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The high hydrogen storage capacity (10.5 wt.%) and release of hydrogen at a moderate temperature make LiAlH4 an appealing material for hydrogen storage. However, LiAlH4 suffers from slow kinetics and irreversibility. Hence, LaCoO3 was selected as an additive to defeat the slow kinetics problems of LiAlH4. For the irreversibility part, it still required high pressure to absorb hydrogen. Thus, this study focused on the reduction of the onset desorption temperature and the quickening of the desorption kinetics of LiAlH4. Here, we report the different weight percentages of LaCoO3 mixed with LiAlH4 using the ball-milling method. Interestingly, the addition of 10 wt.% of LaCoO3 resulted in a decrease in the desorption temperature to 70 °C for the first stage and 156 °C for the second stage. In addition, at 90 °C, LiAlH4 + 10 wt.% LaCoO3 can desorb 3.37 wt.% of H2 in 80 min, which is 10 times faster than the unsubstituted samples. The activation energies values for this composite are greatly reduced to 71 kJ/mol for the first stages and 95 kJ/mol for the second stages compared to milled LiAlH4 (107 kJ/mol and 120 kJ/mol for the first two stages, respectively). The enhancement of hydrogen desorption kinetics of LiAlH4 is attributed to the in situ formation of AlCo and La or La-containing species in the presence of LaCoO3, which resulted in a reduction of the onset desorption temperature and activation energies of LiAlH4. [ABSTRACT FROM AUTHOR]

The present investigation elucidated the influence of nanoparticle volume fraction and temperature on the thermal conductivity and viscosity of water-based CuO, TiO2 and ZnO nanofluids. All the nanoparticles used in the present study were synthesised using the chemical co-precipitation method and their structural and morphological features were explored by XRD and FESEM techniques, respectively. The investigated fluids were prepared using the two-step method by dispersing 0.1–0.5 wt% nanoparticles in distilled water. The thermal conductivities of all the nanofluids were determined in the temperature range of 30–70°C and viscosity in the range of 300–360 K. The experimental study demonstrated that the thermal conductivity and viscosity of the nanofluids depend on volume fraction and temperature. The dynamic viscosity and the thermal conductivity of all the nanofluids increased with the increase in the volume concentration of solid particles. The viscosity decreased and thermal conductivity increased with an increase in temperatures. When the three nanofluids are compared at the specified temperature range, CuO nanofluids showed higher thermal conductivity of 0.5856–0.6332 W / mK for 0.1 wt% and 0.6476–0.7465 W / mK for 0.5 wt% volume concentration and better viscosity than TiO2 and ZnO nanofluids. The obtained experimental data were compared with some existing thermal conductivity and viscosity models. While comparing the thermal conductivity models, the P Bhattacharya model showed good agreement, whereas no viscosity model agrees with the experimental results. Thus, the obtained results of the prepared nanofluids are useful for conducting further studies in nanofluids. [ABSTRACT FROM AUTHOR]

Soft-NiFe2O4 (S-spinel), hard-BaFe12O19 (M-type) and BaNi2Fe16O27 (W-type) were successfully prepared via a novel modified sol–gel method. The mechanism of modified sol–gel method is to utilise the esterification reaction between citric acid chelate and 2-propanol to spontaneously generate more homogeneous esterified-gel. This modified sol–gel method produced pure and highly crystalline ferrite-based oxides with more uniform morphology and effective carbon dioxide (CO2) adsorption. It is a simpler and more efficient method than the traditional sol–gel method. XRD results proved the purity of the prepared ferrite-based oxides and exhibited smaller and comparable crystallite size when determined by the Debye–Scherrer equation. FTIR indicates the presence of metal–oxygen stretching bonds in the samples. Nitrogen sorption analysis confirmed the high surface area of ferrite-based oxides using this improvement method. EDX and XPS analyses verified the purity and chemical composition of the samples. The morphologies of the samples were investigated by SEM and HRTEM analysis. The CO2 adsorption was evaluated by thermogravimetry method for all the samples, and BaNi2Fe16O27 (W-type) shows the maximum CO2 uptake with 20.43 mg/gads compared to hard-BaFe12O19 (M-type) and soft-NiFe2O4 (S-spinel) with 17.33 and 11.31 mg/gads, respectively. All the samples are best fitted with the pseudo-second order in kinetic analysis with high R2 values (> 0.98). Therefore, this improvement modified sol–gel method proved better and promising option and at the same time beneficial for CO2 adsorption. [ABSTRACT FROM AUTHOR]

