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Cu serves as a promising electrocatalyst for converting CO2 into valuable C2 products in CO2 reduction reactions (CO2RR). However, instability in CO* formation is crucial for CO2 adsorption‐ desorption still remains a challenge under reduction conditions. This study explores the impact of lanthanide oxide, particularly CeO2, on Cu‐based catalytic performances. By leveraging Ce's distinctive electronic structure, CO* species are stabilized during the reaction in CeO2─Cu2O, resulting in exceptional catalytic performance for CO2 electroreduction to C2 products. Hybridizing CeO2‐Cu2O with graphene aerogel enhances electrochemical active surface area and CO2RR efficiency. The resulting CeO2─Cu2O(10%)/GA electrocatalyst exhibits a remarkable faradaic efficiency for C2 products, exceeding 62%, alongside exceptional stability over 80 h with wide potential window (−0.8 to −1.2 V) using a H‐cell. Systematic investigations elucidate the intricate interplay between surface properties and catalytic activity. Furthermore, a solar cell‐ powered CO2 reduction system demonstrates consistent performance (−27.8 mA cm−2 at 3.46 V) under solar radiation of ≈100 mW cm−2, showcasing outstanding stability with nearly 100% retention over 4 h of continuous illumination. In short, by harnessing catalytic and electronic effects, this innovation advances the development of electrocatalysts with heightened CO2‐to‐C2 selectivity, bridging fundamental research with technological innovation to tackle critical global challenges. [ABSTRACT FROM AUTHOR]

In this study, V2O5, 5ZnO/10V2O5, and ZnO, 10ZnO/10V2O5 nanocomposites were synthesized by the sol–gel method. The sol–gel technique is an important process for the fabrication of advanced oxide materials with desirable catalytic, optical, and structural properties. The varieties and flexibilities of sol–gel techniques help in preparing materials with extremely specific properties. For the presented samples, three types of phases were assessed. The average crystalline size of V2O5, 5ZnO/10V2O5 and ZnO, 10ZnO/10V2O5 nanocomposites were found to be 25, 26, 14.5, and 15.5 nm, respectively. SEM images showed three different shapes of semi-tube, semi-spherical, and semi-flower. The pure samples of V2O5 and ZnO showed semi-tube shapes. 5ZnO/10V2O5 shows a spherical shape with average dimeter of 0.6 µm. Strong dependence of the direct optical band gap was observed on different compositions that varied within the range of (2.33–2.73 eV). Conversely, the indirect values varied within the range of 2.119–2.35 eV. On the other hand, 10ZnO/10V2O5 has semi flower shape with different layers. Optical parameters, such as optical band gap, extension coefficient, tails of localized states, and refractive index, were gauged for these nanocomposites. In addition, the mean refractive index of ZnO is lower than that of V2O5, with differences observed between 5ZnO/10V2O5 and 10ZnO/10V2O5 nanocomposites.

Environmental remediation evinces sensitive detection and elimination of contaminants from the environment. Recent investigations delineate nanomaterials as potentially useful agents in environment remediation. In this investigation, we have developed multifunctional CdO‐ZnO nanocomposite (NCs) for efficient degradation of organic dyes and sensitive detection of nitrite ions which also exhibits excellent luminescence and antioxidant properties. The CdO‐ZnO NCs were developed through a facile method which improved the yield quantity by decreasing the energy consumption there by reducing the cost. Thus synthesized CdO‐ZnO NCs were characterized through X‐ray diffraction, FT‐IR, SEM, TEM, EDX studies. These studies confirmed the successful formation of CdO‐ZnO composite and the average particle size of the NCs was found to be ~50 nm. Selective reduction of harmful industrial organic dyes from the water bodies is one of the important aspects of water pollution. As prepared CdO‐ZnO NCs degraded the MB dye completely in 30 min under visible light irradiation. The effect of various parameters such as catalytic load, dye concentration and pH on the degradation of dye was assessed and the NCs exhibited maximum degradation efficiency at 25 mg of catalytic load and alkaline pH of 11. The photoluminescence studies reveal that the NCs have inherent excellent luminescence property by exhibiting the emission band at 277 and 282 nm. From electrochemical studies, the CdO‐ZnO NCs proclaimed magnificent nitrite sensing property with the LOD value of 9.8 μM. Additionally, antioxidant studies disclosed that NCs remarkably scavenged the DPPH free radicals with IC50 value of 249 μg/mL. Thus, this study establishes simple method for the development of efficient mixed oxide material CdO‐ZnO for multifunctional properties that could find industrial applications. [ABSTRACT FROM AUTHOR]

Four-component oxide catalysts MnOx–CuO–ZrO2–CeO2 are synthesized by co-precipitation with varying the calcination temperature from 400 °C to 800 °C. Formation and decomposition processes in mixed oxides are studied by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The redox properties of the obtained samples are tested by temperature-programmed hydrogen reduction, and the catalytic characteristics are examined in the CO oxidation reaction. At 400-600 °C homogeneous solid solution MnxCuyZrzCeqO2 with the fluorite structure is formed. Temperature elevation to 700-800 °C facilitates the gradual decomposition of initial oxide, with manganese and copper cations leaving its composition in the form of highly dispersed CuO and CuxMn3–xO4 particles. The occurrence of different active states in the catalyst and their transitions into each other under the temperature effect is shown to maintain the high activity in the CO oxidation reaction up to 800 °C. [ABSTRACT FROM AUTHOR]

Acid–base M2+MgAlO and M2+AlO mixed oxides (where M2+ = Mg, Cu, Co, Zn, and Ni) were obtained by thermal decomposition of the corresponding layered double hydroxide (LDH) precursors and used as catalysts for cyclohexanol and benzaldehyde condensation under solvent-free conditions. The catalysts were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and temperature-programmed desorption of CO2 (TPD-CO2). Gas chromatography–mass spectroscopy (GC/MS) was used for the identification and quantification of the product mixtures. In the reaction of cyclohexanol and benzaldehyde on M2+MgAlO and MgAlO catalysts, a 2,6-dibenzylidene-cyclohexanone was obtained as the main product as a result of consecutive one-pot dehydrogenation of cyclohexanol to cyclohexanone and subsequent Claisen–Schmidt condensation. In the reaction mixture obtained in the presence of NiAlO, CoAlO, and ZnAlO catalysts, a cyclohexyl ester of 6-hydroxyhexanoic acid was detected together with the main product. This is most likely a by-product obtained after the oxidation, ring opening, and subsequent esterification of the cyclohexanol. [ABSTRACT FROM AUTHOR]

Catalytic studies hydrogen production via steam reforming of ethanol (SRE) are essential for process optimization. Likewise, selecting the ideal support for the active phase can be critical to achieve high conversion rates during the catalytic steam reforming process. In this work, copper-based catalysts were synthesized using two different supports, NaY zeolite and Nb2O5/Al2O3 mixed oxides. The materials were prepared using wet impregnation and characterized for their physicochemical properties using different analytical techniques. Differences in the catalyst morphologies were readily attributed to the characteristics of the support. The Cu/NaY catalyst exhibited a higher specific surface area (210.40 m2 g−1) compared to the Cu/Nb2O5/Al2O3 catalyst (26.00 m2 g−1), resulting in a homogeneous metal dispersion over the support surface. The obtained results showed that, at 300 °C, both the Cu/Nb2O5/Al2O3 and Cu/NaY catalysts produced approximately 50% hydrogen and 40% acetaldehyde, but with significant differences in conversion (6% and 56%, respectively). At 450 °C, a greater product distribution and a 10% higher conversion were observed when the catalyst was supported on NaY compared to Nb2O5/Al2O3. Hence, the performance of copper-based catalysts was influenced significantly by the textural properties of the support. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution from water is investigated in Ba–Sr–Ta–O layered compounds possessing two different crystal structures: Sr 2 Ta 2 O 7 (S.G. Cmcm, a (110) type layered pervoskite), and BaSrTa 2 O 7 (S.G. Immm, a (100) type layered perovskite). High purity samples of BaSrTa 2 O 7 and Sr 2 Ta 2 O 7 are successfully prepared by solid state reaction. Hydrogen production under UV irradiation is 26% larger in BaSrTa 2 O 7 (15.2 mmol g−1) than in Sr 2 Ta 2 O 7 (11.4 mmol g−1). The band gaps determined by diffuse reflectance spectroscopy (DRS) are 4 eV and 4.6 eV for BaSrTa 2 O 7 and Sr 2 Ta 2 O 7 , respectively. Density Functional Theory (DFT) calculations provide insights into the crystal and electronic structures of Sr 2 Ta 2 O 7 , BaSrTa 2 O 7 , and their derived series Sr 2-x Ba x Ta 2 O 7 (0 ≤ x ≤ 1). It is found that independently of the Sr/Ba content, the BaSrTa 2 O 7 -derived series show a ∼0.6 eV lower band gap and a wider conduction band than the Sr 2 Ta 2 O 7 -derived series. DFT results indicate that the enhanced hydrogen production of BaSrTa 2 O 7 is related to particular features of its crystal structure which favor Ta–Ta interactions. [Display omitted] • Two Ta-layered perovskites with different structure are unveiled as UV-photocatalysts • Accumulated H 2 evolution is 26 % higher in BaSrTa 2 O 7 than in Sr 2 Ta 2 O 7 • Experiments and calculations agree on a narrower band gap for BaSrTa 2 O 7 • Ba/Sr composition has a minor impact on the crystal and electronic structures • The BaSrTa 2 O 7 crystal structure propitiates the enhancement of H 2 production [ABSTRACT FROM AUTHOR]

In this study, the catalytic activity of calcined M3Al (M: Sr, Cd, Ni, Co, and Ca) and the effect of replacing divalent cations with Ca2+ in calcined MxCa3 − xAl hydrotalcite on the catalytic conversion of benzaldehyde and acetophenone to chalcone via Claisen–Schmidt condensation has been investigated. A series of M3Al and MxCa3 − xAl were synthesized by the co-precipitation method and characterized by SEM, BET, FT-IR, EDS, XRD, CO2-TPD techniques, and the Hammett indicator method. The results showed that the synthesized samples have normal surface area, high crystallinity, and three types of moderate, strong, and stronger basic sites. The catalytic activity is effectively dependent on the number of stronger alkaline sites. The effects of different parameters such as calcination temperature, solvents, catalyst amount, catalyst reusability, and the effects of electron-donating and electron-withdrawing groups were investigated. In optimum conditions over 0.04 wt% Sr0.5Ca2.5Al catalyst, at atmospheric pressure, 60 °C, in ethanol, yield (%) of chalcone was achieved at 87%. [ABSTRACT FROM AUTHOR]

Mn3O4/ZnO-Al2O3-CeO2 catalyst was synthesized through a solid-state process from a 3% Mn-doped Zn-(Al/Ce) layered double hydroxide structure. Detailed structural and optical characterization using XRD, FTIR, UV–visible DRS, and TEM was conducted. By investigating clofibric acid (CA) degradation in aqueous solution, Mn3O4/ZnO-Al2O3-CeO2 photocatalytic activity was evaluated. The results show that the heterostructure mixed oxide catalyst has excellent CA photodegradation performance. Further, the characterization reveals that such photocatalytic efficiency can be attributed to two facts that are summarized in the optical properties and the synergic effect between Mn and Ce elements. The sample demonstrated a narrow band gap of 2.34 eV based on DRS. According to the experimental results of the photodegradation, after 120 min of irradiation, the photocatalyst exhibited the highest photocatalytic activity, with a degradation efficiency of 93.6%. Optimization outcomes indicated that maximum degradation efficiency was attained under the following optimum conditions: catalyst dose of 0.3 g/L, initial dye concentration of 20 mg/L, pH 3.86, and 120 min of reaction time. The quenching test demonstrates that photogenerated electrons and superoxide radicals are the most powerful reactive species. The catalyst could be useful in decreasing the photogenerated charges recombination, which offers more redox cycles simultaneously during the catalytic process. The strong Ce-Mn interaction and the formation of their different oxidation states offer a high degradation efficiency by facilitating electron–hole transfer. The introduction of Mn3O4 in the catalyst can effectively improve the visible absorption properties, which are beneficial in the photocatalytic process by reaching a high catalytic efficiency at a low cost. [ABSTRACT FROM AUTHOR]

Powdered Ni-based catalysts exhibit good performance in the dry reforming of methane (DRM); however, they suffer from limited industrial applicability. Structured monolithic catalysts can overcome these limitations. In this sense, we present the synthesis of Ni–Ce mixed oxide-type catalysts immobilized in cordierite monoliths using a simple coprecipitation method and slurry coating without additives using hydrotalcite precursors for catalyst preparation. Our research explores the role of Ce (0–7 % w/w) as a promoter and the impact of immobilizing mixed oxides (MO) within cordierite monoliths on the physicochemical properties and catalytic performance of non-previously H 2 -reduced materials in DRM at 700 °C. Our findings reveal the favorable impact of Ce on the physicochemical properties of the catalyst in both the powder and monoliths, including smaller crystallite sizes, enhanced CO 2 adsorption, and reducibility with higher Ce loading. The immobilized mixed oxide (MO) maintained its crystalline structure and formed stable, uniform layers with thicknesses below 10 μm in the monoliths. The powders exhibited stable conversions of 70–80% for CH 4 and 66–75% for CO 2 , whereas the monoliths showed conversions of 85–90% for CH 4 and 80–90% for CO 2 at 700 °C and 94,680 mL·g cat −1·h−1. A higher catalyst loading in the monoliths did not result in detrimental catalytic conversion. On average, the monoliths had a higher H 2 /CO ratio (1.25–1.5) compared to the powders (1–1.25), which may explain the increased coke formation rate in the monoliths from methane cracking. Ce improved the stability and reduced coke formation, particularly when the space velocity was lower. This research highlights the significant advantages of immobilizing mixed oxides (MO) in monolithic structures, making them highly promising for potential industrial scale-up. Their stability, recoverability, elimination of high-cost H 2 reduction, and reusability in subsequent catalytic tests contributed to their favorable characteristics. [Display omitted] • Coprecipitation simplifies slurry coatings for monolith immobilization. • Monoliths were prepared without additives. • The monoliths exhibited high stability and consistent performance upon reuse. • Ce improved stability and reduced coke formation at lower space velocities. • Immobilized catalysts produced more carbon, but no pressure drops were observed. [ABSTRACT FROM AUTHOR]

The rapid emergence of intelligent textile-based sensors has sparked considerable interest within the scientific community. A pivotal factor in advancing these sensors is the development of semiconductors with tailored band energy levels to enhance their optical properties. This enhancement primarily arises from efficient carrier separation and interfacial charge transfer processes. In pursuit of these objectives, our study presents a novel approach to fabricate flexible thin films composed of mixed oxides, specifically zinc oxide and cadmium tungstate (ZnO/CWO), within a chitosan (CS) matrix, utilizing a cost-effective method. We conducted a comprehensive characterization of the fabricated samples, encompassing structural, morphological, and optical analyses. Techniques such as X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FESEM), iono/photoluminescence, and scintillation strategies were employed. The findings from XRD and Raman spectroscopy unequivocally confirm the presence of hexagonal ZnO and monoclinic CdWO4 structures within the thin film. Notably, the ZnO/CWO composite thin films exhibit robust emissions in the blue-green and orange spectral regions compared to pure CS at room temperature. This phenomenon occurs following excitation by a 290 nm wavelength light source and a proton beam serving as an ionizing radiation source. Furthermore, FESEM/TEM analysis reveals that the synthesized ZnO/CWO composite nanoparticles predominantly exhibit a diverse range of shapes, including cubic, rod-like, and spherical, with an average diameter size of approximately 20–80 nm, demonstrating excellent dispersion within the chitosan matrix. The results obtained in this study suggest that the prepared flexible composite film holds significant promise for future applications in adaptable optical devices. [ABSTRACT FROM AUTHOR]

AbstractOptimizing materials and associated structures for detecting various environmental gas pollutant concentrations has been a major challenge in environmental sensing technology. Semiconducting metal oxides (SMOs) fabricated at the nanoscale are a class of sensor technology in which metallic species are functionalized with various dopants to modify their chemiresistivity and crystalline scaffolding properties. Studies focused on recent advances of gas sensors utilizing metal oxide nanostructures with a special emphasis on the structure-surface property relationships of some typical n-type and p-type SMOs for efficient gas detection are presented. Strategies to enhance the gas sensor performances are also discussed. These oxide material sensors have several advantages such as ease of handling, portability, and doped-based SMO sensing detection ability of environmental gas pollutants at low temperatures. SMO sensors have displayed excellent sensitivity, selectivity, and robustness. In addition, the hybrid SMO sensors showed exceptional selectivity to some CWAs when irradiated with visible light while also displaying high reversibility and humidity independence. Results showed that TiO2 surfaces can sense 50 ppm SO2 in the presence of UV light and under operating temperatures of 298–473 K. Hybrid SMO displayed excellent gas sensing response. For example, a CuO–ZnO nanoparticle network of a 4:1 vol.% CuO/ZnO ratio exhibited responses three times greater than pure CuO sensors and six times greater than pure ZnO sensors toward H2S. This review provides a critical discussion of modified gas pollutant sensing capabilities of metal oxide nanoparticles under ambient conditions, focusing on reported results during the past two decades on gas pollutants sensing. [ABSTRACT FROM AUTHOR]

The hydrogen production by ethanol steam reforming over Ni–Co–Al mixed oxides derived from layered double hydroxides is evaluated in this work. The catalysts were prepared via coprecipitation and characterized through N2 adsorption and desorption measurements, X-ray diffraction (XRD), temperature programmed reduction (TPR), CO2 desorption and oxidation, and scanning electron microscopy. The catalyst activity was evaluated in a fixed bed reactor between 400 and 600 °C, using ethanol and water in a 1:3 ratio, with online analysis of products by gas chromatography. Increasing the amount of Co increased surface area. XRD analysis revealed a mixture of Ni–Al and Co-Al oxides after calcination. The TPR profiles revealed that an increase in Co content leads to a more stable mixed oxide phase. The activity results showed that H2 selectivity increases with reaction temperature and Co content in the catalyst. The high selectivity for H2 is attributed to methane decomposition being favored. Hence the larger production of carbon is promoted by the excess of Co in the catalyst with the highest amount of Co. The decomposition of ethanol producing CO, CH4, and H2 is favored at higher temperatures. The selectivity for H2 remained above 90% in long term tests at 600 °C. XRD analysis after reactions showed that the presence of Co decreases the sintering of catalysts. The compromise between resistance to sintering and carbon deposition points to a medium amount of Co in the catalyst. All catalysts showed metallic phases after the reaction, demonstrating that the reduction step is not necessary for this reaction. [ABSTRACT FROM AUTHOR]

Catalysts based on CoCuMgAl mixed oxides were synthesized and studied in the hydrogenations of furfural and 5-hydroxymethylfurfural under different conditions. The changes in the structural properties of the catalysts at different stages of their preparation were studied using a set of physical methods (XRD, SEM, and TEM). It was shown that the fine regulation of the chemical compositions of the mixed oxides (i.e., changes in the Co/Cu ratio) made it possible to vary the structure, morphology, and catalytic properties of the samples. The phase composition of catalysts with Co/Cu = 1 did not change during the catalytic reaction, although the initial catalysts had a less-homogeneous morphology. 5-hydroxymethylfurfural conversion was higher for the samples with Co/Cu = 1. Furfural conversion increased when raising the Co/Cu ratio. The selectivity toward furfuryl alcohol for the catalyst with Co/Cu = 2 under mild conditions of furfural hydrogenation was more than 99%. The results obtained are important for the development of the scientific foundations of the preparation of hydrogenation catalysts with a fine-tunable composition in order to obtain the desired hydrogenation products. [ABSTRACT FROM AUTHOR]

This work reports on the ultrasonic synthesis of layered double hydroxides (LDH), also known as hydrotalcite-type materials. We have studied the influence of ultrasonic irradiation parameters (power, time, temperature) on the physicochemical properties of Ni2Mg4Al1.8La0.2 hydrotalcite-type precursors and related mixed oxides (MO). The low-frequency acoustic cavitation (22 kHz) was applied during the precipitation and aging steps of co-precipitation synthesis and the results were compared to the classical preparation route. The materials were characterized by ATR-FTIR, XRD, N2 adsorption–desorption, SEM-EDX, S/TEM-HAADF, and XPS. Using the combination of acoustic cavitation-assisted precipitation and aging steps, XRD experiments show a higher purity hydrotalcite phase and a better incorporation of lanthanum ions into the LDH structure. As expected, morphological characterization shows a reduction in average crystallite size and an increase in surface area and pore volume, combined with a drastic reduction in synthesis time (45 min at room temperature versus 19 h at 60 °C in conventional synthesis). The insertion of a larger quantity of La is observed by S/TEM-EDSX mapping which also shows a better distribution of lanthanum atoms within the LDH and mixed oxide structures.

In this study, we prepared Al _2 O _3 -TiO _2 (AT) mixed oxides to synthesize NiW catalysts for sulfur removal reactions. The AT support samples were prepared with various surfactants. Additionally, gallium atoms (2.4 wt%) were introduced as an additive to coat the outer surface layers of AT support that lacked Al ^3+ or Ti ^2+ cations. Characterization results showed substantial differences in textural properties, chemical composition, and surface acidity. The x-ray Photoelectron Spectroscopy (XPS) and High-Resolution Transmission Electron Microscopy (HR-TEM) results demonstrated that the NiW/AT-L-Ga sample has a better combination of dispersion, sulfidation, and promotion among materials. The sulfided NiW/AT-L-Ga catalyst had the highest catalytic activity. After incorporating Ga, XPS observed that the activity could be associated with an increase in the NiWS active phase; however, including a surfactant in the synthesis of the support allowed an increase in the amount of NiWS phase. The active phase was modeled considering the HR-TEM results for the slab length, revealing the atoms at the border susceptible to promotion.

Proton exchange membrane (PEM) water electrolysis represents a promising technology for green hydrogen production, but its widespread deployment is greatly hindered by the indispensable usage of platinum group metal catalysts, especially iridium (Ir) based materials for the energy-demanding oxygen evolution reaction (OER). Herein, we report a new sequential precipitation approach to the synthesis of mixed Ir-nickel (Ni) oxy-hydroxide supported on antimony-doped tin oxide (ATO) nanoparticles (IrNi _y O _x /ATO, 20 wt.% (Ir + Ni), y = 0, 1, 2, and 3), aiming to reduce the utilisation of scarce and precious Ir while maintaining its good acidic OER performance. When tested in strongly acidic electrolyte (0.1 M HClO _4 ), the optimised IrNi _1 O _x /ATO shows a mass activity of 1.0 mA µ g _Ir ^−1 and a large turnover frequency of 123 s ^−1 at an overpotential of 350 mV, as well as a comparatively small Tafel slope of 50 mV dec ^−1 , better than the IrO _x /ATO control, particularly with a markedly reduced Ir loading of only 19.7 µ g _Ir cm ^−2 . Importantly, IrNi _1 O _x /ATO also exhibits substantially better catalytic stability than other reference catalysts, able to continuously catalyse acidic OER at 10 mA cm ^−2 for 15 h without obvious degradation. Our in-situ synchrotron-based x-ray absorption spectroscopy confirmed that the Ir ^3+ /Ir ^4+ species are the active sites for the acidic OER. Furthermore, the performance of IrNi _1 O _x /ATO was also preliminarily evaluated in a membrane electrode assembly, which shows better activity and stability than other reference catalysts. The IrNi _1 O _x /ATO reported in this work is a promising alternative to commercial IrO _2 based catalysts for PEM electrolysis.

• In-situ characterization combined with ab-initio calculations for the determination of key intermediates and reactive sites. • The rate controlling step of 2Cl*→Cl 2 is facilitated by CuO (1 1 1), reducing the accumulation of Cl over CeO 2 and CeVO 4. • O 2 replenishing cycle was accelerated on CeO 2 and CeVO 4 , minimizing the evolution of the Cu-Cl bonding. The utilization of copper-based catalysts for converting by-product hydrogen chloride (HCl) into chlorine gas (Cl 2) offers a promising method for efficient management of HCl waste gas. However, a significant challenge in this process lies in catalyst deactivation, primarily attributed to the loss of active component in the form of Cu-Cl. In this study, we synthesized a Cu 2.4 CeV 0.5 O x catalyst that exhibited remarkable performance, achieving a space-time yield of 2.26 g Cl 2 /gcat*h with stable conversion efficiency at approximately 83 % maintained over 600 h. This level of stability represents a substantial improvement compared to previous studies of copper-based catalysts. In-situ DRFITS combined with ToF-SIMS confirms the reduction evolution of metal-Cl bonds. Additionally, ab-initio calculations elucidated that the rate-limiting step involves oxygen vacancy replenishment by O 2 rather than Cl over CeO 2 and CeVO 4 , thereby inhibiting Cu-Cl bond formation. This study introduces a novel approach for efficienct treatment of HCl waste gas, paving the way for its potential industrial application. [ABSTRACT FROM AUTHOR]

[Display omitted] Thorium oxide is referred to as the world's nuclear fuel of the future for fourth-generation reactors, according to its numerous advantages. So, it is essential to provide practical solutions to improve thoria production technology. Recently, the oxalates co-precipitation method has received much attention as a wet method with many benefits, including reducing the production of radioactive dust and producing a homogeneous product. One of the significant advantages of this method is the possibility of precise control of the final oxide characteristics through the optimization of precipitation and heat treatment conditions. This study attempts to provide a complete report on the effect of multiple parameters of the oxalate precipitation and decomposition method, such as temperature, stirrer, and calcination, on the various properties of the final ThO 2 powder, including size, morphology, and surface area. In addition, the synthesis of (U-Th)O 2 fuels via oxalate co-precipitation and hydrothermal methods is investigated. [ABSTRACT FROM AUTHOR]

Robust electrocatalysts required to drive the oxygen evolution reaction (OER) during water electrolysis are still a missing component toward the path for sustainable hydrogen production. Here a new family of OER active quaternary mixed-oxides based on X-Sn-Mo-Sb (X = Mn, Fe, Co, or Ni) is reported. These nonstoichiometric mixed oxides form a rutile-type crystal structure with a random atomic motif and diverse oxidation states, leading to the formation of cation vacancies and local disorder. The successful incorporation of all cations into a rutile structure was achieved using oxidizing agents that facilitates the formation of Sb 5+ required to form the characteristic octahedral coordination in rutile. The mixed oxides exhibit enhanced stability in both acidic and alkaline environments under anodic potentials with no changes in their crystal structure after extensive electrochemical stress. The improved stability of these mixed oxides highlights their potential application as scaffolds to host and stabilize OER active metals.

MnOX-CeO2 catalysts with different Mn and Ce content were prepared to evaluate the effect of metal content on catalytic properties and activity in the simultaneous NO reduction and o-DCB oxidation, in order to elucidate the most active species for the process. Catalytic properties were evaluated by ICP-AES, XRD, skeletal FTIR, STEM-HAADF, XPS, N2-physisorption, H2-TPR, NH3-TPD and pyridine-FTIR. Catalysts with 85%Mn and 15%Ce molar content have been found to be the most active. Their excellent catalytic performance is related to the coexistence of Mn in different phases, i.e., Mn species strongly interacting with Ce and segregated Mn species. The effect of the preparation methods has also been deeply investigated: Co-precipitation method (CP) leads to Mn segregation as Mn2O3, whereas sol-gel preparation method (SG) promotes the formation of an amorphous powder. The synergy between segregated Mn2O3 species and Mn species in high interaction with Ce (resulting in a mixed oxide phase) leads to the presence of Mn with different oxidation states. This effect, together with the high oxygen mobility caused by structural defects, enhances redox, acidic and oxidative properties. The improvement of catalytic properties with Mn content also favors NO reduction side-reactions, with N2O and NO2 being the most important by-products, whereas it limits the production of chlorinated organic by-products in o-DCB oxidation. [ABSTRACT FROM AUTHOR]

• Sr 0.5 Ca 2.5 Al and Ca 3 Al calcined HT-like catalysts synthesized by co-precipitation method. • Sr 0.5 Ca 2.5 Al is strong solid base, environmentally friendly, and reusable catalyst. • Sr 0.5 Ca 2.5 Al is a highly active catalyst for Knoevenagel condensation reaction. • Catalytic activity is strongly dependent on the number of stronger basic sites. • Conversion (%) of benzaldehyde reaches 97% (selectivity 84%) on 0.04% of Sr 0.5 Ca 2.5 Al. The Knoevenagel condensation reaction is one of the most important reactions in the industry for the synthesis of organic materials, medicinal, and biological compounds. In this work, we have proposed an original and efficient solid-base catalytic system for the Knoevenagel condensation reaction. For the first time, a mixed oxide catalyst derived from hydrotalcite-like Sr 0.5 Ca 2.5 Al precursor was synthesized by co-precipitation method and subsequently calcined for 5 h at 850 °C. The catalysts were characterized by various techniques. The Sr 0.5 Ca 2.5 Al mixed oxide was also compared with the usual Ca 3 Al sample in terms of structural characteristics and catalytic activity in the Knoevenagel reaction between active methylene compounds and benzaldehyde. The findings revealed that the Sr 0.5 Ca 2.5 Al mixed oxide sample is considerably active in this reaction compared to the Ca 3 Al sample due to its stronger basicity. The kinetics of the Knoevenagel condensation reaction over the Sr 0.5 Ca 2.5 Al catalyst was investigated and indicated that it follows from the second-order model. The stability and reusability of the catalyst sample were studied and it was found that the Sr 0.5 Ca 2.5 Al catalyst has high stability and a good lifetime. The effects of reaction time, amount of catalyst, and reaction temperature on benzaldehyde conversion (%) and product selectivity (%) were assessed in this study using the Box-Behnken design. The appropriateness of the quadratic regression model was evaluated through the ANOVA method. Under optimal conditions, the conversion percentage of benzaldehyde and product selectivity reached 97% and 84%, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

The influence of cobalt on the photocatalytic reduction of CO 2 under visible light was examined by using various 3:1 Co-Mg/Al layered double hydroxides (LDHs) obtained by coprecipitation under low oversaturation conditions. CO 2 photoreduction increased with increasing amount of cobalt in the solids. Calcining the LDHs gave basic mixed oxides (LDOs) with considerably decreased activity, thus confirming that the hydroxyl structure of the materials facilitated the photocatalytic process. Attempts at reconstructing the LDOs revealed that only the material with the smallest amount of cobalt regained its original structure —and exhibited excellent performance in the reaction. All solids were characterized by using various instrumental techniques and used as catalysts in the photocatalytic reduction of CO 2. Also, the fully reconstructed material was reused with no substantial loss of activity. • Hydrotalcite structures provided the best results compared to mixed oxides. • LDHs with higher Co amount were the most effective in CO2 photoreduction. • A high amount of cobalt hinders the rehydration process of LDHs. • An increase of the catalyst amount causes a negative quenching effect. [ABSTRACT FROM AUTHOR]

• The ultrasonic-assisted synthesis of hydrotalcite catalysts for methane reforming has been achieved. • The ultrasonic parameters of the synthesis have been optimized. • Ultrasonics can be used to improve the structural properties of materials. • Ultrasound helps insert lanthanum atoms into brucitic layers. This work reports on the ultrasonic synthesis of layered double hydroxides (LDH), also known as hydrotalcite-type materials. We have studied the influence of ultrasonic irradiation parameters (power, time, temperature) on the physicochemical properties of Ni 2 Mg 4 Al 1.8 La 0.2 hydrotalcite-type precursors and related mixed oxides (MO). The low-frequency acoustic cavitation (22 kHz) was applied during the precipitation and aging steps of co-precipitation synthesis and the results were compared to the classical preparation route. The materials were characterized by ATR-FTIR, XRD, N 2 adsorption–desorption, SEM-EDX, S/TEM-HAADF, and XPS. Using the combination of acoustic cavitation-assisted precipitation and aging steps, XRD experiments show a higher purity hydrotalcite phase and a better incorporation of lanthanum ions into the LDH structure. As expected, morphological characterization shows a reduction in average crystallite size and an increase in surface area and pore volume, combined with a drastic reduction in synthesis time (45 min at room temperature versus 19 h at 60 °C in conventional synthesis). The insertion of a larger quantity of La is observed by S/TEM-EDSX mapping which also shows a better distribution of lanthanum atoms within the LDH and mixed oxide structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of Zr and Si addition to CaO based catalysts was evaluated. • The presence of oxide inert phases mitigated the sintering of calcium oxide particles. • Samples containing Si and Zr showed greater stability during CO 2 capture cycles. • Ni/CaZr and Ni/CaSi had high H 2 production during CO 2 enhanced propane steam reform. In this study, the performance of bifunctional catalysts of Ni over CaO, CaO-CaZrO 3 and CaO-Ca 2 SiO 4 was evaluated in CO 2 capture and sorption-enhanced steam propane reforming cycles. Ni/CaO, Ni/CaO-CaZrO 3 , and Ni/CaO-Ca 2 SiO 4 catalysts/sorbent were synthesized by sol-gel process. X-ray diffraction (XRD) results showed the formation of CaZrO 3 and Ca 2 SiO 4 in the catalysts. The thermal stability performance of the samples was evaluated in CO 2 capture and sorption-enhanced steam propane reforming cycles. Both tests confirmed a significant improvement of the performance during both CO 2 capture and steam propane reforming with the addition of Zr and Si. This effect can be attributed to the minimization of CaO sintering due to the higher thermal stability added by the formation of CaZrO 3 and Ca 2 SiO 4. In addition, Ni/CaO-CaZrO 3 sample presented the highest stability during sorption-enhanced steam propane reforming cycles, with pre-breakthrough time close to 50 min and H 2 yields over 90 vol.% in the pre-breakthrough period and close to 71% in the post-breakthrough, in all reaction cycles. Therefore, the results showed that the formation of the mixed oxides CaZrO 3 and Ca 2 SiO 4 improved the thermal stability of the catalysts, which can be good materials for sorption-enhanced steam propane reforming process. [ABSTRACT FROM AUTHOR]

Isomorphous series provide scopes to modulate and improve properties in even in non-stoichiometric compositions. [Display omitted] • Isomorphous series of inorganics are deliberated. • The roles of the ionic radii, components ions and ligands in inorganic assemblies to generate isomorphous series are discussed. • The solid solutions from isostructural series and their material properties are discussed. • The isomorphous series of various assemblies, core shell nano-materials, poly-nuclear and polymeric structures impacting modulation of material properties are discussed. • Future outlooks of isomorphous series of inorganic materials to generate structurally equivalent counterpart to tune properties are being illuminated. Replacement of atoms or molecules of similar size, shape, and electronic configuration in an ensemble of discrete or multi-component system to generate one or more equivalent composition/s provide isomorphous series. Such series may be generated by modifications of sites in the interior or exterior of a core shell structure or a layered structure. The isomorphous series allows one to modulate structure and properties, and also generate equivalent compositions with novel material properties and tunes reactivity. Such series among the ones having isostructural relationship are isomorphic. Study on stereo-electronic aspects different equivalent compositions created from an original one by replacing one or more component/s has emerged as an important topic of research. This article provides the state of the art with examples of different inorganic complexes and composites to set the role of isomorphous series as to study them for comparative studies for improvement of utility of an original composition. [ABSTRACT FROM AUTHOR]

