Bimetallic Oxide Research Articles

Cu–Ce Bimetallic Oxide Catalyst Regulates the Intermolecular Hydrogen Transfer Reaction of 5-Hydroxymethylfurfural

Cu–Ce Bimetallic Oxide Catalyst Regulates the Intermolecular Hydrogen Transfer Reaction of 5-Hydroxymethylfurfural

Self-standing 3D rose-like bimetallic oxides modified nitrogen-doped graphite aerogels as a robust catalyst for efficient oxygen evolution

FeNi bimetallic oxides are considered as a potential catalyst candidate material for efficient oxygen evolution. However, low conductivity, rapid structural collapse, and metal ion release always lead to electrochemical performance and poor stability, which become major challenges in the electrochemical process. Herein, we synthesized self-standing 3D rose-like bimetallic oxides modified nitrogen-doped graphite aerogels (FeNiOx@N/GA) by the facile layer-by-layer self-assembled method. The unique 2D/3D structure composed of 2D ultrathin graphene nanosheets decorated 3D microflowers can provide a large active area and a rapid charge transfer rate. Moreover, both oxidation and nitrogen doping can improve the reaction kinetics of the material, thereby exhibiting higher catalytic activity. FeNiOX@N/GA exhibits excellent oxygen evolution reaction (OER) performance (η10=291 mV) and low Tafel slope (39 mV dec−1) in the 1 M KOH. This work can be expected to provide a novel and valid method for rational design and manufacture of advanced bimetallic oxides-based positive electrode toward efficient OER. Meanwhile, FeNiOx@N/GA is loaded on nickel foam and displays good electrochemical properties as an air-cathode in Zn-Air battery, demonstrating outstanding practicability.

Enhanced catalytic influence of carbon-supported Ti/Co bimetallic oxide nanocomposites on combustion of AP/HTPB propellants

Development and application of solid rockets have put forward new requirements for the combustion performance of AP/HTPB propellants. Herein, carbon-supported Ti/Co bimetallic oxide (MTiCo) nanocomposites with carbon skeleton and porous structure were proposed to use as catalysts for improving the combustion performance of AP/HTPB propellants. For AP decomposition, MTiCo-2 (2.0 wt%) reduced the AP HD temperature by 93.1 °C and enhanced heat release by about 356.3 %. Simultaneously, MTiCo-2 (2.0 wt%) significantly decreased Ea of AP HD stage by 51.4 %. MTiCo-2 (2.0 wt%) also reduced the ignition delay of AP/HTPB propellant by 78.3 % and enhanced combustion rate by 192.0 %. The synergistic effect of catalysis and combustion support of MTiCo-2 provided by the structure of carbon-supported Ti/Co bimetallic oxide was the main mechanism for improving the combustion performance of AP/HTPB propellants.

Enhanced electrochemical disinfection for decentralized sewage treatment through nickel foam cathode modified with CoFe2O4-spinel ferrite and multi-way carbon nanotubes

Electrochemical disinfection is characterized by its simple operation and maintenance, along with effective sterilization capabilities, making it ideal for decentralized wastewater treatment in rural areas. As a bimetallic oxide, spinel ferrite exhibits excellent catalytic activity for the oxygen reduction reaction (ORR). Herein, a novel cathode was fabricated from nickel foam modified with spinel ferrite and multi-way carbon nanotubes (CoFe2O4-MWCNTs@NF). The modification successfully strengthens the electrochemical cathode reaction to generate strong oxidants such as hydrogen peroxide and Hydroxyl radical, enabling the disinfection of water bodies with low chloride concentrations. Compared to other influencing factors (including current density, aeration rate, and electrode spacing), the impact of conductivity on hydrogen peroxide generation is relatively minor. Modified electrodes still exhibited effective disinfection capabilities in water with low conductivity. At a current density of 2 mA/cm², the CoFe2O4-MWCNTs@NF electrode achieved 4.00 log removal of E.coli in real treated sewage within 15 minutes, with an energy consumption of 1.038 kWh/m³. Electrochemical disinfection also had a certain degradation ability for sulfonamides and quinolones antibiotics in water. The disinfection and antibiotic removal effects of the modified electrode demonstrated its potential for practical applications.

