based on recently reported doping methods.

MoO Nanoparticle Catalysts for d-Glucose Epimerization and Their Electrical Immobilization in a Continuous Flow Reactor.

Activity and immobilization of catalysts in liquid-phase reactions seem not to coexist. We report here the excellent activity of an MoO nanoparticle (NP) catalyst for d-glucose epimerization to d-mannose and the electrical immobilization of NPs in a flow reaction. Prior to that, a green and one-pot method to synthesize the MoO NPs (3.

Unraveling the coordination structure-performance relationship in Pt/FeO single-atom catalyst.

Heterogeneous single-atom catalyst (SAC) opens a unique entry to establishing structure-performance relationship at the molecular level similar to that in homogeneous catalysis. The challenge lies in manipulating the coordination chemistry of single atoms without changing single-atom dispersion. Here, we develop an efficient synthetic method for SACs by using ethanediamine to chelate Pt cations and then removing the ethanediamine by a rapid thermal treatment (RTT) in inert atmosphere.

Atomic-Scale Observation of Bimetallic Au-CuO Nanoparticles and Their Interfaces for Activation of CO Molecules.

Supported gold nanoparticles with sizes below 5 nm display attractive catalytic activities for heterogeneous reactions, particularly those promoted by secondary metal (e.g., Cu) because of the well-defined synergy between metal compositions.

Wet-Chemistry Strong Metal-Support Interactions in Titania-Supported Au Catalysts.

Classical strong metal-support interactions (SMSI), which play a crucial role in the preparation of supported metal nanoparticle catalysts, is one of the most important concepts in heterogeneous catalysis. The conventional wisdom for construction of classical SMSI involves in redox treatments at high-temperatures by molecular oxygen or hydrogen, sometimes causing sintered metal nanoparticles before SMSI formation. Herein, we report that the aforementioned issue can be effectively avoided by a wet-chemistry methodology.

Visualizing Formation of Intermetallic PdZn in a Palladium/Zinc Oxide Catalyst: Interfacial Fertilization by PdH.

Controllable synthesis of well-defined supported intermetallic catalysts is desirable because of their unique properties in physical chemistry. To accurately pinpoint the evolution of such materials at an atomic-scale, especially clarification of the initial state under a particular chemical environment, will facilitate rational design and optimal synthesis of such catalysts. The dynamic formation of a ZnO-supported PdZn catalyst is presented, whereby detailed analyses of in situ transmission electron microscopy, electron energy-loss spectroscopy, and in situ X-ray diffraction are combined to form a nanoscale understanding of PdZn phase transitions under realistic catalytic conditions.

A comparative study of nitrobenzene reduction using model catalysts.

A zigzag-type quinone performs better than an armchair-type quinone in the reduction of nitrobenzene. When different kinds of functionalities co-exist, the reaction is dominated by the most active sites, but the most negative sites should also be taken into consideration if the acitive sites have zigzag structures.

Oxygen Electrocatalysis at Mn-O -C Hybrid Heterojunction: An Electronic Synergy or Cooperative Catalysis?

The interface at the metal oxide-carbon hybrid heterojunction is the source to the well-known "synergistic effect" in catalysis. Understanding the structure-function properties is key for designing more advanced catalyst-support systems. Using a model Mn-O single-layer catalyst on carbon, we herein report a full elucidation to the catalytic synergism at the hybrid heterojunction in the oxygen reduction reaction (ORR).

Hydration of phenylacetylene on sulfonated carbon materials: active site and intrinsic catalytic activity.

A series of sulfonated carbon materials (sulfonated glucose-derived carbon, carbon nanotubes, activated carbon and ordered mesoporous carbon, denoted as Sglu, SCNT, SAC and SCMK, respectively) were synthesized and applied as acid catalysts in phenylacetylene (PA) hydration reactions. The sulfonic acid groups (-SOH) were identified to be the only kind of active sites and were quantified with XPS and a cation exchange process. Mechanistic studies revealed that the catalytic PA hydration reaction follows pseudo first order reaction kinetics.

Catalysis by hybrid sp/sp nanodiamonds and their role in the design of advanced nanocarbon materials.