PVA, Chitosan, transition metal oxide nanocomposites, and a chlorinated chalcone moiety were used to create a 0.03 cm−1 thin polymer film. Prepared films were characterized using available techniques. The prepared film shows a semi-crystalline nature, proved by XRD analysis, and the nano-scale crystalline size (40–150 nm) was also observed. The surface of the film was smooth and a blooming flower resembling structure appeared in the SEM images obtained at 5 µm. The XPS and EDX spectra reveal the presence of added transition metals and other elements present in the prepared polymer thin film. The prepared film undergoes multistage decomposition upon heating, which was proved by TGA analysis. FT-IR analysis of the film shows that there was no chemical interaction between the added compound and the host polymer; instead, physical interactions alone persisted. Higher AC conductivity was observed with a value of 1.30 × 10−6 Scm−1 at room temperature for polymer composite film made up of MONC and DCHP. This conductance varies with temperature, and at higher temperatures, both dielectric loss and dielectric constant are high. It was discovered that the presence of chalcone moiety improves the AC conductance and dielectric properties of MONC doped polymer composite film. [ABSTRACT FROM AUTHOR]

Metal oxide-based core–shell nanoparticles (CSNs) have demonstrated great advantages in CO2 adsorption and utilisation. Metal oxide is an excellent material because of its basicity, which can aid in the production of higher core–shell catalytic reactions. Metal oxide can be employed as a core to reduce pore blockage and increase the shell's surface area. Meanwhile, it can also be utilised as a shell to improve the basic sites for CO2 interaction, therefore increasing CO2 adsorption performance. This review focuses on the use of metal oxides as the core or shell of CSNs. The synthesis of CSNs with various shapes and properties via different approaches was discussed. In addition, the application of CSNs in CO2 adsorption and utilisation was highlighted. Significant properties of CSNs such as porosity, surface area, and basicity are crucial for excellent CO2 adsorption and CO2 conversion. [ABSTRACT FROM AUTHOR]

The rational control of the electrochemical properties of polyoxovanadate-alkoxide clusters is dependent on understanding the influence of various synthetic modifications on the overall redox processes of these systems. In this work, the electronic consequences of ligand substitution at the heteroion in a heterometal-functionalized cluster was examined. The redox properties of [V5 O6 (OCH3 )12 FeCl] (1-[V5 FeCl]) and [V5 O6 (OCH3 )12 Fe]X (2-[V5 Fe]X; X=ClO4 , OTf) were compared in order to assess the effects of changing the coordination environment around the iron center on the electrochemical properties of the cluster. Coordination of a chloride anion to iron leads to an anodic shift in redox events. Theoretical modelling of the electronic structure of these heterometal-functionalized clusters reveals that differences in the redox profiles of 1-[V5 FeCl] and 2-[V5 Fe]X arise from changes in the number of ligands surrounding the iron center (e.g., 6-coordinate vs. 5-coordinate). Specifically, binding of the chloride to the sixth coordination site appears to change the orbital interaction between the iron and the delocalized electronic structure of the mixed-valent polyoxovanadate core. Tuning the heterometal coordination environment can therefore be used to modulate the redox properties of the whole cluster.

Several non-metal and metal doped ZnO nanoparticles were produced by a variety of routes, including Sol-gel, hydrothermal, and combustion methods. The methods of synthesis, characterization, and applications of these nanoparticles were surveyed and summarised in this review. This study will improve our understanding of developments in doped ZnO and assist in the creation of new ZnO-based materials with improved structural, photocatalytic, and antimicrobial properties.

