Sol-gel Procedure Research Articles

Controllable fabrication of persimmon wood-inspired macroporous (a%Co-Mn)1.5Al0.5Ox, high desulfurization performance and analysis of deactivation kinetic mechanism

The removal of H2S that seriously threaten the environment and human health is of great significance in enhancing coal cleaning utilization. Herein, a series of persimmon wood-inspired macroporous (a%Co-Mn)1.5Al0.5Ox (a = 0, 3, 6, 10, 15, 20) sorbents were constructed by the self-assembly of vacuum-assisted sol–gel procedure, and their desulfurization efficiency was evaluated on a fixed-bed reactor at 600–800 °C. Among cobalt-doping sorbents, the breakthrough sulfur capacity (BSC, 272.2 mg g−1) and effective utilization (EU, 81.5%) over (15%Co-Mn)1.5Al0.5Ox is greatly high than the value (138.08 mg g−1) over ZnCoO4/SAPO-34@SBA-15, and slightly lower than BSC (286.2 mg g−1) and EU (92.3%). The magnification SEM images of (15%Co-Mn)1.5Al0.5Ox revealed that regularly straight macroporous channel structure inherited from persimmon wood effectively promoted the rapid diffusion of H2S molecules and accelerated the rate of sulfur/oxygen exchange on the interface of the channel wall. In the meantime, the results studied by the deactivation kinetics model also confirm invariable rate constants (ka, kd) with high correlation coefficients due to higher stability and renewable ability of (15%Co-Mn)1.5Al0.5Ox.

Persica Akhani Salicornia as novel biodiesel feedstock production for economic prosperity in salty and water scarcity areas: Optimized oil extraction process and transesterification reaction using new magnetic heterogenous nanocatalysts

As a new biodiesel feedstock, the oil extraction procedure from the seeds of the plant Salicornia (Persica Akhani subspecies) has been developed. Oil extraction from the seeds of the Salicornia Persica Akhani has been researched utilizing two different organic solvents and four different procedures, including the Soxhlet method, the traditional approach, the shaker method, and the ultrasonic probe method. The results indicated that oil yield by ultrasonic probe technique was higher than the other methods in a short time. Based on the outcomes, extracting the oil from Salicornia seeds using hexane resulted in a greater yield of oil than petroleum ether. This was true across all methods of extraction. The Physico-chemical properties and antioxidant activity of extracted oil suggested its suitability for biodiesel production. To transesterification reaction of Salicornia seeds oil with methanol into biodiesel, the heterogeneous magnetic Zn0.4Ni0.6Fe2O4 and Zn0.4Ni0.6Fe2O4@SO3H nanocomposites have been synthesized by sol-gel auto combustion procedure. FT-IR, FE-SEM, EDS, and VSM were used to determine the characteristics of the heterogeneous nanocomposites. These nanoparticles have a strong attraction to an outside magnet, which makes it much easier to collect them from the reaction environment for subsequent reuse. In the process of transesterification of Salicornia oil with methanol, novel sulfonated heterogeneous magnetic catalysts with a high density of superacid sites on the surface (2.50 mmol SO3H g−1) and significant magnetization (60 emu/g) afforded high activity and produced a biodiesel yield of 96%. In addition, the magnetic Zn0.4Ni0.6Fe2O4@SO3H nanoparticles could be reused up to five times in the process of turning oil into biodiesel, which resulted in reduced expenses associated with the manufacture of biodiesel. FT-IR and SEM analyses were performed both before and after the transesterification process, and the results showed that the absorption bands and particle distribution were practically the same in both new and used catalysts. The analysis of the FT-IR spectra reveals indications of the transformation of Salicornia oil into fatty acid methyl esters (FAMEs). Gas chromatography (GC) study of the FAME profiles of the as-prepared biodiesel also indicated that palmitic acid (C16:0) was the most saturated fatty acid (8.44%–8.50%), while linoleic acid (18:2) was the predominant unsaturated fatty acid (60.94%–60.97%).

The development of a novel copper-loaded mesoporous silica nanoparticle as a peroxidase mimetic for colorimetric biosensing and its application in H2O2 and GSH assay.

