Bulk Metal Oxide Research Articles

Chemistry of Formate and Water Ligands on Metal Oxide Cluster Nodes of Metal-Organic Framework hcp Hf-UiO-66: Keys to Understanding Reactivity of Paired μ2-OH and Defect Sites.

Many metal-organic frameworks (MOFs) incorporate nodes that are metal oxide clusters, and ligands that have been observed on these nodes include formates, acetates, water, hydroxyl groups, and others, all of which are potentially important in affecting reactivities for applications in separations, catalysis, and sensing. Formate is a common node ligand, arising from formic acid used as a modulator and from N,N-dimethylformamide used as a solvent in MOF syntheses. Yet only little work has been reported characterizing the reactivities of node formate ligands. Infrared spectra reported here show that formate bonds to two types of sites on the paired Hf6O8 nodes of hcp UiO-66, namely, defect and μ2-OH sites. Quantifying the number of formate ligands by 1H NMR spectroscopy of digested samples showed an almost equal number of formate ligands on the two sites, indicating the likelihood that they neighbor each other. These formate ligands interact with water molecules, reversibly switching their bonding from bidentate to monodentate. The formates on μ2-OH sites of hcp Hf-UiO-66 interact much more strongly with water than those on defect sites of the same node, and both interact more strongly than isolated defect sites of Hf-UiO-66. Correspondingly, the catalytic activities of hcp UiO-66 determined as turnover frequencies on each site are approximately twofold higher than those on UiO-66, bolstering the inference that methanol dehydration is catalyzed by a node defect site and a neighboring node μ2-OH site. The results show how MOFs, with their well-defined node structures, provide unprecedented opportunities to understand details of reactivities and catalysis on metal oxide clusters, in contrast to bulk metal oxide surfaces.

Hydrodeoxygenation of C15 furanic precursor over mesoporous NiMo-ZrO2 composite catalysts for the production of sustainable aviation fuel

Sustainable aviation fuel (SAF) is essential for achieving carbon neutrality in the transportation sector. This study elucidates the production of SAF range C9-C15 branched alkanes by hydrodeoxygenation (HDO) of C15 furanic precursor derived from 2-methylfuran and furfural via hydroxyalkylation-alkylation reaction. HDO reaction was performed using high surface area mesoporous NiMo-ZrO2 composite catalysts that exhibited high selectivity to central SAF alkanes (C13-C14). Deoxygenation follows a complex reaction network involving furanic double bond saturation and furan-ring opening reactions in series, followed by the cascade of HDO, dehydroformylation, and C-C bond cleavage. The present investigation enlightens the impact of calcination temperatures and metal (Mo and Ni) contents on structural stability, physicochemical properties, and catalytic performance of NiMo-ZrO2. Both Ni and Mo stabilized the tetragonal ZrO2 phases with improved surface area. The catalytic activity proliferated with rising calcination temperature till 873 K due to the enrichment of Mo-O-Zr acidic species and deteriorated beyond this temperature owing to the generation of crystalline MoO3/Zr(MoO4)2 species. NiMo alloy formation was enhanced, and concurrently, acidity was reduced with increasing Mo content. 30 wt% MoO3-containing catalyst showed the best catalytic activity due to the proper balance between acidity and NiMo alloy. Oxygenate conversion was boosted by increasing NiO addition up to 15 wt% due to the enhanced Ni and NiMo alloy formation and decreased at 20 wt% owing to the evolution of catalytically inactive bulk metal oxide species. Catalytic cracking was prominent at elevated reaction temperatures, with significant amounts of C13 alkane.

Sonication strategy for anchoring single metal atom oxides (W, Cu, Co) on CeO2-rGO for boosting electrocatalytic oxygen evolution reaction

