Search Results (64)

This study presents the development of Cu-doped NiMo/TiO₂ photoelectrocatalysts for simultaneous green hydrogen production and pharmaceutical pollutant removal under simulated solar irradiation. The catalysts were synthesized via wet impregnation (15 wt.% total metal loading with 0.6 wt.% Cu) and thermally treated at 400 °C and 900 °C to investigate structural transformations and catalytic performance. Comprehensive characterization (XRD, BET, SEM, XPS) revealed phase transitions, enhanced crystallinity, and redistribution of redox states upon Cu incorporation, particularly the formation of NiTiO₃ and an increase in oxygen vacancies. Crystallite sizes for anatase, rutile, and brookite ranged from 21 to 47 nm at NiMoCu400, while NiMoCu900 exhibited only the rutile phase with 55 nm crystallites. BET analysis showed a surface area of 44.4 m²·g⁻¹ for NiMoCu400, and electrochemical measurements confirmed its higher electrochemically active surface area (ECSA, 2.4 cm²), indicating enhanced surface accessibility. In contrast, NiMoCu900 exhibited a much lower BET surface area (1.4 m²·g⁻¹) and ECSA (1.4 cm²), consistent with its inferior photoelectrocatalytic performance. Compared to previously reported binary NiMo/TiO₂ systems, the ternary NiMoCu/TiO₂ catalysts demonstrated significantly improved hydrogen production activity and more efficient photoelectrochemical degradation of paracetamol. Specifically, NiMoCu400 showed an anodic peak current of 0.24 mA·cm⁻² for paracetamol oxidation, representing a 60% increase over NiMo400 and a cathodic current of −0.46 mA·cm⁻² at −0.1 V vs. RHE under illumination, nearly six times higher than the undoped counterpart (–0.08 mA·cm⁻²). Mott–Schottky analysis further revealed that NiMoCu400 retained n-type behavior, while NiMoCu900 exhibited an unusual inversion to p-type, likely due to Cu migration and rutile-phase-induced realignment of donor states. Despite its higher photosensitivity, NiMoCu900 showed negligible photocurrent, confirming that structural preservation and surface redox activity are critical for photoelectrochemical performance. This work provides mechanistic insight into Cu-mediated photoelectrocatalysis and identifies NiMoCu/TiO₂ as a promising bifunctional platform for integrated solar-driven water treatment and sustainable hydrogen production. Full article

Organic electron donors are essential components of Ziegler-Natta (ZN) catalysts to produce isotactic polypropylene. In particular, aromatic or aliphatic diesters are widely used as ‘Internal Donors’ (ID) in MgCl₂/ID/TiCl₄ precatalyst formulations. Diesters are reactive with AlEt₃ (by far the most common ZN precatalyst activator) and are partly removed from the solid phase in the early stages of the polymerization process; this is detrimental for catalyst functioning, and a surrogate donor (‘External Donor’ (ED), usually an alkoxysilane) is added to the system to restore performance. Recent studies, however, demonstrated that even in cases where most of the diester is extracted by AlEt₃, the active sites retain a ‘memory’ of it in several aspects of the catalytic behavior (such as, e.g., the average productivity and the polydispersity index of the polymer produced). Considering that the residual diester is always in molar excess with respect to the active Ti, one may speculate that long-lasting interactions between the latter and diester molecules can occur. In turn, this should imply that the reactivity of AlEt₃ is different with binary MgCl₂/ID or ternary MgCl₂/ID/TiCl₄ mixtures. In this work, the latter hypothesis was explored for a library of diester IDs with large structural diversity. In line with the anticipation, the fractional amount of ID extracted by AlEt₃ was generally lower for ternary mixtures, although to an extent exquisitely dependent on diester structure. Full article

The present work examines pure and palladium photofixed TiO₂ and binary (TiO₂/ZnO) photocatalysts for breaking down tartrazine, a food coloring agent, in distilled water. Powders with the following compositions are obtained using the sol-gel process: 100TiO₂, 10TiO₂/90ZnO, 50TiO₂/50ZnO, and 90TiO₂/10ZnO. The composite materials are analyzed using SEM-EDS, UV-Vis, DTA-TG, and X-ray diffraction. The synthesized gels are then photo-fixed with UV light to incorporate palladium ions and are also examined for tartrazine (E102) degradation. The photocatalytic tests were carried out in a cylindrical glass reactor illuminated by ultraviolet light. Compared to mixed binary catalysts, the prepared pure TiO₂ catalyst demonstrated greater activity in the photodegradation of tartrazine (E102). The further of a specific quantity of zinc oxide reduced the catalytic properties of TiO₂. The recombination of photoinduced electron-hole pairs in ZnO may account for this. In comparison to the pure samples, the co-catalytic palladium-modified gels exhibited higher photocatalytic efficiency. Heterojunction and palladium modification of the composites partially captured and transferred the electrons. Consequently, the longer lifetime of the photogenerated charges improved the catalytic activity of the palladium titanium dioxide and binary gels. Additionally, under UV light, pure and palladium photofixed TiO₂ and binary sol-gel samples displayed excellent stability for tartrazine photodegradation. Full article

