Silica-supported Fe/Fe–O nanoparticles for the catalytic hydrogenation of nitriles to amines in the presence of aluminium additives

The hydrogenation of nitriles to amines represents an important and frequently used industrial process due to the broad applicability of the resulting products in chemistry and life sciences. Despite the existing portfolio of catalysts reported for the hydrogenation of nitriles, the development of iron-based heterogeneous catalysts for this process is still a challenge. Here, we show that the impregnation and pyrolysis of iron(II) acetate on commercial silica produces a reusable Fe/Fe-O@SiO2 catalyst with a well-defined structure comprising the fayalite phase at the Si-Fe interface and alpha-Fe nanoparticles, covered by an ultrathin amorphous iron(III) oxide layer, growing from the silica matrix. These Fe/Fe-O core-shell nanoparticles, in the presence of catalytic amounts of aluminium additives, promote the hydrogenation of all kinds of nitriles, including structurally challenging and functionally diverse aromatic, heterocyclic, aliphatic and fatty nitriles, to produce primary amines under scalable and industrially viable conditions.Web of Science51292

Hematene: A sustainable 2D conductive platform for visible-light-driven photocatalytic ammonia decomposition

The emerging class of 2D non-van der Waals (n-vdW) materials, including 2D iron oxides, possesses unique properties and high applicability, making them attractive for various technological applications. However, the synthesis of these materials through a scalable and eco-friendly method remains a challenge, as most known chemical exfoliation processes require toxic organic solvents. In this study, we report a green synthesis of 2D hematene (α-Fe2O3) using an ultrasound-supported exfoliation method of earth-abundant iron oxide ore in a pure aqueous solution. The resulting hematene sheets, only a few nanometers thick, exhibit superior electrochemical performance in terms of charge transfer processes, making them ideal for photocatalytic applications. By doping a conductive hematene substrate with ruthenium, we demonstrate a synergistic effect for generating electrons and holes under visible light irradiation. Using this approach, we successfully decomposed ammonia into hydrogen and nitrogen, highlighting the potential of this novel class of environmentally-friendly photocatalysts for clean energy production. Overall, our water-assisted scalable synthesis of hematene offers a promising strategy for producing efficient and sustainable photocatalysts.Web of Science34art. no. 10188

Mixtures of l-Amino Acids as Reaction Medium for Formation of Iron Nanoparticles: The Order of Addition into a Ferrous Salt Solution Matters

Owing to Mössbauer spectroscopy, an advanced characterization technique for iron-containing materials, the present study reveals previously unknown possibilities using l-amino acids for the generation of magnetic particles. Based on our results, a simple choice of the order of l-amino acids addition into a reaction mixture containing ferrous ions leads to either superparamagnetic ferric oxide/oxyhydroxide particles, or magnetically strong Fe0-Fe2O3/FeOOH core-shell particles after chemical reduction. Conversely, when ferric salts are employed with the addition of selected l-amino acids, only Fe0-Fe2O3/FeOOH core-shell particles are observed, regardless of the addition order. We explain this phenomenon by a specific transient/intermediate complex formation between Fe2+ and l-glutamic acid. This type of complexation prevents ferrous ions from spontaneous oxidation in solutions with full air access. Moreover, due to surface-enhanced Raman scattering spectroscopy we show that the functional groups of l-amino acids are not destroyed during the borohydride-induced reduction. These functionalities can be further exploited for (i) attachment of l-amino acids to the as-prepared magnetic particles, and (ii) for targeted bio- and/or environmental applications where the surface chemistry needs to be tailored and directed toward biocompatible species

Molecular insights from theoretical calculations explain the differences in affinity and diffusion of airborne contaminants on surfaces of hBN and graphene

Exposed surfaces of two-dimensional (2D) materials are susceptible to the adsorption of various molecules including airborne contaminants, which can affect their performance in real applications. Hexagonal boron nitride (hBN) is structurally the closest relative to graphite and its single layer form to graphene. The adsorption of organic molecules to graphene was subject of extensive research, however, little is known about interaction of adsorbates to hBN surface. We studied the affinity of organic molecules to the surface of hBN by inverse gas chromatography. The adsorption enthalpies of polar molecules including acetonitrile, nitromethane, ethanol, and acetone exhibited strong coverage dependency up to 20 % of a monolayer. Density functional theory and molecular dynamics calculations were employed to understand and interpret experimentally measured adsorption enthalpies. The calculations revealed that the strong affinity of polar molecules at low coverage was due to adsorption on steps and edges of hBN. The calculated surface diffusion barriers of all molecules were rather low, i.e., below 0.5 kcal/mol (except for benzene and cyclohexane), and molecules adsorbed on the surface behaved like a 2D gas. The results demonstrated that coupling inverse gas chromatography with computer simulations can provide vital insights into the mechanism of adsorption at the molecular level.Web of Science565art. no. 15038

Pharmaceuticals, benzene, toluene and chlorobenzene removal from contaminated groundwater by combined UV/H2O2 photo-oxidation and aeration

This study was performed to test the feasibility of several decontamination methods for remediatingheavily contaminated groundwater in a real contaminated locality in the Czech Republic, where apharmaceuticals plant has been in operation for more than 80 years. The site is polluted mainly byrecalcitrant psychopharmaceuticals and monoaromatic hydrocarbons, such as benzene, toluene andchlorobenzene. For this purpose, an advanced oxidation technique employing UV radiation withhydrogen peroxide dosing was employed, in combination with simple aeration pretreatment. The resultsshowed that UV/H2O2was an efficient and necessary step for degradation of the pharmaceuticals;however, the monoaromatics were already removed during the aeration step. Characterization of theremoval mechanisms participating in the aeration revealed that volatilization, co-precipitation andbiodegradation contributed to the process. Thesefindings were supported by bacterial metabolite ana-lyses, phospholipid fatty acid analysis, qPCR of representatives of the degradative genes and detailedcharacterization of the formed precipitate using M€ossbauer spectroscopy and scanning electron micro-scopy. Further tests were carried out in a continuous arrangement directly connected to the wells alreadypresent in the locality. The results documented the feasibility of combination of the photo-reactoremploying UV/H2O2together with aeration pretreatment for 4 months, where the overall decontami-nation efficiency ranged from 72% to 99% of the pharmaceuticals. We recorded even better results for themonoaromatics decontamination except for one month, when we encountered some technical problemswith the aeration pump. This demonstrated the necessity of using the aeration step