In the field of electrocatalysis, single-atomic-layer tungsten, copper, and cobalt oxide on CeO2, ethylene diamine (ED) and reduced graphene oxide (rGO) supported materials shows tremendous potential. Despite the enormous interest in single metal atom oxide (SMAO) catalysts, it is still very difficult to directly convert readily available bulk metal oxide into single atom oxide. It is crucial and tough to create high performance materials for the oxygen evolution reaction (OER) in an alkaline environment. Herein, a single tungsten, copper and cobalt atom oxide (SMAO) anchored on the CeO2 atomic layer and overall components deposited on the rGO (rGO-ED-CeO2-WCuCo) is prepared through a one-pot sonication technique. The presence of SMAO is identified by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging. The electrocatalytic performance of final rGO-ED-CeO2-WCuCo-30 nanocomposite for the OER in 1 M KOH electrolyte is evidenced by providing low overpotential of 283 mV at 10 mA cm−2. The Tafel slope for OER using rGO-ED-CeO2-WCuCo-30 electrocatalysts is 57.03 mV dec−1. The electrocatalytic activity of rGO-ED-CeO2-WCuCo-30 nanocomposites for OER was noticeably increased when compared to bare CeO2 nanorods (401 mV), rGO-ED-CeO2-WCo-30 (345 mV), rGO-ED-CeO2-WCu-30 (340 mV) and rGO-ED-CeO2-WCuCo-20 (321 mV) samples.

Regulating the C–H Bond Activation Pathway over ZrO2 via Doping Engineering for Propane Dehydrogenation

The efficient activation of the C–H bond in light alkanes and their catalyst design are significant for alkane-related catalytic processes in view of theoretical and practical aspects. Here, we report the C–H bond activation mechanism and structure–reactivity relationships of Ga-doped ZrO2 catalysts in propane dehydrogenation. Experimental and theoretical calculation results suggest that the introduction of Ga into the framework of ZrO2 alters the C–H bond activation pathway from a stepwise mechanism to a concerted mechanism involving simultaneous cleavage of two C–H bonds in propane, leading to a superior C–H bond activation ability and a lower reaction barrier than state-of-the-art metal oxide catalysts. In addition, a volcano-type dependence of the rate of propene formation on the Ga/Zr ratio is established due to a compromise of intrinsic activity and active site concentration. The strategy of metal incorporation into bulk metal oxide may provide an alternative solution to control the C–H bond activation pathway for efficient propene production.

Aluminum oxide/polydimethylsiloxane-based Q-switched mode-locked erbium-doped fiber laser

A Q-switched mode-locked (QSML) erbium-doped fiber laser integrating aluminum oxide saturable absorber (Al2O3-SA) is demonstrated. With the help of polydimethylsiloxane polymer, Al2O3 powder was securely transferred on a tapered fiber surface and functioned as SA. A QSML pulse sequence was realized at a central wavelength of 1567.4 nm from 80 to 320 mW pump power with its envelope repetition rate ranging from 30.59 to 77.46 kHz. The short duration of 2.54 µs Q-switched envelope comprised of 8.3 ns ML pulses with 252 nJ pulse energy was realized at the maximum pump power of 320 mW. The high damage threshold of Al2O3-SA of beyond 7 GW/cm2 contributes to the future exploration of bulk metal oxide for high-energy optical pulse generation in near-infrared wavelengths.

Effect of postsynthesis preparation methods on catalytic performance of Ti-Beta zeolite in ketonization of propionic acid

Heteroatom metal-zeolite, with heteroatom metal (oxide) dispersed in the zeolite framework, enables the reactions typically catalyzed by bulk metal oxide counterpart but with maximized the atomic utilization. However, the distribution of heteroatoms in the framework is strongly influenced by the preparation method. In this work, Ti-Beta zeolites were postsynthesized using the recrystallization (Ti-Beta-Re) and solid-state ion-exchange (Ti-Beta-SSIE) methods. Characterizations showed that more Ti species were incorporated in the tetrahedral framework site of Ti-Beta-Re to form Lewis acid sites than in that of Ti-Beta-SSIE. In addition, intra-crystallite mesopores were developed in Ti-Beta-Re due to partial dissolution of BEA framework during alkaline etching and subsequent recrystallization of the etched framework. These zeolites were then tested for ketonization of biomass derived propionic acid at 350 °C and atmospheric pressure. The turnover frequency of ketonization was found to be 25% higher on Ti-Beta-Re (0.25 min−1) than on Ti-Beta-SSIE (0.20 min−1), whereas the apparent activation energy of 80 kJ/mol on Ti-Beta-Re is lower than 95 kJ/mol on Ti-Beta-SSIE. Moreover, the selectivity of 3-pentanone kept > 95% on Ti-Beta-Re while it dropped to ∼63% on Ti-Beta-SSIE with increase of reaction time at a space time of 2 h. This work demonstrated that the tetrahedrally coordinated Ti species are the active sites and the presence of intra-crystallite mesopores facilitates selective ketonization of carboxylic acids.