This paper deals with synthesizing Zn, Cu, and AgNPs supported on the surface of zeolite Y for catalytic and antimicrobial applications. Firstly, the zeolite Na-Y was exchanged with solutions containing metal precursors and then a chemical treatment was used to transform the metal cations into metal nanoparticles. The different samples were characterized by different characterization methods. The reduction of methylene blue (MB) and orange (OG) dyes in the presence of NaBH₄ and nanocatalysts in a simple and binary system showed good results. It was shown in this study that the concentration of the reagents, the nature of metal species, and the nature of the dye can influence the conversion of the dye. The calculated kapp obtained by the best catalyst (Ag/Y) in a simple system was 1.882 min⁻¹ and 1.115 min⁻¹ for MB and OG dyes, respectively. It was found that the Ag/Y catalyst was more selective via MB in the binary system containing OG+MB dyes. The reuse of the Ag/Y catalyst in five cycles showed good results via the conversion of the MB dye without losing its performance. For antimicrobial activities, encouraging results have been recorded on different strains having inhibition zones between 14 and 25 mm. Full article

Natural deep eutectic solvents (NADESs) are a sustainable, green option for extraction and reaction media in biorefineries and various chemical and biotechnological applications. Particularly, enzymatic reactions profit from NADES applications, as these solvents help to maintain high substrate solubility while improving both enzyme stability and efficiency. Recent studies confirmed that NADESs can perform multiple functions simultaneously, as reaction media for biocatalytic conversions, but also as substrates and catalysts for reactions, fulfilling the role of a reactive solvent. This study reports the beneficial effect of designed reactive natural deep eutectic solvents (R-NADESs) on the esterification activity and thermal stability of free and immobilized lipases in the synthesis of polyol- and carbohydrate-based biosurfactants. We manufactured and characterized 16 binary and ternary R-NADES systems with choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and carbohydrate polyols; mono-, di-, and oligosaccharides; urea (U); N-methyl urea (MU); and water as the hydrogen bond donors (HBDs), in different combinations and molar ratios, most of which are reported for the first time in this paper. We determined their physicochemical, thermal, and molecular properties, including among others viscosity, polarizability, and the number of hydrogen bonds, and we showed that these properties are controlled by composition, molar ratio, molecular properties, temperature, and water content. Many lipases, both native and immobilized, showed high stability and remarkable catalytic performance in R-NADESs during esterification reactions. Full article