Promising antifungal behavior of biosynthesized bimetallic silver-copper oxide nanoparticles and Bacillus safensis against some strawberry rots

Promising nanomaterials combined with beneficial microbes contributed to bio-modulations that might increase yields. In order to combat several fungal infections that invade strawberries (Fragaria ananassa), this study assessed the interactions between the synthesized CuO NPs, bimetallic Ag–CuO NPs, and Bacillus safensis (BS-22) under various treatment circumstances. The effectiveness of BS-22, CuO NPs, and bimetallic Ag–CuO NPs against four different pathogens that cause gray mold disease and root rot on strawberry plants was determined. It was possible to successfully extract twenty-four endophytic bacterial isolates from hygienic strawberry plants that were indigenous. BS-22 isolate, which produced the most hydrogen cyanide (HCN), siderophores, gibberellic acid (GA3), and indole-3-acetic acid (IAA), was identified molecularly as Bacillus safensis. The most extensively studied treatments (foliar CuO NPs at 200 ppm + foliar Ag–CuO NPs at 200 ppm + BS-22) decreased the frequency and severity of black root rot disease in strawberry plants. Foliar CuO NPs (50 ppm) + foliar Ag–CuO NPs (50 ppm) showed significant increase of the total suspended solids (TSSs), total antioxidant capacity (TAC) content, and the total polyphenols content compared to the control and other treatments. The same treatment recorded the highest value in all characters of cell wall components except lignin character where BS-22 treatment had the best effect. All tested treatments significantly decreased disease incidence and severity when strawberry fruit stored at 22 °C ± 2 for 25 days on average. According to this study, foliar CuO NPs (200 ppm) + foliar Ag–CuO NPs (200 ppm) + BS-22 (as a soil drench) might be used as a substitute for gray mold and root rot diseases in strawberry development and biocontrol.

Preparation of Fe/Co bimetallic oxide loaded hydrophobic & catalytic bifunctional membrane and its catalytic performance in sulfite oxidation

Sulfite oxidation is critical for the stable operation of desulfurization process and the treatment & recovery of desulfurization by-products. The Fe and Co oxides modified super hydrophobic layer was prepared on tubular ceramic membranes using hydrothermal synthesis and surface modifications to realize the combination of the membrane catalysis and membrane aeration. These two oxides were approximately two-layer distributed on the membrane surface, among which the Fe2O3 located in the bottom layer and the Co3O4 located in the upper layer. The catalytic rate of the bifunctional membrane was about 5.8 times than that of the original ceramic membrane, which was decreased with the increasing of Fe/Co ratio and declined after an initial rise with the increase of urea and cetyltrimethylammonium bromide. The conjoint effect of Fe and Co could improve the catalytic performance and reduce the dissolution loss of catalyzer. The oxidation rate tended to be constant after a 15 % decrease in 7 times experiments.

Synthesis and characterisation of mixed oxides of Co–Ni catalyst and its application in microwave mediated synthesis of Benzo[b]Pyrans

We present an easy and sustainable procedure for the productive preparation of tetrahydrobenzo[b]pyran derivatives by means of many compounds condensation of dimedon, malononitrile and several aromatic aldehydes utilizing mixed bimetallic oxides of Co–Ni as a catalyst under microwave irradiation. Present protocol involves green synthesis of mixed Co–Ni oxide catalyst using milky latex of Euphorbia neriifolia. The prepared mixed Co and Ni oxide was analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Fourier Transform Infra-Red Spectroscopy (FT-IR), Energy Dispersive X-ray Analysis (EDAX), X-ray Photoelectron Spectroscopy (XPS) & Brunauer-Emmett- Teller Analysis (BET). This green approach's significance is demonstrated by its one-pot synthesis, convenient without use of solvent shows good isolated yields. Multiple analytical techniques such as Fourier transform infrared spectroscopy (FT-IR), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy are utilized to derive the structural properties. The mixed metal oxides of Co and Ni was found to be catalytically active and can be reused 12 times without significant loss of catalytic activity.

