Oxide Research Articles

Fabrication of Cu2O/CuO Nanowires by One-Step Thermal Oxidation of Flexible Copper Mesh for Supercapacitor Applications

This study focuses on the growth of Cu2O/CuO nanowires by one-step thermal oxidation using a flexible copper mesh at oxidation temperatures in the range of 300 to 600 °C in a controlled atmosphere of mixed-flow Ar and O2 gases. Thermal oxidation is one of the simplest used methods to obtain nanowires on a metal surface, offering advantages such as low production costs and the ability to produce metal oxides on a large scale without the use of hazardous chemical compounds. The growth of metal oxides on a conductive substrate, forming metal/oxide structures, has proven to be an effective method for enhancing charge-transfer efficiency. The as-synthesized Cu/Cu2O/CuO (Nw) electrodes were structurally and morphologically characterized using techniques such as XRD and SEM/EDX analysis to investigate the structure modification and morphologies of the materials. The supercapacitor properties of the as-developed Cu/Cu2O/CuO (Nw) electrodes were then examined using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS). The CV curves show that the Cu/Cu2O/CuO (Nw) structure acts as a positive electrode, and, at a scan rate of 5 mV s −1, the highest capacitance values reached 26.158 mF cm−2 for the electrode oxidized at a temperature of 300 °C. The assessment of the flexibility of the electrodes was performed at various bending angles, including 0°, 45°, 90°, 135°, and 180°. The GCD analysis revealed a maximum specific capacitance of 21.198 mF cm−2 at a low power density of 0.5 mA cm−2 for the oxidation temperature of 300 °C. The cycle life assessment of the all of the as-obtained Cu/Cu2O/CuO (Nw) electrodes over 500 cycles was performed by GCD analysis, which confirmed their electrochemical stability.

Straw Biochar and Graphite Oxide Enhanced External Pressure Ultrafiltration for Leaded Wastewater Treatment.

In order to solve the problem of the low treatment efficiency of wastewater containing heavy metals in mining areas, straw biochar and graphene oxide enhanced external pressure ultrafiltration (SGU) was used to treat wastewater containing high concentrations of Pb2+. The operation parameters such as pH and temperature were optimized, and the removal efficiency of CODCr, NH3-N, turbidity and Pb2+ via SGU, straw biochar ultrafiltration (SU), ultrafiltration (UF), and conventional treatment (CT) were systematically investigated. The results showed that the pH and temperature of polluted water were 4.8-5.2 and 21-30 °C, respectively, the average removal rates of CODCr, NH3-N, turbidity and Pb2+ by SGU reached 91%, 97%, 98% and 95%, respectively, and the removal effect was better than that of other processes. In addition, under the backwash conditions of clean water, weak acid, and weak alkali, the membrane flux recovered 65%, 88%, and 89% of the new membrane, respectively. This study provides scientific and theoretical support for the advanced treatment of polluted water in mining areas.

Tailoring oxygen vacancies by synergy of dual metal cations in LaCo0.8M0.2O3 (M = Cu, Ni, Fe, Mn) towards catalytic oxidation of toluene

Enhancing the catalytic performance of transition metal oxide catalysts is prerequisite for the efficient catalytic oxidation of VOCs. Here the B-site partially substituted LaCoO3 (LaCo0.8M0.2O3, M = Cu, Ni, Fe and Mn) catalysts was synthesized for the catalytic oxidation of toluene. Among these catalysts, LaCo0.8Ni0.2O3 catalyst exhibits remarkable catalytic performance for toluene with T50 = 226 °C and T90 = 239 °C at an initial toluene concentration of 1000 ppm, whose T50 (and T90) reduced by 13 °C (and 34 °C) compared with that of LaCoO3. Confirmed by BET, XPS, and EPR characterizations, Ni substitution improves the specific surface area, Co3+/Co2+ ratio, Oads/Olatt ratio, and oxygen vacancies concentration. This improvement indicates the improvement of adsorption and activation of reactant, mobility of oxygen species, thereby contributing to the superior catalytic performance in toluene oxidation. The B-site of LaCoO3 occupied by dual cations caused the lattice distortion and formation of oxygen vacancies due to the ionic radii difference between Co and Ni cations. Moreover, the apparent activation energy of LaCo0.8Ni0.2O3, as the determining factor for the catalytic oxidation rate, was remarkably reduced. Our findings confirmed the synergy effect of Co and Ni cations at B-site on the enhancement of catalytic activity, which provides a promising strategy for oxygen vacancy engineering.

Insights into the Electrochemical CO2RR Performance and Binding of Small Molecules on Quaternary Thiospinels Ag2FeSn3S8 and Cu2FeSn3S8.