Hybrid sp2/sp3 nanocarbons, in particular sp3-hybridized ultra-dispersed nanodiamonds and derivative materials, such as the sp3/sp2-hybridized bucky nanodiamonds and sp2-hybridized onion-like carbons, represent a rather interesting class of catalysts still under consideration. Their characteristics, properties and catalytic reactivity are presented, with an analysis of the state-of-the-art of their use in gas- and liquid-phase reactions, including photo- and electro-catalysis. It is remarked that intrinsic differences exist between these and other nanostructured carbon catalysts.

Biomass-Derived Graphene-like Carbon: Efficient Metal-Free Carbocatalysts for Epoxidation.

N-doped graphene-like layered carbon (NG) could be synthesized via a metal-free pyrolysis route from glucose, fructose, and 5-hydroxymethylfurfural (5-HMF), which are cheap and widely available biomass or biomass derivatives. A well-developed thin-layer structure with large lateral dimensions could be obtained when 5-HMF was used as the precursor. More importantly, the 5-HMF-derived NG gave superior performance in epoxidation reactions compared with the conventional carbon catalysts and the performance of 5-HMF derived NG was even similar to that of a cobalt catalyst.

Pt NPs immobilized on a N-doped graphene@AlO hybrid support as robust catalysts for low temperature CO oxidation.

Platinum nanoparticles (Pt NPs) immobilized on a N-doped graphene@Al2O3 hybrid support (Al2O3@CNx) were synthesized and employed for low temperature CO oxidation. The superior catalytic activity was attributed to a strong metal-support interaction between Pt NPs and the N-doped graphene surface which was also confirmed in the direct dehydrogenation reaction.

Probing the enhanced catalytic activity of carbon nanotube supported Ni-LaO hybrids for the CO reduction reaction.

Oxygenated functionalized carbon nanotube (oCNT) supported LaO-promoted Ni nanoparticles (10Ni-xLa/oCNT) were prepared by the co-impregnation method and tested for synthetic natural gas from the CO reduction reaction. Several advanced characterization methods, including atomic resolution scanning transmission electron microscopy (STEM), temperature programmed experiments (TPSR, CO-TPD, and H-TPR) and X-ray photoelectron spectroscopy (XPS), were applied to explore, for the first time, the origin of structure modulation of LaO species on oCNT supported Ni-LaO hybrids and the structure-activity relationship over the CO reduction reaction. The Z-contrast STEM-HAADF results revealed that the LaO species are mostly in the size of the sub-nano scale and highly dispersed on the surface of Ni nanoparticles and oCNT, and consequently no diffraction peak of LaO was observed from XRD results.

A Heterogeneous Metal-Free Catalyst for Hydrogenation: Lewis Acid-Base Pairs Integrated into a Carbon Lattice.

Designing heterogeneous metal-free catalysts for hydrogenation is a long-standing challenge in catalysis. Nanodiamond-based carbon materials were prepared that are surface-doped with electron-rich nitrogen and electron-deficient boron. The two heteroatoms are directly bonded to each other to form unquenched Lewis pairs with infinite π-electron donation from the surrounding graphitic structure.

Oxidative Dehydrogenation on Nanocarbon: Insights into the Reaction Mechanism and Kinetics via in Situ Experimental Methods.

Sustainable and environmentally benign catalytic processes are vital for the future to supply the world population with clean energy and industrial products. The replacement of conventional metal or metal oxide catalysts with earth abundant and renewable nonmetallic materials has attracted considerable research interests in the field of catalysis and material science. The stable and efficient catalytic performance of nanocarbon materials was discovered at the end of last century, and these materials are considered as potential alternatives for conventional metal-based catalysts.

Oxidative dehydrogenation reaction of short alkanes on nanostructured carbon catalysts: a computational account.

Recent progress from first principles computational studies is presented for catalytic properties of nanostructured carbon catalysts in the oxidative dehydrogenation (ODH) reaction of short alkanes. Firstly, a brief introduction is given on the development of carbon catalysts in ODH since 1970. Oxygen functional groups have pivotal importance for ODH on nanostructured carbon catalysts.

An Efficient Metal-Free Catalyst for Oxidative Dehydrogenation Reaction: Activated Carbon Decorated with Few-Layer Graphene.