Elucidating the local structure and electronic properties of a highly active overall alkaline water splitting NixCo1-xO/hollow carbon sphere catalyst

A NixCo1-xO/HCS catalyst with superior water-splitting is presented. High water-splitting reaction kinetics and enhanced durability were observed. The structure-function relationship was investigated with XPS, which demonstrated the presence of dominant Ni2+ and Co2+ species and a functionalized HCS support where nucleation of small metal oxide nanoparticles occurred. The PDF showed broadened Nickel/Cobalt-oxide bonds and expansion of the metal-metal pair distances. The alteration of the Metal-Oxide and Metal-Metal-Oxide bonds favored better HER and OER electrocatalysis, also as supported by DFT. EXAFS showed the existence of the bimetallic oxide catalyst and the stretching of the Ni–O bonds due to the coordination of the Ni–O with the Co. The composite exhibited higher activity and enhanced electrocatalytic mechanism towards water splitting through higher exchange current densities (0.615 and 0.886 mA cm−2) and low charge transfer resistance (14 and 10 Ω) respectively. Chronoamperometry proved the catalyst's stability during prolonged electrolysis.

Co3V2O8 composite carbon hollow spheres bidirectionally catalyze the conversion of lithium polysulfide to improve the capacity of lithium‐sulfur batteries

Although lithium‐sulfur batteries have a high theoretical energy density that is higher than lithium‐ion batteries, their development is limited by the slow kinetics of lithium polysulfide conversion. In this research, we utilize the excellent bidirectional catalysis and adsorption of lithium polysulfide by the bimetallic oxide Co3V2O8 composite carbon hollow sphere to address the kinetic obstacle of lithium‐sulfur battery. On the one hand, the carbon hollow sphere substrate provides a cavity that can hold a large amount of sulfur. On the other hand, it can limit the diffusion of lithium polysulfide by van der Waals forces. The combination of the above two points improves the capacity and stability of lithium‐sulfur batteries. It has a specific capacity of 1237.2 mAh g‐1 at 0.2 C current density and retains 603 mAh g‐1 after 100 cycles. At a high current density of 2 C, the specific capacity is 976.2 mAh g‐1. After 1000 cycles, it holds at 338.3 mAh g‐1, and the capacity retention rate per cycle is 99.89%. This work discovers the new potential of Co3V2O8 as an electrocatalyst and proposes a process that can widely prepare carbon materials with complex uniform distribution of electrocatalysts to achieve high specific capacity of lithium‐sulfur batteries.

Peroxydisulfate-based Non-radical Oxidation of Rhodamine B by Fe-Mn Doped Granular Activated Carbon: Kinetics and Mechanism Study.

While numerous persulfate-based advanced oxidation processes (AOPs) have been studied based on fancy catalysts, the practical combination of Fe or Mn modified granular activated carbon (GAC) has seldom been investigated. The present study focused on a green and readily synthesized Fe-Mn bimetallic oxide doped GAC (Fe-Mn@GAC), to uncover its catalytic kinetics and mechanism when used in the peroxydisulfate (PDS)-based oxidation process for degrading Rhodamine B (RhB), a representative xenobiotic dye. The synthesized Fe-Mn@GAC was characterized by SEM-EDS, XRD, ICP-OES and XPS analyses to confirm its physicochemical properties. The catalytic kinetics of Fe-Mn@GAC+PDS system were evaluated under varying conditions, including PDS and catalyst dosages, solution pH, and the presence of anions. It was found Fe-Mn@GAC exhibited robust catalytic performance, being insensitive to a wide pH range from 3 to 11, and the presence of anions such as Cl-, SO4 2-, NO3 - and CO3 2-. The catalytic mechanism was investigated by EPR and quenching experiments. The results indicated the catalytic system processed a non-radical oxidation pathway, dominated by direct electron transfer between RhB and Fe-Mn@GAC, with singlet oxygen (1O2) playing a secondary role. The catalytic system also managed to maintain a RhB removal above 81 % in successive 10 cycles, and recover to 89.5 % after simple DI water rinse, showing great reusability. The catalytic system was further challenged by real dye-containing wastewater, achieving a decolorization rate of 84.5 %. This work not only provides fresh insight into the kinetics and mechanism of the Fe-Mn@GAC+PDS catalytic system, but also demonstrates its potential in the practical application in real dye-containing wastewater treatment.

Elucidation of synergism in Ce-Zr/SBA-15 mesoporous catalysts and the effects on the activity in selective glycerol to lactic acid reaction

The continued conversion of glycerol to value-added chemicals is essential in ensuring the sustainable development of the biodiesel industry. Selective catalytic oxidation of glycerol to lactic acid provides an alternative approach to valorizing glycerol. A mesoporous SBA-15 supported mixed-metallic oxide catalyst is deemed essential to selectively produce lactic acid in this mixed parallel and multi-step reaction. SBA-15-supported bimetallic Ce and Zr oxides were proved to be highly efficient catalysts for the selective glycerol oxidation into lactic acid in base-free media. The synergism between Ce and Zr in the bimetallic oxide compounds could enhance the creation of oxygen vacancies in the catalyst via the reduction of Ce4+ to Ce3+. The 2:1CeZr/SBA-15 catalyst exhibited prominent catalytic activity in selectively oxidizing glycerol to lactic acid, with a glycerol conversion of 91.8% and a lactic acid yield of 35.1%. This work achieved superior catalytic performance compared to previously conducted studies, primarily due to the significantly higher initial glycerol concentration employed in this study. To ascertain the intrinsic active sites of the catalyst, the physicochemical properties of the catalyst were thoroughly examined using BET, FTIR, XRD, FESEM, TEM, CO2-TPD, O2-TPD, and H2-TPR analysis. This work concluded that the synergistic interaction of the active sites, which led to the formation of active oxygen species, facilitated primary dehydrogenation of the terminal -OH bond in glycerol. Hence, in this work, a plausible glycerol conversion mechanism over the 2:1CeZr/SBA-15 catalyst was also proposed.

Hybridization of bimetallic cobalt-molybdenum oxide multihole nanosheets with selenium adulteration as advanced bifunctional electrocatalysts for boosting overall water splitting

Electrocatalytic water splitting produces green and pollution-free hydrogen as a clean energy carrier, which can effectively alleviate energy crisis. In this paper, bimetallic and selenium doped cobalt molybdate (Se-CoMoO4) nanosheets with rough surface are resoundingly prepared. The multihole Se-CoMoO4 nanosheets display ultrathin and rectangular architecture with the dimensions of ∼ 3.5 μm and 700 nm for length and width, respectively. The Se-CoMoO4 electrocatalyst shows remarkable water electrolysis activity and stability. The overpotentials of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are 270 and 63.3 mV at 10 mA cm−2, along with low Tafel slopes of 51.6 and 62.0 mV dec-1. Furthermore, the Se-CoMoO4 couple electrolyzer merely requires a cell voltage of 1.48 V to achieve 10 mA cm−2 current density and presents no apparent attenuation for 30 h. This investigation declares that the hybridization of transition bimetallic oxide with nonmetallic adulteration can afford a tactic for the preparation of bifunctional non-precious metal-based electrocatalysts.

