Amount Of Catalyst Research Articles

High-temperature planar asymmetric ceramic membranes: Effect of the Pt amount and dispersion on the H2 separation performance

This work investigates for the first time the effect of Pt catalyst amount and dispersion on hydrogen permeation performances of BaCe0.65Zr0.20Y0.15O3−δ–Gd0.2Ce0.8O2−δ (BCZY–GDC) composite planar Cer-Cer membranes with asymmetrical architecture, aiming to maximize the ratio between the permeated hydrogen and the metal content. To boost the hydrogen separation reactions, Pt must be deposited on both the dense and porous sides of the membrane. Moreover, the complex architecture of the porous layer can be used to disperse Pt particles providing a good interaction with the membrane. To fulfil this aim BCZY-GDC membranes composed of a 20 μm thick active dense layer and a 600 μm thick, porous support were produced by tape casting and impregnated with different amounts of platinum. Hydrogen permeation properties were thoroughly investigated examining the composition of the feed and the sweep gasses, temperature, stream humidification, catalyst amount and nature of the dispersion media. The effect of Pt-catalysed hydrogen permeation and water splitting reaction at the permeate side was investigated and discussed. It was found that using an optimal amount of Pt solution to activate the porous side of the membranes is paramount to increase hydrogen permeation in the whole operating temperature range while keeping low the amount of noble metal catalyst. Moreover, the selection of a proper solvent with good interaction with the membrane allows the obtainment of smaller Pt nanoparticles resulting in higher permeation. The best performances in terms of hydrogen permeation (0.74 and 1.29 mL min−1 cm−2 at 750 °C using a feed stream with respectively 50 % and 80 % of H2 in He) were obtained using an acetone-based solution for depositing 1.5 mg cm−2 of Pt at the porous side. This work suggests that the metal deposition plays a non-trivial role in the hydrogen separation process and should be fully evaluated to increase the final performance while cutting down the cost of the Pt catalyst and therefore, of the final device.

Functionalized Phosphorus‐Doped Porous Organic Polymers (FPPOPs)‐Promoted Pd‐Catalyzed Arylation of Hydrosilanes

The development of novel catalyst systems, especially as highly efficient heterogeneous catalysts for Si‐C bond ‐forming arylation reaction of hydrosilanes is highly desirable. Herein, we developed a simple and eco‐friendly methodology for construction of functionalized phosphorus‐doped porous organic polymers (FPPOPs) and its heterogeneous palladium catalyst through anchoring on FPPOPs bearing a phosphine ligand, in which the fabrication of FPPOPs was completed through the vinyl‐substituted triphenylphosphine (ViPPh3) and vinyl‐substituted polyhedral oligomeric silsequioxane (ViPOSS) as well as functional olefins via radical co‐polymerization. All these FPPOPs could act as a phosphine ligand for Pd‐catalyzed arylation of hydrosilanes have been characterized by SEM, FTIR, and X‐RAD. Moreover, the POSS‐based functionalized phosphorus‐doped porous organic polymers (POSS‐PPOPs) proved to be a high efficiency catalyst system for Si‐C bond ‐forming arylation of hydrosilanes with aryl iodides and with good yields as well as excellent chemoselectivity with low amount of catalyst under mild conditions. The mechanistic studies supported the effect of functional group on the catalytic activity of Pd/FPPOPs catalyst, which revealed that the weak coordination as well as non‐covalent interaction between porous organic polymers and substrate played important role in the enhancement of chemoselectivity.

Harnessing palladium-decorated g-C3N4 nanosheets for selective catalytic benzyl alcohol synthesis

The selective reduction of benzaldehyde to benzyl alcohol (a pivotal model reaction for the low-temperature stabilization of bio-oil) was meticulously investigated. This study delved into the catalytic prowess of Pd-modified g-C3N4 nanosheets (PdxCN) within a liquid-phase environment, utilizing H2 as the reducing agent under benign conditions. A series of photocatalysts were synthesized by impregnating graphitic carbon nitride nanosheets (NS-CN) with varying weight percent loadings of Pd nanoparticles. In the context of this selective hydrogenation, the catalytic activity of Pd2CN catalysts outshone that of pure NS-CN and other reference catalysts, exhibiting remarkable efficacy with benzyl alcohol yields nearing perfection at approximately 99%. Moreover, these catalysts demonstrated enduring catalytic reusability and reproducibility. The optimization of experimental parameters, encompassing weight percent loading of co-catalyst, catalyst quantity, temperature, and reaction duration, was systematically undertaken to achieve optimal benzyl alcohol yield.

