ε-Iron carbide as a low-temperature Fischer–Tropsch synthesis catalyst

Porous Graphene-Confined Fe-K as Highly Efficient Catalyst for CO2 Direct Hydrogenation to Light Olefins

We devised iron-based catalysts with honeycomb-structured graphene (HSG) as the support and potassium as the promoter for CO₂ direct hydrogenation to light olefins (CO₂-FTO). Over the optimal FeK1.5/HSG catalyst, the iron time yield of light olefins amounted to 73 μmol_CO2 g_Fe^-1 s^-1 with high selectivity of 59%. No obvious deactivation occurred within 120 h on stream. The excellent catalytic performance is attributed to the confinement effect of the porous HSG on the sintering of the active sites and the promotion effect of potassium on the activation of inert CO₂ and the formation of iron carbide active for CO₂-FTO.

On the dynamic nature of Mo sites for methane dehydroaromatization

The dynamic catalytic site on Mo/HZSM-5 for methane dehydroaromatization is formed during the initial phases of the reaction. Labelling experiments show that carbon from the carbidic active site is incorporated into the final products.

The mechanism of methane activation on Mo/HZSM-5 is not yet fully understood, despite the great interest in methane dehydroaromatization (MDA) to replace aromatics production in oil refineries. It is difficult to assess the exact nature of the active site due to fast coking. By pre-carburizing Mo/HZSM-5 with carbon monoxide (CO), the MDA active site formation was isolated from coke formation. With this a clear ¹³C NMR signal solely from the active site and not obscured by coke was obtained, and it revealed two types of likely molecular Mo (oxy-)carbidic species in addition to the β-Mo₂C nanoparticles often mentioned in the literature. Furthermore, separating the active site formation from coking by pre-carburization helped us examine how methane is activated on the catalytic site by carrying out MDA using isotopically labelled methane (¹³CH₄). Carbon originating from the pre-formed carbide was incorporated into the main products of the reaction, ethylene and benzene, demonstrating the dynamic behavior of the (oxy-)carbidic active sites.

Widening control of fin inter-rays in zebrafish and inferences about actinopterygian fins

The amputation of a teleost fin rapidly triggers an intricate maze of hierarchically regulated signalling processes which ultimately reconstruct the diverse tissues of the appendage. Whereas the generation of the fin pattern along the proximodistal axis brings with it several well-known developmental regulators, the mechanisms by which the fin widens along its dorsoventral axis remain poorly understood. Utilizing the zebrafish as an experimental model of fin regeneration and studying more than 1000 actinopterygian species, we hypothesized a connection between specific inter-ray regulatory mechanisms and the morphological variability of inter-ray membranes found in nature. To tackle these issues, both cellular and molecular approaches have been adopted and our results suggest the existence of two distinguishable inter-ray areas in the zebrafish caudal fin, a marginal and a central region. The present work associates the activity of the cell membrane potassium channel kcnk5b, the fibroblast growth factor receptor 1 and the sonic hedgehog pathway to the control of several cell functions involved in inter-ray wound healing or dorsoventral regeneration of the zebrafish caudal fin. This ray-dependent regulation controls cell migration, cell-type patterning and gene expression. The possibility that modifications of these mechanisms are responsible for phenotypic variations found in euteleostean species, is discussed.

Enhanced Fischer–Tropsch performances of graphene oxide-supported iron catalysts via argon pretreatment

Argon pretreatment is used to modify the properties of graphene-supported iron catalysts with the purpose of enhancing FTS performances.

Simple and large-scale synthesis of β-phase molybdenum carbides as highly stable catalysts for dry reforming of methane

The catalytic stability of monometallic β-Mo₂C/CNTs was found to be superior to that of bimetallic Ni/β-Mo₂C under similar reaction conditions.

On the nature of active phases and sites in CO and CO2 hydrogenation catalysts

Advanced characterisation techniques are shedding new light on the identification of active CO_x hydrogenation phases and sites.