An Integrated Process Intensification (IPI) technology-based roadmap is proposed for the utilization of renewables (water, air and biomass/unavoidable waste) in the small-scale distributed production of the following primary products: electricity, H₂, NH₃, HNO₃ and symbiotic advanced (SX) fertilizers with CO₂ mineralization capacity to achieve negative CO₂ emission. Such a production platform is an integrated intensified biorefinery (IIBR), used as an alternative to large-scale centralized production which relies on green electricity and CCUS. Hence, the capacity and availability of the renewable biomass and unavoidable waste were examined. The critical elements of the IIBR include gasification/syngas production; syngas cleaning; electricity generation; and the conversion of clean syngas (which contains H₂, CO, CH₄, CO₂ and N₂) to the primary products using nonthermal plasma catalytic reactors with in situ NH₃ sequestration for SA fertilizers. The status of these critical elements is critically reviewed with regard to their techno-economics and suitability for industrial applications. Using novel gasifiers powered by a combination of CO₂, H₂O and O₂-enhanced air as the oxidant, it is possible to obtain syngas with high H₂ concentration suitable for NH₃ synthesis. Gasifier performances for syngas generation and cleaning, electricity production and emissions are evaluated and compared with gasifiers at 50 kWe and 1–2 MWe scales. The catalyst and plasma catalytic reactor systems for NH₃ production with or without in situ reactive sequestration are considered in detail. The performance of the catalysts in different plasma reactions is widely different. The high intensity power (HIP) processing of perovskite (barium titanate) and unary/binary spinel oxide catalysts (or their combination) performs best in several syntheses, including NH₃ production, NO_x from air and fertigation fertilizers from plasma-activated water. These catalysts can be represented as BaTi_1−vO_3−x{#}_yN_z (black, piezoelectric barium titanate, bp-{BTO}) and M⁽¹⁾_3−jM⁽²⁾_kO_4−m{#}_nN_r/SiO₂ (unary (k = 0) or a binary (k > 0) silane-coated SiO₂-supported spinel oxide catalyst, denoted as M/Si = X) where {#} infers oxygen vacancy. HIP processing in air causes oxygen vacancies, nitrogen substitution, the acquisition of piezoelectric state and porosity and chemical/morphological heterogeneity, all of which make the catalysts highly active. Their morphological evaluation indicates the generation of dust particles (leading to porogenesis), 2D-nano/micro plates and structured ribbons, leading to quantum effects under plasma catalytic synthesis, including the acquisition of high-energy particles from the plasma space to prevent product dissociation as a result of electron impact. M/Si = X (X > 1/2) and bp-{BTO} catalysts generate plasma under microwave irradiation (including pulsed microwave) and hence can be used in a packed bed mode in microwave plasma reactors with plasma on and within the pores of the catalyst. Such reactors are suitable for electric-powered small-scale industrial operations. When combined with the in situ reactive separation of NH₃ in the so-called Multi-Reaction Zone Reactor using NH₃ sequestration agents to create SA fertilizers, the techno-economics of the plasma catalytic synthesis of fertilizers become favorable due to the elimination of product separation costs and the quality of the SA fertilizers which act as an artificial root system. The SA fertilizers provide soil fertility, biodiversity, high yield, efficient water and nutrient use and carbon sequestration through mineralization. They can prevent environmental damage and help plants and crops to adapt to the emerging harsh environmental and climate conditions through the formation of artificial rhizosphere and rhizosheath. The functions of the SA fertilizers should be taken into account when comparing the techno-economics of SA fertilizers with current fertilizers. Full article

This work focuses on the preparation and application of silver nanoparticles/organophilic clay/polyethylene glycol for the catalytic reduction of the contaminants methylene blue (MB) and 4-nitrophenol (4-NP) in a simple and binary system. Algerian clay was subjected to a series of treatments including acid treatment, ion exchange with the surfactant hexadecyltrimethylammonium bromide (HTABr), immobilization of polyethylene glycol polymer, and finally dispersion of AgNPs. The molecular weight of polyethylene glycol was varied (100, 200, and 4000) to study its effect on the stabilization of silver nanoparticles (AgNPs) and the catalytic activity of the resulting samples. The results showed that the catalyst with the highest molecular weight of polyethylene glycol had the highest AgNP content. Catalyst mass, NaBH₄ concentration, and type of catalyst were shown to have a significant influence on the conversion and rate constant. The material with the highest silver nanoparticle content was identified as the optimal catalyst for the reduction of both pollutants. The measured rate constants for the reduction of methylene blue (MB) and 4-nitrophenol (4-NP) were 164 × 10⁻⁴ s⁻¹ and 25 × 10⁻⁴ s⁻¹, respectively. The reduction of MB and 4-NP in the binary system showed high selectivity for MB dye, with rate constants of 64 × 10⁻⁴ s⁻¹ and 9 × 10⁻⁴ s⁻¹ for MB and 4-NP, respectively. The reuse of the best catalyst via MB dye reduction for four cycles showed good results without loss of performance. Full article

This study introduces a metal-free binary catalytic system for coupling CO₂ with cyclohexane oxide (CHO) under mild conditions, allowing for tunable product selectivity. Using trans-cyclohexane diol (trans-CHD) and phosphazene superbase (P₄) as catalysts, the system selectively produces cyclic carbonates and oligocarbonates at 1 bar CO₂ pressure and 80 °C. By adjusting the catalyst ratio, varying proportions of cis-cyclohexane carbonate (cis-CHC), trans-cyclohexane carbonate (trans-CHC), and oligocarbonate are achieved, with 51 mol% CHO conversion and respective selectivities of 36%, 31%, and 33%. The catalytic efficiency and precise control of product outcomes underscore this system’s potential. Full article