Control of burning rate pressure sensitivity for solid propellants by changing the interfacial contact of Al/HMX/AP with precisely located graphene-based energetic catalysts

The control of burning rate pressure sensitivity is essential for stable and reliable combustion of solid propellants. It has been proved that the combustion behavior of propellants can be effectively tuned by interfacial control of Al/oxidizers. In this work, core-shell Al-based composites, using oxidizers such as ammonium perchlorate (AP) and cyclotetramethylene tetranitramine (HMX) as the shell layer, have been prepared with a well-controlled location of graphene-based carbohydrazide complexes (GO-CHZ-M, M = Co2+ or Ni2+) as the catalysts. The catalysts can be located inside HMX or embedded on the surface of AP particles. The decomposition of AP and HMX could be greatly promoted with a trace amount of catalyst. Under the synergistic effects of Al/oxidizer interfacial control and GO-CHZ-M, the ignition delay time is shortened by >48 % with increased in flame radiation. More importantly, the burning rate (r) and pressure exponent (n) of the solid propellants are effectively regulated in a wide range. In particular, the use of Al@HMX/Co results in a lowered n of 0.29 within 1∼20 MPa compared to 0.79 for the blank reference sample. The agglomeration of Al particles during combustion was also inhibited due to the micro-explosion effect of Al@HMX composites. Novelty and Significance statementThe innovative approaches of integrating Al/HMX/AP composites and precise catalysis of graphene-based energetic catalysts in solid propellants have successfully achieved, regarding the modulation of the burning rates and pressure sensitivity. Moreover, the effect of catalyst location on the ignition delay and burning rates has also been studied thoroughly and clarified. This paper provides new insight into the regulation of combustion performance of solid propellants, with improved reaction efficiency and maintained energy density.

Synthesis of the acidic/magnetic catalyst x-MoO3/Ni0.5Zn0.5Fe2O4 by combustion reaction and evaluation of its catalytic potential/reuse in biodiesel production

The objective of this work was to synthesize a new catalyst x-MoO3/Ni0.5Zn0.5Fe2O4 using the combustion reaction method and to evaluate its catalytic potential and reuse in biodiesel production from waste oil, optimizing the process through experimental design. The catalysts were characterized in terms of structure by X-ray diffraction and phase quantification by Rietveld refinement, surface area by the Brunauer-Emmett-Teller technique, experimental density by helium pycnometry, acidity tests by ammonia desorption at programmed temperature, chemical analysis by X-ray fluorescence, morphology by scanning and transmission electron microscopy, and catalytic properties. The products of the simultaneous transesterification and esterification reactions were characterized by gas chromatography and acidity index. The results indicate the formation of catalysts with surface area ranging from 1.5 to 1.7 m2/g and density ranging from 4.5 to 5.1 g/cm3, composed of major crystalline phases of MoO3 in the orthorhombic configuration and cubic Ni0.5Zn0.5Fe2O4 ferrite, with total acidity ranging from 70 to 182 μmol/g of NH3. Morphological characterization revealed that the catalyst comprises irregular plates of various sizes and shapes with a wide range of cluster sizes. In the simultaneous transesterification and esterification reactions of residual oil, the catalysts were active under all conditions tested, with emphasis on the catalyst containing 50 % Mo ions and 50 % Ni0.5Zn0.5Fe2O4 presenting the best catalytic performance with a conversion of 95 % in ethyl esters and a reduction of 71 % in acidity, with a service life of 6 cycles, an average conversion of 90 % and good thermal and structural stability after use. The experimental design was significant and predictive, with a confidence level of 95 %. Statistical analysis identified that all input variables (temperature, time, and amount of catalyst) were significant for the adopted design. The new catalyst composed of molybdenum, iron, nickel, and zinc has a positive impact on biodiesel synthesis from frying oil and ethanol.

