Metal Oxide Composites Research Articles

Development of starch-based amorphous CoOx self-supporting carbon aerogel electrocatalyst for hydrogen evolution

Hydrogen energy is turning into a major research topic in this complex and changing world. In recent years, more and more research has been done on transition metal oxides and biomass composites. In this study, potato starch and amorphous cobalt oxide were assembled into carbon aerogel by sol-gel method and high-temperature annealing (CoOx/PSCA). The connected porous structure of the carbon aerogel is conducive to HER mass transfer, and its structure can avoid the agglomeration of transition metals. It also has great mechanical properties and can be directly used as a self-supporting catalyst for electrolysis with 1 M KOH for hydrogen evolution, which showed excellent HER activity and yielded the effective current density of 10 mA cm−2 at 100 mV overpotential. Electrocatalytic experiments further showed that the better performance of CoOx/PSCA for HER can be attributed to the high electrical conductivity of carbon and the synergistic effect of unsaturated catalytic sites on the amorphous CoOx cluster. The catalyst comes from a wide range of sources, is easy to produce, and has good long-term stability, so it can be used in large-scale production. This paper provides a simple and easy method to make biomass-based transition metal oxide composites for electrolyzing water to produce hydrogen.

Facile Fabrication of Fe2O3/TiO2 Composite from Titanium Slag as Adsorbent for As(V) Removal from Aqueous Media

Mixed metal oxide composites have been widely used as adsorbents for the removal of heavy metal ions from wastewater. In this work, Fe2O3/TiO2 composite was sustainably prepared via the treatment of titanium slag with a low-concentration sulfuric acid solution (20%) and used for the removal of As(V) from aqueous solutions. The resulting products were characterized by X-ray diffraction (XRD), N2 adsorption−desorption, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The batch adsorption was employed to investigate the removal efficiency of the Fe2O3/TiO2 adsorbent toward As(V). The Langmuir and Freundlich isotherms were plotted in order to study the adsorption process. The adsorption of As(V) on FeO3/TiO2 fitted well with the Freundlich isotherm model, suggesting a multilayer adsorption process with an adsorption capacity of 68.26 mg·g−1. The adsorption kinetics study demonstrated that the adsorption behavior of the Fe2O3/TiO2 composite for the As(V) was pseudo-second-order. With low-cost preparation and high adsorption capacity, the prepared Fe2O3/TiO2 adsorbent could be used as an effective adsorbent for As(V) removal from contaminated water sources. The approach utilized in this research is viewed as a sustainable route for creating a proficient adsorbent for the purification of water.

Prediction of Chemical Corrosion Rate and Remaining Life of Buried Oil and Gas Pipelines in Changqing Gas Field

Green synthesis and metal oxide composites have attracted much attention from researchers of industry and academia. As a typical application of green synthesis and metal oxide composites, the continuous change of industrial technology and the continuous improvement of the social and economic level, the demand for oil and gas are also increasing. However, the spatial gap between the place of origin and the place of demand for oil and gas resources is large, so the long-distance oil and gas pipeline came into being. However, under the action of time, coupled with the corrosion effect of the soil due to deep burial, some pipelines have serious aging and corrosion phenomena. Therefore, in order to give corresponding guarantees for economic development, we need to conduct in-depth research and analysis of the corrosion of oil and gas long-distance pipelines and give effective solutions. In this paper, the corrosion rate prediction of buried oil and gas pipelines is studied in Changqing gas field. By improving the inertial weights and learning factors of the traditional particle swarm algorithm, the parameters of the generalized regression neural network are optimized and selected, and the corrosion rate prediction model of buried pipelines is finally constructed. Comparative analysis with other swarm intelligence algorithms shows that the improved particle swarm algorithm has stronger convergence ability and higher prediction accuracy than the BP model and SVM model. In addition, based on the detection data collected at the site of the gathering and transportation pipeline in Changqing gas field, this paper uses the extreme value distribution theory and the local corrosion progress formula to establish a prediction model for the residual life of corrosion of buried pipelines. The model established in this paper can effectively determine the risk pipe segment of buried pipeline and provide a decision-making basis for pipeline management departments. The work provides an important application guidance to green synthesis and metal oxide composites.