Experimental methods in chemical engineering: Temperature programmed surface reaction spectroscopy—TPSR

AbstractTemperature programmed surface reaction spectroscopy (TPSR) is a powerful technique to determine the surface chemistry of bulk metal, supported metal, bulk metal oxide, supported metal oxide, zeolite, and molecular sieve catalysts. It can provide both qualitative and quantitative analysis of the surface active sites present on the catalyst surface, the reaction mechanisms, and kinetics occurring on the catalyst surface by using chemical probe molecules such as alcohols, carboxylates, and specific acidic‐basic reacting gases. In this tutorial review, the highly informativeCH3OHchemical probe molecule was used to highlight the information that can be obtained fromCH3OH‐TPSR experiments. TheCH3OHmolecule readily interacts with the catalyst surface to form surfaceCH3O·andHCOO·intermediates that react to produce HCHO/HCOOCH3/(CH3O)2CH2,CH3OCH3, andCO/CO2products related to the surface redox, acid and basic nature, respectively. Integration of theCH3OH‐TPSR spectra peaks provide the number of surface active sites. The surface kinetic information provided byCH3OH‐TPSR allows to discriminate between different reaction mechanisms (first‐order, second‐order, Langmuir‐Hinshelwood, and Mars‐van Krevelen). We discuss the uncertainty inherent inCH3OH‐TPSR experiments and address source of errors and detection limits. Web of Science indexed over 800 articles citing TPSR since 1990. A bibliometric analysis identified four clusters of reactions and catalysts: the dominant catalysts for partial oxidation and water gas shift were Ni, Ru, and Pt;CeO2, Co, Cu, Rh, Pd, and perovskites were the main catalysts for combustion and hydrogenation; Ag and zeolites were grouped with reduction; and,Al2O3,ZrO2,SiO2, andV2O5were applied for dehydrogenation.

Controlled syntheses of monodispersed metal oxide nanocrystals from bulk metal oxide materials

High quality metal oxides nanocrystals are synthesized from bulk metal oxides in the presence of surfactants and high boiling point solvent.

TCAD Simulation and Analysis of Selective Buried Oxide MOSFET Dynamic Power

Low power consumption has become one of the major requirements for most microelectronic devices and systems. Increasing power dissipation may lead to decreasing system efficiency and lifetime. The BULK metal oxide semiconductor field-effect transistor (MOSFET) has relatively high power dissipation and low frequency response due to its internal capacitances. Although the silicon-on-insulator (SOI) MOSFET was introduced to resolve these limitations, other challenges were introduced including the kink effect in the current-voltage characteristics. The selective buried oxide (SELBOX) MOSFET was then suggested to resolve the problem of the kink effect. The authors have previously investigated and reported the characteristics of the SELBOX structure in terms of kink effect, frequency, thermal and static power characteristics. In this paper, we continue our investigation by presenting the dynamic power characteristics of the SELBOX structure and compare that with the BULK and SOI structures. The simulated fabrication of the three devices was conducted using Silvaco TCAD tools in 90 nm complementary metal oxide semiconductor (CMOS) technology. Simulation results show that the average dynamic power dissipation of the CMOS BULK, SOI and SELBOX are compatible at high frequencies with approximately 54.5 µW. At low frequencies, the SOI and SELBOX showed comparable dynamic power dissipation but with lower values than the BULK structure. The difference in power dissipation between the SELBOX and BULK is in the order of nano watts. This power difference becomes significant at the chip level. For instance, at 1 MHz, SOI and SELBOX exhibit an average dynamic power consumption of 0.0026 µW less than that of the BULK structure. This value cannot be ignored when a chip operates using thousands or millions of SOI or SELBOX MOSFETs.

