Catalytic Oxidation Properties Research Articles

Cerium/sulfur co-doped spinel iron-cobalt oxide@carbon interconnected mesh networks as superior peroxymonosulfate activator for tetracycline degradation

Transition metal spinel oxides have potential applications in activating peroxymonosulfate (PMS) to generate reactive substances for degrading organics in polluted water. However, many catalytic materials have low efficiency, indicating the need for advancements in material design. In this study, we present the one-step fabrication of Ce, S-codoped spinel iron-cobalt oxide@carbon (Ce-FeCo2O4@SxC) with interconnected mesh networks for efficient PMS activation in degrading tetracycline hydrochloride (TCH). Among the Ce-FeCo2O4@SxC samples, Ce-FeCo2O4@S1.5C demonstrates the highest catalytic performance, achieving a TCH degradation efficiency of 97.2 % in 30 min. Moreover, the catalytic system also exhibits anti-interference abilities against various anions and shows universality in degrading organic pollutants. Characterization and experimental tests confirm the co-existence of radical (SO4•−, •OH and O2•−) and non-radical pathways (1O2 and direct electron transfer), with 1O2 identified as the primary reactive species. Three plausible pathways for TCH removal are proposed based on detected intermediate products. Toxicity evaluation reveals a significant reduction in the toxicity of the original TCH solution during the degradation process with the PMS activator. This study introduces a simple yet effective co-doping strategy to enhance the catalytic properties of spinel oxides for PMS activation in degrading organic contaminants in aquatic environments.

Nickel oxide electroplating and electrode surface modification for electrochemical detection of glutamate

The electrochemical behavior and catalytic properties of nickel oxide (NiOx) are enhanced through cathodic electroplating and subsequent electrochemical activation in an alkaline aqueous electrolyte. The electrochemical detection of ʟ-glutamate becomes feasible by introducing an amine group through immobilizing APTES ((3-aminopropyl)triethoxysilane) on the NiOx surface, resulting in a positive charge. The synergistic effect of electrochemically activated electroplated NiOx and the APTES-modified surface facilitates the effective electrochemical detection of trace ʟ-glutamate. The APTES-activated NiOx electrode exhibits a linear detection range of 0.2 nM to 2 mM for glutamate. This relatively wide concentration range is promising for the analysis of human biological fluids.

Enhancing the catalytic properties of a biochar-supported copper oxide in nitric oxide selective reduction with hydrogen

Enhancing the catalytic properties of a biochar-supported copper oxide in nitric oxide selective reduction with hydrogen

Delafossite CuGaO2-Based Chemiresistive Sensor for Sensitive and Selective Detection of Dimethyl Disulfide.

Dimethyl disulfide (DMDS) is a common odor pollutant with an extremely low olfactory threshold. Highly sensitive and selective detection of DMDS in ambient humid air background, by metal oxide semiconductor (MOS) sensors, is highly desirable to address the increased public concern for health risk. However, it has still been a critical challenge up to now. Herein, p-type delafossite CuGaO2 has been proposed as a promising DMDS sensing material owing to its striking hydrophobicity (revealed by water contact angle measurement) and excellent partial catalytic oxidation properties (indicated by mass spectroscopy). The present CuGaO2 sensor shows a selective DMDS response, with satisfied humidity resistance performance and long-term stability at a relatively low operation temperature of 140 °C. An ultrahigh response of 100 to 10 ppm DMDS and a low limit of detection of 3.3 ppb could be achieved via a pulsed temperature modulation strategy. A smart sensing system based on a CuGaO2 sensor has been developed, which could precisely monitor DMDS vapor in ambient humid air, even with the presence of multiple interfering gases, demonstrating the practical application capability of MOS sensors for environmental odor monitoring.

