Search Results (145)

The world’s growing need for energy, fueled by industrial expansion and a rising population, continues to be a challenge for the scientific community. The heavy reliance on fossil fuels that contribute to environmental degradation and public health concerns, is shifting toward sustainable alternatives, with hydrogen production via advanced catalysts as an energy source emerging as a promising solution. This transition addresses the challenges posed by harmful combustion emissions. In this study, we developed an innovative PANI@Cu-NA-MOF nanocomposite catalyst through a sol–gel synthesis approach that strategically integrates conducting polymers with metal–organic frameworks. The catalyst was characterized using different sets of techniques. Surface morphology and elemental composition were investigated using SEM-EDX, while structural analysis was carried out with FTIR that helped to identify the chemical bonds and functional groups, and UV-Vis spectroscopy provided information on its light absorption properties. In addition, TGA was used to evaluate thermal behavior, and XPS offered detailed surface chemical analysis. It was observed by morphology that PANI@Cu-NA-MOF is a noncapsular-like structure. It is thermally highly stable; a TGA study showed that up to 550 °C, almost 2.5% of weight was lost. The single peak in UV-Vis is the preparation of a successful composite. XPS and FTIR reveal the required peaks of functional groups and elements. The PANI@Cu-NA-MOF composite turned out to be quite effective for water electrolysis, requiring an overpotential of just 0.47 V to drive the reaction. When tested against the reversible hydrogen electrode, we observed onset potentials of 1.6 V/RHE for the oxygen evolution reaction and 0.2 V/RHE for the hydrogen evolution reaction. What makes this particularly interesting is that such performance significantly cuts down on the energy needed for electrolysis, which could make hydrogen production much more practical. Since hydrogen burns cleanly and offers a real alternative to fossil fuels, having an efficient catalyst like this brings us one step closer to sustainable energy. Full article

The shipping sector is responsible for a considerable share of global CO₂ emissions and is under pressure to reduce emissions and adopt carbon-neutral fuels. Among the proposed alternatives, methanol produced from green hydrogen and biogenic CO₂ represents a promising option. However, the feasibility of its production is significantly influenced by the composition and variability of the bio-CO₂ feedstock, which can negatively impact the complete value chain. To address these challenges, sampling campaigns were carried out at actual bio-CO₂-emitting sites, namely biogas and biomass combustion facilities, to characterize the impurity profiles and determine the appropriate conditioning requirements. A novel membrane gas absorption system with a Diethanolamine solution was deployed directly in the field to capture, as well as purify to a certain extent, the CO₂ stream. The system demonstrated high efficiency in removing most impurities, achieving high CO₂ capture rates and impurity reduction close to 90%. However, residual chlorine species were detected in the CO₂ streams from biogas plants, suggesting the need for additional conditioning to meet the purity specifications required for methanol synthesis. Given that the feedstock composition and upstream process conditions could significantly affect the final output and present considerable variations, the implementation of additional cleaning measures is recommended before synthesis. Full article

The growth of the Internet of Things (IoT) has increased the demand for low-cost nanostructured materials. Zinc tin oxide (ZTO) has been widely used as an alternative to current semiconductor technologies, but its production methods remain expensive. Combustion synthesis is a green, low-cost alternative that may allow us to reduce the complexity of ZTO production. In this work, zinc and tin-based nanostructures were produced through combustion synthesis using water and ethanol as solvents and different precursor solutions ratios (1:2, 1:1, and 2:1). The influence of ethylenediamine (EDA) on the crystallographic phase of 2:1 samples of both solvents and Ag doping on 2:1 ethanol samples was also studied. Samples produced with a 2:1 ratio presented a predominance of ZnO, while the 1:1 and 2:1 samples presented a mixture of ZnO, SnO₂, and ZnSnO₃. The use of EDA in the 2:1 ethanol and water samples led to the growth of ZnO after annealing at 600 °C. For the ZTO-Ag samples, X-ray diffraction (XRD) and Raman analysis also revealed the presence of ZnO after annealing at 600 °C. This work showed it is possible to produce ZTO nanostructures through solution combustion synthesis. Full article