Directly transforming copper (I) oxide bulk into isolated single-atom copper sites catalyst through gas-transport approach

Single-atom metal catalysts have sparked tremendous attention, but direct transformation of cheap and easily obtainable bulk metal oxide into single atoms is still a great challenge. Here we report a facile and versatile gas-transport strategy to synthesize isolated single-atom copper sites (Cu ISAS/NC) catalyst at gram levels. Commercial copper (I) oxide powder is sublimated as mobile vapor at nearly melting temperature (1500 K) and subsequently can be trapped and reduced by the defect-rich nitrogen-doped carbon (NC), forming the isolated copper sites catalyst. Strikingly, this thermally stable Cu ISAS/NC, which is obtained above 1270 K, delivers excellent oxygen reduction performance possessing a recorded half-wave potential of 0.92 V vs RHE among other Cu-based electrocatalysts. By varying metal oxide precursors, we demonstrate the universal synthesis of different metal single atoms anchored on NC materials (M ISAS/NC, where M refers to Mo and Sn). This strategy is readily scalable and the as-prepared sintering-resistant M ISAS/NC catalysts hold great potential in high-temperature applications.

Gate diffusion input based 4‐bit Vedic multiplier design

A multiplier is one of the key hardware blocks in most of the processors. Multiplication is a lengthy, time-consuming task. Vedic multiplication in field programmable gate array implementation has been proven effective in reducing the number of steps and circuit delay. Conventionally at the circuit level, complementary metal oxide semiconductor (CMOS) logic is used to design a multiplier. In CMOS circuits, the area is always an issue. Gate diffusion input (GDI)-based logic has been explored in the literature to reduce the number of transistors for various logic functions. Thus, Vedic mathematics, on the one hand, simplifies the multiplication process and reduces the delay; while on the other hand, GDI technique helps in minimising the transistor count (TC) and reduction in power. Therefore, this study puts forth a GDI logic-based 4-bit Vedic multiplier. To study the effectiveness of the GDI logic, the transient response of a 2-bit Vedic multiplier using CMOS and GDI is compared. For the 4-bit Vedic multiplier, two design approaches are taken into consideration. The performance of these circuits is analysed in terms of average power dissipation, delay, and TC. The effect of supply voltage scaling is also studied. The circuit simulations are carried out at 130 nm for bulk metal oxide semiconductor field effect transistor predictive technology model-based device parameters.

Aqueous Mechanical Oxidation of Zn Dust: An Inventive Technique for Bulk Production of ZnO Nanorods

Metal to bulk metal oxide nanoparticles have been successfully processed via a sustainable, facile, and ecofriendly (green) approach, namely, aqueous mechanical-oxidation. Micron-sized zinc (Zn) dust (∼45 μm) was directly wet-milled using ceramic milling media for 72 h, resulting in the production of bulk monocrystalline ZnO nanorods (aspect ratio ∼5.2, hydrodynamic diameter of 315 nm) and voluminous H2 gas by catalyst-free water-splitting reaction. The mill-induced surface oxidation and the chemical purity of the synthesized nano ZnO were carefully studied using the XPS analysis. Other standard analytical tools were also employed to understand the crystallinity, phase purity, morphology, and surface area of the final artifact. The photocatalytic activities of these mechanically grown ZnO nanorods were ascertained from two cationic dye-degradation experiments, using the dyes methylene blue and rhodamine 6G. In a nutshell, the study throws a new insight into a cost-effective, zero-effluent, single-step, an...

Negative Capacitance Field Effect Transistor With Hysteresis-Free Sub-60-mV/Decade Switching

We demonstrate a nearly hysteresis-free sub-60-mV/decade subthreshold swing (SS) operation in a p-type bulk metal–oxide–semiconductor field-effect transistor externally connected to a ferroelectric capacitor. The SS $\mu \text{m}\sim 10$ nA/ $\mu \text{m}$ of drain current) and at large drain current levels. However, the extent of hysteresis is found to be strongly dependent on the drain voltage. At high drain voltages, large hysteresis occurs, indicating the influence of drain voltage in the charge balance with the ferroelectric capacitor.

Role of Metal-Lithium Oxide Interfaces in the Extra Lithium Capacity of Metal Oxide Lithium-Ion Battery Anode Materials

Lithium storage capacities beyond the stoichiometric limit of conversion have been reported for the transition metal oxides MnO, CoO, NiO, CuO, and beyond the alloying limit for the main group metal oxide SnO. This work examines the molecular mechanisms responsible for this extra capacity using first principles plane wave density functional theory with periodic boundary conditions. Energies of the optimized structures were employed to construct first discharge curves. Analysis of lithiated structures of transition metal oxides with moderate lithium content revealed the formation of two different phases within the electrode material, namely bulk metal and lithium oxide, Li2O. At higher lithium content, the interfacial region between the two phases was found to expand, giving rise to “free volume” for additional lithium storage. MnO had the highest free volume in the interfacial region for lithium storage, followed by CoO, NiO, CuO, and SnO. Of particular interest was CuO, which upon lithiation, formed linear and branched chains of Cu atoms that percolated throughout a large portion of the system. This behavior suggests that CuO may better maintain conductivity through the anode material for more cycles than the other transition metal oxides examined.