Mono-and bi-metal catalytic hydrothermal liquefaction of food waste: Screening the process parameter on product yield and characterizations

Biofuels and chemicals derived from wet food waste (FW) can serve as a strategy to significantly reduce emissions and mitigate environmental pollution while preventing the loss of valuable resources. Hydrothermal liquefaction (HTL) is one of the most promising thermochemical techniques for converting wet waste into crude oil-like products (biocrude). In this study, catalytic HTL of FW was carried out using cobalt (Co), magnesium (Mg), and cobalt-magnesium (Co–Mg) supported on ZSM-5 to produce high-quality biocrude. The impact of key operating parameters, such as reaction solvent, temperature, reaction holding time, and catalyst amount, was investigated. In comparison to non-catalytic liquefaction, catalytic liquefaction significantly improved the biocrude yield. The maximum biocrude yield (60.89 wt%) was achieved with bimetallic Co–Mg/ZSM-5 catalysts at 280 °C with 10 wt% of catalyst at a reaction time of 15 min. Various analytical methods, including GC-MS, FT-IR, CHNS, TGA, and NMR, were employed to identify the composition and quality of the biocrudes. Catalytic liquefaction with Co–Mg/ZSM-5 in an ethanol solvent resulted in a higher percentage of ester compounds (74.15%, area percentage). The biocrude obtained through the catalytic process had lower oxygen and nitrogen content, which led to a higher heating value (HHV). Biocrude quantification revealed the presence of 12.16 wt% of linoleic ester compounds. The concentration of total nitrogen (TN) in the catalytic aqueous phase was as high as 2.44 g/L, significantly greater than the 0.32 g/L found in the non-catalytic aqueous phase. Furthermore, the optimum Co–Mg/ZSM-5 catalyst demonstrated excellent reusability and stability in FW liquefaction.

Photocatalytic degradation of methylene blue under visible light using carbon-doped titanium dioxide as photocatalyst

A visible light-active photocatalyst, carbon-doped titanium dioxide (C-doped TiO2) with an anatase phase, was synthesized using a simple and cost-effective method, with glucose serving as the carbon source for doping. The surface morphology, crystal structure and elemental composition of the catalyst was analyzed by SEM, XRD and EDX respectively. Raman spectroscopic and XRD analysis showed the consistency of the anatase phase throughout the preparation process. FT-IR, TGA, and EDX depicted the purity of the prepared catalyst. SEM images revealed that the average particle size of the catalyst is approximately 178 nm, which is smaller than that of pure TiO2. Finally, as a proof-of-concept photocatalytic activity of the catalyst was investigated on a typical organic dye, methylene blue, under two different light sources (UV light and visible light) by varying the catalyst amount, the concentration of dye, and pH of the degrading medium. Results showed that the prepared C-doped TiO2 shows a promising result under the visible light irradiation which seems limited in case of pure TiO2. The optimum photocatalytic degradation conditions are pH 3, catalyst dosage 0.15 g, and dye concentration 3 × 10−5 M. At optimum conditions visible light shows 53 % degradation and UV light degrades almost all the dye molecules. The enhanced photocatalytic activity of C-doped TiO2 in visible light is due to carbon doping, which reduces the bandgap energy and enables the absorption of visible light photons. This convenient technique can be a great solution for the removal of dyeing wastes economically using low-cost visible light or sunlight and large scale production for industrial application.

Synthesis of biochar-doped MgO catalyst for highly efficient conversion of glucose into formic acid at low temperatures

Formic acid (FA) is not only a significant platform chemical but also a promising candidate for hydrogen storage. Although homogeneous catalysts are commonly employed for the conversion of carbohydrate biomass into FA, which often come with substantial costs and inadequate reusability. It is noteworthy that there has been an increasing focus on the development of heterogeneous catalysts in this area, which aim to address these limitations and offer advantages such as easier separation and better reusability. Herein, an eco-friendly and efficient method for the catalytic conversion of glucose to FA by utilizing a biochar-MgO (BC-MgO) catalyst, which is prepared through pyrolysis of coconut husk biochar impregnated with magnesium chloride (MgCl2), is proposed. The FA yield at 74.6% is attained from glucose at 60 °C within only 3 h, utilizing a mere 0.1 g of catalyst and hydrogen peroxide (H2O2) amount of 100%. In conjunction with random forest (RF) algorithms and box-behnken experimental designs, further optimization resulted in an increased yield of 79.1%, with a selectivity of 82.7%, in only 3.8 h at 67 °C, employing 0.1 g of catalyst amount and 125% H2O2 amounts. Notably, the BC-MgO catalyst retains its catalytic efficiency over multiple cycles, only requiring a simple straightforward regeneration procedure. The mechanism underlying the glucose conversion to FA reaction system is demystified via kinetic modeling, time-gradient studies, and model compounds experiments. Life cycle assessment (LCA) indicates that when used for glucose conversion to FA, BC-MgO catalysts generate lower CO2 emissions than traditional homogeneous catalysts such as LiOH. Concurrently, an operation cost analysis indicates that operation cost of FA production from glucose is 4.1 $/kg with the BC-MgO catalyst, which is lower than LiOH catalyst (7.5 $/kg), evidencing the dual advantage of economic viability and an improved environmental impact inherent to this novel process.