Dry reforming of methane (DRM) is a method whereby two greenhouse gases (methane and carbon dioxide) are synthesized into a high-value gas. Suitable catalysts with optimal compositions are still in development, as problems concerning coking and metal sintering remain unresolved. Since the late 20th century, catalysts prepared via solution combustion synthesis (SCS) have been applied for catalytic reactions, as these materials (catalyst or supports) demonstrate high catalytic performance; for example, SCS catalysts have been tested in DRM. This review describes the history of solution combustion synthesis, compares it with traditional methods of preparing catalysts for DRM, and charts recent developments in SCS catalytic systems based on Ni and Co. SCS catalysts are prepared by burning nitrates (oxidizing agents) and fuels (reducing agents) at mild pre-ignition temperatures. In this review, the effects of fuel type and mixed-fuel systems on the catalyst composition, as well as its activity in DRM, are described. These catalysts have shown high metal dispersion, good coke resistance, and stable catalytic performance in long-term tests. This review demonstrates the main reasons for catalyst deactivation, such as coke deposition on the catalyst surface, and suggests ways to reduce them. Full article

The synthesis of VO_x/MgO catalysts by solution combustion synthesis was investigated using varying molar ratios of glycine to oxidant. The effect of varying the fuel amount on morphology, phase composition, surface area, crystallite size, elemental distribution, and coordination environment around V was investigated. The results showed that the morphology, surface area, and crystallite size are all dependent on the flame temperature during the combustion process, which is dependent on the amount of fuel added. Results also suggested that adding glycine in excess lowers the combustion temperature. The catalysts were tested for the ODH of n-octane. The catalyst with superior catalytic properties was the stoichiometric sample, in which equal molar ratios of the fuel and oxidizer were added. The better catalytic performance was related to the contribution of the VO_x species from the magnesium vanadate phase. This is the only sample in which vanadates were detected. Catalysts synthesized under fuel-lean and fuel-rich conditions were characterized by large crystallites and the absence of detectable magnesium vanadates, using XRD. Full article

Copper (Cu) doping is recognized as an effective strategy to enhance the electrochemical properties of LiNi_1−x−yCo_xMn_yO₂ (NCM) cathode materials. However, the influence of Cu²⁺ doping on particle size and grain boundary fusion remains insufficiently explored. A simple microwave-assisted solution combustion synthesis method was used to introduce Cu²⁺ into LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523), aiming to regulate particle size and grain boundary fusion. The results demonstrate that increasing the Cu²⁺ doping content promotes particle growth, while an appropriate doping level reduces the degree of grain boundary fusion and cation mixing. Benefiting from these structural improvements, the optimized LiNi_0.5Co_0.2Mn_0.29Cu_0.01O₂ (Cu–1) cathode exhibits significantly enhanced electrochemical performance, delivering a discharge capacity of 128.6 mAh g⁻¹ after 100 cycles at 0.2 C, which is 32 mAh g⁻¹ higher than value of the undoped sample (96.6 mAh g⁻¹). These findings underscore that tailored Cu²⁺ doping can effectively optimize the microstructure of NCM523, leading to superior cycling stability, and provide new insights into the design of high-performance NCM cathodes. Full article