Tailoring the catalytic properties of Mn-V metal oxide composites for NOx abatement with NH3 under NO– or NO2-rich conditions

Both V2O5 and MnOx on TiO2 are metal oxides widely used for selective catalytic reduction (SCR) with NH3. However, each has a different temperature window for optimal performance, and interpreting the catalytic reaction under various NOx conditions is still challenging. To solve this problem, we explored the reaction characteristics by varying the composition of Mn/V. Under NO-rich conditions, the number of active oxygen and oxygen vacancies at the optimal Mn/V ratio resulted in improved performance. Interestingly, under NO2-rich conditions, an increase in the amount of Mn compared to V led to an increase in the NOx consumption rate with a decrease in activation energy. Importantly, the catalysts synthesized according to the Mn/V ratio resulted in changes in the reaction rate and the type of species adsorbed. Meanwhile, the SCR reactions of all Mn-V composite catalysts follow the Langmuir-Hinshelwood (LH) mechanism type in which NH3 and NOx are adsorbed on the catalyst surface. In addition, durability of the optimal Mn/V is improved by suppressing the adsorption of K+ ions to the acidic site compared to the commercial modified catalyst. As a result, it was suggested that it follows the Eley-Rideal (ER) due to the changed adsorption characteristics.

One pot synthesis of carbon decorated NiO nanorods as cathode materials for high-performance asymmetric supercapacitors

The composites of metal oxides and carbons are of research interest for improving the energy density of supercapacitors. In this work, we have demonstrated a simple one-pot hydrothermal synthesis method to prepare NiO nanorods followed by carbon framework decorated NiO nanorods (NiO@C). The NiO@C electrode showed an excellent specific capacitance of 1360 F g−1 compared to pristine NiO of 890 F g−1 at 1 A g−1 in a voltage range of 0.05 to 0.5 V in 1 M KOH electrolyte. The NiO@C electrodes showed excellent cycle stability over 10,000 cycles with 90 % capacitance retention. Asymmetric supercapacitors fabricated using corncob-derived activated carbon anode, and NiO@C cathode delivers a power density of 4574 W kg−1 at an energy density of 21.6 Wh kg−1. The enhanced capacitance of NiO@C material is due to the synergistic effect of the pseudocapacitive of NiO nanorods and the electric double-layer capacitance of the carbon matrix. Besides, the carbon framework facilitates quick charge acceptance, improved cycling stability, and rate capability. The cost-effective one-pot synthesis and eco-friendly NiO nanorods with easy electrode fabrication open opportunities for developing high-energy-density NiO-based supercapacitors.

Robust lamellar Fe2O3@SnO2 heterostructure for long cycling and high-rate lithium storage

Transition metal oxides (TMOs) have attracted great attention for lithium-ion batteries (LIBs) owing to their high theoretical capacity. Unfortunately, the painful volume expansion and inferior electrical conductivity of TMOs lead to nonreversing structural deterioration, disordered particle agglomeration and sluggish transfer efficiency, which results in low rate performance and poor cycling stability. This work reports a kind of lamellar Fe2O3 @SnO2 heterostructure composite for LIBs by the means of uniform epitaxial growth of the SnO2 nanorods on the lamellar Fe2O3. Due to the “synergistic effect” advantage of the unique heterostructure and two kinds of composition, the lamellar Fe2O3 @SnO2 heterostructure delivers a prominent and impressive capacity (1572.7 mA h∙g−1 at 4 A∙g−1), good rate performance (993.7 mA h∙g−1 at 5 A∙g−1) and stable long-cycle durability (848.4 mA h∙g−1 after 4000 cycles at 4 A∙g−1). The finite element mechanical simulation demonstrates that the stress is concentrated at the gap of SnO2 nanorods by epitaxial growth from the lamellar Fe2O3, the junction of SnO2 nanorods and the lamellar Fe2O3 is safeguarded. Hence, the lamellar Fe2O3 @SnO2 heterostructure has good rate performance in addition to being stable over a long cycling process. Therefore, the present work provides an outstanding method to improve the energy storage performance of metal oxide composites and other types of nanocomposites.

Some Metal Oxide-Natural Rubber Composites for Gamma- and Low-Energy X-Ray Radiation Shielding

This work studied protective material consisting of several metal oxide composites (Pb3O4, WO3, SnO2, and Bi2O3)-natural rubber (NR) for X-ray and gamma-ray shielding. The composites were prepared through open milling and vulcanization processes and further characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), rheometry analysis, and density gauge. The attenuation coefficient of the sample was investigated using X-ray generators with voltages ranging from 50 to 140 kV and gamma-ray energies ranging and 356 to 1250 keV, respectively. The experimental results show that the linear attenuation coefficient of NR filled with metal oxides was significantly improved compared to pure NR. For gamma-ray 661 keV, the HVL of NR decreased from 9.0 cm to between 4.4 - 6.2 cm after it was filled with metal oxides. The Bi2O3-NR is the best suitable material for gamma-ray attenuation, followed by Pb3O4-NR, WO3-NR, and SnO2-NR. Meanwhile, for x-rays, the HVL of NR decreased from 2.0 cm to between 0.17 -0.31 cm after it was filled with metal oxides. The proposed metal oxide-NR composites can be appropriate as a flexible protective material for manufacturing wearable radiation shielding products such as gloves, aprons, rubber underwear, and other wearable materials.

Heterogeneous Interface Catalysts with Electron Local Exchange toward Highly Selective Oxidation of Biomass Platform Compounds

Catalytic oxidation conversion of biomass-derived compounds to high value-added products has aroused intensive research interest. Herein, we report a Co3O4/Co2MnO4 metal oxide composites catalyst prepared from layered double hydroxides precursors, which is featured with a uniformly interdispersed two-phase heterogeneous interface. This sample exhibits an enhanced catalytic performance for the selective oxidation reaction of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid with a yield of 98%. A combination study including high-resolution transmission electron microscopy (HR-TEM), X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), and Raman confirms that a strong electron local exchange interaction occurs at the Co3O4/Co2MnO4 heterogeneous interface with electron transfer from Mn in the spinel to Co in the oxide. Both experimental investigations (quasi-in situ XPS, in situ Fourier transform infrared spectroscopy (FTIR), and in situ Raman) and theoretical calculations substantiate that the interfacial metal–oxygen bridge (Co2+–O–Mn4+) serves as an intrinsic active site in determining the reaction pathway: the C═O group in the reactant undergoes activated adsorption at Mn4+, followed by the escape of interfacial lattice oxygen and the oxidation of the aldehyde group to carboxylic acid; subsequently, the O2 molecule undergoes dissociation at the in situ generated oxygen vacancy. This electron local exchange interaction facilitates the mobility of interfacial lattice oxygen, whose universality is demonstrated in catalytic oxidation of other 11 biomass-derived furanoids to the corresponding carboxylic acids.