Constructing asymmetric active Fe3+-OV-Mn4+ sites at the Fe2O3-MnO2 interface for low-temperature soot combustion

Promoting the generation of reactive oxygen species by adjusting the strength of metal-oxygen bonds and constructing interfacial active sites has been proven to effectively enhance soot combustion. Herein, Fe2O3-MnO2 bimetallic oxides (FMO) with a heterogeneous interface were prepared using a simple PBA (Prussian blue analogue) derivation method. The catalysts exhibited superior active oxygen content and strong electron transport capacity. The Fe3+-OV-Mn4+ structure, an asymmetric oxygen vacancy, formed at the interface, and the strength of the metal-oxygen bonds was further regulated at different calcination temperatures, significantly activating lattice oxygen. The FMO-HA catalyst showed the highest activity, with soot conversion temperatures reaching 90 % at 289 °C under tight contact and 382 °C under loose contact. This work offers a dual regulatory strategy to enhance the production of reactive oxygen species and proposes a rational design for high-performance catalysts for soot combustion.

Oxygen vacancy-engineered P-doped MoO3/Ce2Mo4O15 bimetallic heterojunction nanosheet array for enhanced oxygen evolution reaction

Surface oxygen vacancies in defective metals have the capacity to enhance oxygen evolution reaction (OER) activity but easily suffer from instability and deactivation in continuous electrocatalysts. Heterojunction engineering is important for achieving effective catalysis, but its simultaneous engineering remains a challenge. Therefore, it is necessary to develop an effective heterojunction catalyst to improve the electrocatalytic stability of defective metallic oxygen vacancies. In this work, we report a Ce, Mo bimetallic defective heterojunction P-MoO3/Ce2Mo4O15@NF-1 via a facile one-step hydrothermal method and annealing in a tube furnace. Bimetallic oxide heterojunctions offer several advantages over conventional single-metal heterojunctions, including stable structure, more active sites, faster rates of electron transfer, and less pollution of the environment. Meanwhile, P-doped catalyst could enhance the metallicity significantly. In addition, the prepared catalyst P-MoO3/Ce2Mo4O15@NF-1 showed extraordinary catalytic activity for OER in alkaline media. The overpotential and Tafel slope of the catalyst at a current density of 50 mA cm-2 were 270 mV and 87.27 mV dec‑1, respectively. It maintains an impressive balance between electrocatalytic activity and stability. This research explores the co-effects of Ce and Mo bimetallic oxide in defective electrocatalysts and also provides ideas for designing OER catalysts with defective metal heterojunctions.

Bimetallic Mn-Cu oxide catalysts for toluene oxidation: Synergistic effect and catalytic mechanism

A series of Mn-Cu composite oxides with different Mn/Cu molar ratios were synthesized via a facile ethanol-redox precipitation method and investigated for the oxidation of toluene. Among as-synthesized MnxCuy catalysts, Mn5Cu1 showed the most excellent toluene catalytic activity at a weight hourly space velocity (WHSV) of 30000 mL∙g−1∙h−1, with 90 % conversion achieved at 212 °C. Furthermore, the Mn5Cu1 catalyst exhibited exceptional thermal stability over a 12-hour period at 215 °C, along with outstanding resistance to H2O in the range of 5 vol% to 40 vol%. As characterized by XRD, BET, XPS, EPR, H2-TPR, and O2-TPD, it was found that Mn5Cu1 possessed a unique three-phase coexisting structure, large specific surface area (57 m2·g−1), plentiful oxygen vacancies, excellent redox capacity, and strong mobility of oxygen, which were attributable to the synergistic effect between Mn and Cu. This strong synergy between Mn and Cu is the underlying reason for the strong catalytic activity of Mn5Cu1. Moreover, toluene-TPD and TPSR results indicated that appropriate Cu loading was favorable for the adsorption and activation of toluene. The potential reaction pathway for toluene oxidation was presented based on in situ DRIFTS characterization. Maleic anhydride was the critical reaction intermediate species.