Activated carbon (AC) has been widely used in the catalysis field because of its low cost, scalable production, high specific surface area, and abundant exposed edge. Because of the amorphous structure, traditional AC is unstable in presence of O at high temperature, which hinders the application of AC catalysts in oxidative dehydrogenation (ODH) of alkanes. Here, partially graphitic AC decorated with few-layer graphene is facilely fabricated by simple high-temperature calcination.

Oxygenated group and structural defect enriched carbon nanotubes for immobilizing gold nanoparticles.

Surface functionalized and defect enriched carbon nanotubes (oCNTs) by green ozone/HO treatment can efficiently anchor gold nanoparticles. This Au/oCNT could be stabilized and well dispersed after thermal treatment and showed robust catalytic activity (20.6 mmol g h) for the oxidative self-coupling of benzylamine to imine in solvent free conditions.

Fabrication of MgO-rGO hybrid catalysts with a sandwich structure for enhanced ethylbenzene dehydrogenation performance.

MgO-rGO hybrid catalysts with a sandwich structure have been successfully prepared through a simple "solid-solid" method. Obviously enhanced reactivity is observed on the hybrid catalysts in ethylbenzene dehydrogenation reactions, which is attributed to the sandwich structure and the synergistic effect between MgO and rGO.

The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation.

The mechanism of CO oxidation by O on a single Au atom supported on pristine, mono atom vacancy (m), di atom vacancy (di) and the Stone Wales defect (SW) on single walled carbon nanotube (SWCNT) surface is systematically investigated theoretically using density functional theory. We determine that single Au atoms can be trapped effectively by the defects on SWCNTs. The defects on SWCNTs can enhance both the binding strength and catalytic activity of the supported single Au atom.

Efficient and Highly Selective Solvent-Free Oxidation of Primary Alcohols to Aldehydes Using Bucky Nanodiamond.

Selective oxidation of alcohols to aldehydes is widely applicable to the synthesis of various green chemicals. The poor chemoselectivity for complicated primary aldehydes over state-of-the-art metal-free or metal-based catalysts represents a major obstacle for industrial application. Bucky nanodiamond is a potential green catalyst that exhibits excellent chemoselectivity and cycling stability for the selective oxidation of primary alcohols in diverse structures (22 examples, including aromatic, substituted aromatic, unsaturated, heterocyclic, and linear chain alcohols) to their corresponding aldehydes.

Insights into the surface chemistry and electronic properties of sp and sp-hybridized nanocarbon materials for catalysis.

Ultra-dispersed nanodiamond and its derivatives (UNDDs), including bucky nanodiamond and onion-like carbon, offer superior catalytic behavior relative to other nanocarbons. However, a systematic study of their unique properties has been rarely achieved. Their surface chemistry and electronic properties are therefore studied to reveal the essential differences of UNDDs compared to other nanocarbons for catalysis.

Hydrothermal Carbon Enriched with Oxygenated Groups from Biomass Glucose as an Efficient Carbocatalyst.

Metal-free carbocatalysts enriched with specific oxygenated groups with different morphology and size were synthesized from glucose by hydrothermal carbonization, in which cheap and widely available biomass could be converted into functionalized carbon using an environmentally benign process. The hydroxy- and carbonyl-enriched hydrothermal carbon (HTC) could be used in nitrobenzene reduction, and higher conversion was obtained on the sphere morphology with smaller size. In the Beckmann rearrangement of cyclohexanone oxime, carboxyl-enriched HTC exhibited superior performance compared with conventional solid acid (such as HY and HZSM-5), on which the strong acid sites and weak Lewis acid sites lead to high selectivity for the side product.

Rational Design of Zirconium-doped Titania Photocatalysts with Synergistic Brønsted Acidity and Photoactivity.

The preparation of photocatalysts with high activities under visible-light illumination is challenging. We report the rational design and construction of a zirconium-doped anatase catalyst (S-Zr-TiO ) with Brønsted acidity and photoactivity as an efficient catalyst for the degradation of phenol under visible light. Electron microscopy images demonstrate that the zirconium sites are uniformly distributed on the sub-10 nm anatase crystals.