The synergy effect of high K-low Ca-high Si biomass ash-based model system (BAMS) on the synthesis gas output and reaction characteristics of petroleum coke (PC) steam gasification process was studied using three biomass ash (BA) components, KCl, SiO₂, and CaCO₃, which were used as the model compounds. In the ternary model system, the steam gasification experiment of PC was conducted using a fixed bed reactor and gas phase chromatography. The synergistic effects of binary and ternary components in the ternary model system on the gasification of PC were obtained. These investigations were based on the data from the gas analysis and examined the gasification reaction process, syngas release behavior, and reaction characteristics. This study examined the effects of binary and ternary components in the ternary model system on the evolution of semi-char structure during PC gasification. This correlation revealed the synergistic effect of the model system on PC gasification. Scanning electron microscope (SEM) and Raman spectroscopy were used to characterize the structure and surface microstructure of the gasification semi-char. The results showed that the yields of different gases in the ternary model system were in H₂ > CO > CO₂. Compared with single PC gasification, the yields of H₂, CO, syngas, and carbon conversion were increased by 29.42 mmol/g, 20.40 mmol/g, 56.68 mmol/g, and 0.35, respectively. All other components in the ternary model system with high K-low Ca-high Si demonstrated catalytic effect, except for SiO₂ and the Ca-Si system, which showed inhibitory effects on syngas release and reaction features. Integrating SEM and Raman spectroscopic analyses, it was elucidated that CaCO₃ and KCl diminished the degree of graphitization in semi-char through interactions with the carbonaceous matrix. This phenomenon facilitated the gasification process and exhibited a synergistic effect. Secondly, SiO₂ will react with CaCO₃ and KCl, producing inert silicates and inactivating these compounds, leading to the decline of catalysis. Full article

Ferrous oxalate dihydrate is a versatile organic mineral with applications across fields. However, little is known about the feasibility of its synthesis directly from iron-bearing minerals using binary subcritical water (sCW) systems and its associated kinetics. In this study, the sCW+oxalic acid system at either 115 °C or 135 °C was investigated as a reaction medium for ferrous oxalate dihydrate (α-FeC₂O₄∙2H₂O) synthesis, starting from ferrotitaniferous sands. The kinetics of the synthesis reaction were studied, and the physicochemical characterization of the as-synthetized ferrous oxalates was performed. Overall, the sCW synthesis was temperature-dependent, following second-order reaction kinetics according to the proposed precipitation pathway. A high reaction rate constant, significantly high yields (up to 89%), and reduced reaction times (2–8 h) were evident at 135 °C. The as-synthetized product corresponded to the monoclinic α-FeC₂O₄∙2H₂O, showed relatively high specific surface areas (from 31.9 to 33.7 m²∙g⁻¹), and exhibited band gap energies within the visible light range (~2.77 eV). These results suggest that α-FeC₂O₄∙2H₂O can be synthesized using an organic dicarboxylic acid and iron-rich, widely available, low-cost mineral precursors. In addition, the as-prepared α-FeC₂O₄∙2H₂O could be further optimized and tested for catalytic and visible light photocatalytic applications. Full article

FeCo₂O₄/MoS₂ binary composite catalysts were prepared by the hydrothermal method and calcination method. In this paper, the morphology and structure of the materials were characterized by means of SEM, EDS, XRD, and XPS. It was found that MoS₂ has high activity and good stability in HER, and and it has more prospect than noble metal catalysts. In oxygen evolution chemical kinetics, its rich redox potential allowed it to adsorb OH⁻ on (Co²⁺/Co³⁺, Fe²⁺/Fe³⁺) and enhanced the activity of OER. The cross-nanosheet structure of the FeCo₂O₄/MoS₂ composite catalyst exposed more catalytic sites and accelerated charge transfer to achieve more efficient mass transfer. FeCo₂O₄/MoS₂ as an anode and cathode was assembled into a two-electrode system in overall water splitting, which showed good catalytic activity. When the composite ratio of FeCo₂O₄ to MoS₂ was 1:0.3, the composite catalyst had the best catalytic activity. The results show that when FeCo₂O₄/MoS₂ is used as a cathode and anode to assemble an alkaline cell, respectively, the voltage for total water electrolysis is 1.59 V at a current density of 10 mA cm⁻² in a 1 M KOH electrolyte, it can keep good stability in a 10 h test with electrolyzed water, and its current retention rate is 98.5%. Full article