Improved Accuracy of Density Functional Theory Calculations for CO2 Reduction and Metal-Air Batteries

Density functional theory (DFT) calculations have greatly contributed to the atomic level understanding of electrochemical reactions. However, in some cases, the accuracy can be prohibitively low for a detailed understanding of, e.g. reaction mechanisms. Two cases are examined here, i.e. the electrocatalytic reduction of CO2 and metal-air batteries. In theoretical studies of electrocatalytic CO2 reduction, calculated DFT-level enthalpies of reaction for CO2reduction to various products are significantly different from experimental values[1-3]. In theoretical studies of metal-air battery reactions, systematic errors compared to experiments have also been found in calculation of enthalpies of formation for bulk metal oxide, peroxide and superoxide species[4,5]. It is here demonstrated how the errors, which depend explicitly on the choice of applied exchange-correlation functional, can be identified through first principle methods. Ensembles generated using a Bayesian error estimation functional, in this case the BEEF-vdW functional[6], are used for the error identification. The ensembles, which consist of perturbations of the main van der Waals density functional, can be generated at low computational cost. It has previously been demonstrated how these ensembles can be used to estimate the magnitude of functional dependent errors[6]. When here applied for identification of the source of functional dependent systematic errors, ensembles for different reactions are not only examined individually, but compared to determine patterns in functional dependence. The method is exemplified by ensemble comparison of reaction enthalpy to methanol and formic acid depicted in Figure 1. The functional dependence on the calculated reaction enthalpy to methanol is twice as large as that to formic acid. This suggests that the systematic error is due to carbon-oxygen double bonds, as the change in number of carbon-oxygen double bonds in the reaction to methanol is two as compared to one for reaction to formic acid. This is subsequently confirmed by further comparisons of functional dependence and a significant source of systematic errors in DFT-level computational electrocatalytic CO2reduction is hence identified. The new insight adds increased accuracy e.g., for reaction to formic acid, where the experimental enthalpy of reaction is 0.15 eV. Previously, this enthalpy has been calculated without and with correctional approaches to 0.39 eV and 0.30 eV, respectively[2]. Here, correcting the newly identified error in an otherwise similar approach as used previously the enthalpy of reaction is 0.13 eV. For metal-air batteries the previously observed large systematic errors are found not to be intrinsic to the metal oxide species. Errors can be significantly reduced by using metal chlorides as energy reference rather than pure metals. The mean absolute error per oxygen versus experiments for alkali metal peroxide and superoxide species will be 0.03 eV and 0.09 eV, respectively, using metal chlorides as reference, as compared to 0.47 eV and 0.17 eV using metals as reference. The presented approach for error identification is expected to be applicable to a very broad range of systems.

A molecular catalyst for water oxidation that binds to metal oxide surfaces.

Molecular catalysts are known for their high activity and tunability, but their solubility and limited stability often restrict their use in practical applications. Here we describe how a molecular iridium catalyst for water oxidation directly and robustly binds to oxide surfaces without the need for any external stimulus or additional linking groups. On conductive electrode surfaces, this heterogenized molecular catalyst oxidizes water with low overpotential, high turnover frequency and minimal degradation. Spectroscopic and electrochemical studies show that it does not decompose into iridium oxide, thus preserving its molecular identity, and that it is capable of sustaining high activity towards water oxidation with stability comparable to state-of-the-art bulk metal oxide catalysts.