Yolk-shell Fe2O3@mesoporous hollow carbon sphere hybrid sub-micro reactors for effective degradation of organic contaminants

Carbon–metal oxide composites are important class of catalytic materials in persulfate (PS)/peroxymonosulfate (PMS) activation. But, their poor catalytic stability during oxidation limits its practical use. Herein, we demonstrate the yolk-shell architecture strategy for the fabrication of highly stable Fe2O3 mesoporous carbon hollow spheres (Fe2O3@MCHS) catalyst. The prepared material exhibits high PS activation ability for effective degradation of phenolics. The surface properties of hybrid Fe2O3@MCHS system were examined using FE-SEM, TEM, BET and VSM techniques. Physical characterization data confirmed that Fe2O3@MCHS sub-micro reactors possess a magnetic property, high specific surface area (SSA; >1200 m2 g−1), orderly arranged mesopores, and excellent degree of particle dispersion. Owing to the fact, the Fe2O3@MCHS catalyst exhibited highest reactivity for the degradation of 2,4-dichlorophenol and bisphenol-A by PS even with very low catalyst dosage (10 mg L−1). ESR and scavenging experiments exclude the role of reactive radicals and other reactive oxygen species (ROS) (1O2) during pollutant degradation. Open circuit potential (OCP) measurements further reveal that low pollutant degradation efficiencies in the presence of 1O2 scavengers (L-histidine and NaN3) were caused due to strong interaction between scavenging molecules and catalytic surfaces rather than ROS quenching. Electrochemical investigation also supports that degradation occurs through mediating electron transfer from pollutant to Fe2O3@MCHS. This study provides new understanding in PS activation and also in developing stable PS activating hybrid catalytic systems for pollutant degradation.

Interfacial effects promote the catalytic performance of CuCoO2-CeO2 metal oxides for the selective reduction of NO by CO

The establishment of a strongly coupled heterojunction interface between composite metal oxide interfaces is an important strategy to improve the activity of CO-SCR catalysts. A CuCoO2 modified CeO2 catalyst (H-CuCo-CeO2) was synthesized by a hydrothermal method, which exhibited a wide low-temperature activity window, achieved 100 % NO conversion at 175 °C and showed excellent performance in terms of resistance to H2O and SO2. Based on the results of XPS, Raman, OSC and in situ DRIFTS test, the mechanism of the H-CuCo-CeO2 catalyst in the CO-SCR reaction was systematically investigated to reveal the influence of the heterojunction interfaces of the catalyst on the reaction performance. The results show that the modification of the CuCoO2 structure promotes the migration of Cun+ species between the layers of the H-CuCo-CeO2 catalyst and increases the surface Cu+-O-Cu+ active sites, while greatly promoting the formation of oxygen vacancies (O2–(ads) → O-(ads)) on the catalyst surface. In addition, the increased concentration of oxygen vacancies also effectively promoted the dissociation of NO to [N] to produce N2 and transferred the dissociated [O] species to the active site to further complete the degradation of CO. This work not only provides an idea for the study of strongly coupled CuCoO2-CeO2 heterojunction interfaces, but also provides an efficient denitrification catalyst for air pollution control.

MOF-Derived In2 O3 /CuO p-n Heterojunction Photoanode Incorporating Graphene Nanoribbons for Solar Hydrogen Generation.

Solar-driven photoelectrochemical (PEC) water splitting is a promising approach toward sustainable hydrogen (H2 ) generation. However, the design and synthesis of efficient semiconductor photocatalysts via a facile method remains a significant challenge, especially p-n heterojunctions based on composite metal oxides. Herein, a MOF-on-MOF (metal-organic framework) template is employed as the precursor to synthesize In2 O3 /CuO p-n heterojunction composite. After incorporation of small amounts of graphene nanoribbons (GNRs), the optimized PEC devices exhibited a maximum current density of 1.51mA cm-2 (at 1.6V vs RHE) under one sun illumination (AM 1.5G, 100mW cm-2 ), which is approximately four times higher than that of the reference device based on only In2 O3 photoanodes. The improvement in the performance of these hybrid anodes is attributed to the presence of a p-n heterojunction that enhances the separation efficiency of photogenerated electron-hole pairs and suppresses charge recombination, as well as the presence of GNRs that can increase the conductivity by offering better path for electron transport, thus reducing the charge transfer resistance. The proposed MOF-derived In2 O3 /CuO p-n heterojunction composite is used to demonstrate a high-performance PEC device for hydrogen generation.

