Ternary Nanocatalysts Research Articles

A hybrid FeOx/CoOx/Pt ternary nanocatalyst for augmented catalysis of formic acid electro-oxidation

Platinum-based catalysts that have long been used as the anodes for the formic acid electro-oxidation (FAO) in the direct formic acid fuel cells (DFAFCs) were susceptible to retrogradation in performance due to CO poisoning that impaired the technology transfer in industry. This work is designed to overcome this challenge by amending the Pt surface sequentially with nanosized cobalt (nano-CoOx, fibril texture of ca. 200 nm in particle size) and iron (nano-FeOx, nanorods of particle size and length of 80 and 253 nm, respectively) oxides. This enriched the Pt surface with oxygenated groups that boosted FAO and mitigated the CO poisoning. The unfilled d-orbitals of the transition metals and their tendency to vary their oxidations states presumed their participation in a faster mechanism of FAO. Engineering the Pt surface in this FeOx/CoOx/Pt hierarchy resulted in a remarkable activity toward FAO, that exceeded four times that of the Pt catalyst with up to ca. 2.5 times improvement in the catalytic tolerance against CO poisoning. This associated a ca. − 32 mV shift in the onset potential of FAO which increased to − 40 mV with a post-activation of the same catalyst at − 0.5 in 0.2 mol L–1 NaOH, displaying the catalyst's competitiveness in reducing overpotentials in DFAFCs. It also exhibited a favorable amelioration in the catalytic durability in long-termed chronoamperometric electrolysis. The electrochemical impedance spectroscopy and the CO stripping voltammetry were employed to elucidate the origin of enhancement.

Sub-millisecond pulsed laser engineering of CuOx-decorated Pd nanoparticles for enhanced catalytic CO2 hydrogenation

Catalytic CO2 hydrogenation to fuels and chemicals presents a promising avenue for addressing global warming and advancing toward a net-zero economy. Surface atomic rearrangement of catalysts has attracted growing interest as a means to manipulate catalyst activity and selectivity. Herein, we designed a ternary nanocatalyst comprising CuOx species decorated Pd nanoparticles (NPs) supported on Co oxide (denoted as CPCu) for catalytic CO2 hydrogenation. Sub-millisecond laser treatment (1 mJ per pulse) was used to manipulate the surface atomic arrangements of CPCu the catalyst. The CPCu nanocatalyst showed a significant enhancement in both CH4 production and CO production at 300 °C compared to the Pd/Co catalyst. Notably, the CH4 production using the laser-treated nanocatalyst (denoted as CPCu-L) was 66.6 % higher than the untreated one (CPCu) at 300 °C. Comprehensive catalyst characterizations revealed that CuOx species promoted CO2 activation, while neighboring Pd domains effectively dissociated H2 molecules, leading to enhanced CH4 production. This study demonstrates the potential of sub-millisecond laser treatment for tailoring catalyst surfaces, offering a promising strategy to design more active and selective catalysts for CO2 hydrogenation.

Facile one-pot synthesis of ternary Fe doped Cu-ZnO nanocatalyst: An efficient and recyclable solar light driven photocatalyst

Currently, nanoparticles are regarded as excellent materials for degrading and removing dyes due to their beneficial surface features and chemical reactivity. Herein, Cu doped ZnO (CZ) was co-doped with Fe (FCZ) at different concentrations (2, 3, 4 and 8 wt% with respect to CZ) via simple one-step co-precipitation approach. The structural, surface morphology, surface properties, optical and photocatalytic performance of prepared samples were studied. Due to the doping of Fe, the band gap of CZ reduced from 2.7 eV to 2.29 eV, which is beneficial for absorbing visible light. Among doped CZs, 4 wt% Fe-doped CZ (4FCZ) exhibited 97.1% methylene blue (MB) degradation at neutral pH under 60 min of sunlight exposure. Furthermore, the effect of initial concentration of dye, catalyst load, and pH on the degradation process was investigated. The remarkable photocatalytic activity of 4FCZ nanoparticles can be attributed to their advantageous surface properties, such as their high specific surface area, heterostructure morphology, and mesoporous nature. Scavenger study identified •O2−, e−, and h+ as main reactive species. Pseudo-first order kinetics revealed degradation order: 4FCZ>8FCZ>3FCZ>2FCZ>CZ. 4FCZ showed recyclability with 90.9% MB degradation after three cycles. Mineralization of MB was analysed by COD and LC-MS studies. Fe-doped CZ emerges as a promising, cost-effective wastewater treatment under sunlight without special equipment. This study provides new insights on synthesis of ternary nanocatalyst for dye degradation.

