Low-cost activated carbon microspheres from wasted expanded polystyrene with and without iron oxide were successfully synthesized for 4-nitrophenol adsorption, through a facile three-step method: pyrolysis, activation and iron oxide deposition. The carbon microspheres presented short order structure with an average size of 4.50 mu m +/- 1.61 mu m and iron oxide deposited as maghemite nanoparticles, 13.6 nm +/- 3.6 nm average size. Adsorption studies of 4-nitrophenol solutions were carried out via UV-Vis spectroscopy at different concentrations, 5-200 ppm, pH = 5.5 and 30 degrees C. Samples Fe2O3/WEPAC and WEPAC presented noticeable qe values, 85 and 170 mg/g with adsorption models as PSO, Langmuir and Freundlich type. Ex-situ XPS studies revealed changes in iron oxide after adsorption. Additionally, Fe2O3/WEPAC showed sensibility to magnetic fields that facilitates its

Gold nanoparticles (AuNPs) supported on alumina (Au/Al2O3) and confined with alumina (Au/Al2O3@Al2O3) to form a yolk-shell structure were successfully synthesized via the atomic layer deposition technique (ALD) using trimethylaluminum (TMA) as the alumina precursor. The physicochemical properties of the prepared materials were characterized by TEM, FTIR, BET, UV-Vis, and ICP-OES. The synthesized materials exhibit high catalytic performance in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4 as a hydrogen source. The alumina confinement significantly influences both AuNPs catalytic performance and the reaction mechanism, as determined by the Principal Component Analysis (PCA) of broad range UV-Vis spectra (220-550 nm) collected during the catalytic test. Application of PCA allowed to track the simultaneous dynamic transformations of all key species: the initial reagent (4-NP), intermediate (cis-4,4-azobisphenolate), and the final product (4-AP). The analysis demonstrates that contribution of a cis-4,4-azobisphenolate intermediate depends on catalyst structure and reaction conditions. The PCA-enhanced spectroscopy complements traditional kinetic analysis by revealing hidden reaction pathways that would otherwise be obscured in conventional single-wavelength monitoring approaches, thereby distinguishing between competing mechanistic routes with high fidelity. These findings provide a fresh perspective on how catalyst architecture dictates functional pathways and highlights the potential of confinement strategies for tuning the catalytic behavior of metal nanoparticles and provide insights for the rational design of efficient nanocatalysts.

Since their implementation in the secondary battery market, Li-ion batteries have been widely studied in the search for new strategies to boost their energy storage. One of the most attractive ways to improve the specific capacity and electrochemical behavior of the anode is doping the carbon material with other elements. This study presents a novel and facile synthesis method to obtain dual boron- and nitrogen-doped carbon spheres (CBNX, X = ethyl, butyl, hexyl, octyl and decyl) based on the pyrolysis of borane-amine precursors, BH3[(CYH2Y+1)3N], Y = 2, 4, 6, 8 and 10. Of these materials CBNOctyl presented the best electrochemical performance, delivering a specific capacity of 501.9 mAh/g at 120 mA g−1 with high coulombic efficiency (>99.9%) and capacity retention (113%), and moderate charge transfer resistance (84.3 Ω) after 200 cycles. DFT calculations corroborate that co-doping carbon with boron and nitrogen increases its theoretical gravimetric capacity, reaching 534 mAh/g, due to the appearance of new and/or additional auspicious sites for Li storage around boron and nitrogen centers. It is proposed that dual doping of carbon materials could be a promising strategy to boost Li-ion storage at LiB anodes

The development of environmentally benign and efficient catalytic systems is essential for advancing green and sustainable biomass conversion processes. In this study, we report a series of nanostructured ternary mixed oxides based on alumina modified with 10 and 30 wt % ceria-zirconia, synthesized via a sol-gel method, for the catalytic dehydration of xylose to furfural under microwave irradiation. The catalysts were characterized by N2 adsorption, XRD, UV-vis, and XPS techniques, revealing high surface areas, small crystallite sizes of Ce, Zr, and Al, and tunable acidity comprising the Lewis acid sites modulated by the Ce and Zr contents. The CeZr(30)-Al catalyst demonstrated a furfural yield of 65% at 170 degrees C in 40 min, markedly superior to that of pure Al2O3, CeO2, and ZrO2, highlighting the benefits of oxide synergy and microwave-assisted heating. This approach not only reduces reaction time and energy consumption but also avoids the use of corrosive mineral acids, aligning with key principles of green chemistry. These findings demonstrate the potential of CeZr-Al ternary oxides as efficient, sustainable catalysts for lignocellulosic biomass valorization into platform chemicals.