Study of performance scaling of 22-nm epitaxial delta-doped channel MOS transistor

Epitaxial delta-doped channel (EδDC) profile is a promising approach for extending the scalability of bulk metal oxide semiconductor (MOS) technology for low-power system-on-chip applications. A comparative study between EδDC bulk MOS transistor with gate length Lg = 22 nm and a conventional uniformly doped channel (UDC) bulk MOS transistor, with respect to various digital and analogue performances, is presented. The study has been performed using Silvaco technology computer-aided design device simulator, calibrated with experimental results. This study reveals that at smaller gate length, EδDC transistor outperforms the UDC transistor with respect to various studied performances. The reduced contribution of the lateral electric field in the channel plays the key role in this regard. Further, the carrier mobility in EδDC transistor is higher compared to UDC transistor. For moderate gate and drain bias, the impact ionisation rate of the carriers for EδDC MOS transistor is lower than that of the UDC transistor. In addition, at 22 nm, the performances of a EδDC transistor are competitive to that of an ultra-thin body silicon-on-insulator transistor.

Spectroscopic properties of doped and defective semiconducting oxides from hybrid density functional calculations.

CONSPECTUS: Very rarely do researchers use metal oxides in their pure and fully stoichiometric form. In most of the countless applications of these compounds, ranging from catalysis to electronic devices, metal oxides are either doped or defective because the most interesting chemical, electronic, optical, and magnetic properties arise when foreign components or defects are introduced in the lattice. Similarly, many metal oxides are diamagnetic materials and do not show a response to specific spectroscopies such as electron paramagnetic resonance (EPR) spectroscopy. However, doped or defective oxides may exhibit an interesting and informative paramagnetic behavior. Doped and defective metal oxides offer an expanding range of applications in contemporary condensed matter science; therefore researchers have devoted enormous effort to the understanding their physical and chemical properties. The interplay between experiment and computation is particularly useful in this field, and contemporary simulation techniques have achieved high accuracies with these materials. In this Account, we show how the direct comparison between spectroscopic experimental and computational data for some selected and relevant materials provides ways to understand and control these complex systems. We focus on the EPR properties and electronic transitions that arise from the presence of dopants and defects in bulk metal oxide materials. We analyze and compare the effect of nitrogen doping in TiO2 and ZnO (two semiconducting oxides) and MgO (a wide gap insulator) and examine the effect of oxygen deficiency in the semiconducting properties of TiO2-x, ZnO1-x, and WO3-x materials. We chose these systems because of their relevance in applications including photocatalysis, touch screens, electrodes in magnetic random access memories, and smart glasses. Density functional theory (DFT) provides the general computational framework used to illustrate the electronic structure of these systems. However, for a more accurate description of the oxide band gap and of the electron localization of the impurity states associated with dopants or defects, we resorted to the use of hybrid functionals (B3LYP), where a portion of exact exchange in the exchange-correlation functional partly corrects for the self-interaction error inherent in DFT. In many cases, the self-interaction correction is very important, and these results can lead to a completely different physical picture than that obtained using local or semilocal functionals. We analyzed the electronic transitions in terms of their transition energy levels, which provided a more accurate comparison with experimental spectroscopic data than Kohn-Sham eigenvalues. The effects of N-doping were similar among the three oxides that we considered. The nature of the impurity state is always localized at the dopant site, which may limit their application in photocatalytic processes. Photocatalytic systems require highly delocalized photoexcited carriers within the material to effectively trigger redox processes at the surface. The nature of the electronic states associated with the oxygen deficiency differed widely in the three investigated oxides. In ZnO1-x and WO3-x the electronic states resemble the typical F-centers in insulating oxides or halides, with the excess electron density localized at the vacancy site. However, TiO2 acts as a reducible oxide, and the removal of neutral oxygen atoms reduced Ti(4+) to Ti(3+).

Electrically Stable, Solution-Processed Amorphous Oxide IZO Thin-Film Transistors Through a UV-Ozone Assisted Sol-Gel Approach

Metal acetylacetonates are conventional sol-gel precursors used to deposit thin amorphous metal oxide films of In-Zn-O (IZO) suitable for thin-film field effect transistors (TFTs). In this paper, we couple this traditional approach with a postdeposition UV-ozone treatment to effectively reduce carbon impurities prior to any thermal treatment steps. Therefore, we find that the rate of bulk metal oxide formation is enhanced, thus enabling a significant reduction of the processing temperature necessary to achieve high-mobility transistors. Optimized TFT structures processed at 300 °C show n-type mobility of 35 cm2/Vs with on and off ratio of 107. Moreover, positive bias stress tests of such devices are found to exhibit one the lowest threshold voltage shifts of any solution-processed amorphous TFT fabricated without a passivation layer.

Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

The sol–gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni–W–O and Ni–Ti–O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction.