Mesoporous Support Research Articles

Roles of Al2O3 coating layer on an ordered mesoporous Ni/m-Al2O3 for combined steam and CO2 reforming with CH4

To enhance catalytic and thermal stability of Ni nanoparticles for a combined steam and CO2 reforming with CH4 (CSCR), the utilization of an ordered mesoporous Al2O3 support with ∼6 nm of average pore diameter (Ni/m-Al) was proposed in terms of spatial confinement effects of the Ni nanoparticles with the help of successive Al2O3 overlayer protective layers (Ni/m-Al@Al). At an optimal amount of Al2O3 coating layers less than ∼3 wt%, the much higher catalytic activity and stability were observed on the Ni/m-Al@Al(3). The synergy effects of Al2O3 overlayers on the ordered mesoporous Ni/m-Al were mainly attributed to the formation of strongly interacted Ni-Al2O3 interfaces as supported by its higher XPS binding energy in the spatially restricted mesoporous m-Al channels with the protective metal oxide overlayers. Those structures were also responsible for the suppressed migrations of the spatially confined Ni nanoparticles to the outer m-Al surfaces by Al2O3 protective overlayers, which resulted in an excellent long-term stability with small coke depositions by preserving the original Ni nanoparticle sizes.

Facile synthesis of Co-Rh bimetallic catalysts for methane decomposition: Effect of support morphology

In this study, the performance of 10 wt.% Co -1 wt. % Rh/TiO2 catalysts with varying textural properties have been investigated to produce the hydrogen and carbon nanotubes via the methane decomposition process. An improved evaporation-induced self-assembly approach synthesized the mesoporous TiO2 supports, and Co-Rh nanoparticles over the as-synthesized TiO2 supports were created by the co-impregnation method. XRD, BET, TGA, SEM, and TEM studies characterized the fresh and used catalysts. The findings revealed that the texture of TiO2 support has an important influence on catalytic performance. With the increase in calcination temperature, the specific surface area of the catalysts decreases while the anatase content of TiO2 species increases. The catalyst prepared with TiO2 calcined at 600 °C displayed superior catalytic activity and stability due to the better metal dispersion and higher anatase phase content in support. The initial activity depended on the specific surface area, whereas the stability or the hydrogen productivity for the equal deactivation level was related to the anatase composition of the catalyst. The nature of deposited carbon varies due to the phase composition of TiO2. The SEM and TEM images revealed that anatase TiO2 generated smaller multi-walled carbon nanotubes (MWCNTs) with a more consistent diameter distribution than the other catalysts. Catalysts with an amorphous composition increase the formation of CHx carbon species. The apparent activation energies for various Co-Rh catalysts varied between 65 and 85 kJ mol−1. The Co-Rh bimetallic combination had more significant activity than the Ni metal.

Influence of desilication route of ZSM-5 zeolite in mesoporous zeolite supported calcium oxide catalyst for biodiesel production

The application of calcium oxide (CaO) as transesterification catalyst for biodiesel production is restricted as there is a high tendency for the calcium (Ca2+) active species to be leached out during the reaction. To overcome this problem, CaO was supported with mesoporous zeolite. A series of mesoporous zeolite supports were prepared via 3 different desilication routes, which are conventional desilication, desilication in the presence of pore directing agent and surfactant-assisted desilication method. The catalytic efficiency of the synthesized catalyst, which are CaO/Zeo, CaO/Zeo-NaOH, CaO/Zeo-TPAOH and CaO/Zeo-CTAB catalyst, in the transesterification of waste cooking oil (WCO) was evaluated. Results revealed that the surfactant-assisted desilication route demonstrates the partial incorporation of the dissolved Al species into the zeolite framework and thus led to highly crystalline material. An obtained high mesoporosity of the zeolite support through this route caused the high dispersion of CaO species in the pores of zeolite support. As a results, the CaO/Zeo-CTAB catalyst exhibited the best performance with 89% biodiesel yield, due to strong acidic and basic properties together with high surface area. The catalyst also showed the higher resistance against Ca2+ active sites leaching by restraining the agglomeration, due to the stronger interaction between CaO and zeolite. The optimum reaction conditions were found to be 4 wt% catalyst dosage, 4 h reaction time, 5:1 methanol to oil molar ratio and 65 °C reaction temperature. The CaO/Zeo-CTAB catalyst could be reused for 6 consecutive runs without significant loss in biodiesel yield and displayed an excellent tolerance to high free fatty acid (FFA) feedstock. For the final remark, these results suggest that the surfactant-assisted desilication is an efficient route for the production of mesoporous zeolite for catalyst support.

Discovery of Polythioplatinate(II) [Pt3S2(SO3)6]10- and Study of Its Solution and Catalytic Properties.

We have discovered the first polythioplatinate(II), [PtII3S2(SO3)6]10- (1), which was synthesized in aqueous basic medium (pH 11) by hydrothermal heating at 150 °C. Polyanion 1 comprises a discrete, triangular assembly of three Pt2+ ions linked by two μ3-sulfido ligands, and their square-planar coordination geometry is completed by two terminal S-bound sulfito ligands. Polyanion 1 was isolated as a hydrated sodium salt, Na10[PtII3(μ3-S)2(SO3)6]·22H2O (Na-1), which was characterized in the solid state by single-crystal X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectra, and elemental analysis, in solution by 195Pt NMR and atomic absorption spectroscopy, and in the gas phase by electrospray ionization mass spectrometry. Density functional theory calculations were performed, and the 195Pt NMR chemical shifts of 1 were computed theoretically and shown to match well with the experimental data. Furthermore, the discrete title polyanion 1 was immobilized on mesoporous SBA-15 support and used as a precatalyst for the hydrogenation of o-xylene.

Bimetallic Pd‐Au Nanoparticles Supported Monodisperse Porous Silica Microspheres as an Efficient Heterogenous Catalyst for Fast Oxidation of Benzyl Alcohol

AbstractA bimetallic heterogeneous catalyst in the form of PdAu nanoparticle supported monodisperse‐porous SiO2 microspheres (PdAu@APTES@SiO2) was prepared for fast oxidation of benzyl alcohol (BzOH). The mesoporous support obtained by an originally developed staged‐shape templated hydrolysis‐condensation protocol provided large surface area and high pore volume for parking of noble metal nanoparticles. PdAu@APTES@SiO2 provided higher BzOH conversion, benzaldehyde (BzH) selectivity and BzH formation yield with respect to monometallic catalysts containing Pd or Au nanoparticles supported with SiO2 microspheres. BzOH conversions and BzH formation yields higher than 95 % were obtained in 30 min at 80 °C. The maximum TON and TOF values were determined as 300 and 600 h−1, respectively. BzOH conversions and TOF were also higher with respect to similar catalysts prepared using different supports also carrying PdAu nanoparticles. PdAu@APTES@SiO2 exhibited good stability with a decrease of BzOH conversion less than 2.5 % over five consecutive runs.

Selective CO2 reduction to methane catalyzed by mesoporous Ru-Fe3O4/CeOx-SiO2 in a fixed bed flow reactor

Development of a robust catalyst for selective reduction of CO2 directly into hydrocarbon fuels is very challenging from both energy and environmental perspectives as it offers a renewable and green route for the production of fuels. Herein, we report a novel catalyst synthesized via excess solution impregnation of Ru and Fe3O4 nanoparticles (NPs) on ceria promoted mesoporous silica SBA-15 support. The selective catalytic reduction of CO2 to methane was carried out in the presence of H2 over novel Ru-Fe3O4/CeOx-SiO2 (Ce3+/Ce4+, x=1.64) catalyst in a fixed bed reactor. The CO2 conversion was found to be 82% at 0.25 wt% ruthenium loading, 2.5 wt% iron loading, 575 K temperature, 20 bar pressure, 3000 mLg−1h−1 gas hour space velocity and H2 to CO2 mole ratio of 5:1. The close contact between ruthenium and Fe3O4 nanoparticles facilitated the reduction of CO2 through hydrogen spill-over effect at lower temperature, whereas ceria NPs acted as a promoter for this reduction reaction. The catalysts were characterized thoroughly using physicochemical techniques such as CO chemisorption, BET, TPR, TPD, XRD, SEM, HR- TEM, ICP-AES and XPS analyses. High surface area and large mesopores of silica support facilitated the fine dispersion of the active catalytic sites and oxygen vacancy as supported from the DFT study on the catalytic activity. Optimal process conditions could render much higher CO2 conversion efficacy for selective methane synthesis in comparison with previous investigations.

Effects of Impregnated Amidophosphonate Ligand Concentration on the Uranium Extraction Behavior of Mesoporous Silica.

A series of solid-phase uranium extractants were prepared by post-synthesis impregnation of a mesoporous silica support previously functionalized with octyl chains by direct silanization. Five materials were synthesized with 0, 0.2, 0.3, 0.4 and 0.5 mmol of the amidophosphonate ligand DEHCEBP per gram of functionalized solid, and the effect of the ligand concentration on the uranium extraction efficiency and selectivity of the materials was investigated. Nitrogen adsorption–desorption data show that with increasing ligand loadings, the specific surface area and average pore volume decrease as the amidophosphonate ligand fills first the micropores and then the mesopores of the support. Acidic uranium solutions with a high sulfate content were used to replicate the conditions in ore treatment leaching solutions. Considering the extraction kinetics, the equilibration time was found to increase with the ligand concentration, which can be explained by the clogging of micropores and the multilayer arrangement of the DEHCEBP molecules in the materials with their highest ligand contents. The fact that the equilibrium ligand/uranium ratio is about 2 mol/mol regardless of the ligand concentration in the material suggests that all the ligand molecules remain accessible for extraction. The maximum uranium extraction capacities ranged from 30 mg∙g−1 at 0.2 mmol∙g−1 DEHCEBP to 54 mg∙g−1 in the material with 0.5 mmol∙g−1 DEHCEBP. These materials could therefore potentially be used as solid-phase uranium extractants in acidic solutions with high sulfate concentrations.

Low temperature green methanol synthesis by CO2 hydrogenation over Pd/SiO2 catalysts in slurry reactor

The utilization of the greenhouse gas of carbon dioxide (CO2) for fuel and value-added chemicals synthesis has become globally indispensable process for healthy environment. In this context, the hydrogenation of CO2 to methanol is an attractive avenue for achieving such goal. Thus, we prepared mesoporous silica-supported nanocrystalline palladium metal (Pd) for methanol synthesis by CO2 hydrogenation. To investigate the role of Pd metal, the synthesized mesoporous silica was loaded with 1, 2, 3 and 4 wt% of Pd. Physicochemical profile of synthesized mesoporous silica supported Pd catalysts were assessed by Inductively coupled plasma - optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), Field-Emission Scanning Electron Microscopy (FESEM), Nitrogen adsorption–desorption and Temperature Program Reduction (TPR) techniques. ICP-OES measurement confirmed the actual Pd metal loading on the mesoporous silica support. XRD confirmed amorphous and crystalline nature of mesoporous silica and Pd metal, respectively. FESEM images exhibited homogenous and well dispersed Pd metal particles on the surface of mesoporuse silica support. Nitrogen adsorption desorption studies displayed enlargement in BET surface area with Pd promotion. Reduction behaviour of PdO was revealed by TPR data over the studied temperature range. The structure–activity studies suggested the degree of Pd crystallinity and higher dispersions as amongst the main factors contributing to the performance of Pd/SiO2 catalysts for pure CO2 hydrogenation in slurry reactor.

Comparative Catalytic Performance Study of 12-Tungstophosphoric Heteropoly Acid Supported on Mesoporous Supports for Biodiesel Production from Unrefined Green Seed Canola Oil

In this study, three solid acid catalysts, namely mesoporous aluminophosphate-supported 12-tungstophosphoric heteropoly acid (HPW/MAP), mesoporous aluminosilicate-supported 12-tungstophosphoric heteropoly acid (HPW/MAS), and gamma alumina-supported 12-tungstophosphoric heteropoly acid (HPW/γ-Al2O3) were prepared and characterized. Mesoporous aluminophosphate (MAP) and mesoporous aluminosilicate (MAS) were synthesized via sol-gel and hydrothermal methods, respectively, and 25 wt.% of 12-tungstophosphoric heteropoly acid (HPW) was immobilized on the support materials using the wet impregnation method. The features of the fabricated catalysts were comprehensively investigated using various techniques such as BET, XRD, NH3-TPD, TGA, and TEM. The surface area of the supported catalysts decreased after HPW impregnation according to BET results, which indicates that HPW loaded on the supports and inside of their pores successfully. The density and strengths of the acid sites of the support materials and the catalysts before reaction and after regeneration were determined by the NH3-TPD technique. Accordingly, an increase in acidity was observed after HPW immobilization on all the support materials. The catalytic performance of the catalysts was studied through alcoholysis reaction using unrefined green seed canola oil as the feedstock. The maximum biodiesel yield of 82.3% was obtained using 3 wt.% of HPW/MAS, with a methanol to oil molar ratio of 20:1, at 200 °C and 4 MPa over 7 h. The reusability study of HPW/MAS showed that it can maintain 80% of its initial activity after five runs.

Fluorescent Probe of Aminopolymer Mobility in Bulk and in Nanoconfined Direct Air CO2 Capture Supports

Poly(ethylenimine) (PEI) is widely recognized as an efficient carbon capture medium. When loaded onto mesoporous oxide supports, the polymer becomes particularly attractive for direct air capture (DAC) applications given the high surface area of the composites, the low volatility of the polymer, and the excellent cyclability of the system. As polymer segmental mobility is coupled with CO2 uptake and diffusion, understanding how that mobility is influenced by nanoconfinement will ultimately be critical to the development of more efficient DAC systems. Here, we discuss our development of a fluorescent probe molecule based on tetrakis(4-hydroxyphenyl)ethylene. As the fluorescence intensity of this molecule and the shape of the emission spectra are strongly dependent on the viscosity of the supporting medium, doping PEI-composites with this fluorescent probe can provide sensitive indication of polymer glass transition and/or melting temperatures across a wide range of temperatures (−100 to +100 °C). Herein, we demonstrate how this molecule can be used as a ratiometric probe to study bulk PEI dynamics and confinement effects in mesoporous silica as influenced by pore functionality, polymer fill fraction, and polymer architecture.

An Environmentally Friendly Approach for the Synthesis of Au Nanoparticles Supported Mesoporous Silica for Catalytic Applications

Mesoporous silica has received much attention as an attractive support material for metal nanoparticles (NPs) with good dispersion and exceptional stability for various catalytic reactions. However, the lack of synthetic protocols to controlled synthesis of mesoporous silica with high surface area and ideal pore size for supporting metal NPs significantly reduces the catalytic performance and stability of the catalysts. This work reports a facile synthetic route to prepare mesoporous silica-supported Au NPs (Au/SiO2) for efficient catalytic reduction of 4-nitrophenol. An environmentally friendly synthetic route was exploited to prepare mesoporous silica using deep eutectic solvent (DES) derived from choline chloride/urea as an efficient solvent and template in solvothermal reaction. The mesoporous silica was first functionalized with –NH2 groups, and subsequently, Au NPs with an average size of 10 nm were deposited onto the mesoporous silica matrix. Owing to the strong interaction of supported Au NPs with the mesoporous silica support, the resultant composite exhibited excellent catalytic performance towards the reduction of 4-NP to 4-aminophenol with a rate constant of Kapp= 3.04 x10-1 min-1 and exceptionally high stability compared to bare mesoporous silica catalyst. The current green approach to fabricating mesoporous silica and Au/SiO2 catalysts holds great promise since it is a much cheaper and environmentally friendly method for large-scale fabrication of other supported catalysts for different catalytic reactions.

Covalent Immobilization of Aldehyde and Alcohol Dehydrogenases on Ordered Mesoporous Silicas

PurposeThis work studies the immobilization of two enzymes, the alcohol dehydrogenase (ADH) and the aldehyde dehydrogenase (AldDH) both from Saccharomyces cerevisiae, which could be used to produce high value-added molecules from carboxylic acids embedded in anaerobic digestate.MethodsIn particular, three mesoporous siliceous materials, with different specific surface areas and pore sizes, (MSU-H, MSU-F and MCF0.75) were used as supports for covalent immobilization. The support materials were characterized by complementary techniques. Then, after a functionalization, creating a covalent bond between the enzyme and the support was performed. The specific activity and immobilization yield of the biocatalysts were then evaluated.ResultsThe best results were obtained with MSU-H and MSU-F, resulting in an immobilization yield greater than 50% in all cases, a specific activity of 0.13 IU/gsupp with the AldDH/MSU-H, 0.10 IU/gsupp with AldDH/MSU-F, 48.6 IU/gsupp with ADH/MSU-H and 12.6 IU/gsupp with ADH/MSU-H. These biocatalysts were then characterized by optimal pH and temperature and the stability factor was evaluated. With ADH/MSU-F no decrease in activity was observed after 120 h incubated at 50 °C. Finally, the biocatalysts AldDH/MSU-H and ADH/MSU-H were used to perform the reduction reaction and it was seen that after five reaction cycles the residual activity was greater than 20% in both cases.ConclusionThe ADH and AldDH enzymes have been successfully immobilized on mesoporous siliceous supports, considerably increasing their thermal stability and being able to reuse them for several reaction cycles. The use of this immobilization and these supports is adaptable to a wide variety of enzymes.Graphical

Tunable amine loading of amine grafted mesoporous silica grafted at room temperature: Applications for CO2 capture

SBA-15 was employed to study amine-grafting in dry and wet grafting conditions at low temperature. SBA-15 was amine-grafted at 30 °C and for contrast SBA-15 was conventionally grafted at 85 °C to determine how amine-grafting at 30 °C affects amine-grafting outcomes. It was found that under dry grafting conditions, adsorbents grafted at 30 and 85 °C exhibited similar amine loadings. It was also found that when water was added during grafting, adsorbents grafted at 30 °C displayed higher amine loadings than those at 85 °C. At 30 °C, more water can occupy the pore space of the SBA-15 prior to clogging of the pores, resulting in higher amine loading. This results in higher CO2 capacities at 75 °C for adsorbents grafted at 30 °C. The stability of materials grafted at 30 °C and the universality of the studied effects for other aminosilanes and mesoporous silica supports were demonstrated.

Green synthesis of cyclohexanone to adipic acid over Fe–W oxides incorporated mesoporous carbon support

We have prepared iron and tungsten oxides incorporated mesoporous carbon (MC) catalysts using a simple hydrothermal methodology with different carbon sources, and the catalytic performance was investigated for cyclohexanone oxidation. An adequate amount of metal oxide loading has displayed a key role in the selective catalyst for adipic acid (AA) synthesis. The MC catalyst has shown its prime activity under the influence of redox properties of W5+/W6+ and Fe2+/Fe3+ as promoters. The 10%Fe 90%W-MC fructose as a carbon source catalyst has provided its best selectivity of 87% for AA at 120 °C.

Ultrafine PdZn bimetallic nanoparticles anchored on sulfur-doped mesoporous carbon for the partial hydrogenation of alkynols

The catalytic partial hydrogenation of alkynols is a key approach for the synthesis of enols, which are crucial chemical intermediates for pharmaceuticals and essences. Low selectivity is the main challenge of the partial hydrogenation of alkynols due to the easy over-hydrogenation of alkynyl groups. Herein, ultrafine PdZn bimetallic nanoparticles (NPs) were anchored on a S-doped mesoporous carbon catalyst (PdZn/Meso_S-C) and used for the partial hydrogenation of alkynols. Zn metal with a high electron density was used to modify the active metal Pd to change the electronic and geometric configuration of the Pd active sites, which improve the selectivity of enols during the partial hydrogenation of alkynols. Furthermore, the use of a S-doped mesoporous carbon support dispersed and stabilized the ultrafine PdZn NPs due to strong interactions between the metal atoms and S sites. This also prevented PdZn ultrafine NPs from aggregating and increased the partial hydrogenation selectivity. The partial hydrogenation of propynol ethoxylate (PME) catalyzed by PdZn/Meso_S-C reached 96.0% enol selectivity, while the alkynol conversion reached 97.5%. The general applicability of PdZn/Meso_S-C for the partial hydrogenation of various alkynols has also been demonstrated. Thus, this work has great application prospects for the high-efficiency catalytic partial hydrogenation of alkynols.

Mesoporous Silica Materials Loaded with Gallic Acid with Antimicrobial Potential.

This paper aimed to develop two types of support materials with a mesoporous structure of mobile crystalline matter (known in the literature as MCM, namely MCM-41 and MCM-48) and to load them with gallic acid. Soft templating methodology was chosen for the preparation of the mesoporous structures—the cylindrical micelles with certain structural characteristics being formed due to the hydrophilic and hydrophobic intermolecular forces which occur between the molecules of the surfactants (cetyltrimethylammonium bromide—CTAB) when a minimal micellar ionic concentration is reached. These mesoporous supports were loaded with gallic acid using three different types of MCM—gallic acid ratios (1:0.41; 1:0.82 and 1:1.21)—and their characterizations by FTIR, SEM, XRD, BET and drug release were performed. It is worth mentioning that the loading was carried out using a vacuum-assisted methodology: the mesoporous materials are firstly kept under vacuum at ~0.1 barr for 30 min followed by the addition of the polyphenol solutions. The concentration of the solutions was adapted such that the final volume covered the wet mesoporous support and—in this case—upon reaching normal atmospheric pressure, the solution was pushed inside the pores, and thus the polyphenols were mainly loaded inside the pores. Based on the SBET data, it can be seen that the specific surface area decreased considerably with the increasing ratio of gallic acid; the specific surface area decreased 3.07 and 4.25 times for MCM-41 and MCM-48, respectively. The sample with the highest polyphenol content was further evaluated from a biological point of view, alone or in association with amoxicillin administration. As expected, the MCM-41 and MCM-48 were not protective against infections—but, due to the loading of the gallic acid, a potentiated inhibition was recorded for the tested gram-negative bacterial strains. Moreover, it is important to mention that these systems can be efficient solutions for the recovery of the gut microbiota after exposure to antibiotics, for instance.

Adsorption performance of magnetic mesoporous silica microsphere support toward the remediation of acetaminophen from aqueous solution

Magnetic mesoporous silica microspheres (MSMS) were prepared in the present study and the removal of acetaminophen from aqueous solution by the MSMS was evaluated. The prepared MSMS were characterized to understand the surface morphology and magnetization capacity of the adsorbent. The Brauner-Emmett-Teller and vibrating sample magnetometer analysis of the MSMS revealed a large surface area (SBET – 273.8 m2/g), average pore size (26 nm) and a saturation magnetization of 8.3 emu/g which was ideal for the adsorption of contaminants. On optimizing the operating parameters, the maximum removal of the acetaminophen was achieved at pH 5.0, adsorbent dose of 1 g/L and initial adsorbate concentration of 150 mg/L. Further, during the maximum removal, the equilibrium time for acetaminophen was 30 min. The Langmuir adsorption capacity of the MSMS was estimated to be 310.7 mg/g for acetaminophen. The tested models (Langmuir, Freundlich, and Temkin models) showed excellent fits to the adsorption equilibrium data. Further, from the desorption studies, it was observed that the MSMS could be reused for more than 14 adsorption-desorption cycles for the contaminant.

Hierarchical mesoporous SnO2/BiVO4 photoanode decorated with Ag nanorods for efficient photoelectrochemical water splitting

Bismuth vanadate has been extensively investigated as a potential visible light photoanode for PEC water splitting. The performance of BiVO4 is restricted by fast charge recombination and slow oxygen evolution reaction kinetic. To address these issues, hierarchical SnO2 (HSN) mesoporous support is developed via a novel sol-electrophoretic approach, and BiVO4 film is decorated with silver nanorods (Ag NRs). The photocurrent density of HSN/BiVO4 photoanode is 3.98 mA/cm2 at 1.23 V vs. reversible hydrogen electrode (RHE) and onset potential (Vonset) of 0.5 V vs. RHE. The PEC performance is attributed to the appropriate band alignment between SnO2 and BiVO4, as well as the hierarchical structure of SnO2. Ag-HSN/BiVO4 photoanode shows photocurrent density of 4.30 mA/cm2 at 1.23 V vs. RHE and Vonset of 0.28 V vs. RHE. The enhanced photocurrent and negatively shifted Vonset can be attributed to radiative localized surface plasmon resonance decay and catalytic effect of Ag NRs, respectively.

Nanoarchitectured superparamagnetic iron oxide-doped mesoporous carbon nanozymes for glucose sensing

The incorporation of nanoarchitectonics into the development of nanozymes to achieve target-specific geometry, dense active sites, and cascade catalysis is highly demanded for developing ultrasensitive bioassays. The improved dispersion and uniform distribution of metal active sites onto a three-dimensional (3D) mesoporous carbon support (MC) with a high surface area can lead to enhanced substrate binding, mobility, and collision probability and therefore, increased peroxidase mimetic activity. Herein, we report the fabrication of well-dispersed superparamagnetic iron oxide (IO) nanoparticles (NPs) on mesoporous carbon (IO-MC) support with high Fe3+ active sites, high surface area, and ordered mesoporous pore channels that show promising catalytic activity at room temperature. The as-prepared IO-MC shows good nanozyme activity at room temperature with highly favorable Michaelis-Menten constant, Km (0.242 mM) and fast reaction rate (0.193 × 10−7 MS−1). Finally, we demonstrate the functionality and pre-eminence of IO-MC nanozyme for bioassay. As a proof-of-concept, we develop a superior glucose assay that provides a LOD (limit of detection) of 2 µM in the spiked sample. These findings suggest that homogeneously dispersed iron oxide NPs on MC show promising potential as next-generation nanozyme for developing sensitive bioassays.

CO2 utilization in methane reforming using La-doped SBA-16 catalysts prepared via pH adjustment method

In this work, lanthanum-combined silica mesoporous (SBA-16) supported Ni-based catalysts are synthesized and examined for synthesis gas (syngas) production in the dry methane reforming (DMR) process. The pH-adjusted hydrothermal technique has been used to modify the mesoporous silica-based support, which has been then impregnated by Ni particles. The pH value had a substantial impact on creating well-ordered mesostructures and lanthanum ion replacement inside the SBA-16 structure. Therefore, at the ideal pH of 3.80, a zeolite-like mesostructure of Si-La has been produced. Thus, La2O3 species have been inserted in the SBA-16 structure, favoring a larger dispersion of impregnated Ni particles of lower dimensions. In addition to the pH modification during the synthesis step, the effects of lanthanum loading and Ni weight percentage variation on the catalytic performance as well as the physicochemical analyses of the catalysts have been also explored. The calcined catalysts have been tested in the DMR process in the temperature range of 600–750 °C. Furthermore, the coke resistance, activity, and structural changes of optimal catalysts have been studied over 11 h. The results showed that the 15Ni/40La-SBA16(3.80) catalyst performs the best structural characteristics and catalytic activity.