This work evaluated the effect of Zn on the electronic state of copper in the Cu-Zn-mordenite binary system. The samples were prepared in two stages by sequential ion exchange of the initial sodium mordenite, using aqueous solutions of sulfate salts of these two metals, and changing the order of introduction of each of the cations, first Cu2+ and then Zn2+, or in the inverse order. The content of Zn and Cu changed within the 0.02-3.14 wt% interval at various Zn/Cu ratios. The prepared samples were characterized with UV-Vis spectroscopy in situ during temperature-programed oxidation (TPO) in oxygen, temperature-programed reduction (TPR) in hydrogen, and temperature-programed adsorption and desorption of NO (TPD). Cu and Zn have different affinities to mordenite, resulting in competition between them for zeolites sites, their redistribution, and formation of bimetallic Cu-O-Zn species. The order of ion-exchange makes it possible to modify the nature and the relative content of these metal species. Electronic properties of the resulting copper species strongly depend on both the Zn/Cu ratio and the order of exchange of metal ions. The knowledge we have obtained will be useful for designing of new effective catalysts based on copper-exchanged zeolites.

Copper oxide nanoparticles (CuO-NPs) were functionalized with specific antibodies to target their antibacterial activity against Gram-positive or Gram-negative bacteria. The CuO-NPs were covalently functionalized to cover their surface with specific antibodies. The differently prepared CuO-NPs were characterized by X-ray diffraction, transmission electron microscopy and dynamic light scattering. The antibacterial activities of the unmodified CuO-NPs and the antibody-functionalized nanoparticles (CuO-NP-AbGram- and CuO-NP-AbGram+ ) were determined for both Gram-negative Escherichia coli and Gram-positive Bacillus subtilis bacteria. The antibody-functionalized NPs showed a differential increase of their antibacterial activity according to the specific antibody. The CuO-NP-AbGram- in E. coli showed reduced half maximal inhibitory concentration (IC50 ) and minimum inhibitory concentration (MIC) values when compared with unfunctionalized CuO-NPs. On the other hand, the CuO-NP-AbGram+ also showed reduced IC50 and MIC values in B. subtilis, when compared with non-functionalized CuO-NPs. Thus, the functionalized CuO nanoparticles with specific antibodies showed enhanced specificity of their antibacterial activity. The advantages of "smart" antibiotic nanoparticles are discussed.

Mordenite-type zeolites with a SiO2/Al2O3 ratio of 13 in sodium form were subjected to ion exchange using 0.1 N solutions of Ni(NO3)(2) and CuSO4, or mixtures thereof with variable ratio of components at two different temperatures, 20 and 90 C-degrees, varying the volume of Cu:Ni ratio in solution. The diffraction patterns revealed the preservation of the zeolite structure after the ion exchange process. Further ICP-AES measurements showed that the ions exchanged percentage depended on the volume ratio of the components added to the exchange solution. The electronic and chemical states of the species in zeolite were studied by diffuse UV-Vis spectroscopy, TPD-NO, and TPR-H-2 methods. According to the UV-Vis DRS spectra, absorption increased in the charge transference region (200-350 nm) as the ion exchange temperature increased from 20 to 90 C-degrees. On the other hand, evidence for changes in the chemical state was obtained from TPR and TPD-NO profiles. In the TPR experiments, we observed differences in reductivity with increasing ion exchange temperature. Meanwhile by TPD-NO experiments, all materials showed a capacity to desorb NO molecule at low temperature (<350 C-degrees) and changes in the types of present species as was related with the variation in the ion-exchange temperature. The composition and properties of the Ni:Cu/mordenite bimetallic system were affected by the ion-exchange temperature and the volume ratio of Cu:Ni metal solutions.