A portable electrochemical sensor based on binary transition metal oxide (CoO/ZnO) for the evaluation of eugenol in real-time samples

We report a one-step hydrothermal synthesis route of synthesizing the binary transition metal oxide-based composite using zinc acetate and cobalt acetate precursors. A synthesized binary transition metal oxide-based composite is characterized to understand features of crystalline and structural arrangements, functionality, chemical composition, and surface morphologies using the XRD, FT-IR, XPS, FESEM, & HR-TEM techniques. The composite materials tend to show excellent morphology with spherical morphology. Owing to this, the synthesized binary transition metal oxide composite is then modified over the surface of the glassy carbon electrode (GCE) towards the electrochemical sensing of Eugenol (EUG). In this regard, the CoO/ZnO/GCE composite delivers much more improved electrocatalytic activity because of the synergistic features offered by the binary transition metal oxides due to their unique structural morphology, high surface area, and increased active sites which afford rapid electron transfer rate to the CoO/ZnO/GCE when compared to other electrodes. CoO/ZnO/GCE sensor of determining the (EUG) with a wider linear range of 0.049 – 179.8 µM possessed nanomolar level detection (LOD) of under DPV & LSV is calculated to be 4 nM & 7 nM along with sensitivity found to be 1.366 µA µM−1 cm−2 & 1.01 µA µM−1 cm−2. The proposed CoO/ZnO/GCE has better selectivity over interference studies, with practical feasibility features of repeatability, reproducibility, and storage stability. Real-time sample practical applicability with exceptional recoveries of 99 % for the clove sample and urine samples.

Metal oxide composites for detoxification of chemical warfare agent (CWA) simulant with enhanced catalytic activity under IR irradiation

Toxic organophosphate-based nerve agents have become the deadliest agents used in battlefields and terrorist attacks because even their small amounts can cause permanent damage, even after medical treatment. Various catalysts have been developed for the destruction of nerve agents. Among them, metal oxide nanoparticles have become one of the most widely studied materials owing to their excellent stability, high reactivity, and non-toxicity. Herein, we designed and synthesized a photothermally active metal oxide catalyst for the decomposition of DMNP consisting of SBA-15 containing MgO, which is deposited on GO, achieving unprecedented results. Under IR-LED irradiation, MgO@SBA-15@GO was an effective catalyst for the degradation of DMNP, resulting in a 15 min half-life (t1/2) of DMNP in EtOH. GO was employed to convert the absorbed light from IR irradiation to heat. This constant photothermal conversion increases the reaction temperature, resulting in a faster reaction rate without the use of an external heat source. Remarkably, MgO@SBA-15@GO showed no significant change in photothermal catalytic activity even after five cycles of reuse, demonstrating the high stability of the material. The material prepared herein performed well as a photothermally active heterogeneous catalyst for the degradation of DMNP under IR-LED light, indicating great potential for metal oxide catalysts used in combination with photothermal materials for catalytic decomposition of nerve agents.

Photocatalytic Performances and Antifouling Efficacies of Alternative Marine Coatings Derived from Polymer/Metal Oxides (WO3@TiO2)-Based Composites

This work concerns development of alternative antifouling paints for marine applications using composite metal oxides derived from TiO2 and WO3. Composite metal oxides with a variety of tungsten content were prepared via a sol–gel process using titanium isopropoxide and sodium tungstate dihydrate as the precursors. The crystalline phase, bandgap energy, morphology, surface structure, and electronic states of the synthesized products were then characterized and confirmed by XPS, XRD, UV/Vis spectroscopy, SEM-EDX, and TEM techniques. Photocatalytic performance polymer film loaded with composite metal oxides containing 10% by mole of WO3 (10%WO3@TiO2) was confirmed both under UV irradiation and in the dark. The results are discussed in light of oxygen vacancies and the presence of heterojunctions between the TiO2 and WO3 domains in the composites, which eventually lead to suppression of charges recombination. Finally, antifouling and the antimicrobial efficacy of the polymer film loaded with composite metal oxide particles (10%WO3@TiO2) were evaluated under static marine immersion conditions using Zobell Marine agar. After 30 days, the percentage fouling coverage (16.35%), colonies number (CFU value 12 × 103), and percentage reduction of colonies (92.94%), were obtained, which significantly outperformed those of the control (the bare substrate).