One of the most challenging problems for people around the world is the lack of clean water. In the past few decades, the massive discharge of emerging organic pollutants (EOPs) into natural water bodies has exacerbated this crisis. Considerable research efforts have been devoted to removing these EOPs due to their biotoxicity at low concentrations. Heterogeneous photocatalysis via coupling clay minerals with nanostructured semiconductors has proven to be an economical, efficient, and environmentally friendly technology for the elimination of EOPs in drinking water and watershed water. Natural zeolite minerals (especially clinoptilolites) are regarded as appropriate supports for semiconductor-based photocatalysts due to their characteristics of having a low cost, environmental friendliness, easy availability, co-catalysis, etc. This review summarizes the latest research on clinoptilolites used as supports to prepare binary and ternary metal oxide or sulfide semiconductor-based hybrid photocatalysts. Various preparation methods of the composite photocatalysts and their degradation efficiencies for the target contaminants are introduced. It is found that the good catalytic activity of the composite photocatalyst could be attributed to the synergistic effect of combining the clinoptilolite adsorbent with the semiconductor catalyst in the heterogeneous system, which could endow the composites with an excellent adsorption capacity and produce more e⁻/h⁺ pairs under suitable light irradiation. Finally, we highlight the serious threat of EOPs to the ecological environment and propose the current challenges and limitations, before putting the zeolite mineral composite photocatalysts into practice. The present work would provide a theoretical basis and scientific support for the application of zeolite-based photocatalysts for degrading EOPs. Full article

2–(1H–1,2,4–Triazol–3–yl)phenol (CAT–1) was used as an organocatalyst for the coupling reaction of CO₂ and epoxides at an ambient temperature and atmospheric CO₂ pressure (1 bar). This compound has a structure in which a hydrogen bond donor, a hydrogen bond acceptor, and another hydrogen bond donor are adjacent in sequence in a molecule. The binary catalytic system of CAT–1/nBu₄NI showed TON = 19.2 and TOF = 1.60 h⁻¹ under 1 bar CO₂ at room temperature within 12 h using 2–butyloxirane. Surprisingly, the activity of CAT–1, in which phenol and 1H–1,2,4–triazole are chemically linked, showed a much greater synergistic effect than when simply mixing the same amount of phenol and 1H–1,2,4–triazole under the same reaction conditions. In addition, our system showed a broad terminal and internal epoxide substrate scope. Full article

The present work is focused on nickel catalysts supported on La₂O₃-CeO₂ binary oxides without and with the addition of Cu to the active component for the dry reforming of methane (DRM). The catalysts are characterized using XRD, XRF, TPD-CO₂, TPR-H₂, and low-temperature N₂ adsorption–desorption methods. This work shows the effect of different La:Ce ratios (1:1 and 9:1) and the Cu addition on the structural, acid base, and catalytic properties of Ni-containing systems. The binary LaCeO_x oxide at a ratio of La:Ce = 1:1 is characterized by the formation of a solid solution with a fluorite structure, which is preserved upon the introduction of mono- or bimetallic particles. At La:Ce = 9:1, La₂O₃ segregation from the solid solution structure is observed, and the La excess determines the nature of the precursor of the active component, i.e., lanthanum nickelate. The catalysts based on LaCeO_x (1:1) are prone to carbonization during 6 h spent on-stream with the formation of carbon nanotubes. The Cu addition facilitates the reduction of the Cu-Ni catalyst carbonization and increases the number of structural defects in the carbon deposition products. The lanthanum-enriched LaCeO_x (9:1) support prevents the accumulation of carbon deposition products on the surface of CuNi/La₂O₃-CeO₂ 9:1, providing high DRM activity and an H₂/CO ratio of 0.9. Full article

Structure–performance relationships in functional catalysts allow for controlling their performance in a wide range of reaction conditions. Here, the structural and compositional peculiarities in CTAB-templated CeO₂-ZrO₂-MnO_x catalysts prepared by co-precipitation of precursors and their catalytic behavior in CO oxidation and soot combustion are discussed. A complex of physical–chemical methods (low-temperature N₂ sorption, XRD, TPR-H₂, Raman, HR TEM, XPS) is used to elucidate the features of the formation of interphase boundaries, joint phases, and defects in multicomponent oxide systems. The addition of Mn and/or Zr dopant to ceria is shown to improve its performance in both reactions. Binary Ce-Mn catalysts demonstrate enhanced performance closely followed by the ternary oxide catalysts, which is due the formation of several types of active sites, namely, highly dispersed MnO_x species, oxide–oxide interfaces, and oxygen vacancies that can act individually and/or synergistically. Full article