Rigid polyurethane foams (RPUFs) are essential polymeric materials, prized for their low density, high mechanical strength, and superior thermal insulation, making them indispensable in construction, refrigeration, and transportation. Despite these advantages, their highly porous, carbon-rich structure renders them intrinsically flammable, promoting rapid flame spread, intense heat release, and the generation of toxic smoke. Traditional strategies to reduce flammability have primarily focused on incorporating additive or reactive flame retardants into the foam matrix, which can effectively suppress combustion but often compromise mechanical integrity, suffer from migration or compatibility issues, and involve complex synthesis routes. Despite recent progress, the long-term stability, scalability, and durability of surface flame-retardant coatings for RPUFs remain underexplored, limiting their practical application in industrial environments. Recent advances have emphasized the development of surface-engineered flame-retardant coatings, including intumescent systems, inorganic–organic hybrids, bio-inspired materials, and nanostructured composites. These coatings form protective interfaces that inhibit ignition, restrict heat and mass transfer, promote char formation, and suppress smoke without altering the intrinsic properties of RPUFs. Emerging deposition methods, such as layer-by-layer assembly, spray coating, ultraviolet (UV) curing, and brush application, enable precise control over thickness, uniformity, and adhesion, enhancing durability and multifunctionality. Integrating bio-based and hybrid approaches further offers environmentally friendly and sustainable solutions. Collectively, these developments demonstrate the potential of surface-engineered coatings to achieve high-efficiency flame retardancy while preserving thermal and mechanical performance, providing a pathway for safe, multifunctional, and industrially viable RPUFs. Full article

Solution combustion-synthesized BaAl₂O₄: Eu²⁺, Nd³⁺, and Pr³⁺ blue–green long-afterglow phosphors are prepared and systematically investigated. First, XRD confirms the BaAl₂O₄ host and screens for trace residual features. SEM reveals the agglomerated granular morphology typical of combustion products. XPS verifies the valence states (Eu²⁺, Nd³⁺, Pr³⁺) and the chemical environment of the host lattice. UV-Vis diffuse reflectance spectra, transformed via the Kubelka–Munk function and analyzed using Tauc plots (indirect-allowed), indicate a wide band gap of the BaAl₂O₄ host with small, systematic shifts upon Nd³⁺/Pr³⁺ co-doping. PL measurements show Eu²⁺ 4f–5d emission and co-dopant-assisted excitation/defect pathways without altering the Eu²⁺ emission band shape. Afterglow lifetime and decay analyses correlate trap depth/distribution with the extended persistence. Finally, we demonstrate anti-counterfeiting by (i) snowflake printing and (ii) a binary 3 × 3 grid printed with two afterglow inks of different lifetimes to realize multi-level authentication. The sequential evidence links structure, chemistry, optical absorption, carrier trapping, and practical readout, providing a coherent basis for performance enhancement and application. Full article

The decarbonization of hard-to-defossilize sectors, such as international maritime transport, requires innovative, and at times disruptive, energy solutions that combine efficiency, scalability, and climate benefits. Therefore, power-to-liquid (PtL) routes have stood out for their potential to use low-emission electricity for the production of synthetic fuels, via electrolytic hydrogen and CO₂ capture. However, the high energy demand inherent to these routes poses significant challenges to large-scale implementation. Moreover, PtL routes are usually at most neutral in terms of CO₂ emissions. This study evaluates, from a thermo-energetic perspective, the optimization potential of an e-methanol synthesis route through integration with a biomass oxy-fuel combustion process, making use of electrolytic oxygen as the oxidizing agent and the captured CO₂ as the carbon source. From the standpoint of a first-law thermodynamic analysis, mass and energy balances were developed considering the full oxygen supply for oxy-fuel combustion to be met through alkaline electrolysis, thus eliminating the energy penalty associated with conventional oxygen production via air separation units. The balance closure was based on a small-scale plant with a capacity of around 100 kta of methanol. In this integrated configuration, additional CO₂ surpluses beyond methanol synthesis demand can be directed to geological storage, which, when combined with bioenergy with carbon capture and storage (BECCS) strategies, may lead to net negative CO₂ emissions. The results demonstrate that electrolytic oxygen valorization is a promising pathway to enhance the efficiency and climate performance of PtL processes. Full article