Humidity measurement in biomedicals, industry and electronic manufacturing applications needs an accurate and fast measurement of relative humidity by the sensor. In recent years, electronic sensors are utilized in the market, but optical humidity sensors provide several advantages over it. This paper reports the classification of optical fiber humidity sensors based on their working principles, such as fiber Bragg gratings, interferometers, and resonators. Along with the mentioned optical fiber structures, their fabrication process, equipment required for humidity sensing and the coating technique used are explained in this review. Recently, metal oxide semiconductors have been widely used as sensing material, specifically in humidity sensor applications. Thus, this paper explores optical fiber humidity sensors based on the three working principles mentioned, all of which incorporate metal oxide coatings. This review reveals that the most commonly used metal oxide for optical fiber humidity sensing is graphene oxide. This is because graphene oxide offers high sensitivity, fast response and recovery time over the other types of metal oxide. A large number of oxygen-containing groups on the surface and edge of graphene oxide also contribute to humidity sensing performance since it can permeate and absorb more water molecules. The use of hybrid nanomaterials is recently discovered and their potential as emerging coating material for optical applications are not fully exploited yet. Thus, there is still an opportunity for improvement in terms of sensitivity, response and recovery time in the context of optical fiber humidity sensor.

Abstract Background Acute phase response (APR) is characterized by a change in concentration of different proteins, including C-reactive protein and serum amyloid A (SAA) that can be linked to both exposure to metal oxide nanomaterials and risk of cardiovascular diseases. In this study, we intratracheally exposed mice to ZnO, CuO, Al2O3, SnO2 and TiO2 and carbon black (Printex 90) nanomaterials with a wide range in phagolysosomal solubility. We subsequently assessed neutrophil numbers, protein and lactate dehydrogenase activity in bronchoalveolar lavage fluid, Saa3 and Saa1 mRNA levels in lung and liver tissue, respectively, and SAA3 and SAA1/2 in plasma. Endpoints were analyzed 1 and 28 days after exposure, including histopathology of lung and liver tissues. Results All nanomaterials induced pulmonary inflammation after 1 day, and exposure to ZnO, CuO, SnO2, TiO2 and Printex 90 increased Saa3 mRNA levels in lungs and Saa1 mRNA levels in liver. Additionally, CuO, SnO2, TiO2 and Printex 90 increased plasma levels of SAA3 and SAA1/2. Acute phase response was predicted by deposited surface area for insoluble metal oxides, 1 and 28 days post-exposure. Conclusion Soluble and insoluble metal oxides induced dose-dependent APR with different time dependency. Neutrophil influx, Saa3 mRNA levels in lung tissue and plasma SAA3 levels correlated across all studied nanomaterials, suggesting that these endpoints can be used as biomarkers of acute phase response and cardiovascular disease risk following exposure to soluble and insoluble particles.

In this paper, the effect of germanium content in Zn1-xGexO as a buffer layer on the performance and efficiency of a solar cell based copper oxide (Cu2O) is investigated. The physical parameters of the solar cell model were selected according to the experimental data and then the new parameters of ZnGeO buffer layer was calculated based on the interpolated parameters of the energy levels of the band structure of binary compounds ZnO and GeO2 to study the solar cell performance for the germanium composition, ranged from 0.35 to 0.75. First, the accuracy of the initial model of the solar cell was verified by comparing its electrical characteristics with experimental data. Then, the characteristics of the initial model were analyzed and characterized in presence of buffer layer. By examining the cell efficiency for the changes of buffer composition (35% to 75% germanium), the minimum efficiency was observed 5.31% at x = 0.35 and the maximum was 7.02% at x = 0.65. The results show that using Zn0.35Ge0.65O buffer, the short circuit current of the cell reaches 11.15 mA with an open circuit voltage up to 1.08 volts.