In recent years, the development of nanomaterials-based peroxidase mimics as enzyme sensors has been attracting considerable interest due to their outstanding features, including potent stability, and cost-effectiveness toward natural enzymes. In this work, mesoporous silica nanoparticles functionalized by copper (Cu-MSN) were prepared as a new artificial enzyme for the first time through the sol-gel procedure. A comprehensive investigation of the catalytic activity of Cu-MSN was done through the oxidation of chromogenic peroxidase substrates, 3,3',5,5'-tetramethylbenzidine (TMB), and (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), in the presence of H2O2. The results indicate that the peroxidase-like activity of the as-prepared sample is significantly higher than other nanoparticles. Additionally, for the study, a facile and rapid sensing method based on the enzyme-like activity of Cu-MSN to detect H2O2 and glutathione (GSH) was developed to examine the potency of the proposed biosensor. Preliminary analysis revealed that the limit of detection (LOD) of H2O2 and GSH is 0.2 and 0.0126μM, in the range of 0.9-100 and 0.042-1μM, respectively. These findings support the claims for the efficiency of the sensor in detection fields. Also, human serum was utilized as the real sample to obtain additional evidence.

Theory-guided doping of LaCoO3 nanoparticles for enhanced antimicrobial performance

Perovskite-type lanthanum cobaltate (LaCoO3) has been attracting extensive attention in photocatalysis; yet the performance is generally limited by the low structural defects and poor oxygen migration. Herein, results from first principles calculations show that Al and Ce codoping at the A and B sites of LaCoO3 can induce the formation of oxygen vacancies, which, along with the exposed Co (012) facets, facilitate the adsorption of oxygen and water molecules, a critical step in the photocatalytic production of reactive oxygen species that are known as potent antimicrobial agents. Motivated by these theoretical insights, Ce and Al codoped LaCoO3 is prepared experimentally via a simple sol–gel procedure. Spectroscopic measurements show that the cationic doping leads to the generation of abundant oxygen vacancies and Ce4+/Ce3+ species, fast electron transport, as well as a reduced band gap, as compared to the undoped counterpart. These unique structural characteristics enhance the separation and transport of photogenerated carriers and hence the generation of reactive oxygen species. Indeed, the obtained La0.9Ce0.1Co0.9Al0.1O3 exhibits excellent photocatalytic antibacterial activity, where 98.8% of Escherichia coli is eliminated with La0.9Ce0.1Co0.9Al0.1O3 at 1 mg mL−1 under visible photoirradiation for 30 min, in comparison to only 46.8% with undoped LaCoO3. These results underline the significance of structural engineering in enhancing the photocatalytic activity of perovskite materials for antibacterial applications.

Local structural effects of Gd3+ ions incorporation in shell of nanostructured silica core – alumina rich shell microspheres

Non-crystalline nanostructured silica core – alumina rich shell microspheres, with Gd ions in the shell were obtained by sol-gel procedure following a synthesis route based on the Stöber method. The samples were characterized by DTA/TGA, XRD, SEM and TEM, EPR, solid-state NMR and XPS techniques. The effect of increasing Gd ions content on the local structure in alumina rich shell and at its interface with silica core was investigated. It was also found that increasing the concentration of the paramagnetic ions leads to a modification of the local magnetic field at sites of neighboring aluminum and silicon ions. Gadolinium ions are distributed in the aluminum sites from alumina rich shell. As result of increasing the gadolinium incorporation at the core-shell interface the diffusion of aluminum in the silica network, as well as the migration of the silicon in the alumina rich shell, are enhanced. Therefore, Si-O-Al bridges are formed at the interface, leading to stable non-crystalline structures, with Gd ions on the external layer of the shell, as proved by XPS, having potential application as contrast agents for magnetic resonance imaging (MRI).

Effects of Synthesis Methods on the Characteristics of Material Sr3Y1.95Ge3O12: 0.05Eu3+ (SYGO: Eu3+) for White LED Phosphors Applications

Solid-state reaction, co-precipitation, and sol-gel procedures were used to synthesize the Sr3Y1.95Ge3O12:0.05Eu3+ (SYGO: Eu3+) garnet structure. The morphological structure and photoluminescence properties of the samples were studied. Phosphors have morphologies and particle sizes that vary depending on the preparation. According to the X-ray diffraction pattern measurement, the sol-gel sample only appeared to exhibit the SYGO: Eu3+ characteristic that it shows the cubic structure belonging to the Ia3d (230) space group. In comparison to the two approaches of co-precipitation and solid-phase reaction, the sol-gel method has a more single-phase structure. Under the excitation wavelength of 395 nm, all produced samples emitted red light, with the greatest emission peak at 612 nm, corresponding to the 5D0→7F2 transition of Eu3+ ions in the SYGO host lattice. The color coordinates of the sample SYGO: Eu3+ fabricated by the sol-gel method are x = 0.65 and y = 0.35. Therefore, the SYGO: Eu3+ based on sol-gel method’s synthesis is a promising phosphor for the application of White LED.

Preparation and evaluation of high-transparent scratch-resistant thin films on plasma treated polycarbonate substrate

New simple aqueous sol–gel procedure has been used for producing hard transparent organic–inorganic coatings on polycarbonate (PC). Sol-gel thins films were prepared by mixing Si and Al aqueous alkoxides and applied on the plasma treated PC. Tetraethyl orthosilicate (TEOS), 3-glycidoxypropyltrimethoxysilane (GPTMS) and aluminum tri sec-butoxide were used as main precursors. Before applying coatings PC were treated by Dielectric Barrier Discharge (DBD) system being conducted at atmosphere pressure. The effects of temperature, sols volume ratios and aging time on the coatings properties were scrutinized. Chemical, structural, morphological, optical and mechanical analyses of the samples were done by ATR-FTIR, EDS, XRD, FE-SEM, TEM, UV/vis spectroscopy, ellipsometry, pencil hardness and eraser scratch methods. TEM results showed well-dispersed nano-particles in the liquid sol. All of the films showed higher average transmittance (89 %) than the raw PC (86 %) that was stemmed from the lower refractive index (1.481) than raw PC (1.58). Films indicated good adhesion onto the plasma treated substrates (5B). The pencil hardness of the PC substrate (4B) improved to 3H (8 pencil grade increment) with just a single layer coating (775 nm thickness) due to the preparation of new hard structures of interlocked Si and Al atoms.

Mechanical properties of silica aerogels controlled by synthesis parameters

Development of silica aerogels for real applications requires control of their mechanical properties. Based on the sol-gel procedure and using the alkoxide precursor of silica (TMOS), native silica aerogels were synthesized. This work explores the influence of three synthesis parameters, namely, TMOS concentration, catalyst concentration, and solvents (MeOH, EtOH, IPA), on the gel point, shrinkage and mechanical properties of aerogels. Structural studies were conducted to determine how the analysed synthesis parameters influenced the spatial network of aerogels and their elasticity. The analysis of the relationship between Young's modulus (E) and bulk density (ρ), E∝ρα, showed that the catalyst concentration appeared the most interesting parameter because, while the ρ did not change with an increase in the catalyst concentration, there was a significant increase in the E. We associate this observation with an increase in specific surface area, reflecting an increase in bond diameter between secondary particles formed in the aerogel.

Preparation of molecularly imprinted silica particles with amino functionality for chiral separation of (±)-naproxen.

Herein is the synthesis and effective use of an S-naproxen (S-NP) enantioselective adsorbent material with amino functionality for the enantioseparation of a (±)-NP racemic mixture. To begin, the S-NP enantiomer of (3-aminopropyl)triethoxysilane was used to create an amide derivative (S-NP-Si-NH2 ). In order to incorporate the S-NP enantiomeric species into the cross-linked material, the developed S-NP-Si-NH2 derivative was combined with tetraethoxysilane (TEOS) and subjected base-catalyzed sol-gel condensation polymerization procedure. The S-NP is released from the cross-linked matrix by alkaline hydrolysis and subsequent acidification, creating an enantioselective gap filled with cationic ions that are compatible with the S-NP during recombination. With the use of elemental analysis, nuclear magnetic resonance (NMR), and Fourier transform infrared (FTIR) spectroscopy, it was verified that the performed chemical processes on the monomeric precursor and the resulting S-NP molecularly imprinted material (S-NP-Sil) were successful. Furthermore, the morphology alterations were analyzed using scanning electron microscopy images of the sorbent surface. The produced adsorbent particles were also used in the chiral separation of a (±)-NP racemic combination utilizing a column approach, with encouraging separation results shown in both the first loading run (59% ee of R-NP) and the second elution run (85% ee of S-NP).

Analysis of conductivity and band-gap energy of bismuth ferrite nanoparticles as prospective photovoltaic material

Photovoltaic solar cell converts the radiation of sun to electric charge that is a sustainable tool for harvesting renewable energy. Multiferroic bismuth ferrite (BFO) nanoparticles consist of low band-gap energy that proclaims highly promising photovoltaic cells material. The Sol-gel procedure derived nanocrystalline bismuth ferrite (BFO) powders for investigation during the research. X-ray diffractometry (XRD) implementation provided desired output, depicting the crystalline structure and bond formation of sample BFO nano-particles. Field emission scanning electron microscope (FESEM) laid out the proper morphology and sampled BFO powders' structural composition. Application of heat was varied from 50 to 175 °C temperature range upon the synthesized BFO samples. BFO consists of low band-gap energy and lesser efficiency (<2%), proving it to be unfit for practical appliances, even though BFO asserts highly promising photovoltaic characteristics. The dimension of the crystallized structures is 48.71 nm. The morphology of BFO nanoparticles, determined by FESEM microscopic inspection, has been 166.39 nm. The direct as well as indirect band-gap energies, respectively 2.10 and 2.09 eV, indicate the prospective future of BFO as a photovoltaic material. Analysis of the lowest and highest applied temperatures illustrated the conspicuous change in conductivity. Where an increase in temperature seemed to improve the value of conductivity consequently. Band-gap energy was measured and found to be a promising value for a Photovoltaic material.

N-Phenyl acrylamide-incorporated porous silica-bound graphene oxide sheets with excellent removal capacity for Cr(iii) and Cr(vi) from wastewater.

The sophisticatedly altered Hummer's and sol-gel procedures were applied for the synthesis of graphene oxides and porous silica monolith particles respectively. The Fischer esterification protocol was used for coupling silica monoliths with graphene oxides. A N-phenyl acrylamide-incorporated porous polymer was synthesized at the surface of composites via reversible addition fragmentation chain transfer polymerization. The composition was confirmed by Fourier transform infra-red spectroscopy, FE-SEM, X-ray diffraction, zeta potential (zeta pH), Brunauer-Emmett-Teller (BET/BJH) analysis, and EDAX analysis. The resulting polymer-bound composite efficiently removed Cr(vi) and Cr(iii) from waste water. Adsorption parameters such as contact time, pH effect, temperature, and adsorbent and adsorbate concentration were optimized for the optimal output of the composite. The kinetic and equilibrium models were applied to the adsorption of Cr(vi) and Cr(iii) at the adsorbent surface. The maximum adsorption capacity (qe) of Cr(vi) and Cr(iii) was found to be 298.507 mg g-1 and 401.874 mg g-1, respectively, using the same initial concentration of Cr(vi) and Cr(iii) [10-60 ppm]. The adsorption data of both states of the Cr-metal followed the pseudo 2nd-order kinetic model with regression values of 0.996 ∼ Cr(vi) and 0.999 ∼ Cr(iii) at ambient temperature. Similarly, the adsorption data of Cr(vi) best fit into the Langmuir adsorption isotherm (R2 = 0.972) while that of Cr(iii) followed the Freundlich model (R2 = 0.983).

Summerfield scaling model and electrical conductivity study for understanding transport mechanisms of a Cr3+ substituted ZnAl2O4 ceramic.

Solid-state and sol-gel procedures were used to prepare ZnAl1.95Cr0.05O4 nanocrystal spinels. From the results obtained by X-ray diffraction (XRD) and transmission electron microscopy (TEM), it can be concluded that the samples prepared by sol-gel synthesis are better crystallized than the ones resulting from the solid-state method. Studies by spectroscopy of impedance were done in function of frequency (40-107 Hz) and temperature (540-680 K) in the sample prepared by sol-gel synthesis. The electrical conductivity spectra obey Jonscher's law and two models were observed studying the variation of the exponent 's' as a function of temperature, Correlated Barrier Hopping (CBH) and Non-overlapping Small Polaron Tunnelling (NSPT). The predominant conduction mechanism is bipolaron hopping. The scaling behavior of conductivity spectra was checked by Summerfield scaling laws. The time-temperature superposition principle (TTSP) points to a common transport mechanism working for the low and middle frequency ranges. The scaling mechanism fails in the high-frequency ranges suggesting that conduction dynamics, and the usual hopping distance of mobile species, have changed. The values obtained for the activation energy from the hopping frequency, conductivity σ dc, bulk resistance R gb, and relaxation (f max), in the temperature range of 540-680 K, are very close. A higher and negative temperature coefficient of resistivity (TCR coefficient) equal to -2.7% K-1 is found at 560 K. This result shows that our compound is suitable for uncooled infrared bolometric applications and infrared detectors.

Green chemistry synthesis of wolframites: An investigation about stoichiometric ratios, optical, structural, vibrational, and physico-chemical properties

This work aims to use a new route to synthesize nanostructured materials. The method has an eco-frendly perspective, which seeks to produce materials with dual characteristics (fluorescence and/or plasmon band) with various applications in luminescent sensors or particles for spectral optimization. Cobalt tungstate nanoparticles (CoWO4 - wolframite), with non-stoichiometric ratios of 2:1 and 1:2 of the precursor materials (ammonium paratungstate and cobalt nitrate), were prepared by the proteic sol-gel method. For the synthesis of the nanoparticles, two types of polymerizing agents were used: animal gelatin (collagen) and vegetal gelatin extracted from red algae (Rhodophyta). The prepared materials were calcined between 773 and 1073 K for 2 h. XRD results evidenced a variation of the lattice parameters and a monoclinic symmetry of the P21/c type for CoWO4 and of the P21/n type for WO3. Particle sizes, evaluated by the Scherrer equation, ranged from 13 to 30 nm for specimens synthesized at 773 K and from 20 to 51 nm for specimens synthesized at 1073 K. Raman spectroscopy revealed anharmonicity in the vibrational system and its damping according to the presence of distinct symmetries. The experiment was successful in obtaining a reproducible sol-gel procedure for the synthesis of the CoWO4 nanosystem. The procedure allowed the obtaining of plasmonic and photoluminescent properties only by stoichiometric modification of the precursors. Finally, the process was optimized, and the best synthesis conditions were defined. Furthermore, fluorescence and plasmon band investigation revealed that the nanostructures have maximum emission and absorption at 468 and 410 nm, respectively.

Investigation of structural, physical, spectral, photoluminescence, Raman, and dielectric properties of Ba2Co2GdxFe28-xO46 hexaferrites

Nano-crystalline Gd-substituted X-type hexaferrites with the composition Ba2Co2GdxFe28-xO46 (x = 0.00, 0.08, 0.16, 0.24, and 0.32) were synthesized using sol-gel auto-combustion procedure. The establishment of single and pure phases of X-type hexagonal ferrites is verified by X-ray diffraction. The crystallite size ranging from 25 to 31 nm showed the increasing trend with the enhancement of Gd-substitution. The unit cell volume was found in 2502.83–2516.07 Å3. The alteration in lattice parameters and cell volume is due to the difference in ionic radii of the host (Fe) and substituent (Gd) element. FTIR spectra ranging 590-3000 cm−1 revealed the emergence of specific absorption bands verifying the formation of hexagonal ferrites. The behavior of dielectric properties is frequency dependent. The dielectric constant at low frequency for all substitution was high, but over the large frequency values, the dielectric constant was decreased. The dielectric loss factor increases over low frequencies and decreases as frequency rises with a higher concentration level. Higher dielectric parameter values suggest that synthetic material might be good for high-frequency applications and super-capacitors fabrication. The changes in Raman spectra as a function of substitution content are ascribed to the development of strain in the unit cell (x). The XRD investigation well corroborates this conclusion. FESEM images depicted the hexagon shaped particles of the X type hexagonal ferrites. In the PL spectra of synthesized compounds, all emissions invisible (red) zone with PL intensity at 661 nm were observed.

Structural, electrical and magnetic studies of Ni0.7Mn0.2Cu0.1Fe2-Al O4 (x = 0, 0.05, 0.1, 0.15, 0.2 and 0.25) nano-ferrite synthesized by sol-gel technique

• Synthesis of Ni 0.7 Mn 0.2 Cu 0.1 Fe 2- x Al x O 4 ( x =0, 0.05, 0.1, 0.15, 0.2 and 0.25) nano-ferrite materials is successfully done by employing the sol-gel auto-combustion procedure. • Required characterizations are performed on the synthesized samples via XRD, SEM, ESR, dielectric and VSM. • XRD results portrayed that all the samples belonged to a single phase devoid of impurities whatsoever. • Outcomes from other characterizations revealed the obtained values and standard values are in close proximity. • This investigative research work infers that sol-gel auto-combustion procedure is one amongst many effectual chemical routes for manufacturing wide range of ferrites for various applications. In this research analysis, the outcome of aluminum substitution on the structural, magnetic, electric and dielectric features of spinel ferrite is studied. The nano-ferrites Ni 0.7 Mn 0.2 Cu 0.1 Fe 2- x Al x O 4 with x =0, 0.05, 0.1, 0.15, 0.2 and 0.25 are contrived by sol-gel auto-combustion technique. The spinel phase of the synthesized materials is identified by using the XRD diffraction pattern and gives a good confirmation for the development of ferrite. The SEM studies reveal about the uniformity of the materials and the spherical shape of the grains. The IR spectra reveal replacement of Al 3+ ions which broaden and shift the ν 2 band suggesting the occupation of Al 3+ ions on octahedral B-location. Relative permittivity and dielectric loss tangent decline with aluminum concentration rise for every synthesized ferrite. VSM is employed to study the magnetic behavior of the samples at room temperature.

Bi-layered photoelectrodes of TiO2/activated carbon modified with SrTiO3 films boosted sunlight harvesting of dye-sensitized solar cells

• Bi-layered photoanodes were fabricated for dye-sensitized solar cells (DSSCs). • Photoanodes were composed of 0.05 % activated carbon (AC)/TiO 2 and SrTiO 3 layers. • SrTiO 3 perovskite material amount was changed from 5 to 30 % in second layer. • Champion DSSC was composed of 0.05 % AC/TiO 2 –25 % SrTiO 3 photoelectrode. • Highest η = 5.90 %, V OC = 714.71 V, J SC = 14.91 mA/cm 2 , FF = 55.46 % were measured. This work studies the effect of the value of SrTiO 3 material on both the characteristics of 0.05 % activated carbon (AC)/TiO 2 –(5–30 %) SrTiO 3 nanocomposites layers as well as performances of dye-sensitized solar cells (DSSCs). Synthesis of SrTiO 3 as an inorganic perovskite nanocrystalline layer was done by the sol-gel procedure and applied for preparation of various 0.05 % AC/TiO 2 –SrTiO 3 (0–30 %) photoanode nanocomposites for DSSCs. Observing the Sr-element peak in the EDS diagram confirmed the existence of the SrTiO 3 in the composite. The champion DSSC containing the optimum 0.05 % AC/TiO 2 –25 % SrTiO 3 composite illustrated the highest efficiency of η = 5.90 ± 0.01 %. Thus, the 0.05 % AC/TiO 2 –25 % SrTiO 3 nanocomposite enhanced the PCE by about 57 % in comparison with reference device containing bare TiO 2 indicating η = 3.15 ± 0.01 %. Evidently, SrTiO 3 incorporation into the TiO 2 raised J SC and V OC values of devices relative to those measured for solar cell with pristine TiO 2 . Based on electrochemical impedance spectroscopy (EIS) data, in comparison with various concentrations of SrTiO 3 , 0.05 % AC/TiO 2 –SrTiO 3 (25 %) photoelectrode illustrated minimum R CT2 = 29.04 Ω.cm −2 . Improved charge transfer was observed by increasing the value of SrTiO 3 material to minimize recombination. Therefore, application of 0.05 % AC/TiO 2 -SrTiO 3 photoelectrode nanocomposites could highly boost DSSCs performances.

MAl2O4 (M: Mg, Ni, and Co) as unique support for Ni active metal to form a catalyst for renewable biohydrogen and syngas production from glycerol reforming over a microchannel reactor

Different mesoporous aluminate MAl2O4 spinels (with M: Mg, Ni, and Co) were fabricated via a sol–gel procedure. The fabricated spinels each were then used as support for a Ni active metal to synthesize a catalyst, and the performance of the spinel as part of the catalyst used in glycerol steam reforming (GSR) and dry reforming (GDR), respectively, was investigated. Further, the catalysts were characterized using XRD, EDX-Mapping, H2-TPR, TEM, NH3-TPD, and SBET analyses, respectively. Notably, the catalysts each displayed a high BET specific surface area in the range of 130–190 m2/g. In addition, hydrogen production by GSR and GDR under different synthesized catalysts was evaluated in the temperature ranges of 500–700 °C and 600–800 °C, respectively, in a monolithic reactor. In particular, a high glycerol conversion, H2 yield, and CO selectivity, and low CO2 selectivity were achieved using the NiO/NiAl2O4 catalyst in GSR. Further, the order of catalytic performances with regard to glycerol conversion, H2 yield, and CO selectivity was the catalytic performance of NiO/NiAl2O4 > NiO/MgAl2O4 > NiO/CoAl2O4, respectively. Likewise, the H2/CO ratio in the temperature range of 600–800 °C was closest to ∼ 1 in the case of the NiO/NiAl2O4 catalyst used in GDR. Subsequent TGA analysis of each spent catalyst after 32 h of use showed that the amount of coke production in GDR was much higher than that in GSR. In addition, the highest amount of coke deposition was with the use of the NiO/CoAl2O4 catalyst in these reformings.

PtO Nanoparticles Decorated on Mesoporous Cobalt Selenite Networks as a Novel Photocatalyst for Ultrafast Reduction of Cr(VI)

It is a troublesome and urgent issue to design novel photocatalysts for Cr(VI) reduction in wastewater with highly photoactive under visible exposure. A novel mesoporous PtO/CoSeO3 photocatalyst was constructed through a sol-gel procedure by incorporating the non-ionic surfactant F108 for photoreduction of Cr(VI). TEM and XRD data of the synthesized CoSeO3 nanoparticles are quite uniform in size and the monoclinic crystal shape, with particle size of 10 nm. The optimized 1.2%PtO/CoSeO3 photocatalyst exhibited almost 100% reduction efficiency within 30 min, and the apparent rate constant was found at about 0.0803 min−1, which was fostered 3.5 folds greater than the bare CoSeO3. The enhanced photocatalytic ability of PtO/CoSeO3 photocatalyst was ascribed to their fostered separation efficiency of carriers and promoted the absorption of visible light than bare CoSeO3. The photoelectrochemical and photoluminescent responses indicated that the obtained PtO/CoSeO3 inhibited the recombination of carriers, thus promoting the Cr(VI) photoreduction. The present work highlights new insights over PtO/CoSeO3 photocatalysts for the Cr(VI) photoreduction under visible illumination.

Tuning the morphology of Pd aerogels for advanced electrocatalysis of formic acid

Modern inorganic aerogels have drawn great attention in material science and renewable energy fields due to their exceptional physicochemical behavior, tremendous surface area, and large porosity. Despite many attempts, only a few strategies to produce metallic aerogels have been reported. Herein, a novel, surfactant-free, fast, and facile method is proposed to generate palladium aerogels. For the first time, carbon monoxide is used in the presence of HCl by a sol-gel procedure to create palladium aerogels assembled by nanochains. Moreover, palladium aerogels are constructed at low (0.05 M, Pd-AL), medium (0.5 M, Pd-AM), and high (1.0 M, Pd-AH) sol concentrations to assess their role in controlling morphology and electrocatalytic efficiency. The Pd-AL, Pd-AM, and Pd-AL display the porous three-dimensional networks with ultralow densities of 0.016, 0.019, and 0.024 g cm−3, respectively. Based on the comparative analysis, Pd-AL is the optimized form produced through the self-assembly process, with the highest electrocatalytic activity and durability. Pd-AL, Pd-AM, and Pd-AH showcased mass activities of 2.3, 1.7, and 1.3 A mg−1Pd, respectively. In addition, durability testing revealed that the specific activities of Pd-AL, Pd-AM, and Pd-AH toward formic acid oxidation after the 500th cycle retained 87%, 78%, and 65% of the initial mass activities, respectively. Undoubtedly, these self-supported 3D aerogels can be considered as superior candidates for diverse renewable energy applications.

Surface acid properties of Nb2O5–P2O5–SiO2 gel-derived catalysts

Amorphous catalytic materials belonging to the Nb2O5–P2O5–SiO2 system were prepared through an original sustainable sol-gel procedure, and characterized by surface area, porosity and acidity measurements. Their acid properties have been investigated by FT-IR spectroscopy of adsorbed pyridine, ammonia titration and TPR, as well as by titration with 2-phenylethylamine from organic solution. They present Lewis acidity attributed to niobium surface cationic centers, and Brønsted acidity sufficiently strong to protonate pyridine. The total acidity depends on the niobium content. The conversion of ethanol was investigated by vapor phase Temperature Programmed Reaction, steady-state catalytic experiments and static In Situ FTIR experiments. The samples are active in converting ethanol to ethylene with 100% selectivity at low conversion (523–573 K), but also produce acetaldehyde by dehydrogenation at higher temperature and conversion. They show an unusually poor activity for the production of diethylether also at low ethanol conversion. Ethoxy groups act as reaction surface intermediates.