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This study aims to investigate the catalytic activity of spinel-type oxides (NixCoyO4) for the oxidation of toluene and carbon monoxide at low temperatures. A series of Ni/Co catalysts with different mole ratios were synthesized via citric acid assisted sol-gel method and the influence of the nickel to cobalt ratios on the properties and catalytic performance of NixCoyO4 were investigated by characterization such as XRD, SEM-EDX, BET, H2–TPR. The results indicate that the catalyst with the Ni/Co atomic ratio of 1.5/1.5 exhibits the highest complete toluene oxidation activity, with 85% toluene conversion rate at 100 – 250 °C and complete toluene oxidation at 300 °C. However, for the complete oxidation of CO, the Ni/Co atomic ratio of 1/2 exhibits higher activity, converting 100% CO at 150 °C. The results show that NiO and CoOx are proved to be more active than the other for the oxidation of toluene and CO, respectively. The characteristic results show that high surface area, small particle size, good temperature reducibility, and oxygen species with high mobility in low-temperature regions are responsible for the catalytic performance of nickel cobalt spinel-type catalyst for toluene and carbon monoxide oxidation. The good stability of the Ni-Co oxide catalysts for the oxidation reactions originates from the strong Ni-Co interaction. [ABSTRACT FROM AUTHOR]

In recent years, Nb-based oxides, especially Nb2O5, due to their unique structural advantages, have stimulated scholars' extensive research enthusiasm in the field of energy storage systems including lithium ion batteries (LIBs) and sodium ion batteries (SIBs), excellent chemical stability and outstanding rate capability dominated by pseudocapacitive nature. In addition, Nb-based oxides usually have a higher operating voltage (> 1.0 V vs Li+/Li), which can effectively prevent the decomposition of organic electrolytes and the formation of solid electrolyte interface films in batteries. This review systematically summarizes the different crystal structures of Nb2O5 and the lithium storage mechanism based on theoretical calculations, as well as the comparison of various synthesis strategies. In addition, the advanced research progress of niobium-based oxides as anode materials in LIBs and SIBs is summarized from the perspective of nanostructure control engineering that affects electrochemical performance. It also puts forward reasonable cognition and challenges for future research, which is conducive to the design of energy storage equipment that meets the needs of sustainable development. The design and optimization of various synthesis methods facilitate the formation of a variety of heterogeneous nanostructures, leading to reversible storage of Li and Na ions. [ABSTRACT FROM AUTHOR]

This study aimed to determine the photocatalytic activity of photo-Fenton reagent in the photodegradation of 4-Nitrophenol. For this purpose, Fe(III) tetraphenyl porphyrin encapsulated NaY zeolite (FeTPP/NaY) was successfully synthesised via the zeolite synthesis method. The effects of catalyst amount, H2O2 and UV illumination, concentration of 4-Nitrophenol and pH value on the photodegradation process were examined. Ultraviolet–Visible spectroscopy studies revealed that catechol, benzoquinone, and nitrate as the key intermediate species for photodegradation of 4-Nitrophenol. The chemical oxygen demand analysis indicated mineralisation of pollutant which exhibits 85% conversion of 4-Nitrophenol after 120 min irradiation. Rational design of FeTPP/NaY Nanocomposite as Fenton reagent for efficient photodegradation of 4-Nitrophenol was reported, and the possible reaction pathways of the photocatalytic reaction were proposed. [ABSTRACT FROM AUTHOR]

Mesoporous Y zeolites were prepared by the sequential chemical dealumination (using chelating agents such as ethylenediaminetetraacetic acid, H4EDTA, and citric acid aqueous solutions) and alkaline desilication (using sodium hydroxide, NaOH, aqueous solutions) treatments. Specifically, the ultrasound-assisted alkaline treatment (i.e., ultrasonic treatment) was proposed as the alternative to conventional alkaline treatments which are performed under hydrothermal conditions. In comparison with the hydrothermal alkaline treatment, the ultrasonic treatment showed the comparatively enhanced efficiency (with the reduced treatment time, i.e., 5 min vs. 30 min, all with 0.2 mol·L−1 NaOH at 65°C) in treating the deal-uminated Y zeolites for creating mesoporosity. For example, after the treatment of a dealuminated zeolite Y (using 0.1 mol·L−1 H4EDTA at 100°C for 6 h), the ultrasonic treatment produced the mesoporous zeolite Y with the specific external surface area (Sexternal) of 160 m2·g·−1and mesopore volume (Vmeso) of 0.22 cm3·g−1, being slightly higher than that by the conventional method (i.e., Sextemal= 128 m2·g−1 and Vmeso = 0.19 cm3·g−1). The acidic property and catalytic activity (in catalytic cracking of n-octane) of mesoporous Y zeolites obtained by the two methods were comparable. The ultrasonic desilication treatment was found to be generic, also being effective to treat the dealuminated Y zeolites by citric acid. Additionally, the first step of chemical dealumination treatment was crucial to enable the effective creation of mesopores in the parent Y zeolite (with a silicon-to-aluminium ratio, Si/Al = 2.6) regardless of the subsequent alkaline desilication treatment (i.e., ultrasonic or hydrothermal). Therefore, appropriate selection of the condition of the chemical dealumination treatment based on the property of parent zeolites, such as Si/Al ratio and crystallinity, is important for making mesoporous zeolites effectively. [ABSTRACT FROM AUTHOR]

As a metal-free semiconductor, graphitic carbon nitride (g-C3N4) has received extensive attention due to its high stability, nontoxicity, facile and low-cost synthesis, appropriate band gap in the visible spectral range and wide availability of resources. The dimensions of g-C3N4 can influence the regime of the confinement of electrons, and consequently, g-C3N4 with various dimensionalities shows different properties, making them available for many stimulating applications. Although there are some reviews focusing on the synthesis strategy and applications of g-C3N4, there is still a lack of comprehensive review that systemically summarises the synthesis and application of different dimensions of g-C3N4, which can provide an important theoretical and practical basis for the development of g-C3N4 with different dimensionalities and maximises their potential in diverse applications. By reviewing the latest progress of g-C3N4 studies, we aim to summarise the preparation of g-C3N4 with different dimensionalities using various structural engineering strategies, discuss the fundamental bottlenecks of currently existing methods and their solution strategies, and explore their applications in energy and environmental applications. Furthermore, it also puts forward the views on the future research direction of these unique materials. [ABSTRACT FROM AUTHOR]

A simple, practical and precise method for the simultaneous analysis of 32 different polycyclic aromatic hydrocarbon (PAHs) including 16 parent PAHs, 8 oxygenated-PAHs (oxy-PAHs), 4 chloro-PAHs, and 4 nitrogen-containing heterocyclic PACs (N-PACs), in groundwater was established via gas chromatography-mass spectrometry (GC-MS) combined with liquid-liquid extraction (LLE). The obtained detection method possesses instrument detection limits (at a signal to noise of 3:1) in the range of 0.05-10 ng/mL and method detection limits in the range of 1.7-13.2 ng/L. The average recoveries of the 32 analytes were in the range of 54.3%-127.0% with relative standard deviations (RSDs) < 20%, and the recoveries of 16 PAH derivatives ranged from 54.3 to 115.1% with RSDs < 17.9%. The method has been successfully applied to the screening of 64 groundwater samples from eastern China. The results revealed that 30 types of targets including 16 PAHs and 14 PAH derivatives were detected and that the groundwater in most areas is slightly polluted, while the pollution of Jiangsu Province and Shandong Province was more serious. [ABSTRACT FROM AUTHOR]

Abstract: Novel S-doped Fe2O3/C nanocomposite was synthesized via a one-pot hydrothermal method and was used for the first time as an efficient adsorbent for Congo red dye (CR) removal from water solution. The obtained catalyst was characterized by various methods including Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, vibration sample magnetometry, X-ray diffraction and field emission scanning electron microscopy. To improve the adsorption performance, some important parameters affecting dye removal were optimized such as adsorbent dosage, contact time, solution pH, initial dye concentration and ionic strength. At the optimum conditions, the maximum capacity of adsorption for this nanocomposite was 270.2 mg g−1, which is better than other magnetic adsorbents for CR removal. The results of adsorption isotherm were matched with Langmuir model. Kinetic tests show that adsorption experimental data were best fitted by pseudo-first-order model.Graphical abstract: [ABSTRACT FROM AUTHOR]

Gamma alumina is one of the widely used supports in catalyst preparation, possessing a high specific surface area and good thermal stability. Spray drying is an efficient way to produce narrow particle size distribution and spherical shape powders. In this study, spray drying method has been implemented to prepare microspherical nanoporous gamma alumina with a high specific surface area. The nanoporous gamma alumina support was utilized in the preparation of various heterogeneous base catalysts. The highest biodiesel yield of 99% was obtained at 6 wt% loading of K/γ-Al2O3 catalyst, using waste cooking oil as feedstock. The obtained results revealed the great potential of the synthesized nanoporous gamma alumina as an effective support for heterogeneous base catalysts preparation in the transesterification reaction. [ABSTRACT FROM AUTHOR]

This invited review highlights recent progress in the various classes of heterogeneous catalysts for methane combustion. These combustion catalysts provide a high-efficiency, clean energy source for natural gas vehicles and power plants. This review examines bimetallic systems, and a variety of oxides including single metal oxides, perovskites, spinels, and hexaaluminates. Noble metal mixed oxides exhibit superior catalytic activity due material-specific supports, additives, preparation methods, poisoning, regeneration and surface structure. Kinetic aspects, mechanisms, and the latest studies concerning density functional theory modelling are discussed in conjunction with particle oxidation/reduction mechanisms. The extensive background knowledge on the methane combustion reaction provided by this review provides guidance for researchers with interests ranging from the field of heterogeneous catalysis to the engineering of new high performance materials in environmental and chemical engineering. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

A series of cerium-tungsten oxide catalysts was prepared by the co-precipitation method and was evaluated for the selective catalytic reduction of NO by ammonia (NH-SCR) over a wide temperature range. These catalysts were characterized by BET, XRD, XPS and H-TPR analyses. The experimental studies demonstrated that, among cerium-tungsten oxides, CeO-WO with a Ce/W molar ratio of 3/2 exhibited the best activity toward NH-SCR reactions, N selectivity and SO durability over a broad temperature range of 175-500 °C at a space velocity of 47,000 h. The strong interaction between Ce and W could be the main factor leading to the high activity of the CeO-WO mixed oxide catalyst. Graphical Abstract: A series of cerium-tungsten oxide catalysts was prepared by the co-precipitation method and was evaluated for the selective catalytic reduction of NO by ammonia (NH-SCR) over a wide temperature range. These catalysts were characterized by BET, XRD, XPS and H-TPR analyses. The experimental studies demonstrated that, among cerium-tungsten oxides, CeO-WO with a Ce/W molar ratio of 3/2 exhibited the best activity toward NH-SCR reactions, N selectivity and SO durability over a broad temperature range of 175-500 °C at a space velocity of 47,000 h. The strong interaction between Ce and W could be the main factor leading to the high activity of the CeO-WO mixed oxide catalyst.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Versatile superstructures composed of nanoparticles have recently been prepared using various disassembly methods. However, little information is known on how the structural disassembly influences the catalytic performance of the materials. Here we show how the disassembly of an ordered porous La0.6Sr0.4MnO3 perovskite array, to give hexapod mesostructured nanoparticles, exposes a new crystal facet which is more active for catalytic methane combustion. On fragmenting three-dimensionally ordered macroporous (3DOM) structures in a controlled manner, via a process that has been likened to retrosynthesis, hexapod-shaped building blocks can be harvested which possess a mesostructured architecture. The hexapod-shaped perovskite catalyst exhibits excellent low temperature methane oxidation activity (T90%=438 °C; reaction rate=4.84 × 10−7 mol m−2 s−1). First principle calculations suggest the fractures, which occur at weak joints within the 3DOM architecture, afford a large area of (001) surface that displays a reduced energy barrier for hydrogen abstraction, thereby facilitating methane oxidation. [ABSTRACT FROM AUTHOR]

A facile one-step solution reaction route for growth of novel MoS2 nanorose cross-linked by 3D rGO network, in which the MoS2 nanorose is constructed by single-layered or few-layered MoS2 nanosheets, is presented. Due to the 3D assembled hierarchical architecture of the ultrathin MoS2 nanosheets and the interconnection of 3D rGO network, as well as the synergetic effects of MoS2 and rGO, the as-prepared MoS2-NR/rGO nanohybrids delivered high specific capacity, excellent cycling and good rate performance when evaluated as an anode material for lithium-ion batteries. Moreover, the nanohybrids also show excellent hydrogen-evolution catalytic activity and durability in an acidic medium, which is superior to MoS2 nanorose and their nanoparticles counterparts. [ABSTRACT FROM AUTHOR]