Reverse Water-Gas Shift Iron Catalyst Derived from Magnetite

Nanozyme-induced deep learning-assisted smartphone integrated colorimetric and fluorometric dual-mode for detection of tetracycline analogs

In this work, a colorimetric and fluorescent dual-mode probe controlled by NH2-MIL-88 B (Fe, Ni) nanozymes was developed to visually detect tetracycline antibiotics (TCs) residues quantitatively, as well as accurately distinguish the four most widely used tetracycline analogs (tetracycline (TC), chrycline (CTC), oxytetracycline (OTC), and doxycycline (DC)). Colorless substrate 3,3',5,5'-tetramethylbenzidine (TMB) may be oxidized to blue oxidized TMB by the Fe Fenton reaction, which was catalyzed by the NH2-MIL-88 B (Fe, Ni) nanozyme with POD-like activity. The colorimetric detection system allows TCs to interact with NH2-MIL-88 B (Fe, Ni). This inhibits the production of ·OH, weakens the oxidation process of TMB, and ultimately lightens the blue color in the system by blocking the electron transfer between NH2-MIL-88 B (Fe, Ni) and H2O2. Furthermore, TCs can interact with NH2-MIL-88 B (Fe, Ni) as a result of the internal filtering effect, which causes the fluorescence intensity to decrease as TCs concentration increases. Additionally, a portable instrument that combines a smartphone sensing platform with colorimetric and fluorescent signals was created for the quick, visual quantitative detection of TCs. The colorimetric and fluorescent dual-mode nano platform enables color change, with detection limits (LODs) of 0.182 μM and 0.0668 μM for the spectrometer and smartphone sensor, respectively, based on the inhibition of fluorescence and enzyme-like activities by TCs. Overall, the colorimetric and fluorescence dual-mode sensor has good stability, high specificity, and an efficient way to eliminate false-positive issues associated with a single detection mode.

A Facile Approach to Produce Activated Carbon from Waste Textiles via Self-Purging Microwave Pyrolysis and FeCl3 Activation for Electromagnetic Shielding Applications

This study aims to convert composite textile structures composed of nonwoven and woven fabrics produced from cotton-jute wastes into activated carbon textile structures and investigate the possibilities of using them for electromagnetic shielding applications. To this end, the novel contribution of this study is that it shows that directly carbonized nonwoven textile via self-purging microwave pyrolysis can provide Electromagnetic Interference (EMI) shielding without any processing, including cleaning. Textile carbonization is generally achieved with conventional heating methods, using inert gas and long processing times. In the present study, nonwoven fabric from cotton-jute waste was converted into an activated carbon textile structure in a shorter time via microwaves without inert gas. Due to its polar structure, FeCl3 has been used as a microwave absorbent, providing homogeneous heating in the microwave and acting as an activating agent to serve dual purposes in the carbonization process. The maximum surface area (789.9 m2/g) was obtained for 5% FeCl3. The carbonized composite textile structure has a maximum of 39.4 dB at 1 GHz of EMI shielding effectiveness for 10% FeCl3, which corresponds to an excellent grade for general use and a moderate grade for professional use, exceeding the acceptable range for industrial and commercial applications of 20 dB, according to FTTS-FA-003.

Microwave-Assisted Synthesis of Iron-Based Aerogels with Tailored Textural and Morphological Properties

Iron aerogels have been synthesized by microwave heating for the first time. Therefore, it is essential to optimize this synthesis process to evaluate the possibility of obtaining nanometric materials with tailored properties and fitting them to the needs of different applications. Herein, the effect of the ratio between reagents and the time of synthesis on the final textural, morphological, and structural properties has been evaluated. The micro-meso-macroporosity of the samples can be tailored by modifying the ratio between reagents, whereas the time of synthesis has only a slight effect on the microporosity. Both the proportion between reagents and the time of synthesis are essential to controlling the nanometric morphology, making it possible to obtain either cluster- or flake-type structures. Regarding the chemical and structural composition, the samples are mainly composed of iron(II) and iron(III) oxides. However, the percentage of iron(II) can be modulated by changing the ratio between reagents, which implies that it is possible to obtain materials from highly magnetic materials to materials without magnetic properties. This control over the properties of iron aerogels opens a new line of opportunities for the use of this type of material in several fields of applications such as electrochemistry, electrocatalysis, and electrical and electronic engineering.

Catalytic Sabatier Process under Thermally and Magnetically Induced Heating: A Comparative Case Study for Titania-Supported Nickel Catalyst

In the present paper, we compare the activity, selectivity, and stability of a supported nickel catalyst in classical heating conditions and in magnetically activated catalysis by using iron wool as a heating agent. The catalyst, 5 wt% Ni supported on titania (Degussa P25), was prepared via an organometallic decomposition method and was thoroughly characterized by using elemental, microscopic, and diffraction techniques. In the event of magnetic induction heating, the % CO₂ conversion reached a maximum of ~85% compared to ~78% for thermal conditions at a slightly lower temperature (~335 °C) than the thermal heating (380 °C). More importantly, both processes were found to be stable for 45 h on stream. Moreover, the effects of magnetic induction and classical heating over the catalyst evolution were discussed. This study demonstrated the potential of magnetic heating-mediated methanation, which is currently under investigation for the development of pilot-scale reactors.

Effect of Different Iron Phases of Fe/SiO2 Catalyst in CO2 Hydrogenation under Mild Conditions

The effect of different active phases of Fe/SiO2 catalyst on the physio-chemical properties and the catalytic performance in CO2 hydrogenation under mild conditions (at 220 °C under an ambient pressure) was comprehensively studied in this work. The Fe/SiO2 catalyst was prepared by an incipient wetness impregnation method. Hematite (Fe2O3) in the calcined Fe/SiO2 catalyst was activated by hydrogen, carbon monoxide, and hydrogen followed by carbon monoxide, to form a metallic iron (Fe/SiO2-h), an iron carbide (Fe/SiO2-c), and a combination of a metallic iron and an iron carbide (Fe/SiO2-hc), respectively. All activated catalysts were characterized by XRD, Raman spectroscopy, N2 adsorption–desorption, H2-TPR, CO-TPR, H2-TPD, CO2-TPD, CO-TPD, NH3-TPD, and tested in a CO2 hydrogenation reaction. The different phases of the Fe/SiO2 catalyst are formed by different activation procedures and different reducing agents (H2 and CO). Among three different activated catalysts, the Fe/SiO2-c provides the highest CO2 hydrogenation performance in terms of maximum CO2 conversion, as well as the greatest selectivity toward long-chain hydrocarbon products, with the highest chain growth probability of 0.7. This is owing to a better CO2 and CO adsorption ability and a greater acidity on the carbide form of the Fe/SiO2-c surface, which are essential properties of catalysts for polymerization in FTs.

Nanoengineering of Catalysts for Enhanced Hydrogen Production

Hydrogen (H2) has emerged as a sustainable energy carrier capable of replacing/complementing the global carbon-based energy matrix. Although studies in this area have often focused on the fundamental understanding of catalytic processes and the demonstration of their activities towards different strategies, much effort is still needed to develop high-performance technologies and advanced materials to accomplish widespread utilization. The main goal of this review is to discuss the recent contributions in the H2 production field by employing nanomaterials with well-defined and controllable physicochemical features. Nanoengineering approaches at the sub-nano or atomic scale are especially interesting, as they allow us to unravel how activity varies as a function of these parameters (shape, size, composition, structure, electronic, and support interaction) and obtain insights into structure–performance relationships in the field of H2 production, allowing not only the optimization of performances but also enabling the rational design of nanocatalysts with desired activities and selectivity for H2 production. Herein, we start with a brief description of preparing such materials, emphasizing the importance of accomplishing the physicochemical control of nanostructures. The review finally culminates in the leading technologies for H2 production, identifying the promising applications of controlled nanomaterials.

High Loading of Transition Metal Single Atoms on Chalcogenide Catalysts

Transition metal doped chalcogenides are one of the most important classes of catalysts that have been attracting increasing attention for petrochemical and energy related chemical transformations due to their unique physiochemical properties. For practical applications, achieving maximum atom utilization by homogeneous dispersion of metals on the surface of chalcogenides is essential. Herein, we report a detailed study of a deposition method using thiourea coordinated transition metal complexes. This method allows the preparation of a library of a wide range of single atoms including both noble and non-noble transition metals (Fe, Co, Ni, Cu, Pt, Pd, Ru) with a metal loading as high as 10 wt % on various ultrathin 2D chalcogenides (MoS₂, MoSe₂, WS₂ and WSe₂). As demonstrated by the state-of-the-art characterization, the doped single transition metal atoms interact strongly with surface anions and anion vacancies in the exfoliated 2D materials, leading to high metal dispersion in the absence of agglomeration. Taking Fe on MoS₂ as a benchmark, it has been found that Fe is atomically dispersed until 10 wt %, and beyond this loading, formation of coplanar Fe clusters is evident. Atomic Fe, with a high electron density at its conduction band, exhibits a superior intrinsic activity and stability in CO₂ hydrogenation to CO per Fe compared to corresponding surface Fe clusters and other Fe catalysts reported for reverse water-gas-shift reactions.

Inverse iron oxide/metal catalysts from galvanic replacement

Key chemical transformations require metal and redox sites in proximity at interfaces; however, in traditional oxide-supported materials, this requirement is met only at the perimeters of metal nanoparticles. We report that galvanic replacement can produce inverse FeO_x/metal nanostructures in which the concentration of oxide species adjoining metal domains is maximal. The synthesis involves reductive deposition of rhodium or platinum and oxidation of Fe²⁺ from magnetite (Fe₃O₄). We discovered a parallel dissolution and adsorption of Fe²⁺ onto the metal, yielding inverse FeO_x-coated metal nanoparticles. This nanostructure exhibits the intrinsic activity in selective CO₂ reduction that simple metal nanoparticles have only at interfaces with the support. By enabling a simple way to control the surface functionality of metal particles, our approach is not only scalable but also enables a versatile palette for catalyst design.

While typical catalysts involve oxide-supported metals, inverse catalysts of oxides on metal supports offer an attractive alternative. Here, authors prepare FeO_x-coated Rh nanoparticles via galvanic replacement and dissolution-precipitation to form effective CO₂ reduction catalysts.

Editorial: Cobalt and Iron Catalysis

Cobalt and iron have long history of importance in the field of catalysis that continues to this day [...]