The presence of cationic gold species is a key factor for the CO oxidation over the supported gold catalysts based on non-reducible metal oxides. The deactivation of such catalysts is mainly associated with the Au nanoparticles (AuNPs) sintering and the concomitant reduction of cationic Au species. Here we report the high catalytic stability at the CO oxidation of the cationic Au species confined into a mordenite-like zeolite matrix prepared by a one-pot synthesis method. The sample with lowest Au loading (0.32 % wt.) exhibited the higher catalytic performance and stability during CO oxidation. Detailed FTIR analysis showed that the CO oxidation on sample with low Au content (0.32 wt%) occurred preferentially via CO interaction with the cationic interface Au-hydroxyl (Au1+-OH- ) species to produce CO2(g) via decarboxylation. In contrast, the sample with a high Au content (1.56 wt%) displayed lower CO oxidation ability, which was associated with a low content and less stability of cationic gold species. Proposed synthesis method permits to obtain in a one-pot way stable cationic gold species highly effectively for the CO oxidation.

A promising high-capacity anode material, h-Bi2Ge3O9 with benitoite phase, was successfully prepared by a versatile two-step method that involves: (i) an initial sol-gel process, followed by (ii) air thermal treatment at high temperature. Due to its unique physico-chemical and electrochemical features, the h-Bi2Ge3O9-based electrode can reversibly store 18.1 mols of lithium (Li) per mol of h-Bi2Ge3O9, delivering a high capacity of 621.9 mAh/g at 200 mA g-1 with good coulombic efficiency of >99.5 %, reasonable capacity retention of 77 % and low electrode polarization (41 mV) after 200 cycles. According to density functional theory (DFT) calculations, the h-Bi2Ge3O9 structure could store 40Li atoms, Li40Bi2Ge3O9, with a stable formation energy (Ef) of -1.20 eV, suffering a volume expansion of 112 %. Also, the simulation revealed the rupture of Bi-O and Ge-O bonds, which promote the formation of new interactions as Li-Bi, Bi-Bi, Li3Bi, Li-Ge, Ge-Ge and Li4Ge in the h-Bi2Ge3O9 crystal as the concentration of lithium rises upon lithiation. Initially, Li-ions are pref-erentially stored at tetrahedral sites, coordinated with 4 oxygen atoms (Ef = - 0.49 eV), and its diffusion into h-Bi2Ge3O9 crystal occurs via a zig-zag movement through its monolayer with a favorable activation energy barrier of similar to 0.70 eV.

The highly effective Au/Fe2O3-@Au/Fe2O3 nanoreactors for the 4-nitrophenol (4-NP) reduction are successfully obtained by one-pot synthesis using the spray pyrolysis (SP) technique. The Au/Fe2O3-@Au/Fe2O3 nanoreactors manifest superior catalytic activity in the reduction of 4-NP in the presence of sodium borohydride (NaBH4) compared to gold-iron oxide nanoreactors prepared via a colloidal approach. The negative effect of the reaction product accumulation, the 4-aminophenol (4-AP), on the catalytic reduction of 4-NP over Au/Fe2O3-@Au/Fe2O3 is examined by a direct pre-injection of 4-AP to the reaction media. To the best of our knowledge, it is the first experimental evidence of gold active sites blocking by 4-AP. All obtained samples are characterized by the yolk-shell spherical hollow structure mainly consisted of two embedded hollow nanospheres. The reduction of iron oxide precursor concentration diminishes the diameter of final iron oxide nanospheres. According to STEM-EDS analysis and STEM, Au nano species are uniformly dispersed on both iron oxide nanospheres. The SP technique presently used to synthesize Au/Fe2O3-@Au/Fe2O3 nanoreactors manifests high potential for the one-pot fabrication of a large variety of nanoreactors with various active materials applied as heterogeneous catalysts in numerous catalytic processes.

