Catalysts, Volume 13, Issue 9 (September 2023) – 88 articles

In this work, the LDH approach was used to prepare MnCoAl mixed oxides with various textural and structural frameworks for the purpose of enhancing the total oxidation of ethanol. Our results showed that the catalytic activity of the MnCoAl oxides was influenced by the Mn/Co ratio and the gas atmosphere used during synthesis and thermal treatment. Rietveld refinement was processed to estimate the proportion of phases presented in the prepared materials. Our findings indicated that the generation of Mn₂CoO₄ spinel and Mn₅O₈ lamellar phases improved the redox properties and enhanced the active sites in the MnCoAl oxides. Notably, we observed that the catalytic activity at low temperatures of the catalyst increased with the decrease in the cobalt amount. It was also demonstrated that using an N₂ atmosphere during the preparation of the materials is a promising route to prevent the formation of undesirable phases in the LDHs and their corresponding oxides. The presence of an O₂-free atmosphere during the LDH synthesis positively affects the total ethanol transformation to CO₂ over the oxide catalysts. Full article

This study aims to investigate the treatment of real textile wastewater using a novel bentonite clay/TiO₂/ZnO-based ozonation catalyst. In this study, synergic electroflocculation/catalytic ozonation, catalytic ozonation, and ozonation processes are applied in a modified hybrid reactor. To the authors’ knowledge, this is the first application of bentonite clay/TiO₂/ZnO as an ozonation catalyst for treating real textile wastewater. The four operational variables—ozone dose (0.2–0.8 mg/min), reaction time (0–120 min), DC voltage supply (5–15 V), and catalyst dose (0.5–2 g/L)—were studied for decolorization and for the removal of chemical oxygen demand (COD). The results showed that the combined process (electroflocculation + clay/TiO₂/ZnO/O₃) had the highest removal efficiencies for COD and color (97.86% and 97.90%, respectively) at optimum parameters of 10 DC volts. an ozone dose of 0.8 mg/min, and a catalyst dose of 2 g/L in textile wastewater. The results further revealed that the initial pH of wastewater plays an essential role in the process’s overall performance. The studied synergic process was efficient for real wastewater treatment under alkaline pH (6–9). Based on empirical work, we established that the synergic process is suitable for effectively treating textile wastewater. Full article

This article reports on a simple method for producing high-octane gasoline from CO and H₂ on a Co-Al₂O₃/SiO₂/HZSM-5/Al₂O₃ hybrid catalyst. In the selected pressure range (0.5, 1.0, and 2.0 MPa), it was found that a decrease in pressure and an increase in temperature contribute to an increase in the content of branched hydrocarbons. The optimal technological parameters of the process were determined to ensure high selectivity and productivity for C₅–C₁₀ hydrocarbons: pressure—1.0 MPa, ratio H₂/CO = 2, gas space velocity—1000 h⁻¹, temperature—250 °C. The selectivity for the gasoline fraction is 65.2%, and the ratio of branched to linear hydrocarbons (iso/n index) is 2.3. Under the specified technological conditions, an experimental batch of gasoline fraction (1000 cm³) was produced at the pilot plant during 400 h of continuous operation. The main physicochemical and operational parameters of the experimental gasoline fraction of hydrocarbons have been determined. The octane number determined by the research method according to GOST R 52947-2019 is 78.5 units. Full article

This paper studies the photocatalytic performance of graphene-based titanium dioxide (TiO₂) on cementitious composites for the decomposition of Escherichia coli (E. coli) under visible light. Graphene-based TiO₂ was first synthesized through a hydrothermal process. The composites were then evaluated in terms of adsorption capability and degradation of methylene blue dyes. The adsorption test shows a remarkable increase in the amount of dye adsorbed into the composite surface. GO-P25 could adsorb around 60% of the initial dye, while less than 10% of the initial dye was adsorbed by pristine TiO₂-P25. The synthesized graphene-based TiO₂ significantly enhanced the dye degradation activity (94%) compared to pristine P25 (36%) and Krono (52%), even with the longer irradiation time for P25 and Krono. This led to an increase in reaction rate that was almost 20 times that of P25. Considering the good adsorption capabilities and high photodegradation of dye under visible light for GO-P25, cement-based surfaces containing GO-P25 are expected to be improved for the decomposition of Escherichia coli (E. coli) under visible light. Graphene-based TiO₂ on a cement-based surface showed high antibacterial activity with a 77% reduction in number of bacteria compared to a cement-based surface containing pristine TiO₂. This study confirms the effectiveness of the composites for disinfection of E. coli under visible light. Full article