Purpose: The synthesis of nanoscale particles with antibacterial properties has garnered significant attention in pharmaceutical research, driven by the escalating threat of antibiotic-resistant bacteria. This study investigates the antibacterial efficacy of Zn–Co ferrite nanoparticles against virulent, antibiotic-resistant, and biofilm-forming strains of Escherichia coli. Methods: Three nanoparticle variants—S1 (Zn_0.7Co_0.3Fe₂O₄), S2 (Zn_0.5Co_0.5Fe₂O₄), and S3 (Zn_0.3Co_0.7Fe₂O₄)—were synthesized using the solution combustion method by systematically varying the Zn:Co molar ratio. The Scanning Electron Micrograph, X-ray diffraction analysis, Complementary Fourier-transform infrared, Minimum Inhibitory Concentration, and Minimum Bactericidal Concentration were performed. Results: The SEM spectroscopy study revealed distinct morphological differences as a function of the cobalt substitution level within the spinel ferrite matrix. At the highest level of cobalt substitution (Zn_0.3Co_0.7Fe₂O₄), the microstructure displayed significant irregularities, with enhanced agglomeration and a notably broader particle size distribution. X-ray diffraction analysis confirmed the formation of crystalline structures, with an average crystallite size of 12.65 nm. Complementary Fourier-transform infrared spectroscopy revealed characteristic absorption bands in the 400–600 cm⁻¹ range, indicative of the cubic spinel structure of the ferrite nanoparticles. The higher-frequency band was associated with metal–oxide stretching in the tetrahedral sites, while the lower-frequency band corresponded to stretching in the octahedral sites. The Minimum Inhibitory Concentration and Minimum Bactericidal Concentration assays revealed that Zn–Co ferrite nanoparticles possess potent antibacterial activity against virulent, antibiotic-resistant, and biofilm-forming strains of E. coli. Conclusion: Increasing the molar ratio of Zn to Co enhances the antibacterial activity of the nanoparticles. These findings suggest that Zn–Co ferrite nanoparticles could serve as a promising alternative to conventional antibacterial agents for combating multidrug-resistant pathogenic bacteria in the future. Full article

High-entropy alloy (HEA) catalysts have attracted significant attention from researchers. In many cases, HEAs exhibit high activity and selectivity for catalytic reactions due to four “core effects”: high entropy effect, lattice distortion effect, slow diffusion effect, and mixing effect. However, a systematic summary of HEA catalyst design and understanding is lacking. In this review, the reasons for the outstanding performance of HEA catalysts are first discussed from multiple perspectives, such as excellent mechanical properties, ultra-high-performance stability, and the potential for compositional optimization. Furthermore, to deepen our understanding of HEA catalysts, the rational design of HEA catalysts is introduced, covering design principles, element selection, and the use of algorithms for prediction. Next, several common preparation methods for HEAs are introduced, including chemical co-reduction, solution combustion, mechanical alloying, and sol–gel methods. Finally, the research progress of HEA catalysts in hydrogen evolution reactions, oxygen evolution reactions, and oxygen reduction reactions is presented. Unlike existing reviews, this work establishes a unified framework connecting HEA fundamentals (entropy effects), computational design, scalable synthesis, and application-specific performance, while identifying underexplored pathways like lattice-oxygen-mediated mechanisms (LOM) for future research. Full article

This study presents a comparative investigation of 3Ni2Ce/Al catalysts synthesized via different methods dry impregnation (DI), capillary impregnation (CI), and solution combustion synthesis (SC) for the complete oxidation of methane. The aim was to elucidate the influence of the preparation method on the catalytic activity and reduction behavior of the catalysts. Among the samples tested, the catalyst prepared by the solution combustion method exhibited the highest activity: at 500 °C, the methane conversion reached 82%, compared to 43% and 41% for the 3Ni2Ce/Al (CI) and 3Ni2Ce/Al (DI) prepared catalysts, respectively. At 550 °C, the 3Ni2Ce/Al (SC) catalyst achieved 99% conversion, surpassing the 3Ni2Ce/Al (CI) (72.5%) and 3Ni2Ce/Al (DI) (95%) analogs. Hydrogen temperature-programmed reduction (H₂-TPR) analysis revealed that the 3Ni2Ce/Al (SC) catalyst exhibited enhanced hydrogen uptake in the range of 450–850 °C, indicating the presence of more easily reducible NiO species interacting with CeO₂ and the alumina support. Scanning electron microscopy (SEM) further confirmed a more uniform distribution of the active phase on the surface of the 3Ni2Ce/Al (SC) catalyst in comparison to the impregnated samples. Overall, the findings demonstrate that the preparation method has a significant impact on the development of a redox-active catalyst structure. The superior performance of the SC-derived catalyst in methane oxidation is attributed to its improved reducibility and homogenous morphology, making it a promising candidate for high-temperature catalytic applications. Full article