Theoretical Calculations on Metal Catalysts Toward Water-Gas Shift Reaction: a Review.

Water-gas shift (WGS) reaction offers a dominating path to hydrogen generation from fossil fuel, in which heterogeneous metal catalysts play a crucial part in this course. This review highlights and summarizes recent developments on theoretical calculations of metal catalysts developed to date, including surface structure (e. g., monometallic and polymetallic systems) and interface structure (e. g., supported catalysts and metal oxide composites), with special emphasis on the characteristics of crystal-face effect, alloying strategy, and metal-support interaction. A systematic summarization on reaction mechanism was performed, including redox mechanism, associative mechanism as well as hybrid mechanism; the development on chemical kinetics (e. g., molecular dynamics, kinetic Monte Carlo and microkinetic simulation) was then introduced. At the end, challenges associated with theoretical calculations on metal catalysts toward WGS reaction are discussed and some perspectives on the future advance of this field are provided.

Ti/Zr/O Mixed Oxides for the Catalytic Transfer Hydrogenation of Furfural to GVL in a Liquid-Phase Continuous-Flow Reactor

This work aims to develop an efficient catalyst for the cascade reaction from furfural to γ-valerolactone in a liquid-phase continuous reactor. This process requires both Lewis and Brønsted acidity; hence, a bifunctional catalyst is necessary to complete the one-pot reaction. Ti/Zr/O mixed oxide-based catalysts were chosen to this end as balancing metal oxide composition allows the acidity characteristics of the overall material to be modulated. Oxides with different compositions were then synthesized using the co-precipitation method. After characterization via porosimetry and NH3-TPD, the catalyst with equimolar quantities of the two components was demonstrated to be the best one in terms of superficial area (279 m2/g) and acid site density (0.67 mmol/g). The synthesized materials were then tested using a plug flow reactor at 180 °C, with a 10 min contact time. Ti/Zr/O (1:1) was demonstrated to be the most promising catalyst during the recycling tests as it allowed obtaining the highest selectivities in the desired products (about 45% in furfuryl isopropyl ether and 20% in γ-valerolactone) contemporaneously with 100% furfural conversion.

Enhancement in the photocatalytic and optoelectronic properties of erbium oxide by adding zinc oxide and molybdenum

Rare earth metals like erbium oxide (Er2O3) show outstanding photocatalytic properties. However, its high recombination rate and low surface area limit its performance. Therefore, various metal oxide composites with Er2O3 have been reported to improve their photocatalytic and optoelectronic properties. In this study, a composite of Er2O3 and zinc oxide (ZnO) was synthesized using the sol-gel combustion method to enhance its surface area. Moreover, molybdenum (Mo) was loaded on the matrix to suppress the charge recombination. The detailed characterizations were conducted by employing X-ray Diffraction (XRD), Raman Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Brunauer–Emmett–Teller (BET) analysis, Photoluminescence (PL) spectroscopy and UV–Vis spectroscopy. BET analysis revealed the enhancement in surface area by adding ZnO and Mo (from SBET = 29.07 m2/g to SBET = 45.71 m2/g). Additionally, the loading of Mo enhanced the immobilization of carriers that facilitate the photooxidation process and suppressed the electron-holes recombination (from 800 counts to 100 counts) as confirmed by the PL spectroscopy. Photocatalytic studies were comparatively analyzed by degradation of textile dye named methylene blue (MB). The efficiency of Er2O3 improved by up to 80% by adding the ZnO and Mo. The composite of Er2O3 with ZnO and loading of Mo, not only improved the photocatalytic properties but also improved the electrical properties of the Er2O3 (σ = 4.4 × 10−4 Sm−1 to σ = 5.1 × 10−4 Sm−1) as confirmed by the Hall Effect. Due to enhancement in properties, the proposed material can be rendered as one of the most suitable candidates for optoelectronic applications.