The nitroaromatic compounds, known as organic pollutants, have arising attention due to their carcinogenic character, highly dangerous to human health. In this work, the Ag@ZnO/MWCNT ternary nanocomposite synthesized via conjugation of sonochemical and solvothermal treatments manifests high performance in the reduction of 4-nitrophenol in the aqueous media (TOF value of 246 min −1 μ mol metal −1 ). The incorporation of MWCNT onto the nanocomposite structure favored the reusing of the catalysts even after eight consecutive catalytic runs without catalysts cleaning nor product removal. Obtained samples were characterized by XRD, TEM, UV–vis, Raman and FTIR spectroscopies. It was found that ultrasonic treatment at relatively moderate conditions leads to functionalization of MWCNT, the appearance of C=C and OH groups and change of electronic properties of Ag@ZnO/MWCNT composite which provide its stable material dispersion in aqueous solution and high catalytic performance in the 4-nitrophenol reduction. This technique may be effectively applied for the functionalization of carbon including materials for their usage in an aqueous media.

In the current work gold nanoparticles supported on oxides (MgO, Al2O3, ZrO2, TiO2) were used for menthylamine synthesis via menthone oxime hydrogenation. An increase of the gold nanoparticles size and application of metal oxides with a strong basic character such as magnesia favored deoximation to menthone. Au/Al2O3 catalyst with the gold nanoparticles size of 2.0 nm afforded high catalytic activity and selectivity to menthylamine. The reaction kinetics including stereoselectivity to the reaction products and recyclability of the catalyst was studied using Au/Al2O3 in the temperature range 90 - 110 degrees C under hydrogen pressure of 5.5-7.5 bar. The catalytic behavior was influenced by the solvent nature, with higher selectivity to desired amine achieved using methanol. The reaction rate was pressure independent, while has first order with respect to menthone oxime concentration. Stereoselectivity to menthylamines and menthones was independent on the reaction temperature and the hydrogen pressure.

In the present work, the synthesis of silver species such as nanoparticles (NPs), cations and clusters finely dispersed in A4 zeolite (Ag 0.1 wt%) has been successfully obtained by microwave irradiation and ion-exchange method. The prepared samples were analysed by SEM, HR-TEM, XRD, XPS, UV-Vis spectroscopy, ICP-OES and evaluated in the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Physicochemical characterization of samples revealed that ion-exchange method resulted in the main formation of Ag NPs (c.a. 5 nm) while the microwave irradiation promoted the formation of Ag NPs (c.a. 3 nm), Ag cations and clusters as well. The crystalline structure of microporous A4 zeolite was not altered. The sample prepared under microwave irradiation manifested a higher catalytic performance (by 7.5 times in TOF value) in comparison with the reference sample obtained via ion-exchange method. The catalytic activity of the sample prepared by microwave irradiation (TOF value of 396 min(-1)/mu mol-metal) was superior from reference systems reported in the literature. The later confirmed that used synthesis conditions influence the formation of highly active Ag species stabilized on the microporous structure of A4 zeolite. The high capacity for H-2 storage and efficient sorption for the nitroaromatics on A4 zeolite resulted in a promotional effect for the catalytic reduction of 4-NP. Undoubtedly, the obtained results revealed that the selection in the conditions applied for microwave-assisted synthesis and the components of the catalyst (Ag and A4 zeolite) offers an ultra-fast method for the synthesis of highly active catalysts.

Pd1/Au20@ZrO2 nanoreactors with the gold nuclei confined within zirconia shell and decorated with Pd were synthesized using an Au:Pd molar ratio of 20:1. The presence of even trace amounts of Pd on the gold nuclei surface, significantly enhanced catalytic activity of Pd1/Au20@ZrO2 nanoreactors in the 4-nitrophenol to 4-aminophenol transformation by four times compared to Au@ZrO2. In addition, the Pd1/Au20@ZrO2 nanoreactors remained highly stable during the reaction even under harsh conditions, i.e. without nanoreactors cleaning before the subsequent catalytic run, comparable with the stability of Au@ZrO2 nanoreactors. The presently proposed synthesis technique allowed to prepare nanoreactors of uniform structure even with relatively unstable bimetallic NPs (Pd/Au) as nuclei.