Silver nanoparticles and/or nanoclay [particularly montmorillonite] are used in the majority of nanotechnology applications for food packaging. Other nanomaterials, on the other hand, can also be integrated into packaging. Metal oxide nanoparticles have been added to petroleum-based and biopolymers to produce nanocomposites with improved mechanical, barrier, antioxidants and antimicrobial properties. Nanoparticles migration from packaging, on the other hand, is a source of concern due to their potential toxicity in the human body and the environment. The purpose of this article therefore, was to review the available literature on the utilization of metal oxide-based nanoparticles to produce nanocomposites for food packaging application. Advantages of incorporating metal oxide-based nanoparticles into polymers, as well as migration of these nanomaterials from packaging into foods are discussed. Incorporation of metal oxide nanoparticles into polymers allows for the production of nanocomposites with increased mechanical strength, water and oxygen barrier properties, and can also confer other additional functional properties, such as antioxidant, antimicrobial activity and light-blocking properties. According to migration studies, only a small quantity of nanomaterial migrates from packaging into food simulants or foods, implying that consumer exposure to these nanomaterials and the health concerns associated with them are low. Nonetheless, there is a scarcity of information on the migration of nanomaterials from packaging into actual foods, and more research is desperately needed in this area. This manuscript is useful in the food industries as it indicate the applicability and potential of the oxide-based nanocomposites as a promising approach for use in food packaging applications.

Carbon-based materials, metal oxides and metal nanoparticles have been widely used in propellants, explosives and pyrotechnics. Cold plasma technique has been developed for material fabrication and modification at temperatures lower than 200 ⁰C. Due to the low temperatures, cold plasma can efficiently modify material surface properties, and simultaneously maintain material structures well, especially for temperature-sensitive materials. Cold plasma applies gas, e.g. Ar, N2, O2, H2 and air, as working gas, without any harmful substance like acid, alkali and organic solvent. Moreover, material surface properties can be efficiently tuned by simply changing plasma properties, e.g. power, time and working gas. The present review discusses recent progresses in using cold plasma to fabricate carbon-based materials, metal oxides and metal nanoparticles, and to modify surface properties of carbon-based materials, metal oxides and metal nanoparticles. Future research opportunities and challenges are also proposed. It is believed that the present review will stimulate more studies on material fabrication and modification by cold plasma, and help to construct more efficient materials for propellants, explosives and pyrotechnics.

Flexible electronics have seen extensive research over the past years due to their potential stretchability and adaptability to non‐flat surfaces. They are key to realizing low‐power sensors and circuits for wearable electronics and Internet of Things (IoT) applications. Semiconducting metal‐oxides are a prime candidate for implementing flexible electronics as their conformal deposition methods lend themselves to the idiosyncrasies of non‐rigid substrates. They are also a major component for the development of resistive memories (memristors) and as such their monolithic integration with thin film electronics has the potential to lead to novel all‐metal‐oxide devices combining memory and computing on a single node. This review focuses on exploring the recent advances across all these fronts starting from types of suitable substrates and their mechanical properties, different types of fabrication methods for thin film transistors and memristors applicable to flexible substrates (vacuum‐ or solution‐based), applications and comparison with rigid substrates while additionally delving into matters associated with their monolithic integration. [ABSTRACT FROM AUTHOR]

To mimic the human olfactory system, an electronic nose (E-nose, also known as artificial olfactory) has been proposed based on a multiple gas sensor array and a pattern recognition algorithm. Detection of volatile organic components (VOCs) has many potential applications in breath analysis, food quality estimation, and indoor and outdoor air quality monitoring, etc. In this study, a facile single-needle electrospinning technology was applied to develop the four different semiconductor metal oxide (MOS) nanofibers sensor arrays (SnO2, CuO, In2O3 and ZnO, respectively). The array shows a smooth surface and constant diameter of nanofiber (average of 150 nm) resulting in high sensitivity to multiple target analyte gases. Five human health related VOCs gases were measured by fabricated E-nose and different response patterns were obtained from four MOS nanofibers sensors. Combined with feature extraction from the response curves, a principal component analysis (PCA) algorithm was applied to reduce the dimension of feature matrix, Thus, the fabricated E-nose system successfully discriminated five different VOCs gases. Real-time and non-invasive gas monitoring by E-nose is very promising for application in human health monitoring, food monitoring, and other fields. [ABSTRACT FROM AUTHOR]