Using a mechanical synthesis method in the form of ball milling and an additional annealing step, a novel and accelerated route for the synthesis of the thiospinels toyohaite (Ag2FeSn3S8) and rhodostannite (Cu2FeSn3S8) was discovered. Both thiospinels display faradaic efficiencies of up to 73% for CO2 reduction to CO using an organic electrolyte in an H-type cell. The materials were furthermore implemented in a zero-gap electrolyzer, with toyohaite producing 22% CO and 52% H2 at 100 mA cm-2 and rhodostannite 28% CO and 37% H2. The catalytically active sites are studied using density functional theory, revealing strong CO binding interactions on both Ag and Cu, whereas Sn is found to contribute to the decomposition of Ag2FeSn3S8 and Cu2FeSn3S8 by coordination with oxygen. Postmortem analysis of the thiospinel-based electrodes by means of SEM-EDX, XRD, XPS, and Mössbauer spectroscopy showed sulfur leaching from the catalysts after applying 100 mA cm-2. These spectroscopic results-in conjunction with DFT calculations of the oxidized surfaces-suggest that the catalytically active species consists of metal oxides. As a conversion of the metal sulfides into the corresponding metallic species was observed via XRD, the decomposition pathways of both catalysts were also computed using DFT; thus, elucidating the energetically most favorable decomposition products and expanding the possible composition of the catalysts postelectrolysis.

Boosting Photocatalytic Hydrogen Production by MOF‐derived Metal Oxide Heterojunctions with a 10.0% Apparent Quantum Yield

Boosting Photocatalytic Hydrogen Production by MOF‐derived Metal Oxide Heterojunctions with a 10.0% Apparent Quantum Yield

Nanoscopic catalyst-loaded porous metal oxide hollow frameworks using porous block copolymer templates for high performance formaldehyde sensors

Porous and hollow nanostructures functionalized with nanoscopic catalysts have attracted considerable interest in a wide range of applications depending on surface reactions. In this study, we present an efficient and versatile synthetic strategy of porous metal oxide hollow frameworks (HFs) decorated with noble metal nanoparticles (NPs). The key lies in the use of porous and bicontinuous polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) microparticles as templates, which feature pores on the order of several hundred nanometers in size. Homogeneous Pt loading on the surface of the porous microparticles is achieved through the preferential adsorption of Pt precursors onto the P4VP block via electrostatic interactions. Subsequent SnO2 thin film deposition and calcination ultimately yield honeycomb-like SnO2 HFs with macropores and uniform distribution of Pt NPs. The Pt NP-loaded SnO2 HFs exhibit exceptional formaldehyde (HCHO) sensing capabilities, characterized by remarkable sensitivity (31.4 at 5 ppm), rapid response time (4.7 s at 5 ppm), ultra-low detection limit of 10 ppb, and remarkable cross-selectivity. These outstanding features result from their high surface area, gas permeability within porous hollow structures, and well-dispersed Pt NPs, which catalytically activate the sensor. Our study provides great promise for advancing surface catalytic reactions due to their exceptional surface area and gas permeability, paving the way for future applications.

Research Progress on Ammonia Sensors Based on Ti3C2Tx MXene at Room Temperature: A Review.

Ammonia (NH3) potentially harms human health, the ecosystem, industrial and agricultural production, and other fields. Therefore, the detection of NH3 has broad prospects and important significance. Ti3C2Tx is a common MXene material that is great for detecting NH3 at room temperature because it has a two-dimensional layered structure, a large specific surface area, is easy to functionalize on the surface, is sensitive to gases at room temperature, and is very selective for NH3. This review provides a detailed description of the preparation process as well as recent advances in the development of gas-sensing materials based on Ti3C2Tx MXene for room-temperature NH3 detection. It also analyzes the advantages and disadvantages of various preparation and synthesis methods for Ti3C2Tx MXene's performance. Since the gas-sensitive performance of pure Ti3C2Tx MXene regarding NH3 can be further improved, this review discusses additional composite materials, including metal oxides, conductive polymers, and two-dimensional materials that can be used to improve the sensitivity of pure Ti3C2Tx MXene to NH3. Furthermore, the present state of research on the NH3 sensitivity mechanism of Ti3C2Tx MXene-based sensors is summarized in this study. Finally, this paper analyzes the challenges and future prospects of Ti3C2Tx MXene-based gas-sensitive materials for room-temperature NH3 detection.

Structural and interface band alignment properties of transparent p-type α-GaCrO3:Ni/α-Al2O3 heterojunction

Herein, we report epitaxial growth of p-type Ni doped gallium chromium oxide thin film on Al2O3 substrates and studied its band alignment properties with that of the substrate. Thin films are grown using the magnetron-sputtering technique. Synchrotron-based XRD measurements, performed in the coplanar and non-coplanar geometries, confirm high-quality single domain epitaxial growth of p-type α-GaCrO3:Ni. Pendellosung oscillations around the Bragg peak and transmission electron microscopy reveal the high interfacial quality of p-type α-GaCrO3:Ni films with the substrate. Thin film, thickness ∼200 nm, shows around 70% average transmission. The values of valence band and conduction band offsets are determined to be 2.79 ± 0.2 and 0.51 ± 0.2 eV, respectively, which confirm straddling gap band alignment at the heterojunction. This type of alignment creates a threshold barrier for the selective charge carriers and is useful in enhancing the performance of a wide range of devices, including UV photodetectors, metal oxide semiconductor high electron mobility transistors, and light emitters.

Predicting the potential toxicity of the metal oxide nanoparticles using machine learning algorithms

AbstractOver the years, machine learning (ML) algorithms have proven their ability to make reliable predictions of the toxicity of metal oxide nanoparticles. This paper proposed a predictive ML model of the potential toxicity of metal oxide nanoparticles. A dataset consisting of 79 descriptors including 24 metal oxide nanoparticles (MexOy NPs) and their physicochemical and structural characteristics is adopted. The proposed model comprises of three main phases. The first phase is used to analyze the characteristics of nanoparticles along with their toxicity behavior. In the second phase, the problems associated with the metal oxide nanoparticles dataset are tackled. The first problem namely the class imbalance problem is handled through utilizing synthetic minority over-sampling technique (SMOTE). The second problem namely the outliers is handled through applying a novel feature selection algorithm based on the enhanced binary version of the sine tree-seed algorithm (EBSTSA). The proposed EBSTSA is used to find the relevant features affecting toxicity. The density-based spatial clustering of applications with noise (DBSCAN) is utilized as a tool for identifying outliers in the dataset and for visualizing the impact of the feature selection on the performance of the subsequent classification. Finally, in the third phase, the support vector machine (SVM) supervised machine learning algorithm and k-fold cross-validation method are applied to classify the mode of action of each instance of nanoparticle as toxic or nontoxic. The simulation results showed that the EBSTSA-based feature selection algorithm is reliable and robust across 23 benchmark datasets from the UCI machine learning repository. The results also showed that proposed EBSTSA can effectively find the relevant descriptors for nano-particles. Furthermore, the results demonstrated the efficacy of the proposed ML toxicity prediction model. It is obtained on average 1.02% of error rate, 100% of specificity, 98.87% of sensitivity, and 99.47% of f1-score.

Graphitic Carbon Nitride Structures on Carbon Cloth Containing Ultra- and Nano-Dispersed NiO for Photoactivated Oxygen Evolution.

The development of low-cost and high-efficiency oxygen evolution reaction (OER) photoelectrocatalysts is a key requirement for H2 generation via solar-assisted water splitting. In this study, we report on an amenable fabrication route to carbon cloth-supported graphitic carbon nitride (gCN) nanoarchitectures, featuring a modular dispersion of NiO as co-catalyst. The synergistic interaction between gCN and NiO, along with the tailoring of their size and spatial distribution, yield very attractive OER performances and durability in freshwater splitting, of great significance for practical end-uses. The potential of gCN electrocatalysts containing ultra-dispersed, i. e. "quasi-atomic" NiO, exhibiting a higher activity than the ones containing nickel oxide nanoaggregates, is further highlighted by their activity even in real seawater. This work suggests that efficient OER catalysts can be designed through the construction of optimized interfaces between transition metal oxides and carbon nitride, yielding inexpensive and promising noble metal-free systems for real-world applications.

Human Skin-Mimicking Ionogel-Based Electronic Skin for Intelligent Robotic Sorting.

Creating bionic intelligent robotic systems that emulate human-like skin perception presents a considerable scientific challenge. This study introduces a multifunctional bionic electronic skin (e-skin) made from polyacrylic acid ionogel (PAIG), designed to detect human motion signals and transmit them to robotic systems for recognition and classification. The PAIG is synthesized using a suspension of liquid metal and graphene oxide nanosheets as initiators and cross-linkers. The resulting PAIGs demonstrate excellent mechanical properties, resistance to freezing and drying, and self-healing capabilities. Functionally, the PAIG effectively captures human motion signals through electromechanical sensing. Furthermore, a bionic intelligent sorting robot system is developed by integrating the PAIG-based e-skin with a robotic manipulator. This system leverages its ability to detect frictional electrical signals, enabling precise identification and sorting of materials. The innovations presented in this study hold significant potential for applications in artificial intelligence, rehabilitation training, and intelligent classification systems.

Efficient hydrogen production via hydrolysis of NaBH4 by the Co/Co3O4–Cu2O–ZnO catalyst prepared using mixed metal oxides as support material

Efficient hydrogen production via hydrolysis of NaBH4 by the Co/Co3O4–Cu2O–ZnO catalyst prepared using mixed metal oxides as support material

A novel MTCMOS based 8T2M NVSRAM design for low power applications with high temperature endurance

Abstract This research investigates, for the first time, a novel eight-transistor-two-memristor (8T2M) nonvolatile 
static random access memory (NVSRAM) with 7-nm technology. The key innovation in this design lies 
in the incorporation of multiple-threshold complementary metal oxide semiconductor (MTCMOS) 
technology with power gating technique, which enables efficient power management and enhanced 
performance with low leakage current. The implementation of multiple threshold voltage levels allows 
for dynamic control of transistor behavior, optimizing power consumption and read/write speeds. As 
compared to a traditional six-transistor (6T) static random access memory (SRAM) cell, it has been 
ascertained that there is a 33% enhancement in the read margin and an 18% improvement in the write 
margin. Moreover, the delay for read, write ‘0’ and write ‘1’ is also minimized by 63.89%, 37.99% and 
42.77%. Furthermore, the power attenuation is also reduced for read and write by 63.02% and 81.6%, 
respectively with respect to a conventional SRAM.

High Performance Flexible Supercapacitor Based on Single Precursor Derived NiFe2O4 Spinel with Tailored Cationic Distribution and Oxygen Vacancies in Acidic Medium

AbstractSpinel metal oxides are extensively studied for supercapacitors (SCs) in alkaline electrolytes, where charge storage capacity is limited by surface site availability due to surface reconstruction forming metal hydroxides/oxyhydroxides. The use of an acidic medium, which can boost the charge storage capacity of spinel oxides offering an additional channel of intercalation‐deintercalation of protons, is underexplored. Moreover, the impact of chemical compositions and the cationic distributions is crucial on the electrocatalysis performance of spinel oxides, however, such a correlation is first time reported for charge storage properties of spinel ferrite NiFe2O4 nanoparticles (NFO NPs). Besides, a low‐cost and scalable synthesis of NFO NPs involving the thermal decomposition of Ni‐Fe glycolate, followed by controlled air‐calcination is reported. Thus crafted NFO NPs‐based device shows impressive specific capacitance (2112 F g−1 at 10 A g−1) in half‐cell configuration. A flexible all‐solid‐state asymmetric device (full‐cell) configuration depicts impressive energy density (20.7 Wh kg−1), power density (4000 W kg−1), gravimetric capacitance (140 F g−1 at 2 A g−1), and retention of its performance (≈75% after 10,000 charging/discharging cycles). The results depict a new insight toward the tuning of electronic and charge storage properties in NFO, which otherwise are predominately attributed to only the crystallite size and morphological effects.

Junctionless Structure Indium-Tin Oxide Thin-Film Transistors Enabling Enhanced Mechanical and Contact Stability.

In recent years, considerable attention has focused on high-performance and flexible crystalline metal oxide thin-film transistors (TFTs). However, achieving both high performance and flexibility in semiconductor devices is challenging due to the inherently conductive and brittle nature of crystalline metal oxide. In this study, we propose a facile way to overcome this limitation by employing a junctionless (JL) TFT structure via oxygen plasma treatment of the crystalline indium-tin oxide (ITO) films. The oxygen plasma treatment significantly reduced oxygen vacancies in the ITO films, contributing to the significant reduction in the carrier concentration from 4.67 × 1020 to 1.39 × 1016. Importantly, this reduction was achieved without inducing any noticeable structural changes in the ITO, enabling the successful realization of ITO JL TFTs with an adjustable threshold voltage. Furthermore, the ITO JL TFTs demonstrate good stability and reliability under various bias stress conditions, aging in the air atmosphere, and high-temperature processes. In addition, the ITO JL TFTs exhibit low light sensitivity due to the wide bandgap of ITO and further suppression of Vo defects, making them suitable for applications requiring stable performance under light exposure. To compare and analyze the flexibility of the JL structure and conventional structure with additional source/drain (S/D) junction in ITO TFTs with nonencapsulation, we utilized mechanical simulations and transmission line method (TLM). By employing the JL structure in ITO TFT through carefully optimized oxygen plasma treatment, we successfully mitigated stress concentration at the S/D-channel interface. This resulted in a JL ITO TFT that exhibited a change in contact resistance of less than 20% even after 20,000 bending cycles. Consequently, a stable and flexible ITO TFT with field-effect mobility (μFE) of 12.74 cm2/(V s) was realized, outperforming conventionally structured ITO TFTs with additional S/D junction, where the contact resistance nearly tripled.

Применение бентонитовой глины в качестве гидроизоляционного материала

Purpose: analytical study of usability bentonite is a natural mineral with high waterproofing and adsorption properties in various fields. Methods: methods of comparative analysis, synthesis, generalization, analogy were used. Results: this article examines various applications of bentonite, allowing to position bentonite as a universal material, which is widely used in various industries due to its unique properties. The advantages of bentonite over other waterproofing materials are noted, including environmental friendliness, durability, efficiency and economy. The properties of bentonite clay have been studied, the ability of which to swell and create a waterproofing barrier in contact with water makes it an effective material for protection against moisture. It is indicated that the high frost resistance of bentonite is ensured due to the complex structure of the material consisting of metal oxide atoms and silicon atoms, which form a dense structure. The interlayer space in which the exchange cations are concentrated is the physical and physicochemical basis for the sorption activity of bentonite clay rocks. Bentonite has been found to be of value in its self-healing properties, as is the case when used at negative temperatures. This is due to its molecular structure. The microscopic particles that make up bentonite have a negative charge, they are able to adsorb water molecules. Practical significance: waterproofing works are carried out in many areas of construction. However, bentonite materials are not widely used. In this aspect, the article describes in detail such waterproofing materials as bentonite mats, clay lock, injectable bentonite waterproofing. The authors believe that the demand for the use of bentonite as a reliable and promising means of waterproofing in the construction industry will increase.

Efficient hydrogen production via hydrolysis of NaBH4 by the Co/Co3O4–Cu2O–ZnO catalyst prepared using mixed metal oxides as support material

Efficient hydrogen production via hydrolysis of NaBH4 by the Co/Co3O4–Cu2O–ZnO catalyst prepared using mixed metal oxides as support material

Durability of metal oxide nanostructures synthesized by hot water treatment

AbstractMetal oxide nanostructures (MONSTRs) have become popular in various fields. This study investigates the durability of MONSTRs synthesized through hot water treatment (HWT) using copper, aluminum, and zinc as the source metals of choice. The physical durability tests include pressure, scratch, and scotch tape adhesion tests, and chemical durability tests such as corrosion resistance tests, heat resistance, and solar exposure tests. Results showed that MONSTRs synthesized from HWT are highly durable under the tested conditions except for NaOH and HCl immersion tests for copper oxide and zinc oxide. The study concluded that HWT is a sustainable synthesis method for MONSTRs. Graphical Abstract

Transport Properties in GaN Metal–Oxide–Semiconductor Field‐Effect Transistor Almost Free of Interface Traps with AlSiO/AlN/p‐Type GaN Gate Stack

The factors limiting channel mobility in AlSiO/p‐type GaN metal–oxide–semiconductor (MOS) field‐effect transistors are examined by performing Hall‐effect measurements in conjunction with a gate bias, with and without a thin AlN interlayer. In the absence of this interlayer, the free carrier concentration associated with the Hall effect is significantly reduced compared with the net gate charge density estimated from capacitance–voltage data, indicating that electrons are trapped to a significant extent at the MOS interface. These interface traps are found to have an energy ≈20 meV above the Fermi level in strong inversion based on temperature‐dependent Hall effect data. The insertion of a 0.8 nm‐thick AlN interlayer eliminates charge trapping such that almost all gate charges are mobile. The mobility components could be divided into types based on their effect on the effective electric field perpendicular to the channel. Coulomb scattering centers resulting from interface states are evidently reduced by inserting the AlN interlayer, which also enhances the channel mobility to over 150 cm2 V−1s−1.

Durability of metal oxide nanostructures synthesized by hot water treatment

AbstractMetal oxide nanostructures (MONSTRs) have become popular in various fields. This study investigates the durability of MONSTRs synthesized through hot water treatment (HWT) using copper, aluminum, and zinc as the source metals of choice. The physical durability tests include pressure, scratch, and scotch tape adhesion tests, and chemical durability tests such as corrosion resistance tests, heat resistance, and solar exposure tests. Results showed that MONSTRs synthesized from HWT are highly durable under the tested conditions except for NaOH and HCl immersion tests for copper oxide and zinc oxide. The study concluded that HWT is a sustainable synthesis method for MONSTRs. Graphical Abstract