Cerium oxide (IV) hollow nanospheres (@CeO2) were successfully synthesized via the hydrothermal method. Cerium nitrate and urea were used as a ceria precursor and as a hydrolyzing agent, respectively. Obtained @CeO2 nanospheres were characterized using TEM, N2 physisorption, XRD, UV–Vis and Raman spectroscopy. The structural properties of @CeO2 nanospheres have been tuned by a variation of the urea/cerium nitrate weight ratio during the synthesis. The adsorption capacity of @CeO2 nanospheres was shown to be related to the size of ceria crystals forming nanospheres. Thus, the decrease of ceria crystal size permits to improve the efficiency in the adsorption of toxic 4-nitrophenol.

Liquid-phase hydrogenation of crotonaldehyde in non-polar and polar solvents was studied on monometallic Pd, Pt, Ir, Re catalysts using mesoporous Sibunit and Al2O3 as supports. In the presence of Pd the -C=C- bond of crotonaldehyde was preferably hydrogenated to form butanal, while butanal and crotyl alcohol are formed over Ir catalysts. Crotonaldehyde hydrogenation in 1,4-dioxane did not exhibit further butanal to butanol hydrogenation. Application of Re as a catalyst leads to formation of crotyl alcohol, with activity being, however, twofold lower than of Ir catalysts. Pt/C is almost inactive in the hydrogenation of crotonaldehyde. Formation of crotyl alcohol occurs most efficiently over Ir/Al2O3 in aprotic nonpolar solvents (decane), with selectivity to crotyl alcohol increasing with temperature showing 30% at 25% conversion under 180 °C and hydrogen pressure 0.84 MPa. Crotonaldehyde hydrogenation in a polar protonic solvent (ethanol) results in butanal ac

Nanobiocatalysis is the combination of the unique properties of nano-sized materials and the efficiency and sophistication of catalytic properties of enzymes. In this work, Cu(OH)(2) nanocages with an mean size of 170 nm were synthesized and used as a support for the covalent conjugation with fungal ligninolytic enzymes; versatile peroxidase and laccase. Both enzymes have the ability to degrade a wide range of pollutants. The nanocages were characterized, the orthorhombic arrangement of the nanocages was confirmed and TEM images showed that the nanocages are composed of nano-ribbons stacked around the particles. Interestingly, bioconjugated laccase-nanocages exhibited up to 18-times higher catalytic rate that these found for free enzyme, while activity of versatile peroxidase-nanocages was considerably reduced. The total turnover number for free laccase and laccase-nanocages are similar, suggesting that the activity increase is not due to the supply of Cu ions to a possible Cu-depleted active site of laccase. This enhancement of laccase activity when immobilized enzyme onto Cu(OH)(2) nanocages could be important for the actual and potential industrial uses of laccases.

Ultra-thin hollow nanospheres of Ce-Zr-O mixed oxides were successfully synthesized in a one-pot mode via ultrasonic spray pyrolysis, using a highly diluted aqueous solution of cerium and/or zirconium nitrate salts as nanospheres precursors and glycine as a template. The structure, morphology, and physicochemical properties of the samples were carefully studied by SEM, TEM, XRD, FT-IR, UV-Vis, Raman, and XPS. Obtained nanospheres composed of small CexZryO, CeO2, or ZrO2 nanoparticles with low crystallinity featured high uniformity and relatively low wall thickness (c.a. 5 nm) with an external diameter c.a. 100 nm. It was found that interaction between CeO2 and ZrO2 proceeded almost entirely with the formation of the corresponding mixed phases even at a short residence time (c.a. 2 s) in the high-temperature zone of a spray pyrolysis reactor. To the best of our knowledge, this is the first work on the synthesis of uniform ceria-zirconia hollow nanospheres by spray pyrolysis technique. The suggested approach of Ce-Zr nanospheres synthesis opens an effective, promising, and simple way for large-scale preparation of nanospheres and nanoreactors with a tunable microstructure using different precursors for wide commercial applications.