Redox materials have been investigated for various thermochemical processing applications including solar fuel production (hydrogen, syngas), ammonia synthesis, thermochemical energy storage, and air separation/oxygen pumping, while involving concentrated solar energy as the high-temperature process heat source for solid–gas reactions. Accordingly, these materials can be processed in two-step redox cycles for thermochemical fuel production from H2O and CO2 splitting. In such cycles, the metal oxide is first thermally reduced when heated under concentrated solar energy. Then, the reduced material is re-oxidized with either H2O or CO2 to produce H2 or CO. The mixture forms syngas that can be used for the synthesis of various hydrocarbon fuels. An alternative process involves redox systems of metal oxides/nitrides for ammonia synthesis from N2 and H2O based on chemical looping cycles. A metal nitride reacts with steam to form ammonia and the corresponding metal oxide. The latter is then recycled in a nitridation reaction with N2 and a reducer. In another process, redox systems can be processed in reversible endothermal/exothermal reactions for solar thermochemical energy storage at high temperature. The reduction corresponds to the heat charge while the reverse oxidation with air leads to the heat discharge for supplying process heat to a downstream process. Similar reversible redox reactions can finally be used for oxygen separation from air, which results in separate flows of O2 and N2 that can be both valorized, or thermochemical oxygen pumping to absorb residual oxygen. This review deals with the different redox materials involving stoichiometric or non-stoichiometric materials applied to solar fuel production (H2, syngas, ammonia), thermochemical energy storage, and thermochemical air separation or gas purification. The most relevant chemical looping reactions and the best performing materials acting as the oxygen carriers are identified and described, as well as the chemical reactors suitable for solar energy absorption, conversion, and storage. [ABSTRACT FROM AUTHOR]

In the current study, copper oxide (CuO) and manganese oxide (MnO) nanoparticles (NPs) were synthesized through a simple, cost-efficient, and green method using watermelon seed shell extract as a stabilizing and reducing agent. The synthesized CuO and MnO NPs were characterized by using scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and Ultraviolet spectroscopy (UV). The particle sizes of CuO and MnO NPs were determined to be in the range of 15–97 and 6–51 nm, respectively, by TEM and XRD analysis. The photocatalytic performance of the CuO and MnO NPs used as catalysts were investigated for the photocatalytic reduction of methylene blue in an aqueous solution. In the photocatalytic reduction of methylene blue, sodium borohydride (NaBH4) was used as the reducing agent. The CuO and MnO NPs were capable to remove 96.58% (in 70 min) and 96.60% (in 140 min) of methylene blue from aqueous media, respectively. Besides, the kinetics of the photocatalytic reaction was investigated by a pseudo-first order model, and the reaction rate coefficient for methylene blue with CuO and MnO NPs were calculated as 0.0426 and 0.0235 min−1, respectively. The results demonstrated that the synthesized CuO and MnO NPs through the green method were promising catalysts to improve the photocatalytic reduction performance of methylene blue. The copper oxide (CuO) and manganese oxide (MnO) nanoparticles (NPs) were synthesized from watermelon seed extract by the green synthesis method. The watermelon seed shell, which is left as waste to the environment, has been transformed into a product with high added value. The particle sizes of CuO and MnO NPs were determined to be in the range of 15–97 and 6–51 nm, respectively. The photocatalytic performance of the CuO and MnO NPs used as catalysts were investigated for the photocatalytic reduction of methylene blue in an aqueous solution. In the photocatalytic reduction of methylene blue, sodium borohydride (NaBH4) was used as the reducing agent. The CuO and MnO NPs were capable to remove 96.58% (in 70 min) and 96.60% (in 140 min) of methylene blue, respectively. It was determined that UV light was effective in the photocatalytic reduction of methylene blue with NaBH4. The reaction rate coefficient for the photocatalytic reduction of methylene blue with CuO and MnO NPs was calculated as 0.0426 and 0.0235 min−1, respectively. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of TiO2–SnO2–C/carbide hybrid electrode materials for Li‐ion batteries (LIBs) via two different methods of controlled oxidation of layered Ti2SnC. The material was partially oxidized in an open‐air furnace (OAF) or using a rapid thermal annealing (RTA) approach to obtain the desired TiO2–SnO2–C/carbide hybrid material; the carbide phase encompassed both residual Ti2SnC and TiC as a reaction product. We tested the oxidized materials as an anode in a half cell to investigate their electrochemical performance in LIBs. Analysis of the various oxidation conditions indicated the highest initial lithiation capacity of 838 mAh/g at 100 mA/g for the sample oxidized in the OAF at 700°C for 1 h. Still, the delithiation capacity dropped to 427 mAh/g and faded over cycling. Long‐term cycling demonstrated that the RTA sample treated at 800°C for 30 s was the most efficient, as it demonstrated a reversible capacity of around 270 mAh/g after 150 cycles, as well as a specific capacity of about 150 mAh/g under high cycling rate (2000 mA/g). Given the materials' promising performance, this processing method could likely be applied to many other members of the MAX family, with a wide range of energy storage applications. [ABSTRACT FROM AUTHOR]

The search for inexpensive, environmentally friendly, and highly effective catalysts to activate C-H bonds in propane dehydrogenation (PDH) reactions is still a major challenge. Co-based catalysts have gained significant attention in recent years due to their excellent ability to activate C-H bonds and their high selectivity towards olefins, despite being a non-noble and environmentally unfriendly metal. However, further improvements are necessary for practical utilization, particularly in terms of activity and anti-carbon deposition capacity. In this study, we synthesized Al2O3 nanorods with abundant pentacoordinated Al3+ (Al3+penta) sites. The supported Co on the Al2O3 nanorod (Co/Al2O3-NR) exhibited higher selectivity (>96% propylene selectivity) and stability (deactivation rate 0.15 h−1) compared to Co supported on an Al2O3 nanosheet with fewer pentacoordinated Al3+ sites. Various characterizations confirmed that Co(II) mainly exists as CoAl2O4 rather than Co3O4 in the form of Co/Al2O3-NR, which inhibits the reduction of Co(II) to Co0 and accordingly improves catalyst stability. [ABSTRACT FROM AUTHOR]

Semiconducting metal oxide thin films of ZnO and NiO with different impurity of n-type and p-type conductivity were grown on a Si substrate by magnetic sputtering method. The structural characteristics, i.e. crystalline characteristics and crystalline order or amorphousness of layers, were investigated by X-ray diffraction. The PL spectrum of ZnO samples doped with N and Al had a peak at a wavelength of approximately 370 nm, which is close to band gap energy of ZnO, and the highest intensity was observed in the PL spectrum of AZO sample. The effect of nanoparticle size of grown layers and their effect on performance of joints were investigated. Evaluation of the performance of metal oxide structures with current and voltage diagrams of connections and their applications in electronic devices showed that the smallest ideal diode factor is related to the Si-n/NZO-p connection with a value of 1.23, which showed the best behavior of the diode. [ABSTRACT FROM AUTHOR]

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The dissolution process of metal oxide catalysts in the alcoholysis of urea by 1, 2‐propylene glycol (PG) to the synthesis of propylene carbonate (PC) was investigated. It was found that the reaction was mainly catalyzed by homogeneous catalysts. The metal oxide reacted with ammonia and isocyanate acid, the decomposition products of urea, to form a complex and dissolved into the reaction system. The dissolved amount of catalyst was positively correlated with the PC yield by using different oxides and salts as catalysts. The Fourier‐transform infrared spectroscopy (FTIR) result of the catalysts reacting with urea showed that the dissolution‐precipitation process of the catalysts was related to the decomposition of urea. The results of catalytic test indicated that both the dissolved amount of catalysts and the structure of the complex affected PC yields. A reaction mechanism was proposed based on the results. From the mechanism, a complex catalyst with at least two ammonia ligands is better for this reaction. [ABSTRACT FROM AUTHOR]

Metal oxide-based conductometric gas sensors (CGS) have showcased a vast application potential in the fields of environmental protection and medical diagnosis due to their unique advantages of high cost-effectiveness, expedient miniaturization, and noninvasive and convenient operation. Of multiple parameters to assess the sensor performance, the reaction speeds, including response and recovery times during the gas–solid interactions, are directly correlated to a timely recognition of the target molecule prior to scheduling the relevant processing solutions and an instant restoration aimed for subsequent repeated exposure tests. In this review, we first take metal oxide semiconductors (MOSs) as the case study and conclude the impact of the semiconducting type as well as the grain size and morphology of MOSs on the reaction speeds of related gas sensors. Second, various improvement strategies, primarily including external stimulus (heat and photons), morphological and structural regulation, element doping, and composite engineering, are successively introduced in detail. Finally, challenges and perspectives are proposed so as to provide the design references for future high-performance CGS featuring swift detection and regeneration. [ABSTRACT FROM AUTHOR]

In the last decade, TiO2 nanotubes have attracted the attention of the scientific community and industry due to their exceptional photocatalytic properties, opening a wide range of additional applications in the fields of renewable energy, sensors, supercapacitors, and the pharmaceutical industry. However, their use is limited because their band gap is tied to the visible light spectrum. Therefore, it is essential to dope them with metals to extend their physicochemical advantages. In this review, we provide a brief overview of the preparation of metal-doped TiO2 nanotubes. We address hydrothermal and alteration methods that have been used to study the effects of different metal dopants on the structural, morphological, and optoelectrical properties of anatase and rutile nanotubes. The progress of DFT studies on the metal doping of TiO2 nanoparticles is discussed. In addition, the traditional models and their confirmation of the results of the experiment with TiO2 nanotubes are reviewed, as well as the use of TNT in various applications and the future prospects for its development in other fields. We focus on the comprehensive analysis and practical significance of the development of TiO2 hybrid materials and the need for a better understanding of the structural–chemical properties of anatase TiO2 nanotubes with metal doping for ion storage devices such as batteries. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) and metal oxides are two materials that have various applications, including active sensors. PANI provides several benefits over other conductive polymers, including ease of synthesis, affordability, and high conductivity. Depending on the benefits of PANI, here we report the fabrication of PANI/metal oxide composites as an active material for gas sensors, especially LPG. By oxidatively polymerizing aniline at room temperature, PANI was formed. PANI/metal oxide composites were produced by using an in-situ polymerization technique. The PANI/MgO and PANI/ZnO nanocomposites were successfully fabricated, as shown by FTIR and XRD characterization results. The sensitivity of PANI/metal oxide nanocomposites to LPG has been proven. The result shows that PANI/metal oxide sensitivity is better than bare- PANI/MgO, which is one of the kinds of metal oxide used. Several concentrations of gas were used at low ppm: 50, 100, and 200 ppm to identify the sensitivity of PANI. The size of the pores with a radius of 285 Ă of the PANI/MgO nanocomposite shows that the value sensitivity was improved. The PANI/MgO nanocomposite has the best sensitivity to LPG exposure because it works well at all concentrations. [ABSTRACT FROM AUTHOR]

In the current study, three different ZnO nanostructures (Z1, Z2, and Z3) were synthesized using solid-state thermal decomposition, homogeneous precipitation, and wet chemical methods. The nanostructures were characterized using different techniques. Formation of ZnO nanostructures with wurtzite structure is demonstrated by powder XRD. FESEM and TEM studies show rod-like morphology of Z1 and Z2 nanostructures, while the morphology of Z3 nanostructures is hierarchical assembly consisting of nanorods. From TEM studies, average length of rods in Z1 and Z2 nanostructures are about 0.33 and 1.43 µm, while the average diameter of rods in Z1, Z2, and Z3 nanostructures are in the range of 16–90 nm. SAED results indicate single crystalline nature of Z1 and Z2 and polycrystalline nature of Z3 nanostructures. DRS studies indicate that the band gap of Z1, Z2, and Z3 nanostructures is about 3.20–3.30 eV. After characterization, the antibacterial activity of ZnO nanostructures was evaluated against Escherichia coli and Staphylococcus aureus by zone of inhibition and sprinkle methods. The current study was undertaken to evaluate and compare antibacterial activity of ZnO nanostructures with different shapes synthesized using three different methods. In the zone of inhibition method, ZnO nanostructures exhibit better antibacterial activity against S. aureus than E. coli, while in the sprinkle method, Z2 and Z3 nanostructures exhibit complete antibacterial activity at 10 and 20 mg concentrations against S. aureus while only Z3 nanostructures exhibit complete antibacterial activity at 10, 20 and 30 mg concentrations against E. coli. [ABSTRACT FROM AUTHOR]

Mg/Cr-layered double hydroxide (Mg/Cr-LDH) and Mg/Al-layered double hydroxide (Mg/Al-LDH) intercalated metal oxide (Mg/Cr-Cu and Mg/Al-Cu) were synthesized by the co-precipitation method which is indicated by the X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer Emmett Teller (BET) analysis. Mg/Cr-LDH intercalated metal oxide increased its surface area from 21.5 to 38.9 m²/g, while the surface area of Mg/Al-LDH from 23.2 to 30.5 m²/g. The adsorption capacity of Mg/Cr-Cu is 64.156 mg/g for methyl orange (MO) and 78.740 mg/g for methyl red (MR), and the adsorption capacity of Mg/Al-Cu is 97.087 mg/g for MO and 108.696 mg/g for MR. Equilibrium time on the adsorption process occurred at 90 minutes with adsorption kinetics followed by pseudo-second-order (PSO). The adsorption isotherm followed the Langmuir isotherm equation. Data of thermodynamic parameters indicate that the adsorption process in this study occurs spontaneously and endothermically. The regeneration results show that Mg/Cr-Cu and Mg/Al-Cu can be used for the 5 cycles regeneration process of MO and MR adsorption process. Interactions that occur between adsorbents and adsorbate include physical interactions, interactions with the involvement of hydrogen bonds, and electrostatic interactions. [ABSTRACT FROM AUTHOR]

Metal oxides have an extraordinary ability to generate charge carriers with significant importance in environmental remediation. For the degradation of different dyes, a one-step hydrothermal method was adopted to synthesize Al-doped BiSbO 4. While bismuth antimonate composite with reduced graphene oxide was synthesized by the simple ultra-sonication method. To investigate the structural confirmation, X-ray diffraction (XRD) was used. For studying morphology, scanning electron microscopy (SEM) was conducted. UV–Visible spectroscopy (UV) and Fourier transform infrared spectroscopy (FTIR) were used to observe the optical properties and vibrational modes of the as-synthesized BiSbO 4 nanoparticles and doped Al–BiSbO 4. The above-mentioned studies verify the formation of nanoparticles of Al-doped BiSbO 4. The synthesized composite was used to degrade the organic dyes such as methylene blue and crystal violet. The degradation efficiency of doped, undoped and composite is studied and compared. The results indicate the extraordinary efficiency of BiSbO 4 /rGO composite to doped and bare samples for the degradation of dyes. It is confirmed by the degradation of different dyes that the BiSbO 4 /rGO composite shows the best catalytic efficiency. [ABSTRACT FROM AUTHOR]

Cuprous oxide is a potential photocatalyst for the reduction of CO2. However, its high rate of charge recombination and low ability to adsorb CO2 limit its activity, particularly when gaseous CO2 was used. Herein, a Cu-based metal-organic framework (Cu-MOF-74) with high CO2 adsorption is coated onto Cu2O nanowires by a topotactic transformation method. The optimized Cu2O@Cu-MOF-74 composite thin film showed a CH4 evolution rate 4.5 times higher than that of bare Cu2O under visible light illumination ( > 420 nm), with water vapor as the electron donor. Analysis results of electrochemical impedance spectroscopy, transient photocurrent measurements, and fluorescence spectroscopy collectively suggest that the decoration of Cu2O with Cu-MOF-74 facilitates electron extraction from excited Cu2O, thereby inducing long-lived photocharges for the reduction of CO2. This study provides insights into the modification of transition metal oxides for application in photocatalysis by coating the surface with metal-organic frameworks. [ABSTRACT FROM AUTHOR]