Influence of iron doping in mesoporous ceria on the physicochemical properties and catalytic activity in styrene oxidation

A series of nanosized Fe-Ce binary oxides (2, 5, 10, 20, and 30 wt% Fe) and pure oxides of Fe and Ce were prepared by the template-assisted coprecipitation method and evaluated for styrene oxidation. The synthesised binary oxides were investigated by Powder X-ray diffraction(PXRD), N2-physisorption, X-ray fluorescence (XRF), Field emission scanning electron microscopy (FE-SEM), Highresolutiontransmission electron microscopy (HR-TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), Ultraviolet–Visiblediffuse reflectance spectroscopy (UV–Vis DRS), X-ray photoelectron spectroscopies (XPS), and Hydrogen-temperature programmed reduction (H2-TPR). In particular, the influence of quantity of doped iron on the structure, phase composition, surface morphology, reducibility, and the catalytic performance of ceria is deeply investigated. All the synthesized Fe-doped ceria catalysts exhibited the formation of solid solutions, but a little α-Fe2O3 segregated on the surface of ceria at 20 and 30 wt% Fe doped ceria. Among all Fe-Ce binary oxides, the 10 wt% Fe-doped ceria catalyst demonstrated superior efficiency due to its optimal Fe content which achieved the high surface area, lattice oxygens, reducibility, and low crystallinity, as confirmed by BET (Brunauer-Emmett-Teller) measurements, XPS, H2-TPR and powder XRD analysis, respectively. To optimize the reaction conditions, effect of several experimental variables, such as reaction temperature, duration, catalyst quantity, styrene/tert-Butyl hydroperoxide (TBHP) mole ratio, and solvent polarity were investigated. Furthermore, the catalyst stability and consistent activity were confirmed by testing six reusability cycles.

Synthesis of cobalt- ferrite and zinc oxide metal nanoparticles based-bentonite using SDS and their investigation as catalysts in synthesis of benzylbarbiturocoumarins.

In this research, a suitable and efficient CoFe2O4@ZnO@Bentonite nano-catalyst was designed and synthesized by using zinc oxide (ZnO) and cobalt ferrite (CoFe2O4) nanoparticles and bentonite by microwave irradiation. Characteristics of the synthesized nanocomposite were investigated by Fourier transform infrared (FT-IR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), transmission electron microscope (TEM), X-ray diffraction (XRD), Bruner- Emmett-Teller (BET) and vibrating sample magnetometer (VSM) techniques. The produced catalyst was effectively employed as a supported solid acid catalyst in mildly agitated three-component reactions involving aromatic aldehydes, 4-hydroxycoumarin, and 1,3-dimethyl-barbituric acid in a single pot to produce benzylbarbiturocoumarins. Starting materials were condensed via three C-C bond formation by CoFe2O4@ZnO@Bentonite as an efficient, recyclable, and environmentally safe nanocatalyst to obtain target products. The advantages of this method include using a natural substrate, small amounts of catalyst, aqueous media, performing reactions at ambient temperature, simple separation and purification of products, and good yields with short reaction times.

Chemocatalytic Oxidation of 5‐hydroxymethylfurfural into 2,5‐furandicarboxylic Acid Over Nickel Cobalt Oxide

AbstractThe present study reports the synthesis, characterization, and application of NiCo bimetallic catalysts to produce 2,5‐furandicarboxylic acid (FDCA) via the oxidation of bio‐renewable 5‐hydroxymethylfurfural (HMF). FDCA is a biopolymer precursor and a potential replacement for terephthalic acid (TPA). The catalysts were synthesized via the co‐precipitation method in different molar ratios of NiCo, followed by calcination in a muffle furnace. As a result, the complete conversion of HMF and a maximum 84.89 % FDCA yield was measured at 50 °C in 50 minutes in the presence of NiCo(3 : 1) catalyst. In addition, effect reaction parameters, including catalyst amount, temperature, time, base, and oxidant amount on the FDCA yield, were studied, and the process was optimized. The NiCo(3 : 1) catalyst showed a negligible loss in activity for at least five cycles. The higher catalytic activity and stability are attributed to the synergistic effect of bimetallic catalysts, such as higher lattice oxygen. Accordingly, the catalyst was characterized using BET, XRD, H2‐TPR, CO2‐TPD, HR‐TEM, and XPS to correlate their properties and activity. The reaction products were analyzed quantitatively using HPLC and qualitatively using HR‐MS.