• DRIFT-MS operando monitoring of the reforming of ethanol. • Evolution of organic species on the surface and proposed reaction mechanism. • Comparison between Ni, Co and the Ni-Co bimetallic phase in the reaction with TOF. The oxidative steam reforming of ethanol (OSRE) reaction to produce hydrogen under non-equilibrium conditions was successfully achieved using mixed oxides (MO) of Ni and Co. The catalysts were synthesized with hydrotalcite (HT) type as a precursor by simultaneous coprecipitation assisted by microwaves. The solids were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscopy (TEM), N 2 adsorption–desorption isotherms, and X-ray photoelectron spectroscopy (XPS). The OSRE reaction was also implemented under operando conditions by diffuse reflectance infrared spectroscopy with Fourier transform coupled to mass spectrometry (DRIFT-MS) to study the path of molecules on the surface of these solids. The results confirmed the presence of the reduced phases of Ni and Co for all the systems and revealed that the O II /O I ratio increased for the samples containing Co, indicating that the greatest number of oxygen vacancies is present in these solids, which explains their high capacity to oxidize CO to CO 2 in the catalytic test. It was possible to show that the NiCo bimetallic phase presents better catalytic performance for the production of hydrogen by effectively breaking the C-C bond and oxidizing the CH x species on the surface, which is reflected in the complete conversion of ethanol and a high selectivity to CO 2 and H 2 over other products such as CO, CH 4 , and acetaldehyde. [ABSTRACT FROM AUTHOR]

The oxides LiMn 2 O 4 , LiFe 0.75 Zn 0.25 MnO 4 , and LiFe 0.25 Zn 0.25 Mn 1.5 O 4 , referred to as LMO, LFZMO 0.75–0.25, and LFZMO 0.25–0.25, were synthesized at 800 °C using ultrasound-assisted thermal decomposition of nitrates (UA-TDN). X-ray diffraction (XRD) analyses confirmed the spinel structure (Fd3m space group) for all materials. Raman spectroscopy validated the characteristic absorption bands of the spinel phase. Energy-dispersive spectroscopy (EDS) verified the uniform distribution of Fe, Zn, Mn, and O in all samples and proved the expected stoichiometry for the different oxides. Scanning electron microscopy (SEM) images showed irregular polyhedral agglomerates in the synthesized oxides, with grain sizes ranging from approximately 600 to 800 nm. Electrochemical characterization was performed under N 2 and O 2 atmospheres, revealing electron-withdrawing effects with increasing iron content in the oxide composition. LFZMO 0.75–0.25, with a higher iron content, displayed better performance than LMO and LFZMO 0.25–0.25 in terms of discharge capacity and cycling performance at various rates. The greater discharge capacity of LFZMO 0.75–0.25 (47 mA h g −1) was in line with the cyclic voltammetry findings, wherein lower energy (∆G Li + / Li 0 = 55.5 kJ mol−1) for lithium insertion correlated with an increased discharge capacity. Electrochemical Impedance Spectroscopy (EIS) was employed to determine diffusion constants, providing insights into Li+ insertion kinetics in the cathodic electrode and highlighting the significant influence of Zn and Fe incorporation on the lithium manganese oxide. Our findings are intriguing as the diffusion coefficient of D Li + in LFZMO 0.75–0.25 (2.3 ×10−12 cm2 S−1) surpasses that of LMO (8.5 ×10−14 cm2 S−1) and LFZMO 0.25–0.25 (9.4 ×10−18 cm2 S−1). This observation further elucidates the more positive formal potential for Li+ insertion in LFZMO 0.75–0.25. [Display omitted] • The presence of Fe and Zn in LiMn 2 O 4 affects the charge/discharge capacity. • Cycling voltammetry approaches the energy required for lithium insertion in the charging process. • The diffusion rate of lithium-ion is enhanced by the Zn atom in LFZMO 0.75-0.25, giving a more electronegative environment. • At High Fe concentration Mn4+/Mn3+ dismutation is avoided improving LFZMO 0.75-0.25 performance. [ABSTRACT FROM AUTHOR]

Nitrogen oxides are notorious air pollutants and the catalytic reduction of NO x by CO for removing NO x has attracted extensive attention. Herein, we present a series of ZnCu-layered double hydroxides (LDH) decorated with nanoparticles of metals (Me: In, Zn or Au) and the derived oxides as novel catalysts for NO reduction by CO. MeNP/ZnCu heterostructures were successfully prepared by taking advantage of the structural reconstruction of ZnCu LDH, via the structural memory effect, in the aqueous solutions of Me salts. X-ray diffraction (XRD), FTIR spectroscopy, H 2 -Temperature programmed reduction (H 2 -TPR), transmission electron microscopy TEM, X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy have been used to characterize the structural, chemical composition, optical and nano/micromorphology of MeNP/ZnCu catalysts and the mixed oxides derived after the thermal treatment. Results indicate that on MeNP/ZnCu the reduction of NO by CO was 3 times higher than that of ZnCu while CO conversion was above 90%. Further, MeNP/ZnCu and the derived oxides demonstrated good stability in subsequent catalytic cycles while NO conversion was influenced by the molar ratio O 2 /CO. These findings indicate that the memory effect of the LDH can be effective as a simple strategy in the development of novel LDH-based heterostructured catalysts. [Display omitted] • MeNP/LDH heterostructures by exploiting the "structural memory effect". • mixed oxides derived from MeNP/LDH. • catalysis of NO reduction by CO. [ABSTRACT FROM AUTHOR]