Pioneering superior efficiency in Methylene blue and Rhodamine b dye degradation under solar light irradiation using CeO2/Co3O4/g-C3N4 ternary photocatalysts

In this research work, we have successfully synthesized the CeO2/Co3O4/g-C3N4 ternary nanocomposite for hydrothermal method for photocatalytic applications. The synthesized nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy TEM, Photoluminescent spectra (PL), X-ray photoelectron spectroscopy (XPS), Brunauer- Emmett-Teller (BET) and Ultraviolet diffuse reflectance spectroscopy (UV-DRS) technique. As per the optical spectroscopic investigations CeO2/Co3O4/g-C3N4 ternary nanocomposite exhibited the high optical absorption range and its band gap is reduced from 2.95 eV to1.83 eV. The PL spectra showed the lowered emission peak intensity of ternary nanocomposite which is revealed that the better charge separation and slow recombination of electron hole pairs. The highest photocatalytic degradation efficiency of CeO2/Co3O4/g-C3N4 ternary nanocomposite showed 93 % and 86 % towards the pollutant methylene blue and Rhodamine B. Moreover, photodegradation of the pollutants followed pseudo-first order kinetics with a very high-rate constant of 0.02211 min−1 and 0.017756 min−1. Additionally, the ternary nano catalyst was delivered the remarkable stability performance even after five cycles. This research may provide a low-cost approach for synthesized visible light responsive catalysts for use in environmental remediation applications.

Carbon-supported Ternary Nanocatalyst Palladium-Vanadium-Cobalt for Hydrodechlorination of 2,4-Dichlorophenol

M ultimetallic nanocatalysts have remarkably revealed activities in various catalytic applications. Herein, the ternary nanocatalysts based on palladium-vanadium-cobalt were successfully synthesized through the reduction of their salts with the combination of sodium borohydride and ethylene glycol as reducing agents, including impregnating of activated carbon (AC) substrate with colloid solution of metallic nanoparticles (PdVCo/C). The immobile of trimetallic PdVCo on AC was evidenced by XRD, EDX analysis, transmission electron microscopy (TEM) and specific surface area (BET). Therein, TEM imaging showed that the PdVCo particles size is about 7 nm. The trimetallic nanocatalysts were evaluated in the hydrodechlorination of dichlorinated substrates which was defined by GC (FID detector). The obtained result was that the conversion of 2,4-dichlorophenol was over 91% in the case of PdVCo nano-catalyst in the presence of potassium hydroxide and the high catalytic stability was observed.

Lattice Strain and Composition Effects on the Methanol Oxidation Performance of Platinum-Ruthenium-Nickel Ternary Nanocatalysts.

Ternary Pt-based structures are a positive progress in addressing the disadvantages of monometallic and bimetallic Pt-based alloys for the electrochemical oxidation process of simple alcohols, which is a vital half-reaction in fuel cell technologies. We herein report a facile NaBH4-assisted ethylene glycol reduction process for fabricating a series of nanosized PtRuNi ternary alloys to explore the relationship between physicochemical properties and electrocatalytic behaviors for the acidic methanol oxidation reaction (MOR). Owing to a balance between lattice strain and synergistic effects, the Pt60Ru20Ni20/C electrocatalyst shows the highest MOR efficiency with the mass activity/specific activity of 844.48 mA mgMetal-1/1.93 mA cm-2, being a 1.94 and 2.38 times increase compared to those of the PtRu catalyst, respectively. Also, the Pt60Ru20Ni20/C catalyst possesses superior CO-tolerance and durability in strongly acidic electrolytes. This work suggests that optimizing the surface strain and electronic effects can boost the overall MOR efficiency of multicomponent Pt-based materials, which can help to further develop next-generation catalysts for energy conversion-related technologies.

Rational design of a CoFe-prussian blue analogue-derived three-dimensional ternary nanocatalyst with efficient ORR/OER catalytic performance for Zn-air batteries

To effectively alleviate the aggregation of catalytic active sites, the rational design and simple preparation of a nanocatalyst with an ideal configuration plays a decisive role. Herein, a CoFe-prussian blue analogue (PBA) decorated with composite carbon/nitrogen sources (C/Ns) is prepared as the precursor to synthesize a three-dimensional (3D) ternary nanocomposite by a two-step calcination method. In this 3D nanocomposite, the 0D CoFe alloy nanoparticles derived from the PBA are mostly embedded in 1D N-doped carbon nanotubes (NCNTs) and partially loaded on 2D N-doped carbon nanosheets. Accordingly, the aggregation of alloy nanoparticles is greatly alleviated while a 3D nanostructure with large specific surface area, porosity, good electron transport properties and exposed active sites can be formed. The alloy nanoparticles are excellent electrocatalysts for oxygen reduction/oxygen evolution reactions, while also facilitating the formation of conductive NCNTs. Density Functional Theory calculations confirm the synergy between the Fe, N doped carbon and (110) crystal plane of the CoFe alloy that accounts for the electrocatalytic activity. The assembled Zn-air batteries show an open circuit voltage of 1.510 V, power density of 196.1 mW cm−2 and an operational durability of 300 h. Moreover, the assembled all-solid-state batteries display the potential for practical applications. This work demonstrates that the configuration of the electrocatalyst can significantly affect its catalytic performance.

Ligand-free synthesis of PtPdCu ternary nanostructures with controllable morphologies for efficient methanol oxidation

Nanocatalysts prepared by the ligand-free synthesis method generally exhibit superior catalytic activity due to the absence of ligand interference. Nevertheless, the morphologies of nanocatalysts and the components, particularly for ternary nanoalloys, in ligand-free synthesis are challenging to regulate. In this work, we successfully fabricated a range of ligand-free PtPdCu ternary nanocatalysts with controlled morphologies and sizes employing the Cu2O template sacrificial method while precisely adjusting the components of Pt, Pd, and Cu. The synthesized PtPdCu ternary nanocatalysts have two types: PtPdCu ternary nanodendrites with varied sizes, and PtPdCu ternary nanoboxes with different arm thicknesses. In all the synthesized PtPdCu nanocatalysts, the molar ratio of Pt/Pd is maintained at 1/3, and the proportion of Cu in the ultimate nanocatalysts is positively correlated with the proportion of the initial Cu2O. Due to the synergistic ternary composition, distinct morphology, and unique surface electronic configuration of PtPdCu ternary nanocatalysts, they show significantly enhanced activity and stability for the methanol oxidation reaction. This paper provides novel insights into the ligand-free synthesis of morphology-regulated and multi-component-controlled nanocatalysts, which can be used for high-performance catalysis.

Graphene-based strontium niobate-zinc oxide heterojunction photocatalyst for effective reduction of hexavalent chromium

A hydrothermal technique was employed to synthesize a Sr2Nb2O7-rGO-ZnO (SNRZ) ternary nanocatalyst, in which ZnO and Sr2Nb2O7 were deposited on reduced graphene oxide (rGO) sheets. The surface morphologies, optical properties, and chemical states, of the photocatalysts were characterized to understand their properties. The SNRZ ternary photocatalyst was superior over the reduction of Cr (VI) to harmless Cr (III) compared to the efficiencies obtained using bare, binary, and composite catalysts. The effects of various parameters, including the solution pH and weight ratio, on the photocatalytic reduction of Cr (VI) were investigated. The highest photocatalytic reduction performance (97.6%) was achieved at pH 4 and a reaction time of 70 min. Photoluminescence emission measurements were used to confirm efficient charge migration and separation across the SNRZ, which improved the reduction of Cr (VI). A feasible reduction mechanism for the SNRZ photocatalyst is proposed. This study presents an effective, inexpensive, non-toxic, and stable catalyst, for the reduction of Cr (VI) to Cr (III) using SNRZ ternary nanocatalysts.

Green approach for the fabrication of a ternary nanocatalyst (Ag-ZnONPs@Cy) for visible light-induced photocatalytic reduction of nitroarenes to aminoarenes.

In recent times, the incorporation of metal oxide nanoparticles with organic dyes has piqued the interest of numerous researchers due to their diverse applications under visible light instead of UV radiation. This investigation employed a three-step methodology to fabricate cyanidin-sensitized silver-doped zinc oxide nanoparticles (Ag-ZnO@Cy). Initially, cyanidin dye was extracted from fresh black mulberry fruit, followed by the eco-friendly synthesis of Ag-ZnO nanoparticles (Ag-ZnONPs). The successful integration of the prepared cyanidin dye with Ag-ZnONPs was achieved through a straightforward, environmentally benign, and cost-efficient procedure. The resultant ternary composite underwent comprehensive characterization and confirmation utilizing various techniques, such as SEM, FT-IR, EDX, DRS, elemental mapping, and XRD. The experimental results for Ag-ZnONPs@Cy demonstrated that the nanocrystalline wurtzite exhibited spherical shapes with an average crystal size of 27.42 nm. Moreover, the photocatalytic activity of the synthesized Ag-ZnONPs@Cy was meticulously investigated under blue LED light irradiation. This inquiry encompassed examinations of catalyst amount, regeneration, stability, reusability, and the influence of light source on the hydrogenation of nitroarenes to the corresponding aminoarenes. The findings shed light on the potential of this composite for diverse photocatalytic applications.

Towards effective dye degradation and antimicrobial behavior of chitosan and C3N4-doped CdS nanoparticles

In this study, co-precipitation has been employed to develop carbon nitride (C 3 N 4 ) and chitosan (CS)-doped CdS nanoparticles (NPs) to investigate the doping effect of CS and C 3 N 4 on CdS to degrade MB dye and assess their antibacterial activity. Comparatively, the maximum dye degradation achieved by the previously reported binary blend of CdS-C 3 N 4 was 85%, whereas the maximum degradation achieved by the currently prepared ternary nano-catalyst was 99.75%. Furthermore, CdS NPs were doped with a fixed amount of CS at various concentrations (2 and 4 wt. %) of C 3 N 4 . Numerous techniques have been utilized to characterize doped NPs. The hexagonal phase of CdS was confirmed by XRD results, and doping caused a decrease in crystallite size, as calculated by the Debye Scherrer formula. Functional group existence was determined by FTIR; CdS was confirmed at 662 and 758 cm −1 , and doped CdS exhibited bond stretching and absorption at 1061, 1388, 1627, and 3434 cm -1 . The UV-Vis absorption spectra with blueshift after doping resulted in increased bandgap energy, which could be attributed to a reduction in crystallite size. PL spectra were utilized to observe the charge carrier transfer and trap sites of doped NPs. The presence of CdS formation and doping was observed using EDS. The morphology of the product was examined using HRTEM, which revealed spherical NPs agglomeration. C 3 N 4 -doped NPs demonstrated significant methylene blue (MB) dye degradation, while doped CdS samples exhibited considerable antimicrobial activity against Staphylococcus aureus and Escherichia coli bacteria.

BN/Fe3O4/MIL-53(Fe) ternary nanocomposite for boosted ibuprofen degradation by visible light assisted photocatalytic activation of persulfate

In this paper, ternary nanocatalysts BN/Fe3O4/MIL-53(Fe) (BNCFe) were derived from ion-based metal organic framework (MIL-53(Fe)) and boron nitride (BN) composites through calcination, and used for the photocatalysis of ibuprofen (IBP) with the addition of persulfate (PS). After calcination, the obtained BNCFe composites had roughly surface structure, larger aperture and narrower band gap compared with BN/MIL-53(Fe), which could improve the photocatalytic performance of the composites. The coexistence of BN, Fe3O4 and MIL-53(Fe) in the synthesized catalyst was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characteristics. BNCFe composites obtained at calcination temperature of 350 °C showed the best catalytic activity and the degradation efficiency of IBP reached 100% within 180 min. The addition of HCO3− hindered the decomposition of IBP, while Cl− promoted the degradation efficiency of IBP at low concentration and inhibited it at high concentration. In addition, quenching experiments and electron spin resonance results showed that three strong oxidizing free radicals (O2·−, ·OH and SO4·−) played a crucial role in the photocatalytic process. Finally, the distribution of electrostatic potential showing that the side chain was the most easily attacked sites of free radicals, and the reasonable degradation pathways of IBP were proposed based on the intermediate product analysis and density functional theory (DFT) calculations. It was expected that this BN/Fe3O4/MIL-53(Fe) (BNCFe) ternary heterojunction photocatalyst would be a promising candidate for IBP treatment.

Nonthermal Plasma‐Modified Carbon‐Carrying Sn‐Based Ternary Nanocatalyst for High‐Performance Direct Dimethyl Ether Fuel Cells

A Vulcan XC72 carbon‐supported Sn‐based ternary metal catalyst (Pt3Pd3Sn2/C) is reported to have yielded the highest specific power density (90 mW mg−1 PGM) as compared with other catalysts tested for direct dimethyl ether (DME) fuel cells. However, the micropores present in Vulcan XC72 limit fuel utilization by causing Pt agglomeration. Vulcan XC72 composed of nongraphitized carbon species is also prone to corrosion. Therefore, herein, carbon supports such as multiwalled carbon nanotubes (MWCNT), black pearl 2000 (BP2000), and their cold N2 plasma‐treated counterparts are tested to further enhance the activity of the catalyst and systematically describe the comparative advantages over the Vulcan XC‐72 carbon. Electroanalytical tests show that Pt3Pd3Sn2/BP2000 exhibit excellent performance in terms of electrochemical active surface area, peak current density, and DME oxidation charge. A beneficial effect of plasma activation on the activity is observed only in the case of MWCNT while having no or negative effect on the other carbons. Laboratory fuel cell test indicates that Pt3Pd3Sn2 nanoparticles supported on optimized binary carbon support containing 75% plasma‐activated MWCNT and 25% BP2000 (Pt3Pd3Sn2/75M25B) provides the highest reported power density of 117 mW mg−1 PGM at 70 °C fuel cell temperature and ambient pressure.

Cathodic Pd1-XNiX Nanocatalyst Development for Alkaline Fuel Cell Applications

Alkaline fuel cells are a versatile, low-emission alternative energy source for use in transportation, as well as for portable and stationary power applications. These systems use chemical energy from the electrochemical conversion of hydrogen and oxygen gas to produce electrical energy, with only water and heat as by-products. They operate through two interdependent redox reactions within the cell consisting of oxidation of hydrogen fuel at the anode and reduction of oxygen at the cathode. One of the most significant barriers that fuel cells face is the sluggish nature of the oxygen reduction reaction (ORR) and its dependence on platinum (Pt), a rare and costly metal, as a catalyst for the reaction. Through the development and optimization of the structures and materials, the amount of precious metal catalyst can be decreased without sacrificing performance and enabling an increase in the commercial viability of the device.An alternative cathode material is palladium (Pd), which possesses similar chemical properties to Pt but is more stable in alkaline media and available in a greater abundance. Additionally, the catalytic ability of Pd is comparable to that of Pt, but due to the electronic structure of Pd, it bonds oxygen to a stronger extent, leading to a reduced activity. Theoretical analyses of the Pd electronic structure have shown that tuning the metal d-band decreases the oxygen-metal adsorption strength and increases the catalytic ability.1 Tuning of the metal d-band can be achieved experimentally through the addition of ancillary metals, thus altering the electronic structure of the catalyst. Furthermore, volcano trends of metal alloys in acidic media have shown a significant increase in activity when plotted against the oxygen adsorption strength.2 The increase in activity is particularly evident when Pt, for example, is alloyed with ancillary nickel (Ni). Due to the decreased stability of Pt in alkaline media, this study aims to assess the variations in activity of Pd through the addition of varying amounts of Ni. The incorporation of Ni increases the Pd utilization and incorporates a more cost-effective and abundant transition metal, enabling a decrease in the amount of precious metal required for the catalyst. Furthermore, the use of nanoparticles as the basis for the cathode catalyst creates a high surface area on which the ORR can occur. Nanoparticles allow for a more efficient use of the catalyst materials and, consequently, decrease the amount of metal required and the overall cost of the catalyst.This study assesses the viability of palladium-nickel nanocatalysts synthesized using a water-in-oil microemulsion3 method. The synthetic method was optimized to produce small, well-dispersed nanoparticles with a narrow size distribution ideal for the ORR. Furthermore, the synthesis was tuned to produce the desired ratios of Pd to Ni to determine an optimal composition for increased catalytic performance. The analysis of these nanocatalysts includes assessing the relationship between their composition, structure, and function using a combination of electrochemical and microscopy techniques. The results demonstrate a promising catalytic activity, indicating a comparable performance for all compositions. The consistent performance allows for a significant decrease in the precious metal content through the replacement with a more abundant and cost-effective metal. Further studies are being carried out to better understand the stability of these materials in alkaline media under a range of operating conditions relevant to the ORR. These studies aim to enhance the durability and to increase the overall viability of the catalyst. B. Hammer, J.K. Nørskov, Theoretical surface science and catalysis - calculations and concepts, Adv. Catal. 45 (2000) 71-129.A. Holewinski, H. Xin, E. Nikolla, S. Linic, Identifying optimal active sites for heterogeneous catalysis by metal alloys based on molecular descriptors and electronic structure engineering, Curr. Opin. Chem. Eng. 2 (2013) 312-319.S. Lankiang, M. Chiwata, S. Baranton, H. Uchida, C. Coutanceau, Oxygen Reduction Reaction at Binary and Ternary Nanocatalysts Based on Pt, Pd and Au. Electrochim. Acta. 182 (2015) 131–142.

Photocatalytic activity of ZrO2/TiO2/Fe3O4 ternary nanocomposite for the degradation of naproxen: characterization and optimization using response surface methodology

In this study, ZrO2, TiO2, and Fe3O4 components were synthesized by co-precipitation, sol–gel, and co-precipitation methods, respectively. In addition, solid-state dispersion method was used for synthesizing of ZrO2/TiO2/Fe3O4 ternary nanocomposite. The ZrO2/TiO2/Fe3O4 nanocomposite was characterized by different techniques including XRD, EDX, SEM, BET, FTIR, XPS, EELS, and Photoluminescence (PL). The FTIR analysis of ZrO2/TiO2/Fe3O4 photocatalyst showed strong peaks in the range of 450 to 700 cm−1, which represent stretching vibrations of Zr–O, Ti–O, and Fe–O. The results of FTIR and XRD, XPS analyses and PL spectra confirmed that the solid-state dispersion method produced ZrO2/TiO2/Fe3O4 nanocomposites. The EELS analysis confirmed the pure samples of Fe3O4, TiO2 and ZrO2. The EDAX analysis showed that the Zr:Ti:Fe atomic ratio was 0.42:2.08:1.00. The specific surface area, pores volume and average pores size of the photocatalyst were obtained 280 m2/g, 0.92 cm3/g, and 42 nm respectively. Furthermore, the performance of ZrO2/TiO2/Fe3O4 nanocomposite was evaluated for naproxen removal using the response surface method (RSM). The four parameters such as NPX concentration, time, pH and catalyst concentration was investigated. The point of zero charge of the photocatalyst was 6. The maximum and minimum degradation of naproxen using photocatalyst were 100% (under conditions: NPX concentration = 10 mg/L, time = 90 min, pH = 3 and catalyst concentration = 0.5 g/L) and 66.10% respectively. The stability experiment revealed that the ternary nanocatalyst demonstrates a relatively higher photocatalytic activity after 7 recycles.

Reduced graphene oxide-assisted graphitic carbon nitride@ZnO rods for enhanced physical and photocatalytic degradation

Herein, ternary nano photocatalysts of reduced graphene oxide assisted graphitic carbon nitride and zinc oxide were investigated to degrade the hazardous methylene blue (MB) dye in aqueous solution. The ternary nanocatalyst, rGO@g-C3N4/ZnO, showed increased photocatalytic MB degradation of 91.5% under visible light after 70 min compared with ZnO (55.31%), g-C3N4 (16.83%), and g-C3N4/ZnO (73.83%). MB degradation could be altered by changing the experimental conditions. The catalyst dosage and irradiation time were varied, and changes in the rGO@g-C3N4/ZnO degradation efficiency were observed. In addition to the experimental observations, a theoretical prediction of MB degradation was proposed through response surface methodology, and a preliminary equation was identified. A photocatalytic degradation mechanism that explained the role of rGO and g-C3N4 to enhance the photocatalytic efficiency of rGO@ g-C3N4/ZnO was also proposed based on the experimental results and theoretical modeling. The optical, structural, and chemical state and the surface morphology were also investigated, and the findings support the suggested photocatalytic mechanism. The findings of this study could be useful for applying nanocatalysts to degrade organic dyes.

CO hydrogenation reaction on Fe–Co–Mn nanocatalyst: impact of support and process conditions on performance and structure

AbstractThe hydrothermal method was used in order to prepare Fe–Co–Mn nanocatalysts. The prepared specimens were evaluated for the CO hydrogenation reaction. The impact of different kinds of supports such as Al2O3, SiO2, ZSM5, TiO2, MgO, ZSM5–Al2O3, ZSM5–TiO2, Al2O3–TiO2, Al2O3–SiO2, SiO2–ZSM5 and Al2O3–MgO on the behavior and structural characteristics of the Fe–Co–Mn ternary nanocatalysts was investigated. Evaluation of these various supported samples was performed under the same process conditions. Al2O3‐supported sample showed better performance for light olefin production chosen as an optimum sample. Furthermore, the influence of a change of support type on the rate of surface reactions was studied. The impact of operating parameters was also investigated, with the conditions of T = 623 K, P = 2 bar and H2/CO = 2 determined as the optimum reaction conditions. Catalyst characteristics were defined using a variety of methods. © 2021 Society of Chemical Industry (SCI).

Microwave-assisted sol–gel synthesis of TiO2-mixed metal oxide nanocatalyst for degradation of organic pollutant

Abstract Titanium dioxide (TiO2) is the most effective photocatalysts for low-cost degradation of organic pollutant; however, the wide band gap and the high recombination rate of the charge carriers are drawbacks that hinders it practical application. In this study, TiO2 and titanium mixed metal oxides ternary (V/Ag/TiO2) nanocatalyst was synthesized through a microwave-assisted sol–gel route using Ti(C4H9O)4, NH4VO3, and AgNO3 as precursors. The XRD analysis of the synthesized TiO2 and V/Ag/TiO2 depicts lattice fringes for rutile and anatase crystalline phases. Raman spectra indicate the formation of a mesoporous multiphase sample mixture of rutile and anatase phases. The spectrum shift to the visible light region was demonstrated by the UV-visible spectroscopy analysis. Diffuse reflectance spectroscopy (DRS) reveals a reduced band gap of 2.9 eV for TiO2 and 2.65 eV for V/Ag/TiO2. Brunauer–Emmett–Teller (BET) indicates a large surface area of 92.8 and 84.8 m2 g−1 for TiO2 and V/Ag/TiO2, respectively. Nitrogen adsorption–desorption isotherm exhibits type IV isotherm, signifying the presence of the mesoporous structure. SEM portrays a cluster of rod-like aggregate particles, while the HRTEM analysis illustrates nanoparticles of rod-like cylindrical shape with a homogeneous size diameter. The synthesized nanocatalyst demonstrated a significant photocatalytic ability in the degradation of methyl orange (MO) and methylene blue (MB). V/Ag/TiO2 shows higher activity in the visible region. Thus, the present report suggests efficient, suitable, and economical microwave-assisted sol–gel techniques to yield V/Ag/TiO2 nanocatalysts with harnessed photocatalytic performance for the degradation of toxic organic pollutants in the presence of visible light irradiation.

Ternary mixed-oxide synergy effects of nano TiO2-FexOy-MOk (M = Mn, Ce, Co) on α-pinene catalytic oxidation process assisted by nonthermal plasma

Biomass fuel from plant waste is an important substitute for fossil fuels. The odorous volatile organic compounds (VOCs) is released during the drying process of biomass, which causes harm to the ecological environment and human health. The α-pinene is a typical odorous VOC generating during plant waste drying. Ternary nanocatalyst composed of TiO2, Fe x O y and MO k (M = Mn, Co, Ce) was manufactured by ultrasonic assisted hydrothermal process. The α-pinene catalytic oxidation property of ternary nanocatalysts were investigate in a dielectric barrier discharge reactor assisted by nonthermal plasma. The pore structure parameters of ternary nanocatalysts were observed qualitatively and analyzed quantitatively by transmission electron microscopy (TEM) and N2 adsorption test, respectively. The phase composition and active element valence of these three kinds nanocatalysts were analyzed and compared by X-ray diffraction (XRD) and X-ray Photoelectron spectroscopy (XPS). The test data showed TiO2-Fe x O y -CoO k ternary nanocatalyst had more complete microporous and mesoporous pore structure, better element dispersion and stronger redox performance. Meanwhile, TiO2-Fe x O y -CoO k sample had the best performance with α-pinene catalytic conversion achieving 83.3% and CO2 selectivity higher than 90% at specific energy density (SED) of 620 J·l−1, which was almost half of the energy consumption of single non-thermal plasma catalytic reaction during the nonthermal plasma-catalyst (NTP-C) synergistic catalytic activity experiments. At the same time, the ternary nanocatalysts could obviously reduce the generation concentration of O3 and NO x in the process of α-pinene catalytic oxidation. The synergy effect between TiO2, Fe x O y and CoO k was better than that of TiO2, Fe x O y and CeO k or MnO k . It could be expected as an effective method to improve the redox performance of ternary nanocatalysts by optimizing the microstructure and elemental composition, which would also be a promising way to enhance odorous VOCs catalytic oxidation efficiency and reduce the energy consumption in the NTP-C synergistic catalytic system.

Assessment of composition and calcination parameters in Fischer-Tropsch synthesis over Fe–Mn–Ce/γ-Al2O3 nanocatalyst

The effects of nanocatalyst composition and calcination parameters on the performance of the Fe–Mn–Ce ternary nanocatalysts supported on alumina granules in a laboratory fixed bed microreactor have been evaluated. Nanocatalysts were synthesized by incipient wetness impregnation under vacuum method (simultaneous impregnation of metal species). The samples used for hydrogenation of carbon monoxide via Fischer-Tropsch synthesis. The optimum nanocatalyst composition for production of light olefins (C=2 – C=4) from synthesis gas is 75 wt%Fe–20 wt%Mn–5 wt%Ce. The calcination parameters (temperature, time and atmosphere) were investigated and their effects on the structure and performance of the nanocatalysts were determined. The maximum ratio of olefins/(methane + paraffin) and the best activity and selectivity belonged to the nanocatalyst which was calcined in static air at 500 °C for 7 h. The nanocatalyst precursors and calcined samples (fresh and used) were characterized by XRD, N2 physisorption, FE‒SEM, EDAX, MAP, TG, DSC, and H2–TPR. The present study results confirm that the structural, morphological and physic-chemical properties of the nanocatalyst have been impressed with metal species and calcination parameters.