Understanding the Impact of Conditioning Protocols for Water Electrolyzers on Durability

The global push towards climate neutrality has intensified research efforts on green hydrogen production technologies. Among them, proton exchange water electrolysis (PEMWE) stands out as a highly efficient technology for producing green hydrogen using renewable energies. Nevertheless, a significant reduction in the cost of PEMWE while maintaining its durability over its operational periods is imperative. The DOE’s Hydrogen Earthshot target aims to achieve $1 per 1kg of H2 production within the decade. Reducing the amount of expensive iridium catalysts also reduces the durability of PEMWE. Hence, understanding the degradation mechanisms of low Ir loading PEMWE holds utmost importance. One key step in the evaluation of PEMWE is the break-in or conditioning step. Ensuring optimal conditioning is crucial to guarantee the peak performance of membrane electrode assembly (MEA) before assessing the durability of the catalyst thereby ensuring representative and reproducible results.This research aims to comprehensively evaluate various conditioning protocols for PEMWE and their impact on durability. Utilizing a combination of electrochemical, electron, and X-ray characterization techniques. Accelerated stress tests (AST) will be conducted after each conditioning protocol to evaluate the degradation rate of the catalyst. Ex-situ characterization of the MEA post-conditioning as well as post-AST offers a comprehensive understanding of how the catalyst’s initial state, such as the iridium oxidation state, following the conditioning step directly influences the durability. The goal is to develop an optimal conditioning protocol for PEMWE, that considers the performance and durability challenges associated with low catalyst loading. Acknowledgment This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office through the Hydrogen from Next-generation Electrolyzers of Water (H2NEW) consortium with support from Dave Peterson and McKenzie Hubert.

A Spray-Drying Approach for Highly Active Amorphous NiFe2O4 for AEM Water Electrolysis

Water electrolysis, a key process for hydrogen production, holds immense potential in mitigating carbon dioxide emissions when powered by renewable energy sources, thereby contributing to a sustainable and clean energy future. Commercially available and widely recognized technologies for water electrolysis include the proton exchange membrane water electrolysis (PEMWE) and the traditional alkaline water electrolysis (AWE). In order to use the benefits of both systems, the anion exchange membrane water electrolysis (AEMWE) method is proposed, enabling the utilization of non-noble catalyst materials and achieving high current densities at low cell voltages [1].In the present work, the influence of a spray-drying approach compared to a co-precipitation method on the bimetallic non-noble NiFe2O4 catalysts on the oxygen evolution reaction (OER) activity is systematically investigated. State of the art catalyst for OER is Iridium oxide and so far, the best non-noble catalyst has not been found yet. A widely used non-noble catalyst is NiFe- layered double hydroxide but it suffers from low electric conductivity [2]. Another promising catalyst is the NiFe2O4, which also provides low OER overvoltage. However, amorphous oxides are said to have a higher activity than crystalline [3]. Furthermore, the use of a spray drying approach is highly reproducible, with which the crystallinity can be set very easily [4, 5].The experimental study of the catalysts was carried out in a commercial Baltic-Fuel Cell with a geometrical area of 25 cm² at 60 °C in 1 M KOH electrolyte and a contact pressure of 1.25 MPa. The electrodes were prepared by directly spray coating the desired amount of catalyst onto the anode and cathode substrates. A Bekipor® 2NI 18-0.25 nickel felt was used as the substrate for the anode, while AvCarb MGL370 carbon paper was employed for the cathode. As cathode catalyst Pt/C from Tanaka (TEC10E40E, 37.2 % Pt) was used, while a loading of 0.5 mg cm-2 Pt was targeted during the spraying procedure. On the anode, the NiFe2O4 loading was set to 2 mg cm-2. Both electrodes were separated by a Sustainion® X37-50 Grade T membrane. For determination of relevant catalyst activity data chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) were carried out.Figure 1 reveals that the spray-dried NiFe2O4 (amorphous, red curve) has a superior performance compared to the precipitated NiFe2O4 (green curve), which is partly crystalline. With the spray-dried catalyst, a reduction in overvoltage of approx. 60 mV at 1 A cm-2 can be achieved. With a cell voltage of less than 1.7 V at a current density of 1 A cm-2, our recently developed catalyst ranks among the most outstandingly described in the literature to date [6]. These findings can contribute to a further development of amorphous catalysts with even higher activity.[1] Cossar, E., Murphy, F. and Baranova, E.A. (2022), Nickel-based anodes in anion exchange membrane water electrolysis: a review. J Chem Technol Biotechnol, 97: 1611-1624.[2] Jeon, S.S., Lim, J. Kang, P.W., Lee, J.W., Kang, G., Lee, H. (2021), Design Principles of NiFe-Layered Double Hydroxide Anode Catalysts for Anion Exchange Membrane Water Electrolyzers. ACS Appl Mater Interfaces,13 (31): 37179-37186.[3] Shi, G., Arata, C., Tryk, D., Tano, T., Yamaguchi, M., Iiyama, A., Uchia, M., Iida, K., Watanabe, S., Kakinuma, K. (2023), NiFe Alloy Integrated with Amorphous/Crystalline NiFe Oxide as an Electrocatalyst for Alkaline Hydrogen and Oxygen Evolution Reactions. ACS Omega, 8: 13068−13077.[4] Kreitz, B., Arias, A. M., Martin, J., Weber, A. P., Turek, T. (2020), Spray-Dried Ni Catalysts with Tailored Properties for CO2 Methanation, Catalysts, 10 (12): 1410.[5] Arias, A. M., Weber, A. P. (2019), Aerosol synthesis of porous SiO2-cobalt-catalyst with tailored pores and tunable metal particle size for Fischer-Tropsch synthesis (FTS), J Aerosol Sci, 131: 1-12.[6] Du, N., Roy, C. Peach, R., Turnbull, M., Thiele, S. and Bock, C. (2022), Anion-Exchange Membrane Water Electrolyzers. Chem Rev, 122: 11830-11895. Figure 1