Construction of graphdiyne-based photocatalysts with strong built-in electric field by loading bimetallic oxides to promote the photocatalytic hydrogen evolution activity

The novel carbon material graphdiyne (GDY) is a two-dimensional planar structure material formed by the hybridization of sp and sp2, which has abundant carbon–carbon bonds and stable semiconductor properties. In this work, CoTiO3 was coupled with a carbon material GDY to successfully construct an S-scheme GDY/CoTiO3 heterojunction. This form of heterojunction can effectively promote the separation of charge carriers and shorten the electron transfer pathn. The loading of CoTiO3 effectively enhances the charge transfer rate of GDY and increases the number of photo-generated electrons involved in the hydrogen production reaction, thereby promoting hydrogen generation. The tests results demonstrate that GDY/CoTiO3-25 achieves a hydrogen production of 123.95 μmol under visible light irradiation, which is 13 times higher compared to GDY. This work provides insights into improving the photocatalytic performance of the novel carbon material GDY.

Reusable CS-Ca@PEI/CuMnO2 Hydrogel Beads for Peroxymonosulfate-Activated Degradation of Congo Red.

Metal oxides can activate peroxymonosulfate (PMS) for the catalytic degradation of organic dyes. However, achieving high catalytic efficiency, structural stability, ease of recovery, and recyclability remains challenging for both research and practical applications. To address these requirements, a bimetallic oxide, CuMnO2, was synthesized using a simple hydrothermal approach and was encapsulated to create hydrogel beads, CS-Ca@PEI/CuMnO2. Subsequently, CS-Ca@PEI/CuMnO2 was used to activate PMS and establish a solid-liquid heterogeneous oxidation system (CS-Ca@PEI/CuMnO2/PMS) for the degradation of Congo red (CR). The effects of various parameters such as different systems, catalyst dosages, initial pH values, PMS concentrations, temperatures, and anion types on the catalytic degradation properties of CS-Ca@PEI/CuMnO2 for CR were systematically evaluated. The results indicated that CS-Ca@PEI/CuMnO2 has exceptional degradation capacity, achieving 91.0% degradation of CR at pH 7. After three degradation cycles, the catalyst maintained an 86.9% degradation efficiency compared to its original performance, highlighting its robust structural stability. The presence of reactive radicals, specifically 1O2 and •O2-, were confirmed through quenching experiments, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance spectroscopy (EPR). Liquid chromatography-tandem mass spectrometry (LC-MS) revealed ten proposed intermediates in the catalytic degradation process. Due to its exceptional catalytic performance, structural durability, recyclability, and ease of retrieval, the catalyst shows great potential for effectively removing organic pollutants from industrial wastewater.

α-Fe2O3/, Co3O4/, and CoFe2O4/MWCNTs/Ionic Liquid Nanocomposites as High-Performance Electrocatalysts for the Electrocatalytic Hydrogen Evolution Reaction in a Neutral Medium.

Transition metal oxides are a great alternative to less expensive hydrogen evolution reaction (HER) catalysts. However, the lack of conductivity of these materials requires a conductor material to support them and improve the activity toward HER. On the other hand, carbon paste electrodes result in a versatile and cheap electrode with good activity and conductivity in electrocatalytic hydrogen production, especially when the carbonaceous material is agglomerated with ionic liquids. In the present work, an electrode composed of multi-walled carbon nanotubes (MWCNTs) and cobalt ferrite oxide (CoFe2O4) was prepared. These compounds were included on an electrode agglomerated with the ionic liquid N-octylpyridinium hexafluorophosphate (IL) to obtain the modified CoFe2O4/MWCNTs/IL nanocomposite electrode. To evaluate the behavior of each metal of the bimetallic oxide, this compound was compared to the behavior of MWCNTs/IL where a single monometallic iron or cobalt oxides were included (i.e., α-Fe2O3/MWCNTs/IL and Co3O4/MWCNTs/IL). The synthesis of the oxides has been characterized by X-ray diffraction (XRD), RAMAN spectroscopy, and field emission scanning electronic microscopy (FE-SEM), corroborating the nanometric character and the structure of the compounds. The CoFe2O4/MWCNTs/IL nanocomposite system presents excellent electrocatalytic activity toward HER with an onset potential of -270 mV vs. RHE, evidencing an increase in activity compared to monometallic oxides and exhibiting onset potentials of -530 mV and -540 mV for α-Fe2O3/MWCNTs/IL and Co3O4/MWCNTs/IL, respectively. Finally, the system studied presents excellent stability during the 5 h of electrolysis, producing 132 μmol cm-2 h-1 of hydrogen gas.

Mn-Fe bimetallic oxide catalytic oxidation combined with ultrafiltration for treating secondary effluent: EfOM molecular transformation and membrane fouling control mechanism

Despite extensive application and research of membrane technology in secondary effluent treatment, fouling induced by effluent organic matter (EfOM) remains a challenge. Herein, a pretreatment strategy involving Mn-Fe bimetallic oxide-activated peroxymonosulfate (MnFeO/PMS) was used before ultrafiltration to decompose EfOM and tackle membrane fouling. Results showed that membrane fouling was effectively alleviated, with reductions in reversible and irreversible fouling resistances of 88.3 % and 58.9 %, respectively. Theoretical analyses illustrated a more pronounced adsorption energy and decomposition tendency of PMS on the MnFeO surface. The generated OH and SO4− played a key role in the degradation of EfOM. The parallel factor analysis along with self-organizing maps revealed the preferential oxidative degradation of humic acids and fulvic acids over tryptophan-like substances, which contributed to the reversible fouling mitigation. In addition, MnFeO/PMS transformed high and middle molecular weight organics into low molecular weight compounds. The primary molecular reactions involved in the degradation of EfOM included oxygen addition, dealkylation and deamination, which changed the properties of EfOM and contributed to the mitigation of membrane fouling. Morphology analysis further indicated that the fouling layer on the membrane surface was inhibited when filtering the MnFeO/PMS-pretreated sample. This study offers revelations for integrating oxidation with ultrafiltration in secondary effluent treatment to alleviate EfOM-induced membrane fouling.

Catalytic performance and mechanism of PtxVW catalyst for selective catalytic oxidation of high-concentration NH3

It is foreseeable that a high-concentration NH3 may exist in exhaust gas of NH3-fuel engines, which may result in some negative damages to ecological environment. Herein, a series of PtxVW catalysts with extremely low Pt doping amounts were synthesized with the aim to remove high-concentration NH3 efficiently via selective catalytic oxidation (SCO) method. The results showed that, Pt0.04VW catalyst (0.04 wt% Pt) achieved a complete NH3 conversion at 250 ºC. Both catalytic activity and N2 selectivity of Pt0.04VW catalyst were much superior over Pt/Al2O3 catalyst (1 wt% Pt) in a wide temperature range of 250–450 ºC. XPS, Raman and H2-TPR results indicated that Pt existed in the lattice of VOx and formed Pt-V bimetallic oxides. The interaction between Pt and V played a key role in the NH3-SCO reactions. DFT calculation demonstrated that dual electron transfer pathways between Pt and V atoms in PtxVW catalysts were beneficial for NH3 coordination on Lewis acid sites, then enhancing NH3-SCO reactions. In-situ DRIFTS and NH3-TPD product analysis suggested that NH3-SCO reactions on Pt0.04VW catalyst surface abide by internal selective catalytic reduction (i-SCR) and hydrazine mechanisms. Moreover, coordinated NH3 species on Lewis acid sites, bidentate nitrate species were the main intermediates in NH3-SCO reactions over Pt0.04VW catalyst.