Monodispersed ZIF-67 in situ nucleated on CoAl-LDH nanosheets for efficient carbamazepine degradation via activation of peroxymonosulfate

Abundant exposed ligand-unsaturated sites of Co have been found to enhance the catalytic oxidation property of ZIF-67 material for peroxymonosulfate (PMS) catalysis. Nevertheless, serious stacking of ZIF-67 still poses a challenge to its application. Herein, we employed a specific in situ growth strategy to establish an LDHNS@ZIF-67 composite based on morphology modulation and performance optimization for carbamazepine (CBZ) degradation. ZIF-67 crystals were successfully grown in situ via nucleating on the CoAl-LDH nanosheets (LDHNSs) substrate surface, which facilitated the crystals’ dispersion. LDHNS@ZIF-67 (0.1 M) was optimized to display outstanding PMS catalytic activity for CBZ degradation, with almost 100% degradation in 5 min (PMS dose, 0.2 mM, catalyst dose, 25 mg/L, and CBZ concentration, 5 ppm). Quenching and electron paramagnetic resonance (EPR) tests confirmed that both radical substances (SO4•-) and nonradical substances (1O2) dominated the reaction system. As the active site, Co(II) ions on the LDHNS@ZIF-67 (0.1 M) surface effectively promoted active substance formation. The intermediate degradation products and pathways for CBZ were investigated. Toxicity assessment for CBZ and its intermediates was conducted. This work will broaden the application of ZIF-67 materials in advanced oxidation process design based on persulfate.

Kinetic Analysis of the Non‐Monotonic Response of Ethene Hydrogenation Rates to Ceria Surface Reduction

The precise effect of oxide understoichiometry on bulk oxide catalytic properties continues to remain a subject of intense investigation. Of specific interest in this regard is the role of oxygen vacancies present on bulk ceria catalysts that have recently been reported to represent a more cost‐effective alternative to the more toxic and expensive catalysts used industrially for the selective hydrogenation of acetylene to ethylene. Contrasting claims as to the effect of surface reduction on hydrogenation rates exist in the open literature, with vacancy formation attributed, in separate studies, either a favorable or a deleterious role in effecting hydrogenation turnovers. We report here the non‐monotonic behavior of ethene hydrogenation rates that subsumes both of these trends as a function of degree of surface reduction over a sufficiently large range of pre‐reduction temperatures. Steady state transient kinetic and isotopic exchange data combined with in‐situ titration experiments suggest that this non‐monotonic trend can be attributed not to a change in either the kinetic relevance of specific elementary steps or the hydrogenation mechanism, but rather to site requirements that stipulate the need for two distinct, proximal sites.

VOx@ graphene electro-catalysts for water splitting and dopamine sensing

Vanadium oxide@graphene (VOG) composites were synthesized using facile hydrothermal method by varying the synthesis time from 6 to 24 h. The samples with best catalytic characteristics were reprepared by replacing graphene oxide with N-doped graphene in the initial hydrothermal reaction. The role of graphene/N-doped graphene in determining the catalytic properties of vanadium oxide was effectively studied using various characterizations viz. X-ray diffraction, Fourier Transform Infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Maximum hydrogen evolution reaction (HER) activity with high current density of –31.07 mA/cm2 (Tafel slope = 162 mVdec−1) has been achieved for VONG-24 sample, indicating Volmer reaction as rate determining step. The high electrochemical surface area (ECSA) of VOG-24 sample in 1 M KOH corroborated the enhanced current density of 144.90 mA/cm2 (Tafel slope = 83 mVdec−1) for maximum oxygen evolution reaction (OER) activity. The VOG12/GCE sample with a 0.29 μM limit of detection (LOD) proved to be the best electrochemical sensor for dopamine (DA) in a wide linear detection range i.e., 1–150 μM. Both catalytic as well as sensor responses of VOG samples were deeply influenced by the amount of O-species along with relative ratios of the V3+, V4+ and V5+. The nature of the graphene in the initial mixture emerged as a crucial parameter in tailoring the vanadium valence state content in the composites.

CHEMISORPTION-CATALYTIC PROPERTIES OF ZINC OXIDE IN THE PROCESS OF REDUCTION OF PROPYL MERCAPTAN

In this work, the adsorption and catalytic properties of zinc oxide, which it exhibits in the process of desulfurization of propyl mercaptan, are studied. It is shown that zinc oxide obtained by ammonia-carbonate technology has a specific surface area of 40.34 m2/g. Nitrogen adsorption-desorption isotherms refer to type IV according to the IUPAC classification, which is typical for mesoporous materials. The calculation of the pore size distribution shows that ZnO contains pores with a diameter of 2 to 40 nm. The characteristics of the chemisorption-catalytic activity of zinc oxide are given. It has been established that during the catalytic reduction of C3H7SH with hydrogen, the formation and absorption of H2S with the formation of zinc sulfide occur. In this case, depending on the time of operation, there is a gradual decrease in the average size of crystallites of the ZnO phase and an increase in the size of crystallites of the zinc sulfide phase. The study of catalytic activity in the hydrogenation reaction of propyl mercaptan with hydrogen was studied during the full cycle of ZnO operation at temperatures of 350 and 400 °C in a flow-type installation. The stages of the process of interaction of the components of the gas mixture (propyl mercaptan and hydrogen sulfide) with zinc oxide are revealed. It is shown that in the initial period of ZnO operation, intense absorption of hydrogen sulfide occurs with the formation of a zinc sulfide phase. The appearance of hydrogen sulfide at the outlet of the catalytic reactor is fixed after 100-200 min of operation. The second stage is characterized by a rapid increase in the concentration of hydrogen sulfide at the outlet of the catalytic reactor with a simultaneous decrease in the concentration of propyl mercaptan. The third stage occurs after 450-550 min of operation and is characterized by the constancy of the composition of the gas mixture at the outlet of the reactor.

Dual Pt atoms stabilized by an optimized coordination environment for propane dehydrogenation

Tailoring atomically dispersed catalysts by various methods has been the subject of intense current research in heterogeneous catalysis. In this work, the structural stability and propane dehydrogenation performance of Pt-TiO2 catalysts with single, dual, and triple Pt atoms doped on the reduced TiO2 surface have been examined. Experimental results indicate the atomically dispersed Pt is thermally very stable and shows exceptionally high activity (TOFpropane = 4.93 s−1) and selectivity (∼98.5 %) for the dehydrogenation reaction. The recently developed machine-learning-based SSW-NN method is then employed to explore the global potential energy surface of the atomically dispersed Pt atom-doped TiO2, which suggests that the single and dual Pt atoms can be tightly held by the vacancies created on the reduced transition-metal oxide, as confirmed by DFT + U calculated energetics. After that, advanced characterization techniques are used in conjunction with microkinetic analysis to establish the quantitative structure–activity relationships. It is found that the dual-Pt-atom structure with two Pt atoms embedded in adjacent Ti and O vacancies is the only active ensemble that dramatically promotes the CH bond activation and hydrogen recombination, as compared to single Pt atoms accommodated by either Ti or O vacancies. These results provide new and direct evidence in support of the idea that specific function can be imparted to specific active sites by tuning their coordination environments, which makes it possible to tailor the catalytic properties of metal oxides to a particular reaction such as propane dehydrogenation.

Effect of Mn2+ substitution on catalytic properties of Fe3-xMnxO4 nanoparticles synthesized via co-precipitation method

Mn-substituted magnetite samples Fe3-xMnxO4 (x = 0.0; 0.02; 0.05; 0.1; 0.15; 0.2; 0.25) were synthesized using the co-precipitation method. X-ray diffraction patterns confirmed the formation of pure, well-crystallized manganese ferrite with a cubic spinel structure. The crystallites size increases sharply for the minimum degrees of substitution, with a subsequent tendency to decrease with the growth of manganese ions content. The catalytic properties of Fe3-xMnxO4 were investigated for the degradation of oxytetracycline (ОТС) and inactivate E. coli. There is a correlation between particle size and catalytic activity. The Fe2.95Mn0.05O4 sample exhibited the highest catalytic activity in the destruction of OTC. The effect of electromagnetic heating (EMH) on the catalytic properties of iron oxides were investigated. The Fe2.9Mn0.1O4 sample with electromagnetic heating achieved 100 % efficiency in decomposing 5 mg/L of OTC. Fe3-xMnxO4 samples reduce the number of Gram-negative bacteria E. coli at concentrations of 104 and 106 CFU/mL. Electromagnetic heating experiments demonstrated high performance, achieving inactivation of 6 logs of E. coli in the presence of Fe2.98Mn0.02O4 and Fe2.95Mn0.05O4 catalysts within 135 minutes. Studies on ecotoxicity have shown that Daphnia magna is a sensitive bioindicator of residual H2O2 concentration. An increase in the Mn2+ content in the synthesized catalysts resulted in a decrease in the toxicity of purified water. The study suggests that Mn-substituted magnetite catalysts are effective materials for catalytic decomposition of OTC and inactivation of E. coli bacteria.

Synthesis of Mixed La–Al Oxides by Treatment in a Water Fluid Medium and Their Catalytic Properties in Methane Oxidation

Synthesis of Mixed La–Al Oxides by Treatment in a Water Fluid Medium and Their Catalytic Properties in Methane Oxidation

Catalytic oxidation properties of 3D printed ceramics with Bouligand structures

Catalytic oxidation properties of 3D printed ceramics with Bouligand structures

Ethanol-Coordinated Dioxidomolybdenum(VI) Complexes with Aroylhyrazone Ligands: Synthesis, Spectroscopic Characterization, Crystal structures and Catalytic Oxidation Property

Two new dioxidomolybdenum(VI) complexes, [MoO2L1(EtOH)] (1) and [MoO2L2(EtOH)] (2), derived from the aroylhydrazone ligands N’-(2-hydroxyl-3-methoxybenzylidene)-3-methylbenzohydrazide (H2L1) and 4-fluoro-N’-(2-hydroxylbenzylidene) benzohydrazide (H2L2), respectively, were prepared in ethanol under ambient temperature. Both complexes were characterized by elemental analysis, IR and UV-Vis spectroscopy, as well as single crystal X-ray determination. The Mo atoms in the complexes are in octahedral coordination. Crystal structures of the complexes are stabilized by hydrogen bonds. The catalytic property for epoxidation of styrene by both complexes was studied.

Hydrogen production from biomass via moving bed sorption-enhanced reforming: Kinetic modeling and process simulation

This study explored a process intensification approach for hydrogen production through biomass gasification. Sorption-enhanced reforming (SER) in an autothermal countercurrent moving bed reformer is proposed as an alternative to multiple units traditionally required for syngas conditioning. This process utilizes the selective sorption and catalytic properties of calcium oxide to integrate multiple reforming reactions into a moving bed reactor. A multistage kinetic model was used to analyze and optimize the key operating parameters of the reformer. Results showed that the moving bed reformer completely converts all tars and increases the hydrogen concentration of syngas from 23 mol% to 80 mol% (dry basis). A comparison between equally sized models showed that the moving bed reformer outperforms a fluidized bed reformer under similar conditions. Simulation of the entire process showed that the hydrogen yield of the proposed SER process is 5% higher than the conventional process. In addition, the proposed process produces surplus electricity, while the conventional process has a 26% power deficit. The overall efficiency of the proposed process is 3.5% higher than the conventional process. The improved process efficiency, coupled with the potentially lower costs of a streamlined process, indicates that the proposed process is a promising route for green hydrogen production.

Fluorine-doped and carbon-coated porous SnO2-NiO composite as a high performance anode material for lithium ion batteries

A novel fluorine-doped porous SnO2-NiO@C-F (SNCF) composite anode material was synthesized by NaCl template method through high-energy ball milling and calcination under nitrogen atmosphere. This pore-like structure promotes electrolyte penetration as well as provides good intergranular electrical contact, which shortens the Li+ transport distance of electrons and F doping enhances the loading of SnO2-NiO particles on the surface of carbon materials and enhances electron transport and Li+ diffusion in the composite. In addition, NiO with relatively small content and distribution along the carbon substrate can improve the irreversible decomposition process of Li2O due to the catalytic properties of Ni-based oxides. The encapsulated carbon can buffer the volume expansion and avoid the accumulation of active materials, thus improving the material properties. Hence, the porous SnO2-NiO@C-F composite has a large capacity of 989.2 mAh g−1 after 150 cycles at 0.2 A g−1, as well as a long-time cycling stability that still shows a capacity of 768.9 mAh g−1 after 1000 cycles at 1 A g−1. In addition, it has excellent rate property, reaching a capacity of 389.0 mAh g−1 even at 5 A g−1. Therefore, the porous SnO2-NiO@C-F is a prospering anode material for lithium ion batteries (LIBs).

Enhancement of the redox reactions of the La0.8Sr0.2MnO3 catalyst by surface acid etching: A simple synthesis strategy to high-performance catalysts for methane combustion

Methane emission and treatment is an extremely important environmental problem, and the key and core treatment method are the application and development of catalysts in the after-treatment system. In this study, a new non-noble metal catalyst, which named OALSM, was fabricated by etching La0.8Sr0.2MnO3 with oxalic acid for the removal of methane. Related experiments and theoretical explorations by scholars had shown that acid etching of perovskite surfaces could achieve effective optimization of the catalytic oxidation properties and microscopic physical and chemical properties of the materials. And the oxalic acid reacted with high-valence state Mn to generate abundant coordination unsaturated Mn3+ sites, which could produce more active oxygen species. In addition, OALSM showed a higher methane catalysis capability than the samples that were not subjected to acid etching. Among all the as-prepared catalysts, OALSM-0.01 M demonstrated the optimal methane catalytic activity with the T50 value of 336 °C, the T90 value of 417 °C, the activation energy of 47.02 kJ·mol−1, and the favorable structural stability and toxicity resistance. This integration strategy can rationalize an innovative protocol to into the design of composite catalysts for methane oxidation, to broaden the application of acid etching in VOC oxidation.

Revisiting the Low-Index Surfaces of LaCoO3 with a Passivation Strategy

A proper modeling is essential for calculating the surface properties of complex oxides, for example, perovskite oxides. Many studies have shown that traditional selections of slab models, either symmetric or asymmetric ones, may vary the calculated results of the polar surfaces, which will finally affect the perception of surface properties. To solve this issue, we proposed a passivation method to handle the complex polar surfaces, where the pseudo-atoms with fractional charges were used to balance non-zero net charges on one side of the surfaces. Based on this method, we revisited the low-index surfaces of LaCoO3, including (11̅02), (1̅104), and (0001) surfaces, with different terminations. The results suggested that the (11̅02)-LaO, (11̅02)-CoO2, and (0001)-LaO3 terminations were stable surfaces in different O and Co chemical environments. The oxygen vacancy formation energies (EOv) of the (11̅02)-LaO and (11̅02)-CoO2 terminations were also evaluated. Different from the unpassivated cases, the EOv of the passivated LaO and CoO2 terminations converged rapidly when slab thickness increased. The upward shift trend of the EOv after passivation was more consistent with the experimental results. The electronic structure analysis indicated that the oxygen vacancy mainly changed the valence state of the surrounding Co atoms. This work provides a more accurate calculation method, which may benefit the study on catalytic properties of complex oxides.

Ferric oxide nanosheet-engineered Mg alloy for synergetic osteosarcoma photothermal/chemodynamic therapy

• Fe 3 O 4 nanosheets were prepared on Mg alloy by transforming Mg-Fe LDH. • Fe 3 O 4 nanosheets are composed of dense nanoparticles. • Fe 3 O 4 nanosheets enhanced corrosion resistance and biocompatibility of Mg alloy. • Fe 3 O 4 nanosheet-engineered Mg alloy showed PTT/CDT synergetic antitumor property. Osteosarcoma (OS) is a malignant tumor with a high rate of recurrence. Recently, biodegradable Mg-based implants have become a new therapeutic platform for bone-related diseases. However, poor biosafety and deficient intelligent tumor-killing ability of Mg-based implants are still the main challenges for the precise treatment of OS. Herein, based on the excellent catalytic and photothermal conversion properties of nanozyme ferric oxide (Fe 3 O 4 ), a novel two-step hydrothermal method for in situ preparation of Fe 3 O 4 nanosheets on the surface of plasma electrolytic oxidation (PEO)-treated Mg alloy using Mg-Fe layered double hydroxides (Mg-Fe LDH) as precursor was proposed. Compared with Mg alloy, there were no obvious corrosion cracks on the surface of Fe 3 O 4 nanosheets-coated Mg alloy (Fe 3 O 4 -NS) immersed in 0.9 wt.% NaCl for 14 days, which demonstrated the corrosion resistance of Mg alloy was significantly enhanced. Cytocompatibility experiments and hemolysis assay confirmed the great biocompatibility of Fe 3 O 4 -NS, especially, hemolysis ratio was lower than 1%. Meanwhile, Fe 3 O 4 -NS presented excellent catalytic oxidation capacity in the presence of H 2 O 2 , and its temperature can significantly increase from 27 °C to approximately 56 °C under NIR irradiation. Therefore, intelligent responsive Fe 3 O 4 nanosheets-engineered Mg-based implants demonstrated excellent antitumor properties in vivo and in vitro due to their photothermal and chemodynamic synergetic effects. This study provides a novel approach for the preparation of Fe 3 O 4 coatings on the surface of Mg alloys and a new strategy for the treatment of OS.

Hydroxyl adsorption derived reactive oxygen species from carbon paper-supported Cu2O for enhanced electrochemical glucose sensing

Engineered sensitive copper nanostructured superelectrode systems have become an important part of electrochemical sensing of glucose because of their high sensitivity, specificity, abundant natural reserves, and environmental friendliness. However, the factors affecting the electrochemical catalytic activity of glucose remain a challenging issue, which largely limits the overall electrochemical sensing performance of glucose. This paper reports the design of a carbon fiber loaded cuprous oxide nanoparticle (Cu2O NPs) electrochemical sensor with electrochemical catalytic properties for glucose oxidation. The copper grown on carbon nanofibers was subjected to cyclic redox treatment to obtain Cu2ONPs with good glucose detection ability. The detection range of the prepared Cu2ONPs was 0.05 mM − 3 mM with a sensitivity of 3 mA mM−1 cm−2. The differences in the properties of copper and cuprous oxide are analyzed in depth and the reasons for the variability are explored. By observing the electrocatalytic behavior and oxygen evolution reaction behavior of the glucose oxidation process, we hypothesized that the difference in the oxygen source provided by hydroxyl adsorption would lead to the difference in the properties of cuprous oxide and copper. Our proposed differences in the oxygen source generated by hydroxyl adsorption affecting the performance of glucose detection will provide new ideas for the design of glucose electrochemical microelectrodes.

Catalytic oxidation properties of an acid-resistant cross-bridged cyclen Fe(II) complex. Influence of the rigid donor backbone and protonation on the reactivity.

The catalytic properties of an iron complex bearing a pentadentate cross-bridged ligand backbone are reported. With H2O2 as an oxidant, it displays moderate conversions in epoxidation and alkane hydroxylation and satisfactory ones in aromatic hydroxylation. Upon addition of an acid to the reaction medium, a significant enhancement in aromatic and alkene oxidation is observed. Spectroscopic analyses showed that accumulation of the expected FeIII(OOH) intermediate is limited under these conditions, unless an acid is added to the mixture. This is ascribed to the inertness induced by the cross-bridged ligand backbone, which is partly reduced under acidic conditions.