Co₃O₄ nanoparticles synthesized by solution combustion synthesis present a versatile platform for the development of porous nanostructures with tunable morphology and physicochemical properties. Synthesis conditions and parameters such as fuel type; fuel-to-oxidizer ratio and temperature control lead yielding; and Co₃O₄ NPs with fine particle size, surface area, and porosity result in enhancing their electrochemical and catalytic capabilities. This review evaluates present studies about SCS Co₃O₄ NPs to study how synthesis parameter modifications affect both surface morphology and material structure characteristics including porosity features, which make their improved performance ideal for lithium-ion batteries and supercapacitors. Moreover, the integration of dopants with carbon-based hybrid composites enhances material conductivity and stability by addressing both capacity fading and low electronic conductivity concerns. This review mainly aims to explore the significant relation between fundamental material design principles together with practical uses and provides predictions about future research advancements that aim to enhance the performance of Co₃O₄ NPs in next-generation energy and environmental technology applications. Full article

Methanol synthesis from CO₂ is a key strategy for carbon capture and utilization, offering a viable solution to mitigate climate change. The direct synthesis of methanol not only reduces greenhouse gases but also produces valuable chemicals for industrial applications. The aim of this study is to model and optimize the methanol synthesis process from CO₂, focusing on maximizing methanol yield while minimizing CO₂ content in the product stream. In this work, a detailed methanol synthesis process simulation was developed using the Soave–Redlich–Kwong equation of state in the Aspen Plus V11 commercial software environment. Pure CO₂ streams, which are produced from the post-combustion carbon capture process, and renewable hydrogen streams were used. The results are compared with open literature sources. In addition, a sensitivity analysis was employed to evaluate the effects of the pressure, temperature, and recirculation fraction on process efficiency. The results showed that the highest methanol yield of 76,838 kg/h was obtained at 80 bar, 276 °C, and a recirculation fraction of 0.9. The lowest CO₂ content in the final product (73 kg/h) occurred at 80 bar, 220 °C, and a recirculation fraction of 0.6. These findings demonstrate the trade-off between maximizing methanol output and reducing unreacted CO₂. In conclusion, optimal operating conditions for both the high yield and low CO₂ content were identified, providing a foundation for further process refinement. Future work will involve developing a more complex multi-reactor model and conducting economic assessments for large-scale industrial implementation. Full article

We report a method for synthesizing different phases of samarium–cobalt particles through microwave-assisted combustion combined with high-temperature reduction and diffusion, and identify the optimal temperature for forming the 1:5 phase using this approach. Initially, the samarium-to-cobalt ratio in a nitrate solution was determined. Using urea as both a reductant and fuel, samarium–cobalt oxides were synthesized via microwave-assisted combustion. The main components of the oxides were confirmed to be SmCoO₃ and Co₃O₄. Subsequently, samarium–cobalt particles were synthesized at various diffusion temperatures. The results indicate that at 700 °C, the oxides were reduced to elemental Sm and Co. As the reduction temperature increased, the alloying of samarium and cobalt occurred, and the particle size gradually increased. At 900 °C, a pure 1:5 phase was formed, with particle sizes of approximately 800 nm, a coercivity of 35 kOe, and a maximum energy product of 14 MGOe. Based on the microwave-assisted combustion method, this study clarifies the transition temperatures of samarium–cobalt phases during the reduction and diffusion process, and further establishes the synthesis temperature for the 1:5 phase, providing new insights into the preparation and development of samarium–cobalt materials and potentially other rare earth materials. Full article