Highly efficient Fischer–Tropsch synthesis over an alumina-supported ruthenium catalyst

A highly active catalyst for Fischer–Tropsch synthesis at 423 K was prepared, on which the adsorbed CO dissociated at 303 K.

Iron carbide nanoparticles: an innovative nanoplatform for biomedical applications

Iron carbide nanoparticles (ICNPs) are nano-intermetallic compounds that consist of iron and carbon. Benefiting from the magnetic and chemical activity of iron, and/or mechanical strength and chemical inertness of carbon, they have been widely applied in energetic and biomedical-related fields. Particularly in biomedicine, ICNPs have shown high colloidal stability and good performance in magnetic-dependent diagnosis and therapies such as magnetic resonance imaging (MRI) and magnetic hyperthermia (MH), due to their high magnetization and moderate coercivity. The carbon content protects ICNPs from oxidation and corrosion (ion release), which prolongs their life time and reduces their toxicity in physiological environments, and endows nanoparticles (NPs) with high performance in carbon-relevant theranostics as well. On this basis, ICNPs have great promise in multi-modal imaging or imaging-guided tumor-selective therapy to realize precise diagnoses with mild side effects. This paper aims to cover the state of the art applications of ICNPs in biomedicine, primarily including MRI, MH, magnetic targeting (MT), magnetic separation (MS), photothermal therapy (PTT) and photoacoustic tomography (PAT). The biocompatibility of ICNPs is also addressed.

Synthesis of a ceria-supported iron–ruthenium oxide catalyst and its structural transformation from subnanometer clusters to single atoms during the Fischer–Tropsch synthesis reaction

The transformation from subnanometer clusters to single atoms during Fischer–Tropsch synthesis was revealed by X-ray absorption fine structure analysis of a ceria-supported iron–ruthenium oxide catalyst.

Simple synthesis of ultrasmall β-Mo2C and α-MoC1−x nanoparticles and new insights into their catalytic mechanisms for dry reforming of methane

Ultrasmall β- and α-molybdenum carbide particles were synthesized by a resin route and they showed different oxidation–recarburization cycles.

The evolution of Fe phases of a fused iron catalyst during reduction and Fischer–Tropsch synthesis

The phase composition of a fused Fe catalyst during reduction and reaction was quantitatively determined, and the initial FTS activity was correlated to the iron carbide surface area.

Mössbauer Spectroscopy of Iron Carbides: From Prediction to Experimental Confirmation

The Mössbauer spectroscopy of iron carbides (α-Fe, γ'-FeC, η-Fe2C, ζ-Fe2C, χ-Fe5C2, h-Fe7C3, θ-Fe3C, o-Fe7C3, γ'-Fe4C, γ''-Fe4C, and α'-Fe16C2) is predicted utilizing the all electron full-potential linearized augmented plane wave (FLAPW) approach across various functionals from LDA to GGA (PBE, PBEsol, and GGA + U) to meta-GGA to hybrid functionals. To validate the predicted MES from different functionals, the single-phase χ-Fe5C2 and θ-Fe3C are synthesized in experiment and their experimental MES under different temperature (from 13 K to 298 K) are determined. The result indicates that the GGA functional (especially, the PBEsol) shows remarkable success on the prediction of Mössbauer spectroscopy of α-Fe, χ-Fe5C2 and θ-Fe3C with delocalized d electrons. From the reliable simulations, we propose a linear relationship between Bhf and μB with a slope of 12.81 T/μB for iron carbide systems and that the proportionality constant may vary from structure to structure.

The effect of the unpaired d-orbital electron number in Fe and Co catalysts on Fischer–Tropsch synthesis

The unpaired d-orbital electron number was calculated, and the results showed that it can be used as an indicator in Fischer–Tropsch synthesis.

Graphene-supported metal/metal oxide nanohybrids: synthesis and applications in heterogeneous catalysis

This minireview outlines recent advances in the design and catalytic applications of graphene-supported metal/metal oxide nanohybrids.