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Doping of graphene-based nanomaterials with heteroatoms is a flexible and widely used approach to modify their electronic structure and chemical properties. Applications of these doped materials may imply thermal treatment, so this work was devoted to the transformations of nitrogen-containing functional groups during heating. Jellyfish-like few-layer graphene nanoflakes with the bulk and surface localization of N-groups were synthesized by different techniques: CVD growth, post-doping, CVD growth followed by oxidation, and nitric acid treatment. Synthesized materials contained a wide range of N-functionalities. The mechanism of their thermal transformations and decomposition was studied using XPS and TGA–MS. The activation energies for the decomposition of different nitrogen-containing groups were estimated by the Kissinger method.

Outdoor or indoor ozone pollution recently regains the attentions due to new findings on its risk even at very low level. The room-temperature catalytic material is key to abate indoor ozone pollution. Here we prepared a series of vanadium-doped MnO2 (V-MnO2) via a one-step hydrothermal redox reaction between MnO4− and Mn2+ with addition of vanadate. The vanadium-doped MnO2 exhibited weaker crystallinity with exposure of high-index facets such as (301), much larger specific surface area, enhanced surface acidity and had lower oxidation state of Mn. Accordingly, the amount of oxygen vacancies was greatly increased, which is not only revealed by H2-TPR and O2-TPD but also confirmed by stronger peroxide signals in electron paramagnetic resonance. V-MnO2(0.15) with the largest specific surface area of 309.8 m2/g not only exhibited stable activity for high concentration of ozone under humid condition, it also showed high ozone removal efficiency when it was coated on the low pressure-drop nonwoven fabric under the real filtration velocity. Thus, vanadium-doping is a facile method to improve the room-temperature activity of MnO2 for indoor ozone decomposition under the humid condition.

Thin-felt microfibrous-structured Pd-Co-MnOx/Al2O3/Al-fiber catalysts (named Pd-Co-MnOx-Al) with low Pd-loading engineered from micro- to macro-scale are developed for the high-throughput catalytic decomposition of high level gaseous ozone (O3) under humid conditions. The catalysts are obtained by highly dispersing Pd-Co-Mn active components onto the γ-Al2O3 nanosheets endogenously grown on the thin-felt microfibrous structure consisting of 10 vol% 60 μm-Al-fiber and 90 vol% voidage, using impregnation method. This approach effectively and efficiently couples the unique form factor, thin-sheet feature, and high permeability with the high activity, markedly improved stability, and enhanced moisture resistance. The most promising 0.1Pd-Co-MnOx-Al (0.1 wt% Pd, 0.36 Co/Mn molar ratio, Co2O3 + MnO2 loading of 5 wt%) catalyst remains full O3 conversion for at least 4 h at 25 °C for a feed gas containing 1500 ± 45 ppm O3 even at a high relative humidity (RH) of 70%, using a high gas hourly space velocity of 48,000 mL gcat.–1 h–1; the full O3 conversion quickly slides to a flat of ~96% during 4 h testing at 90% RH whereas it is retrievable immediately after switching the feed gas to a dry one. The remarkable improvement of activity, stability and moisture resistance by Pd-doping of Co-MnOx-Al is, in nature, due to the highly improved and stabilized low-valent-Mn related oxygen vacancies (i.e., active sites) and markedly weakened H2O adsorption on the catalyst surface, which are verified by XRD, H2-TPR, O2-TPD, H2O-TPD and XPS measurements.

Rb-promoted nanocrystalline Co3O4-CeO2 catalysts were prepared by the impregnation of the Co3O4-CeO2, previously prepared using the solution combustion route, with an aqueous solution of Rb2CO3 (Rb/Co ratios 0.0125–0.20) and subsequent calcination at 500 °C. The obtained catalysts and the un-promoted Co3O4 and Co3O4-CeO2 catalysts have been characterized using XRD, FT-IR, SEM, TEM, XPS, H2-TPR and N2 physisorption techniques. The activity of the various catalysts was tested for N2O direct decomposition. All the Rb-promoted catalysts exhibited better performance than the bare Co3O4-CeO2 catalyst, where the highest activity was obtained using the catalyst with Rb/Co ratio of 0.025. The activity performance of the various catalysts was discussed in terms of the electronic properties modification accompanying the Rb-doping. For the optimum catalyst, further experiments were conducted in the presence of O2 and NO in the reactor feed.

The concurrent production of COx-free hydrogen and multi-walled carbon filaments by thermocatalytic decomposition of methane is advantageous in the environmental and energy catalysis. In the present work, a facile “one-pot” evaporation-induced self-assembly strategy was effectively adopted to fabricate the nickel catalysts supported on mesoporous Al2O3, SiO2, TiO2, and MgO, and their catalytic activities for methane decomposition were evaluated for the first time. The structural, textural, and redox properties of the as-obtained materials were characterized using a number of analytical techniques. The nitrogen sorption analysis indicated the presence of a mesoporous structure due to homogeneous aggregation of the catalyst particles with a high specific surface area of 32–236 m2/g. Among all of the catalysts, Ni/MgO exhibited the best catalytic activity for methane decomposition (65% methane conversion at 600 °C and GHSV of 48,000 mL/(g h)). The activity increased when Ni loading increased from 25 to 55 wt%. The investigation on the correlation between catalytic performance and promoter doping effect suggests that incorporating copper into the MgO support considerably enhanced the catalytic activity and stability at high temperatures. The XPS results reveal that doping of Cu to Ni/MgO enhanced the adsorption and activation of oxygen molecules. In addition, the disordered crystalline carbon filaments with different diameters and good crystallinity were generated on the surface of the Cu-doped Ni/MgO catalysts.

Recently, TiO2 photocatalysts have been applied in various ways for outdoor air purification. The main challenge with these applications is the stability of the photocatalysts, as the surface of TiO2 can be easily deactivated by contaminants found in outdoor environments. For example, it is difficult to remove oily contaminants with water once they are exposed to the photocatalyst surface since the hydrophilicity of TiO2 is not sufficiently high to allow for self-cleaning. In the present work, we modified the surface of commercial TiO2 nanoparticles to be more hydrophilic; this was done by coating them with a thin polydimethylsiloxane (PDMS) layer and applying a subsequent heat treatment under vacuum. The surface-modified TiO2 showed outstanding ability to repel oily contaminants deposited on its surface upon exposure to water droplets due to its superhydrophilic properties. Then, we evaluated the UV-light-driven photocatalytic activity of the surface-modified TiO2 for the decomposition of acetaldehyde. The surface-modified TiO2 showed photocatalytic activity for the decomposition of acetaldehyde that was comparable to that of bare TiO2. We show that our hydrophilic-surface-modified TiO2 has high potential for applications in outdoor air purification for an extended time period.

In this paper, the adsorption models of three SF6 decomposition gas (SO2, SOF2, SO2F2) on the Ni-doped ZnO (100) surface were established based on density functional theory (DFT). The structural and electronic properties of intrinsic and Ni-doped ZnO (100) surface after gas adsorption were analyzed to clarify the adsorption capacity and sensing mechanism. In addition, the adsorption parameters of Ni-doped ZnO (100) surface and intrinsic ZnO (100) surface were compared. The results show that Ni-doped ZnO (100) surface has a strong chemical adsorption effect on SO2 and SO2F2, while exhibits weaker physical adsorption to SOF2. Compared with intrinsic ZnO (100) surface, the adsorption capacity of three gas molecules were obviously enhanced after Ni doping, implying Ni dopant can significantly improve the sensitivity and selectivity of ZnO materials to SO2, SOF2, SO2F2 gases. Meanwhile, gas sensing experiment of intrinsic and Ni-doped ZnO materials towards SO2, SOF2, and SO2F2 was carried out. All results lay a solid foundation for exploring high-performance ZnO based sensors to detect SF6 decomposition components for GIS partial discharge defect diagnose.

Ammonia has become an attractive source for COx-free hydrogen production for fuel cell applications. The catalytic performance of Ce0.6Zr0.3Y0.1O2 solid solutions supported Ni, Co and Ni Co bimetallic catalysts are evaluated in the temperature range of 300–600 °C at atmospheric pressure. Due to the synergistic effect between Ni and Co, CZY supported Ni Co bimetallic catalysts show higher ammonia decomposition activity compared to Ni or Co monometallic samples. The Ni Co bimetallic catalyst with the Ni/Co mass ratio of 1/9 exhibits the highest NH3 conversion with the GHSV of 6000 mL h−1 gcat−1, which reaches 100% conversion at 600 °C. Moreover, the Ni1Co9/CZY catalyst shows good thermal stability during the 72 h reaction time. The Ni1Co9/CZY have the highest total H2-uptake of 0.35 mmol‧g−1 and the highest TOFH2 value (40.57 min−1) at 350 °C among all the catalysts. Our characterization confirms the formation of Ni Co alloy is responsible for the high activity of Ni1Co9/CZY catalyst for the ammonia decomposition.

In this study, the structural distortion of graphitic carbon nitride (g-C3N4) has been done through potassium salt tempting towards an extended optical absorbance. Optical and morphological studies affirm that the potassium doping stimulate n − π∗ electronic transition ascribing towards a diminished charge recombination, high conduction band edge, and a narrow band gap. A comparative photocatalytic study of potassium doped g-C3N4 (0.8 K+-g-C3N4) with g-C3N4 has been performed through a solar-powered photocatalytic reactor to treat phenolic effluent, and the effect of operational parameters i.e. solar irradiance, pH, H2O2 concentration, and flow rate was also examined. It was observed that 0.8 K+- g-C3N4 shows 89.06% decomposition of phenol while with g-C3N4 exhibits 63.53% under optimum conditions.

HKUST-1 is a strictly microporous crystalline metal organic framework with pore sizes of 5, 11, and 13.5 A. Detailed gas adsorption measurements show that its adsorption capacity for water at 20 °C is higher than that for nitrogen at −196 °C, and far exceeds that for methane at 0 °C. Extended exposure to water vapour at high relative humidity, or consecutive adsorption-desorption cycling of water vapour, destroys both the MOF crystal structure and its adsorption capacity, after a reduced number (

N, P dual-doped carbon nanosheets was prepared by an in-situ foaming technology. The crude lecithin extracted from egg yolk was explored to prepare this novel carbon material. In the synthesis process, the crude lecithin molecular is as the Gemini surfactant and the graphitic carbon nitride (g-C3N4) plays the role of self-sacrificing template. At the high temperature, the sandwich-mixture “lecithin/C3N4/lecithin” expanded and carbonized with the decomposition of g-C3N4. This induces the formation of many multi-wrinkled nanosheets and synchronously constitute a multi-doped carbon foam. This unique carbon material exhibits a super-efficient catalytic activity towards oxygen reduction reaction, with the limited current density of 6.7 mA cm−2 tested at 1600 rpm in 0.1 M KOH solution, which is far larger than that of Pt/C (20%) catalyst (5.5 mA cm−2). It was demonstrated that this novel catalyst also possesses great catalytic stability. After about 9 h continuous test, the current density of this catalyst remained above 91%. These results demonstrate that the N, P dual-doped multi-wrinkled carbon nanosheets can be used as the high-efficient metal-free electrocatalyst towards oxygen reduction reaction.

Fe-doped TiO2 nanoparticles with highly exposed (0 0 1) facets are directly synthesized from Ti-bearing tailings by a facile method for the first time. The effects of F-based additive on the decomposition rate of Ti-bearing tailings as well as exposure percentage of (0 0 1) facets are systematically investigated in this work. The results demonstrate that F-based additive agent effectively promotes decomposition of Ti-bearing tailings during the acidolysis process. What’s more, F-based additive agent also plays a key role in the exposure of high-energy (0 0 1) facets for the obtained TiO2 nanoparticles. Synthesized F-drived TiO2 nanoparticles present outstanding photocatalytic activity on pollution degradation under visible and UV light. This study demonstrates a promising way to achieve advanced materials from secondary resources.

In this work, a carbon felt cathode modified by dopamine (DPA/CF) was explored to enhance the cathodic reduction of Cr(VI) in a two chambers photoelectrochemical system, which was driven by solar light irradiation using BiVO4 photoanode. In the anode chamber, the bisphenol A (BPA) decomposition can be significantly improved by increasing pH to 8. The electron-hole pairs photogenerated on the surface of BiVO4 were efficiently separated by the application of the DPA/CF cathode. At the optimal conditions, 86% of low-concentration BPA was removed within 60 min. In the cathodic chamber, 80% of Cr(VI) was removed at pH of 4. Based on the XPS and electrochemical analyses, it was proposed that the positively-charged groups on the DPA/CF cathode led to the multilayer adsorption of Cr(VI) anions, which enhanced the reduction of Cr(VI) with the electrons generated on the BiVO4. On the other hand, the C O groups on the DPA/CF electrode also played an important role as electron transfer mediator for Cr(VI) reduction. The prepared DPA/CF cathode associated with BiVO4 photoanode could be a potential application for efficient removal of Cr(VI) and organic pollutants under solar light irritation.

Sol-gel method was used for preparation of TiO2 having different structure and phase composition. Prepared titania samples were applied for acetaldehyde decomposition under UV light irradiation. The obtained results showed, that TiO2 consisted from mixed phases of anatase and brookite, which was prepared at neutral pH and calcined at 450 °C was the most active. Charge separation of free carriers was investigated by measurements of electron traps density. It was proved, that density of electron traps can be enhanced by nitrogen doping or by coexisting of two phases such as anatase and brookite. However nitrogen doping to TiO2 did not increase of its photocatalytic activity towards acetaldehyde decomposition. Therefore preparation of TiO2 having mixed phases of anatase and brookite appeared to be the most favourable towards elimination of acetaldehyde under UV at ambient conditions. Moreover, temperature of calcination such as 450 °C was the most optimal, because at that temperature total crystallisation of amorphous titnia occurrs and then interparticle contact increases, which facilitates the interfacial charge transfer between titania particles.

One important dynamic decomposition pathway for a surface corrosion-inhibitor: barium dimethyl- naphthalene-sulfonate, is investigated on a clean Al3Mg (0 0 1) binary-alloy surface using ab-initio molecular dynamics based upon density functional theory. Each inhibitor molecule is oriented its functional groups of sulfonic-oxygen bases toward the surface, starting at an initial impact velocity. The dynamic decomposition pathway occurs upon molecular collision with the surface, leading to the decomposed fragments that may clearly represent the initial formation stage of additive thin-film on the surface during a plastic substrate deformation. In addition, three important factors: initial impact speed acting on molecule (kinetic effect), substrate temperature (thermal effect) and initial molecular orientation (geometric effect) etc, are employed to analyze their influences on molecular decomposition. An approach of design-of-experiment (DOE) is applied to an analysis of relative importance for each factor and all factor interactions in above, so as to figure out the best way of surface protection. Final DOE analysis indicates that the most significant factor for promoting molecular decomposition on surface is the substrate temperature, i.e., the higher the substrate temperature, the more rapid decomposition of molecule on surface. While initial impact velocity plays a smaller role, and initial molecular orientation performs less importance to molecular decomposition.

The competitive water adsorption in the practical environment usually causes severe deactivation of the O3 decomposition catalysts. In this study, MnCO3 was used as precursor to prepare efficient and stable MnO2 catalyst for gaseous O3 decomposition in humid stream. The sample S-300, prepared by calcining MnCO3 at 300 °C for 6 h, exhibited 63% (80%) of removal efficiency for 120 (43) ppm of O3 under a high space velocity of 600 L g−1 h−1 and 50% (40%) of relative humidity at 25 °C, which is superior to the commercial O3 scrubber (oxide compound of Cu and Mn) and α-MnO2. However, even lower or higher treatment temperature did not further promote humid O3 decomposition. Thorough characterizations, especially by the temperature programmed and in situ DRIFTs experiments, demonstrate that the large amount of active oxygen vacancies and strong Lewis-acid sites together with the easy recovery of the occupied oxygen vacancies and weak interaction with water molecules accounted for the excellent O3 decomposition activity in humid stream. Besides, the developed pores by thermal decomposition of MnCO3 might also facilitate O3 removal. This study provides an easy and rational design of affordable and efficient catalysts for environmental application.

The serious charge recombination originates from the thermal instability of perovskite/ZnO and the low electron injection efficiency of ZnO. It is the important issue to be improved in ZnO-based perovskite solar cell (PSC). In this paper, the core-shell structure of ZnO@TiO2 nanorod arrays (NRs) is designed as electron transport layer (ETL) for PSC. A novel synthesis of PSC based on ZnO@TiO2 NRs in ambient atmosphere was proposed. The photoelectric conversion efficiency (PCE) of the core-shell device is 50.46% higher than that of common ZnO nanorod device. This is due to the improved interface contact between nanorods and perovskite layer, and the suppression of charge recombination. The PCE of the TiO2 modified device shows still more than 83% after 168 h, compared to that of the pristine one which decreased to less than 50%. This is due to TiO2 modification which can serve as a buffer layer to avoid direct contact between perovskite films and ZnO NRs, and inhibit s the decomposition of perovskite film on ZnO NRs. Both theoretical calculation and Raman test result show that the interaction between CH3NH3PbI3 and TiO2 is mainly the bonding between I atoms of PbI2 slabs and Ti atoms of the TiO2 surface at PbI2/TiO2 interface. The mechanism of carrier transport and recombination in the PSC based on ZnO and ZnO@TiO2 NRs was also discussed. These results highlight the potential of ZnO@TiO2 NRs as ETL for all-solid-state PSC with high efficiency and good stability.

In this paper, we present a study of the adsorption and sensing performances of V atom-doped GaSe (V-GaSe) gas sensor towards the decomposition products of SF6. The decomposition products include H2S, SO2, SO2F2, and SOF2. Firstly, we compared the doping structures, band structures, and state densities of GaSe and V-GaSe sensors. Subsequently, we comparatively explored the adsorption structure and energy, charge transfer, density of state, molecular orbitals, and charge distribution of the two sensors. The results indicate that the V-GaSe sensor has a higher conductivity and a greater gas adsorption capacity than the GaSe sensor. The decomposition products are physically adsorbed by the V-GaSe sensor, and the adsorption ability and gas sensitivity of the V-GaSe sensor towards the individual decomposition product is sorted as SOF2 > SO2F2 > SO2 > H2S. The study proves that the V-GaSe gas sensor exhibits excellent adsorption of the decomposition products of SF6, enabling it a promising tool for monitoring the insulation condition of gas-insulated switchgear (GIS).

SF6 decomposition characteristic components detection is currently one of the effective technical means for SF6 gas insulation equipment condition monitoring, and sensors are the key to achieving this goal. In this paper, two-dimensional MXene is used as a sensing material, combined with DFT method to study the adsorption behaviour of Ti3C2Tx with different termination groups (O, F, OH) on the main decomposition characteristic components of SF6 such as H2S, SO2, SOF2 and SO2F2.The most stable structure, α-model Ti3C2Tx was obtained and various gas adsorption structures were constructed and geometrically optimized. The most stable adsorption structures of different Ti3C2Tx surfaces were obtained by comparing the adsorption energy. The electron density, band structure and density of states of the adsorption system were further analyzed. The results show that target gases adsorb spontaneously on Ti3C2O2 and Ti3C2(OH)2, while on Ti3C2F2 external energy is required to form stable adsorption structures. Charge transfer induced by gas adsorption gradually decreases at the order of Ti3C2(OH)2, Ti3C2O2 and Ti3C2F2. Hydroxyl groups terminated Ti3C2Tx MXene performed better sensing ability over oxygen and fluorine terminated ones. And 2D Ti3C2(OH)2 is a promising candidate for SF6 decomposition characteristic components sensor, surpassing graphene and transition metal dichalcogenides.

International audience; Porous carbons are used in various applications for energy storage. Nitrogen doping of these carbons modifies their electrochemical and chemical properties and co-doping them with fluorine atoms, appears as a promising route to further tailor their physical and chemical properties. The present paper focuses on the gas/solid fluorination with molecular fluorine (F2) of various types of N-doped porous carbons. The consequences of the fluorination on the porosity of these materials were studied as well as their Csingle bondF bonding type. Mild conditions avoid a huge decomposition in F2 gas of these materials and a drastic decrease of their specific surface area. Micropores, which are hosting most of the FeNx catalytic sites, are the most affected by fluorination, and a new N1s XPS peak assigned to pyridinic-N---Csingle bondF has been identified, coinciding with that of the XPS binding energy of N1s in FeNx. However, molecular fluorine did not react directly with nitrogen atoms in these materials, whatever their type since no Nsingle bondF containing volatile products were evolved during the treatment. Finally, a dual Csingle bondF bonding, characterized by the coexistence of Csingle bondF bonds with weakened covalence and covalent Csingle bondF, is evidenced in all fluorinated N-doped porous carbons.

The bulk properties of β-Ga2O3 are sensitive to temperature and atmosphere; therefore, suitable annealing conditions are required. This study was performed to investigate the effects of annealing conditions on the ( 2 ¯ 0 1 ) surface of β-Ga2O3 crystal using atomic force microscopy, optical transmission/ luminescence spectroscopy, and X-ray photoelectron spectroscopy. Annealing was performed in air and in evacuated glass capsules at different temperatures. After annealing at 900 °C in air, the sample became a colorless insulator, and faceting was observed. On the other hand, sample decomposition was observed after annealing in the evacuated capsules. While, after annealing at 300 °C in air, step-terrace formation was observed. With increase of the annealing temperature, faceting was observed after annealing at 600 °C exposing the (1 0 0) and (0 0 1) surfaces. These results demonstrate the need for optimized annealing conditions for different surface orientations to obtain desirable β-Ga2O3 surfaces for heterointerfaces.

In the present study, we investigate the catalytic ability of Heusler alloys towards N2 decomposition which is the main obstacle to nitrogen reduction reaction (NRR). First-principles methods were used to calculate the adsorption energies and dissociation barriers of nitrogen molecules on the (1 1 0) and (0 0 1) surfaces of Ru-based Heusler alloys (Ru2YZ, Y = Sc, Ti, V, Fe; Z = Sn, Ga, Ge, As, P). The electron-rich Ru atoms on the Ru-based Heusler alloy surfaces can significantly improve the adsorption activity and reduce the decomposed energy barrier of N2 molecules. A linear relationship between charges of all components, d-band-center, and N2 adsorption energy is predicted to reveal the factors that affect adsorption. The (0 0 1) surfaces of Ru2ScZ and Ru2TiZ are highly effective for N2 activation with lower N2 energy barriers around 0.4 eV. The unique catalytic performance of Ru-based Heusler alloys can be attributed to the synergistic role of the electronic effect and geometric effect of the active sites on the ordered alloy surfaces. Our theoretical results provide a strategy for the rational design of high-performance NRR electrocatalysts.

Garnet-type Li7La3Zr2O12 (LLZO) solid electrolyte (SE) has been widely used as a promising material providing protection for Li anode in lithium-ion and hybrid-electrolyte cells due to its high ionic conductivity and superior stability against Li metal. So far much efforts have been expended on addressing the issues at LLZO/Li metal interface, but relatively little attention was placed on the interface between LLZO and liquid electrolyte (LE), while this interface is also crucial for the successful implementation of protected Li metal batteries. Herein, we devote an effort to clarifying the characteristics of the SLEI between Li6.4La3Zr1.4Ta0.6O12 (LLZTO) and LiPF6-based LE. Furthermore, the reaction mechanism and improved approaches are particularly emphasized and discussed. The presence of trace water in LE plays an important role in the formation of SLEI, as it can accelerate the H+/Li+ exchange of LLZTO and self-decomposition of LiPF6. LiF generated from LiPF6 decomposition and HF corrosion is confirmed as the main component of SLEI via X-ray photoelectron spectroscopy (XPS) depth profiling. The thickness of the SLEI increase with time, the maximum thickness is about 40 nm after immersion in LE for 48 h. We expect that this systematic methodology can serve as a reference for investigating various SLEI for broader applications.

The role of NO adsorption/desorption on soot oxidation activity of MnOx-CeO2 mixed oxides was investigated in this work. NO adsorption/desorption on MnOx-CeO2 results in a visible promotion of the low-temperature reactivity. Physico-chemical characterization reveals that the formation of NO adsorbed species, mainly nitrates, leads to changes in the surface Ce/Mn states and in an increase of oxygen vacancies. Moreover, TPD-MS indicates that the decomposition of surface nitrates accelerates the desorption of oxygen in the catalyst. Soot-TPR-MS confirms that the oxygen species desorbed from nitrates decomposition play an important role during soot oxidation. The isothermal experiments evidence that NO adsorption/desorption enhances soot oxidation rate, with active oxygen playing a key role in a cooperative C + NO2 + O2 reaction with the catalyst.

SF6 decomposition components detection plays an important role in diagnosing and evaluating the electric discharge faults in SF6-insulated equipment. In this paper, Pt3-supported TiO2(1 0 1) was used to study the influence of the Pt clusters modification on the gas sensing property of TiO2(1 0 1) material to the characteristic decomposition components of SF6: H2S, SO2, SOF2 and SO2F2. The theoretical calculation results show that the intrinsic TiO2(1 0 1) only shows adsorption performance to H2S. Due to the strong chemical activity of Pt3, it significantly increases the electrical conductivity and gas sensing properties of TiO2(1 0 1). SF6 decomposition components adsorption decreases the electrical conductivity of the adsorption system. According to the different change degrees of electrical conductivity, it can be used to recognize the type and concentration of each SF6 decomposition component. By building the relationship between the type and concentration of SF6 decomposition components, and the type and severity of discharge faults, it provides an effective online way to diagnose and evaluate the discharge faults in SF6-insulated equipment.

This contribution describes the influence of the ratio of polyvinyl alcohol (PVA), TiO 2 and wire opening of metal meshes for the construction of a structured catalyst with a uniform coating, that present high adherence and photocatalytic activity. The best coating results were observed for a PVA/TiO 2 mass ratio of 0.37 and mesh opening of 546 µm. This coating exhibited a uniform distribution, high adherence and the maintenance of anatase and rutile phases. These aspects can be related to three variables: (i) the structure of the stainless-steel metal mesh, (ii) the thermal pretreatment and (iii) the amount of organic additive (PVA/TiO 2 ratio) employed in the suspensions. The most important achievement of this work was the fabrication of a structured catalyst with excellent stability, without losing activity for the degradation of endocrine-disrupting nonylphenol ethoxylate (NP 4 EO) in synthetic solution, without poisoning of the catalytic surface. In fact, the results showed that even with a real wastewater matrix, a high photocatalytic activity for NP 4 EO degradation (91%) was obtained, meaning that this structured catalyst can be applied to solve serious environmental problems as the contamination by endocrine-disrupting NP 4 EO, without subsequent catalyst recovery and recycle steps. Fil: de Moraes Da Trindade, Carolina. Universidade Federal do Rio Grande do Sul; Brasil Fil: da Silva, S.W.. Universidade Federal do Rio Grande do Sul; Brasil Fil: Bortolozzi, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Banus, Ezequiel David. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Bernardes, Andrea Moura. Universidade Federal do Rio Grande do Sul; Brasil Fil: Ulla, Maria Alicia del H.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina

In this paper, nitrogenous bases adenine (A), guanine (G), cytosine (C), and uracil (U), were used to tailor the hydrogen-bonded network of melamine cyanurate (MCA) and were noted as A-MCA, G-MCA, C-MCA, U-MCA, respectively. The results showed that the size, morphology and thermal behavior of MCA are regulated by base due to the formation of hydrogen bonds between them. These modified MCAs were used to improve the flame retardancy of polyamide 6 (PA6) which was evaluated by using the limiting oxygen index (LOI) and the vertical burning (UL-94) test, etc. The results showed that the PA6 sample containing 9 wt% C-MCA achieves the UL-94 V-0 rating and has a LOI value of 30.7%, while the other samples with equal amounts of MCA only pass the UL-94 V-2 rating. The flame retardant mechanism was studied, and the results reveal that C-MCA with smaller size has greater contact area with PA6 which helps to catalyze the decomposition of PA6; Thus the PA6/C-MCA releases more NH3, CO2 etc., and produces more droplets than others, which dilutes combustible gas and takes away heat to make the samples extinguish.

To obtain a clearer understanding of the catalytic bio-oil reforming mechanism, we performed density functional theory calculations on the decomposition of formic acid over a stepped Ni surface. Formic acid was selected as a model bio-oil compound. Fourteen elementary reactions were considered. All the zero-point-energy corrected activation energies and reaction energies were obtained. The kinetic parameters of the reaction rate constants and thermodynamic equilibrium constants in the temperature range of 300–1000 K were revealed. COOH formation and its subsequent dissociation are energetically easier than that of HCOO. When combined with kinetic modeling, the most preferable pathway for formic acid dissociation on the surface is HCOOH → COOH → CO. The rate-determining step is COOH dehydroxylation to CO, associating with an activation energy of 0.51 eV and a rate constant of 5.16 × 109 s−1 at 773 K. In addition, HCOO will be slowly accumulated on the surface as the temperature rises.

MnO2 catalysts are important for low-temperature removal of air pollutants. Sometimes the unavoidable moisture is not conductive to the desired reactions, therefore, water-resistant materials are desirable. However, the reported methods are not easily fulfilled for practical applications and the underlying mechanism for the improved hydrophobicity has not been clarified. In this study, highly water-resistant birnessite-type MnO2 was designed for humid ozone (O3) decomposition, which is important for alleviating global O3 pollution. The sample treated by nitric acid (H-MnO2) exhibited stable O3 conversion of ∼50% within 24 h under 50% of relative humidity (115 ppm of O3, 600 L·g−1·h−1 of space velocity, 25 °C). However, the pristine MnO2 was quickly deactivated with O3 conversion dropping to ∼10% within 30 min. Detailed characterizations show that higher amount of acid sites and oxygen vacancies together with their improved water-resistant properties facilitates adsorption and subsequent decomposition of humid O3 over the H-MnO2. DFT calculations demonstrate that compared with the pristine MnO2, oxygen vacancies were more easily formed over the H-MnO2, and the surface of the H-MnO2 was more hydrophobic and more attractive to O3 adsorption. Finally, a mechanism involving acid sites and oxygen vacancies for gaseous O3 decomposition was proposed.

A series of MFI zeolites with different Si/Al ratios were pretreated by a basic solution and their catalytic activity was evaluated in N2O decomposition after iron exchange. The performance of Fe-ZSM-5 catalysts could be improved by alkaline pretreatment. Among these samples, the activity curve of Fe-Z5-250-S sample could move to low temperature by >100 °C with a good preservation of hydrothermal stability. It is found that with the meso-microporous hybrid structure, the content of iron as active metal is significantly increased. Additionally, well preservation of the chemical environment around the tetrahedral aluminum and the site accessibility probably may be the other important factors to influence the catalytic activity.