The Structural Stability Limit of Layered Lithium Transition Metal Oxides Due to Oxygen Release at High State of Charge and Its Dependence on the Nickel Content

The composition of layered transition metal oxides (LiMO2, M = Ni, Co, Mn) as cathode active materials (CAMs) is currently trending towards higher nickel contents, which can provide more capacity and energy. The origin of this performance improvement is often ascribed to the lower potential of nickel-rich CAMs, suppressing detrimental electrochemical electrolyte oxidation. In this study, it is shown that the stability limit of LiMO2-based CAMs is not determined by the stability window of typical electrolytes in terms of potential but by the CAM composition, governing the structural stability at high degrees of delithiation. The latter is investigated for five CAMs with distinct composition (LCO, NCM111, NCM622, NCM851005, and LNO) as a function of upper cutoff potential and thus state of charge (SOC). Short-term cycling experiments with an increasing upper cutoff potential as well as extended cycling to selected SOCs reveal stability limits between 66 and 86 %SOC depending on the CAM composition. On-line electrochemical mass spectrometry (OEMS) does not only allow to exclude any impact of electrochemical electrolyte oxidation on the determined stability window of the CAMs but also illuminates the concurrence of capacity fade and lattice oxygen release, with the latter being the origin of the CAM degradation.

Novel statistically optimized one pot synthesis of inherently photoluminescent and electroactive graphene oxide nanosheets as 1, 4 dioxane sensor

1, 4 dioxane predominantly found in industrial effluents and air force plants, is of great concern worldwide due to its toxic and carcinogenic nature. Currently, there are limited research on 1,4 dioxane sensors and most of these sensors are intricate metal oxide composites. This study reports the fabrication of novel inherently electroactive graphene oxide nanosheets derived from a natural polyphenolic compound, and the process parameters were statistically optimized using TOPSIS based Taguchi L9 orthogonal array. The proposed novel sensor was employed in the linear range (0.1µM to 3µM) that conforms with the WHO guideline (0.56 µM) for dioxane in water, showed good sensitivity (117 nAnM-1 cm-2 ), detection limit (20.51 nM) and quantification limit (62.16 nM) which is far superior compared to the reported literature on dioxane sensing systems.

High-Voltage Layered NaNi0.5Co0.1Ti0.3Sb0.1O2 Cathode for Sodium-Ion Batteries

Developing a high-voltage cathode material for sodium-ion batteries is a great challenge. Herein, we report an O3-type layered NaNi0.5Co0.1Ti0.3Sb0.1O2 cathode composition, which can operate at a high voltage (4.35 V). Inclusion of different valence state transition metals, like Ni, Co, and Ti, and a metalloid Sb in the sodium metal oxide composition leads to the formation of a cationic disordered structure, which enhances redox, electronic conductivity, cycling stability, and working voltage. The structural characterizations reveal that the composition is free from superstructure reflections, and electrochemical studies show that the composition suppresses multiphase transitions. As a result, NaNi0.5Co0.1Ti0.3Sb0.1O2, exhibits initial charge and discharge capacities as 129 and 112 mAh/g, respectively, at the current rate of 9.1 mA/g for 2.0–4.35 V. Thus, the high voltage, improved capacity, and retention characteristics of NaNi0.5Co0.1Ti0.3Sb0.1O2 would open up the way for bulk production of Na-ion batteries.