In recent years, studies on the efficient spatial charge separation for broad solar light absorption and water remediation have been a major priority. Moreover, the development of transition metal-doped nanocomposites for this purpose is a new endeavor in current research. Here, we constructed an Fe³⁺-doped CdO/ZnS nanocomposite with a low doping level and investigated the effect of doping on the charge transfer and recombination behavior for improved photocatalytic performance. The X-ray diffraction analysis results indicate that both materials, CdO and ZnS, exhibit a cubic phase structure with an average crystallite size of 35 nm. Morphology analysis of the Fe³⁺-doped CdO/ZnS nanocomposite confirms the formation of irregularly shaped particle-like structures. From the optical studies, the bandgap energies of CdO/ZnS and Fe³⁺-doped CdO/ZnS nanocomposites are 3.19 eV and 2.87 eV, respectively, which proved that the iron ions doping reduced the bandgap energy and extended the absorption to the visible range. The efficiency of photodegradation in the tested samples was evaluated using tetracycline under solar light exposure. The experimental results demonstrated that the Fe³⁺-doped CdO/ZnS nanocomposite outperformed the other samples, exhibiting a significantly higher photocatalytic activity. After 80 min, it achieved a remarkable degradation rate of 97.06%. The Fe³⁺-doped CdO/ZnS nanocomposite demonstrated good stability and recyclability after five cycles. Radical trapping experiments showed that hydroxyl (•OH) radicals play a key role in photodegradation. Full article

Terephthalohydrazide chitosan hydrogel (TCs) was prepared and investigated as an ecofriendly biopolymeric catalyst for synthesis of some novel thiazole and thiadiazole derivatives. Thus, TCs was used as a promising ecofriendly basic biocatalyst for preparation of three new series of thiazoles and two thiadiazoles derivatives via reacting 2-(2-oxo-1,2-diphenylethylidene) hydrazine-1-carbothio-amide with various hydrazonoyl chlorides and α-haloketones under mild ultrasonic irradiation. Also, their yield% was estimated using chitosan and TCs in a comparative study. The procedure being employed has the advantages of mild reaction conditions, quick reaction durations, and high reaction yields. It also benefits from the catalyst’s capacity to be reused several times without significantly losing potency. The chemical structures of the newly prepared compounds were confirmed by IR, MS, and ¹H-NMR. Docking analyses of the synthesized compounds’ binding modes revealed promising binding scores against the various amino acids of the selected protein (PDB Code—1JIJ). SwissADME’s online tool is then used to analyze the physiochemical and pharmacokinetic characteristics of the most significant substances. The majority of novel compounds showed zero violation from Lipinski’s rule (Ro5). Full article

The evolution of the early atmosphere was driven by changes in its chemical composition, which involved the formation of some critical gases. In this study, we demonstrate that nitrous oxide (N₂O) can be produced from Miller’s early atmosphere (a mixture of CH₄, NH₃, H₂, and H₂O) by way of photocatalysis. Both NH₃ and H₂O were indispensable for the production of N₂O by photocatalysis. Different conditions related to seawater and reaction temperature are also explored. N₂O has a strong greenhouse gas effect, which is more able to warm the Earth than other gases and offers a reasonable explanation for the faint young Sun paradox on the early Earth. Moreover, the decomposition of N₂O into N₂ and O₂ can be boosted by soft irradiation, providing a possible and important origin of atmospheric O₂ and N₂. The occurrence of O₂ propelled the evolution of the atmosphere from being fundamentally reducing to oxidizing. This work describes a possible vital contribution of photocatalysis to the evolution of the early atmosphere. Full article

Benzoic acid has found a wide range of applications in the chemical industry. The selective oxidation of benzyl alcohol is one of the main routes to produce benzoic acid. In this work, tris(4-bromobiphenyl)phosphine was chosen as a building block to synthesize PAF-181 with a high specific surface area and high yield via a Yamamoto–Ullmann reductive coupling reaction. Subsequently, the WO₄@PAF-181 catalyst was successfully prepared via methylation and ion exchange, in which PAF-181 acts as a carrier while WO₄²⁻ serves as the active catalytic site. The synergistic effect between functional carriers and active sites endows WO₄@PAF-181 with distinctive catalytic property for efficient selective oxidation of benzyl alcohol to benzoic acid. Importantly, the catalyst can be conveniently recovered and reused by simple filtration, still maintaining its high catalytic activity. Full article

Per- and polyfluoroalkyl substances (PFASs) are an emerging group of persistent organic pollutants in aquatic environments with high levels of toxicity and bioaccumulation. The risks posed by PFASs to the environment and health have attracted increasing attention. To remove them from water, advanced oxidation processes (AOPs), with the merits of high efficiency and low cost, are mainly used. Photo/electrocatalytic heterogeneous AOPs, with the assistance of nanostructured catalysts and external energy in the form of light/electricity, have emerged as one of the most powerful techniques, overcoming the difficulty associated with defluorination and achieving the effective and complete degradation of PFASs in water. The structures of photo/electrocatalysts play a critical role in the production of reactive oxygen species, the electron transfer process, and the degradation pathway and its efficiency. Herein, to elucidate the structure–performance relationship, a review of photo/electrocatalysts for the enhanced degradation of PFASs in heterogeneous AOPs, organized according to their composition and nanostructure design, is provided. This review article is mainly focused on (1) the mechanisms and pathways of PFAS degradation by heterogeneous photo/electrocatalytic AOPs, and (2) the structural designs and modifications of photo/electrocatalysts for the enhanced degradation of PFASs by heterogeneous AOPs. Finally, the challenges and prospects for future research into photo/electrocatalysts of heterogeneous AOPs in the field of PFAS remediation are discussed. Full article

The electrocatalyst of oxygen reduction reactions is one of the basic components of a fuel cell. In addition to costly Pt/C benchmark catalysts, cost-effective carbon-based catalysts have received the most attention. Enormous efforts have been dedicated to trade off the catalyst performance against the economic benefit. Optimizing composition and/or structure is a universal strategy for improving performance, but it is typically limited by tedious synthesis steps. Herein, we have found that directly introducing CNT into MOF-derived carbonaceous nanopolyhedra, i.e., introduced carbon nanotubes (CNTs) penetrated porous nitrogen-doped carbon polyhedra (NCP) dotted with cobalt nanoparticles (denoted as CNTs-Co@NCP), can optimize the catalytic activity, stability, and methanol tolerance. The hierarchical architecture combines the 0D/1D/3D Co/CNT/NCP interfaces and 1D/3D CNT/NCP junctions with the frameworks with a greatly exposed active surface, strengthened mass transport kinetics, stereoscopic electrical conductivity networks and structural robustness. The sterical self-consistency of MOF-self-assembly triggered by introduced CNTs demonstrates tactful ORR electrocatalytic activity regulation. Eventually, the CNTs-Co@NCP showed a half-wave potential (E_1/2) of 0.86 V and a diffusion-limited current density (J_L) of 5.94 mA/cm² in alkaline electrolyte. The CNTs-Co@NCP was integrated into the cathode of a direct methanol fuel cell (DMFC) with an anion-exchange membrane, and an open-circuit voltage (OCV) of 0.93 V and a high power density of 46.6 mW cm⁻² were achieved. This work successfully developed a catalyst with competitive ORR performance through plain parameter fine-tuning without complex material design. Full article

TiO₂ is one of the most promising heterogeneous photoredox catalysts employed in oxidative pollutant destruction, CO₂ reduction, water splitting, disinfection, solar cell design and organic synthesis. Due to the wide bandgap of TiO₂, visible light energy is not sufficient for its activation, and electron/hole pairs generated upon UV irradiation demonstrate limited selectivity for application in organic synthesis. Thus, the development of TiO₂-based catalytic systems activated by visible light is highly attractive. In the present work we demonstrate the generation of t-BuOO• radicals from tert-butylhydroperoxide catalyzed using commercially available unmodified TiO₂ under visible light. This finding was used for the highly selective CH-peroxidation of barbituric acids, which contrasts with the behavior of the known TiO₂/H₂O₂/UV photocatalytic system used for deep oxidation of organic pollutants. Full article

Recently, sterically demanding N-heterocyclic cyclometalated ruthenium were reported as efficient Z-selective catalysts for cross-metathesis, showing a different reactivity in the function of the auxiliary ligand and the bulky ligand. To understand the origin of this behavior, we carried out density functional (M06-L) calculations to explore the reaction mechanism and insight from the energetic contributions into the determinant step. We emphasize the differences that occur when the 2,6-diisopropylphenyl (Dipp) and 2,6-diisopentylphenyl (Dipep) are employed. The results show that the barrier energies, $\Delta G^{‡}$, increase when the bulky ligand is greater, using nitrate as an auxiliary ligand, while the opposite behavior is obtained when pivalate is the auxiliary ligand. This tendency has its origin in the low reorganization energy and the less steric hindrance (%V_bur) obtained in catalysts that involve nitrate ligand and Dipep group. Moreover, by scrutinizing the energy decomposition analysis (EDA), it is found that the electronic contributions are also dominant and are not uniquely the steric effects that control the Z-selectivity. Full article

Tannase from Aspergillus ficuum was immobilized by two different techniques for comparison of kinetic and thermodynamic parameters. Tannase was either entrapped in calcium alginate beads or covalently-immobilized onto magnetic diatomaceous earth nanoparticles. When immobilized on nanoparticles, tannase exhibited lower activation energy (15.1 kJ/mol) than when immobilized in alginate beads (31.3 kJ/mol). Surprisingly, the thermal treatment had a positive effect on tannase entrapped in alginate beads since the enzyme became more solvent exposed due to matrix leaching. Accordingly, the proposed mathematical model revealed a two-step inactivation process. In the former step the activity increased leading to activation energies of additional activity of 3.1 and 26.8 kJ/mol at 20–50 °C and 50–70 °C, respectively, while a slight decay occurred in the latter, resulting in the following thermodynamic parameters of denaturation: 14.3 kJ/mol activation energy as well as 5.6–9.7 kJ/mol standard Gibbs free energy, 15.6 kJ/mol standard enthalpy and 18.3–29.0 J/(K·mol) standard entropy variations. Conversely, tannase immobilized on nanoparticles displayed a typical linear decay trend with 43.8 kJ/mol activation energy, 99.2–103.1 kJ/mol Gibbs free energy, 41.1–41.3 kJ/mol enthalpy and −191.6/−191.0 J/(K·mol) entropy of denaturation. A 90-day shelf-life investigation revealed that tannase immobilized on nanoparticles was approximately twice more stable than the one immobilized in calcium alginate beads, which suggests its use and recycling in food industry clarification operations. To the best of our knowledge, this is the first comparative study on kinetic and thermodynamic parameters of a tannase produced by A. ficuum in its free and immobilized forms. Full article

To clarify the Ni species of NiO/SiO₂-Al₂O₃ catalysts that are active for ethylene oligomerization, 18 types of NiO/SiO₂-Al₂O₃ were prepared using three Ni-loading methods (i.e., ion-exchange, impregnation, and homogeneous precipitation), with different Ni-loadings (1–20 wt%), and examined with respect to their structure and catalytic activity for ethylene oligomerization. Characterized by N₂ adsorption, powder XRD, FE-SEM, H₂-TPR, NH₃-TPD, and C₂H₄-TPD showed that Ni species in the catalysts prepared by ion-exchange were mainly ion-exchanged Ni cations. In contrast, Ni species in the catalysts prepared by impregnation were a mixture of ion-exchanged Ni cations and NiO particles, and those in the catalysts prepared by homogeneous precipitation were all NiSiO₃ particles. Catalytic-reaction tests at 300 °C and 0.1 MPa revealed the following: the ion-exchanged Ni cations showed the highest C₂H₄ conversion rate; the NiSiO₃ particles showed a moderate reaction rate; and the NiO particles were not active for ethylene oligomerization. We concluded that the high catalytic activity of the ion-exchanged Ni cations was a result of their high dispersion and medium-strength acidity, which together promoted the adsorption and activation of ethylene on, and the desorption of oligomerization products from, the catalyst. Full article

While the reverse water-gas shift (RWGS) reaction holds great promise as a method of converting CO₂ to CO and subsequently into valuable fuels, achieving its commercial viability requires the development of highly efficient, selective, durable, and low-cost catalysts. Recently, thin-film nanocatalysts produced through plasma deposition (PECVD) have garnered significant attention in this domain. Among them, FeOx-based catalytic films deposited using Fe(CO)₅ as a precursor, under reduced pressure (4–5 Pa) and a 13.56 MHz glow discharge, have demonstrated particular interest. Our study shows that by appropriately tuning the parameters of the plasma deposition process, it is feasible to generate nanocatalyst films exhibiting exceptional CO₂ conversion (38% at 673 K) and CO selectivity (97%). Moreover, the study has revealed the formation of a carbon deposit containing carbon nanotubes (CNTs) during the RWGS reaction, significantly increasing the catalytic activity of the films. Through an analysis involving X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electron microscopy techniques (SEM and HRTEM), we have determined that CNTs not only serve as carriers for highly catalytically active Fe nanoparticles but also create nanoscale heterojunctions (p-n) with Fe₂O₃ nanoparticles, thereby enhancing their catalytic effect. This paper attempts to elucidate the differences and changes in the surface structure of FeOx-based films dictating the catalytic activity, which stems from both the conditions of plasma deposition and the environmental impact during the catalytic process. Full article

Isomerization of aldoses to ketoses is an essential step in carbohydrate valorization routes in biorefineries to produce a wide variety of bioproducts. In this work, selective isomerization of aldoses into ketoses was investigated using different commercial Brønsted basic anion resins at low temperature conditions. Weak and strong basic resins were tested under different reaction conditions. Amberlite IRA-900 and Amberlyst A-26 (strong resins) and Amberlite IRA-67 and Amberlyst A-21 (weak resins) were tested to assess their catalytic properties. Strong basic resins provided high yields of fructose. IRA-900 was also tested in the isomerization of different sugar monosaccharides conventionally present in lignocellulosic biomass (xylose, arabinose, galactose, glucose and mannose) aiming to explore the performance of this material in hemicellulose-derived sugar mixtures. Very promising performance was observed for IRA-900, yielding fructose selectivity higher than 75% and fructose yield of 27% in the isomerization reaction. Notably, basic anionic resins were not suitable for reuse in different reaction cycles, although the use of organic cosolvents, specifically ethanol, improved the reusability of the tested resins. Full article

Organochalcogen-bearing heterocycles are important scaffolds in compounds under the spotlight of scientific interest in optoelectronic fields and for biological applications. The use of transition metals has been a versatile and reliable way to carry out the synthesis of these molecules efficiently, delivering products in high yields and with a wide functional diversity. In the last 10 years, many classes of heterocycles have been synthesized under the cyclization reaction of acyclic alkenes and alkynes with the incorporation of a chalcogen atom on its structure. Transition metal catalysts including Cu, Co, Pd, Ni, In, Ag, and Fe salts have been used in the development of new methodologies, the expansion of substrate scope, and mechanistic studies. This review provides an overview of these recent approaches with the aim of being a useful resource for interested researchers in this area. Full article

The use of biolubricants as an alternative to petroleum-based products has played an important role in the last decade. Due to the encouragement of global policies, which mainly support green chemistry and circular economy, there has been an increasing interest in bio-based products, including biolubricants, from scientific and industrial points of view. Their raw materials, production, and characteristics might vary, as biolubricants present different applications for a wide range of practical uses, making this field a continuously changing subject of study by researchers. The aim of this work was to study biolubricant production from vegetable oil crops from a bio-refinery perspective, paying attention to the main raw materials used, the corresponding production methods (with a special focus on double transesterification), the role of catalysts and some techno-economic studies. Thus, the main factors affecting quality parameters such as viscosity or oxidative stability have been covered, including catalyst addition, reaction temperature, or the use of raw materials, reagents, or additives were also analyzed. In conclusion, the search for suitable raw materials, the use of heterogeneous catalysts to improve the effectiveness and efficiency of the process, and the optimization of chemical conditions seem to be the most interesting research lines according to the literature. Full article

Niobium oxide supported on ZrO₂ and mixed oxide of NbO_x-ZrO₂ was prepared and characterized. Mechanical treatment was followed by the microwave heating procedure of catalysts with more advanced textural parameters. The amount of Lewis (LAS) and Brønsted (BAS) acid sites rose with the increasing Nb content in the catalysts. The catalytic properties of samples of niobia-zirconia (NbZr samples, NbZr catalysts) were studied in a cellulose hydrolysis–dehydration reaction at 453 K under an inert Ar atmosphere in a batch reactor. Glucose and 5-hydroxumethylfurfural (5-HMF) were the major products. The initial reaction rate could be tuned by the density of acid sites on the surface of solid. At a low density of acid sites (0.1–0.3 µmol·m⁻²), the initial reaction rate had a pronounced inverse correlation. Increasing the LAS/BAS from 0.3 to 2.5 slightly stimulated the formation of the target products. The catalytic properties of NbZr catalysts prepared by microwave treatment were studied in cellulose transformation in a flow set-up. Glucose was found to be the major product. The maximum yield of glucose was observed in the presence of the sample of 17%Nb/ZrO₂. Increasing Nb content resulted in the formation of Nb-associated acid centers and, in turn, increasing catalyst acidity and activity. Full article

Bioenergy production from hydrochar via catalytic thermal conversion is of increasing importance to easing the energy shortage. The catalytic pyrolysis characteristics of hydrochar derived from sawdust (HSD) with calcined eggshell (CES) were investigated by the thermogravimetric–Fourier transform infrared spectroscopy–mass spectrometry (TG-FTIR-MS) method. Kinetic and thermodynamic parameters were determined by two iso-conversional model-free methods, namely, Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO). The results demonstrated that HSD exhibited a high fuel quality, with elevated carbon content (54.03%) and an increased high calorific value (21.65 MJ Kg⁻¹). CES significantly enhanced the pyrolysis behavior of HSD by promoting the secondary cracking of organic vapors under the synergistic effect of CaO and mineral elements. Compared to non-catalytic pyrolysis, the residual mass and average activation energy of HSD-CES decreased by 29.61% and 14.10%, respectively, and the gaseous products of H₂ and CO from HSD-CES increased by 26.14% and 22.94%, respectively. Furthermore, the participation of CES effectively suppressed the emission of pollutants in the HSD pyrolysis process, with a 27.13% reduction in CH₄, a 22.76% reduction in HCN, and a 20.28% reduction in NH₃. This study provides valuable guidance on the potential use of hydrochar for renewable energy production. Full article

The environmental impact and the forecasted scarcity of fossil fuels have intensified research on renewable energy sources. Hydrogen is a versatile energy carrier that can be produced from renewable sources and plays a key role in achieving global decarbonization targets. Biogas, produced by anaerobic digestion of organic compounds, is rich in methane and carbon dioxide and can be used to produce renewable hydrogen by dry reforming. This review focuses on the recent advances in Ni-based catalysts for biogas reforming. The effect of supports and promoters on catalyst activity, stability, and resistance to carbon deposition will be systematically discussed. This review provides a better understanding of the influence of the synthesis method, metal-support interaction, acid/base sites, and oxygen mobility on catalytic activity. Special emphasis will be given to the development of core-shell structure catalysts and bimetallic catalysts of Ni with other transition metals and noble metals. Full article

The alkylation of benzene with methanol can effectively generate high-value-added toluene and xylene out of surplus benzene, which is now achieved primarily using solid acids like H-ZSM-5 zeolites as catalysts. In this work, two H-ZSM-5 samples with distinct framework aluminum (Al_F) distributions, but otherwise quite similar textural and acidic properties, have been prepared by employing tetrapropylammonium hydroxide (TPAOH) and n-butylamine (NBA) as organic structure-directing agents (OSDAs). Systematical investigations demonstrate that Al_F is preferentially located at the intersections in MFI topology when TPAOH is adopted. In contrast, less Al_F is positioned therein as NBA is utilized. Density functional theory (DFT) calculations reveal that the transition-state complexes cannot be formed in the straight and sinusoidal channels due to their much smaller sizes than the dynamic diameters of transition states, whereas there are adequate spaces for the formation of transition states at the intersections. Benefitting from abundant Al_F at the intersections, which provides more acid sites therein, H-ZSM-5 synthesized from TPAOH is more active relative to the counterpart obtained from NBA. At a WHSV of 4 h⁻¹ and 400 °C, the former catalyst gives a 52.8% conversion, while the latter one affords a 45.9% conversion. Both catalysts display close total selectivity towards toluene and xylene (ca. 84%). This study provides an efficient way to regulate the distribution of acid sites, thereby enhancing the catalytic performance of H-ZSM-5 zeolite in the titled reaction. Full article

The formation of valuable chiral skeletons through asymmetric gold catalysis has made considerable progress due to the unrivaled affinity of gold complexes with multiple carbon–carbon bonds. The renaissance of chiral ligands in recent decades has enabled the elaborate design of chiral gold complexes, which are of great significance to control chiral formation in these catalytic reactions. Therefore, this review intends to highlight the design and central role of versatile chiral ligands in asymmetric gold catalysis. Specifically, the seminal applications of various chiral ligands with representative examples in various gold-catalyzed asymmetric reactions are comprehensively explored. In addition, the reaction mechanisms are mentioned when the crucial interactions between ligands and activated substrates are introduced. Furthermore, the applications of enantioselective gold catalysis in the construction of chiral functional organic materials and drug molecules are also presented. Full article

The release of toxic effluents and microfibers during the frequent washings of textiles poses a major threat to the environment. On the one hand, the detrimental effluents from detergents pose a threat to marine biota in peril, and on the other, microplastics have even been found in breastmilk. According to this study, functionalized metal-doped TiO₂ nanoparticles can be immobilized to create fabrics that are hygienic and antibacterial. There is a need to reduce the amount of different detergents, surfactants and chemicals used to remove stains. The manufacture of pristine and Cu-, Ag- and Zn-doped TiO₂ nanoparticles having trace molar ratios of dopant chosen with a simple sol–gel approach using pad–dry–cure silane coupling agents, firstly with the functionalization and then the immobilization of nanoparticles, was successfully performed on cotton fabric. The as-obtained fabrics were evaluated for their crystallinity, chemical functionalities, surface morphologies and elemental compositions. The photodegradation potentials of unfunctionalized materials were assessed in ambient sunshine against five commercial colors. Within three hours of sunshine exposure, according to color strength analysis and antibactericidal activities, 95–98% of the dye was degraded from the functionalized fabric surface. Additionally, the treated content kept its mechanical and comfort qualities. Full article

Different concentrations (1, 3 and 5 wt%) of dysprosium (Dy³⁺)-doped ZnO/SnS (ZSD) nanophotocatalysts using the one-step facile hydrothermal method at 230 ℃ are presented. Their structure, morphological appearance, inclusion of constituent elements, bandgap engineering and luminescent nature are confirmed by the XRD, TEM, XPS, UV-DRS and PL techniques. The photocatalytic activity (PCA) of the prepared nano photocatalysts is studied in the presence of a model pollutant MB under solar light illumination. The degradation kinetics and charge separation mechanism of the ZSD photocatalysts are also presented. Our XRD analysis showed the mixed-phase occurrence of ZnO (hexagonal) and SnS (orthorhombic) from their JCPDS numbers with no additional traces of a doping element, which in turn indicates the purity, substantial crystal structure and high dispersion of the samples. TEM micrographs revealed the appearance of a flake structure and more agglomeration when increasing the dopant concentration. The XPS spectra confirmed the Zn²⁺, Sn²⁺, S²⁻, O²⁻ and Dy³⁺ oxidation states of the constituent elements along with carbon and nitrogen peaks. The Tauc plots showed a decreasing trend in the optical bandgap, i.e., a redshift due to the loading of Dy³⁺ ions into Sn²⁺ ions. The lower recombination rate of photoinduced e⁻-h⁺ pairs is noted when increasing the Dy³⁺ ion content; i.e., the luminescent intensity is suppressed when increasing the concentration of Dy³⁺ ions. The obtained degradation efficiency of the MB dye using the ZSD3 nano photocatalyst is around 98% for a duration of 120 min under solar light irradiation. The prepared ZSD photocatalyst follows pseudo first-order kinetics, and the evidence for attaining a robust Z-scheme PCA is presented in the form of the charge separation mechanism. Full article

A Pt(II) complex bearing chelating tridentate bis-aryloxide tetrahydropyrimidinium-based N-heterocyclic carbene (NHC) was synthesized and characterized by using different techniques. Both cyclic voltammetry and differential pulse voltammetry were used to study the electrochemical properties of the complex, revealing two reversible one-electron oxidation processes. The chemical generation and isolation of one-electron-oxidized species were performed oxidizing the initial complex by means of AgBF₄. A combination of spectroscopic (UV-Vis/NIR- and EPR-) and theoretical (density functional theory (DFT)) studies suggests the formation of a Pt(II)-phenoxyl radical complex. The latter open-shell derivative was structurally characterized by means of X-ray diffraction analysis. Finally, the neutral platinum complex was tested as a mediator in the process of electrocatalytic oxidation of 2-(methylamino)ethanol (MEA). Full article

The issue of organic contaminants in water resulting from industrial, agricultural, and home activities makes it necessary to effectively address the problems of water scarcity. Using modern technologies that can effectively remove pollutants from wastewater is the way to address this key problem. The use of nanoparticles (NPs) has been advocated due to their unique physical and chemical characteristics and advantageous applications. NPs’ surface stability and synthesis routes are core concerns for environmental remediation and biological applications. In this work, we demonstrated the biogenic synthesis of silver NPs (Ag-CS NPs) by using Caralluma subulata (CS) aqueous extract as a reducing and capping/template agent. The synthesized Ag-CS NPs were characterized by UV-visible absorbance spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, powdered X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Zeta potential. The performance of Ag-CS NPs was evaluated on methylene blue (MB) dye degradation and antibacterial activity tests against bacterial and fungal isolates. The results showed that Ag-CS NPs (0.05%, 20.0 μL) reduced MB by 95.52% within 28 min in the presence of NaBH₄ (10.0 mM, 0.980 μL). The degradation of MB followed pseudo zero-order chemical kinetics (R² = 0.9380), with the reaction rate constant 0.0508 mol L⁻¹ min⁻¹. In addition, Ag-CS NPs were applied as antibacterial agents against 19 bacterial isolates. Ag-CS NPs showed inhibition in both Gram-positive and Gram-negative bacterial, as well as fungal isolates. As a greener ecofriendly approach, multifunctional Ag-CS NPs make a promising candidate for the remediation of contaminated water, as well as for important bioapplications. Full article

Zn–air batteries are becoming the promising power source for small electronic devices and electric vehicles. They provide a relatively high specific energy density at relatively low cost. This review presents exciting advances and challenges related to the development of molecular catalysts for cathode reactions in Zn–air batteries. Bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play the main role in improving performance of reversible fuel cell and metal–air batteries. The catalyst development strategies are reviewed, along with strategies to enhance catalyst performance by application of magnetic field. Proper design of bifunctional molecular ORR/OER catalysts allows the prolongment of the battery reversibility to a few thousand cycles and reach of energy efficiencies of over 70%. Full article

Solid oxide fuel cells (SOFCs) represent a breed of eco-friendly, weather-independent, decentralized power generation technologies, distinguished for their broad fuel versatility and superior electricity generation efficiency. At present, SOFCs are impeded by a lack of highly efficient oxygen reduction catalysts, a factor that significantly constrains their performance. The double perovskites LnBaCo₂O_5+δ (Ln = Lanthanide), renowned for their accelerated oxygen exchange and conductivity features, are widely acclaimed as a promising category of cathode catalysts for SOFCs. This manuscript offers a novel perspective on the physicochemical attributes of LnBaCo₂O_5+δ accumulated over the past two decades and delineates the latest advancements in fine-tuning the composition and nanostructure for SOFC applications. It highlights surface chemistry under operational conditions and microstructure as emerging research focal points towards achieving high-performance LnBaCo₂O_5+δ catalysts. This review offers a comprehensive insight into the latest advancements in utilizing LnBaCo₂O_5+δ in the field of SOFCs, presenting a clear roadmap for future developmental trajectories. Furthermore, it provides valuable insights for the application of double perovskite materials in domains such as water electrolysis, CO₂ electrolysis, chemical sensors, and metal–air batteries. Full article

This multi-disciplinary paper aims to provide a roadmap for the development of an integrated, process-intensified technology for the production of H₂, NH₃ and NH₃-based symbiotic/smart fertilizers (referred to as target products) from renewable feedstock with CO₂ sequestration and utilization while addressing environmental issues relating to the emerging Food, Energy and Water shortages as a result of global warming. The paper also discloses several novel processes, reactors and catalysts. In addition to the process intensification character of the processes used and reactors designed in this study, they also deliver novel or superior products so as to lower both capital and processing costs. The critical elements of the proposed technology in the sustainable production of the target products are examined under three-sections: (1) Materials: They include natural or synthetic porous water absorbents for NH₃ sequestration and symbiotic and smart fertilizers (S-fertilizers), synthesis of plasma interactive supported catalysts including supported piezoelectric catalysts, supported high-entropy catalysts, plasma generating-chemical looping and natural catalysts and catalysts based on quantum effects in plasma. Their performance in NH₃ synthesis and CO₂ conversion to CO as well as the direct conversion of syngas to NH₃ and NH₃—fertilizers are evaluated, and their mechanisms investigated. The plasma-generating chemical-looping catalysts (Catalysts, 2020, 10, 152; and 2016, 6, 80) were further modified to obtain a highly active piezoelectric catalyst with high levels of chemical and morphological heterogeneity. In particular, the mechanism of structure formation in the catalysts BaTi_1−rM_rO_3−x−y{#}_xN_z and M₃O_4−x−y{#}_xN_z/Si = X was studied. Here, z = 2y/3, {#} represents an oxygen vacancy and M is a transition metal catalyst. (2) Intensified processes: They include, multi-oxidant (air, oxygen, CO₂ and water) fueled catalytic biomass/waste gasification for the generation of hydrogen-enriched syngas (H₂, CO, CO₂, CH₄, N₂); plasma enhanced syngas cleaning with ca. 99% tar removal; direct syngas-to-NH₃ based fertilizer conversion using catalytic plasma with CO₂ sequestration and microwave energized packed bed flow reactors with in situ reactive separation; CO₂ conversion to CO with BaTiO_3−x{#}_x or biochar to achieve in situ O₂ sequestration leading to higher CO₂ conversion, biochar upgrading for agricultural applications; NH₃ sequestration with CO₂ and urea synthesis. (3) Reactors: Several patented process-intensified novel reactors were described and utilized. They are all based on the Multi-Reaction Zone Reactor (M-RZR) concept and include, a multi-oxidant gasifier, syngas cleaning reactor, NH₃ and fertilizer production reactors with in situ NH₃ sequestration with mineral acids or CO₂. The approach adopted for the design of the critical reactors is to use the critical materials (including natural catalysts and soil additives) in order to enhance intensified H₂ and NH₃ production. Ultimately, they become an essential part of the S-fertilizer system, providing efficient fertilizer use and enhanced crop yield, especially under water and nutrient stress. These critical processes and reactors are based on a process intensification philosophy where critical materials are utilized in the acceleration of the reactions including NH₃ production and carbon dioxide reduction. When compared with the current NH₃ production technology (Haber–Bosch process), the proposed technology achieves higher ammonia conversion at much lower temperatures and atmospheric pressure while eliminating the costly NH₃ separation process through in situ reactive separation, which results in the production of S-fertilizers or H₂ or urea precursor (ammonium carbamate). As such, the cost of NH₃-based S-fertilizers can become competitive with small-scale distributed production platforms compared with the Haber–Bosch fertilizers. Full article