Advanced Nanostructured Textile Catalysts for Enhanced Hydrogen Production in PEM Water Electrolysis: An Overview and Recent Developments

As the global focus shifts towards a zero-emission society, hydrogen has emerged as a critical element in various industries, particularly in green hydrogen production. A promising method for this is Polymer Electrolyte Membrane Water Electrolysis (PEMWE), which uses pure water and electricity to produce high-purity hydrogen. However, the efficiency of PEMWE is highly dependent on the effectiveness of its catalysts, particularly in the context of the catalyst-coated membranes (CCMs) employed in these systems. Conventional preparation of these CCMs involves multiple steps, including synthesis and application of a catalyst ink, which often leads to catalyst agglomeration and requires high Ir (Iridium) loadings to maintain uniformity and performance.In our latest study, we have developed a novel approach using ultralight conductive IrO2 nanostructured textiles (NST) as a catalyst layer for PEMWE. This innovative method successfully circumvents the issue of electrically isolated inactive catalysts, a common problem with lower Ir amounts in traditional catalyst layers. By employing a process of sputtering IrO2 onto water-soluble polymer nanofibers, we have achieved facile CCM preparation and demonstrated unprecedented long-term hydrogen evolution with ultra-low Ir mass loadings at high rates. Our study revealed that the high performance of these CCMs is derived from their low resistivity and unique porous three-dimensional structure.The preparation of NST involves dissolving polyvinylpyrrolidone (PVP) in methanol, followed by electrospinning this solution onto a metal-foil collector. The resulting PVP nanofibers then undergo a sputtering process to deposit IrO2, forming the nanostructured textiles. This method eliminates the need for wet chemical routes and labor-intensive processes typically associated with conventional catalyst layer preparations, thus offering a more environmentally friendly and scalable alternative.Our performance evaluations of these NST CCMs, with varying Ir mass loadings, have shown significant advancements. The operational cell voltages of CCMs containing as little as 0.05 mg-Ir cm−2 were suppressed across all investigated current densities compared to conventional CCMs. Notably, operational voltages remained below 2 V even at the highest current density of 7 A cm−2. This level of performance is unprecedented for CCMs with such low catalyst amounts. Additionally, the long-term stability of these CCMs was remarkable, with operational times exceeding 1500 hours without significant increases in voltage, showcasing their potential for practical applications.An essential aspect of our study was the analysis of the electrical properties and the surface structure of the IrO2 NSTs. We observed that the electrical conductivity of these textiles was significantly higher than that of conventional catalyst layers. This high conductivity, coupled with the unique interconnected structure of the textiles, ensures efficient electrical contact between nano catalysts and the current collector, thus avoiding the formation of isolated catalysts. Our analyses revealed that the IrO2 NSTs have unique surface terminations and a high number of undercoordinated surface Ir atoms, contributing to their high intrinsic catalytic activity.Further insights were gained through operando X-ray absorption spectroscopy (XAS) measurements, which showed that the IrO2-nanostructured textiles possess a large number of D-band holes and are intrinsically highly active. This finding is crucial as it links the unique chemical state of the textiles to their high activity in oxygen evolution reactions (OER), a key process in PEMWE.Our recent developments in nanostructured textile catalysts for PEMWE mark a significant leap in hydrogen production technology. By demonstrating high-rate hydrogen production at low operational voltages and with significantly lower Ir mass loadings compared to conventional CCMs, we have addressed major challenges in the field. These advancements not only enhance the efficiency and sustainability of hydrogen production but also open avenues for applying this technology to other electrochemical conversion cells, paving the way for broader applications and further research. In this talk, we discuss the latest activity on NST, and highlight the challenges and opportunities for hydrogen production.

Compatibilizing and foaming of PC/PMMA composites with nano‐cellular structures in the presence of transesterification catalyst

AbstractCompatibility of polycarbonate (PC) and polymethyl methacrylate (PMMA) alloys was improved by using a transesterification catalyst (SnCl2·2H2O). Modified PC/PMMA alloys exhibit single Tg, and their initial island phase existing in the SEM were transformed into uniform surface. Besides, the transmittance of the modified alloys was increased from original 40% to 85%. Moreover, PC/PMMA alloys and PC foams with micro‐cellular and nano‐cellular structures were prepared by solid‐state CO2 foaming in the presence of transesterification catalyst. Distinctively, there are obvious nano‐cellular structures existing in the PC samples, but no related nanostructures were found in PMMA samples, after treated by same amount of catalyst and foaming process for pure PC and PMMA matrix. Furthermore, the effects of foaming temperature and segment structure on their foaming behavior were also studied. Additionally, a uniaxial stress experiment was conducted at a specific temperature to simulate the biaxial stress during the foaming process for discovering the mechanism of nanopore formation. Therefore, the concept of nano‐cellular structures will point out a direction for the development of high‐performance, heat insulation PC materials of the next generation.Highlights Transesterification catalysts enhanced compatibility between PC and PMMA. Nanopore structures were successfully constructed in PC foams. Segment stretching was the main reason for the formation of nanopores.

Highly efficient visible light active iron oxide-based photocatalysts for both hydrogen production and dye degradation

Photocatalysis is essential for wastewater cleanup and clean energy, and in this current study, we have synthesized nanomaterials (iron oxide-based) for photocatalytic pollution degradation and hydrogen production. The performance of aluminium oxide/ferric oxide (Al2O3/Fe2O3), samarium oxide/ferric oxide (Sm2O3/Fe2O3) and yttrium oxide/ferric oxide (Y2O3/Fe2O3) were compared for the production of hydrogen (H2) and degradation of dye under natural sunlight. Various characterisation equipment was used to characterize these photocatalysts’ structure, morphology, elemental content, binding energy and band gap. The hydrogen recovery efficiency of iron oxide-based photocatalysts from sulphide-containing wastewater is assessed. Y2O3/Fe2O3 has shown the highest hydrogen production of 340 mL/h. The influence of operating factors such as sulphide ion concentration, catalyst quantity, and photocatalyst photolytic solution volume on hydrogen production is studied. The optimal values were 0.25 M, 0.2 g/L, and 1L, respectively. The developed photocatalyst passed multiple cycles of stability testing. Fe2O3 has shown the highest Rhodamine B (RhB) dye degradation efficiency of 94% under visible light.

Synthesis and characterization of azo cross‐linked polymer as a new catalyst for the production of hydrogen gas by methanolysis of NaBH4

AbstractThe intensive use of fossil fuels has profound impacts on all ecosystems, primarily contributing to global warming through greenhouse gas emissions. To mitigate these impacts, alternative energy sources like hydrogen are crucial. In this study, azo cross‐linked polymer with 4‐aminophenyl sulfone and resorcinol were synthesized by a green synthesis method. The polymer was extensively characterized by Fourier‐transform infrared spectroscopy, Brunner‐Emmett‐Teller analysis, thermogravimetric analysis, and scanning electron microscopy‐energy dispersive x‐ray spectroscopy analyses. Subsequently, the catalytic performance of the polymer in hydrogen production from NaBH4 via methanolysis was investigated. At this stage, the parameters affecting hydrogen production (catalyst and NaBH4 amounts, MeOH volume and temperature) were systematically studied to determine optimum conditions. The maximum HGR values of the polymer was 13,100 and 27,000 mL min−1 gcat−1 at 30 and 60°C, respectively and its activation energy was 10.45 kJ mol−1. After optimization, the reusability of azo polymer was tested with 5 cycles. The theoretical volume of hydrogen was produced in all 5 cycles. But with each cycle, the hydrogen production time increased. The main purpose of this study was to demonstrate novel azo‐linked polymers with high catalytic activity in hydrogen production. The results revealed significant potential of the polymer for hydrogen generation. Overall, this research highlights the promising role of azo cross‐linked polymers as effective catalysts for hydrogen production, offering new perspectives and pathways towards sustainable energy solutions.

Synthesis of benzoic acid from catalytic co-pyrolysis of waste wind turbine blades and biomass and their kinetic analysis

This work aims to study the catalytic co-pyrolysis of waste wind turbine blades (WTB: consists of fiberglass/unsaturated polyester resin) and woody biomass (WB) over ZSM-5 and Y-type zeolite catalysts for the production of benzoic acid. The experiments were performed on an equal combination of WTB and WB (WTB/WB) and a fixed amount of catalyst (50 wt%) using a thermogravimetric (TG) analyser at 10, 20 and 30 °C/min. The evolved products from the catalytic co-pyrolysis process were recognized using TG-FTIR and GC/MS. The kinetic and thermodynamic characteristics of catalytic co-pyrolysis was studied using various linear and nonlinear approaches. Also, the decomposition curves were predicted mathematically using an artificial neural network algorithm. The results revealed that the mixture was decomposed in the presence of both catalysts in the form of dual decomposition peaks at 361–374 °C and 428–443 °C, respectively. Based on TG-FTIR results, the CO stretching and carbon dioxide clusters were their main functional groups. While the GC-MS analysis revealed that the released vapours were completely free of toxic styrene (the main compound of resin) and the catalytic co-pyrolysis treatment succeeded in converting it into highly abundant benzoic acid, especially at 10 °C/ min, with an estimated 71.4 % (ZSM-5) and 64 % (Y-type). Whereas the activation energy was estimated at 262–295 kJ/mol (ZSM-5) and 319–357 kJ/mol (Y-type) with almost similar reaction complexity when compared to the case of absence of catalysts. Finally, the developed ANN algorithm showed high efficiency in predicting TG decomposition zones for both WTB/WB mixtures over zeolite catalysts with R2 more than 0.99. These results demonstrate that WB and zeolite catalysts can be used for upgrading the pyrolysis oil of WTB and eliminate its toxic styrene and convert it into benzoic acid and other aromatic hydrocarbons compounds (such as benzene, alanine, and 2-Propanamine).

Preparation and characterization of micro-cellular melamine foam supported SiO2 aerogel for building thermal insulation

This study aims to complement the advantages of SiO2 aerogel and melamine foam (MF) to produce high-performance building insulation materials. The optimal sol–gel scheme was determined by controlling system temperature, water content, amount of ethanol and amount of acid-base catalyst (orthogonal experiment). The density and porosity of MF/SiO2 aerogel were regulated by adjusting aging time, aging temperature and type of aging agent. Furthermore, the effects of different volume fractions hydrophobic modifier on the surface free energy and wettability of MF/SiO2 aerogel were also investigated. The experiment results showed that the prepared MF/SiO2 aerogel satisfies requirements for low density (0.089 g/cm3), low thermal conductivity at room temperature (0.0256 W m−1·K−1), and excellent hydrophobic performance (the contact angle was 140.1°). Meanwhile, it was found that SiO2 aerogel was stably and uniformly distributed in the pores of the MF and effectively enhanced the mechanical property (a maximum compressive strength of 0.2058 MPa), heat-shielding performance, flame retardant property, and sound absorption capacity(αmax = 0.76, αave = 0.31).Therefore, the MF/SiO2 aerogel composites exhibit exceptional application potential in comparison to conventional building insulation materials (such as EPS, Rock wool board, etc.) due to their significantly low thermal conductivity and remarkable flame retardant properties.

Copper-Catalyzed P-H Bond Functionalization to Construct Biaryl Phosphafluorene Oxides.

In this study, in the presence of a certain amount of cuprous chloride catalyst and the synergistic action of ligand and base, the P-H bond activation of secondary biarylphosphine oxides and the attack on the β-site of orthoaryl groups were investigated. Phosphafluorene oxide was synthesized by C-H bond activation and an intramolecular dehydrogenation coupling reaction to construct a C-P bond. Subsequently, we conducted a control experiment and made reasonable speculations about its mechanism. In addition, the use of phosphafluorene as a ligand in some synthetic catalytic reactions has shown excellent results, demonstrating its excellent catalytic properties.