Search Results (183)

Owing to high electrical conductivity, layered structure, and abundant surface functional groups, transition metal carbides/nitrides (MXenes) have received enormous interest in the field of gas sensors at room temperature. In this work, we synthesize a heterostructured nanocomposite with indium oxide (In₂O₃) decorated on titanium carbide (Ti₃C₂T_x) nanosheets by electrostatic self-assembly and develop it for high-selectivity NO₂ gas sensing at room temperature. Self-assembly formation of multiple heterojunctions in the In₂O₃/Ti₃C₂T_x composite provide abundant NO₂ gas adsorption sites and high electron transfer activity, which is conducive to improving the gas-sensing response of the In₂O₃/Ti₃C₂T_x gas sensor. Assisted by rich adsorption sites and hetero interface, the as-fabricated In₂O₃/Ti₃C₂T_x gas sensor exhibits the highest response to NO₂ among various interference gases. Meanwhile, a detection limit of 0.3 ppm, and response/recovery time (197.62/93.84 s) is displayed at room temperature. Finally, a NO₂ sensing mechanism of In₂O₃/Ti₃C₂T_x gas sensor is constructed based on PN heterojunction enhancement and molecular adsorption. This work not only expands the gas-sensing application of MXenes, but also demonstrates an avenue for the rational design and construction of NO₂-sensing materials. Full article

Two-dimensional (2D) material-based resistive random-access memory (RRAM) has emerged as a promising solution for neuromorphic computing and computing-in-memory architectures. Compared to conventional metal-oxide-based RRAM, the novel 2D material-based RRAM devices demonstrate lower power consumption, higher integration density, and reduced performance variability, benefiting from their atomic-scale thickness and ultra-flat surfaces. Remarkably, 2D layered metal oxides retain these advantages while preserving the merits of traditional metal oxides, including their low cost and high environmental stability. Through a multi-step dry transfer process, we fabricated a Pd-MoO₃-Ag RRAM device featuring 2D α-MoO₃ as the resistive switching layer, with Pd and Ag serving as inert and active electrodes, respectively. Resistive switching tests revealed an excellent operational stability, low write voltage (~0.5 V), high switching ratio (>10⁶), and multi-bit storage capability (≥3 bits). Nevertheless, the device exhibited a limited retention time (~2000 s). To overcome this limitation, we developed a Gr-MoO₃-Ag heterostructure by substituting the Pd electrode with graphene (Gr). This modification achieved a fivefold improvement in the retention time (>10⁴ s). These findings demonstrate that by controlling the type and thickness of 2D materials and resistive switching layers, RRAM devices with both high On/Off ratios and long-term data retention may be developed. Full article

Transition metal-based catalysts designed for efficient urea oxidation reactions (UOR) are essential for hydrogen production via urea-assisted water electrolysis. A series of amorphous nickel–cobalt boride catalysts supported on nickel foam were in situ synthesized via a stepwise chemical deposition method (SCDM). The systematic investigation focused on the relationships between synthesis parameters (deposition cycles, reactant feed ratio), morphological characteristics, and UOR performance. Notably, the optimized Co-NiB@NF catalyst exhibits a porous hierarchical architecture composed of metallic nanoparticles encapsulated by surface-wrinkled nanosheets, forming abundant exposed active sites. Electrochemical measurements demonstrate that this catalyst requires a low cell potential of 1.29 V to achieve a current density of 10 mA cm⁻². Moreover, it maintains 83% of the initial current density after 10 h of continuous electrolysis, highlighting its superior durability. The structural-property relationship revealed here provides valuable insights into the rational design of efficient amorphous boride catalysts for urea-assisted hydrogen production. Full article

Transition metal oxides (TMOs) are considered to be highly promising materials for supercapacitor electrodes due to their low cost, multiple convertible valence states, and excellent electrochemical properties. However, inherent limitations, including restricted specific surface area and low electrical conductivity, have largely restricted their application in supercapacitors. In this paper, core–shell heterostructures of nickel–iron layered double hydroxide (NiFe-LDH) nanosheets uniformly grown on CuCo₂O₄ nanoneedles were synthesized by hydrothermal and calcination methods. It is found that the novel core–shell structure of CuCo₂O₄@NiFe-LDH improves the electrical conductivity of the electrode materials and optimizes the charge transport path. Under the synergistic effect of the two components and the core–shell heterostructure, the CuCo₂O₄@NiFe-LDH electrode achieves an ultra-high specific capacity of 323.4 mAh g⁻¹ at 1 A g⁻¹. And the capacity retention after 10,000 cycles at 10 A g⁻¹ is 90.66%. In addition, the assembled CuCo₂O₄@NiFe-LDH//RGO asymmetric supercapacitor device achieved a considerable energy density (68.7 Wh kg⁻¹ at 856.3 W kg⁻¹). It also has 89.36% capacity retention after 10,000 cycles at 10 A g⁻¹. These properties indicate the great potential application of CuCo₂O₄@NiFe-LDH in the field of high-performance supercapacitors. Full article

The persistent contamination of aquatic systems by antibiotics, particularly tetracycline (TC), which induces antibiotic resistance genes and chronic toxicity to aquatic organisms, necessitates advanced oxidation processes. Herein, cobalt phosphonate (CoP) nanosheets with tailored Co/P ratios were synthesized to activate peroxymonosulfate (PMS) for TC degradation under visible light. Through a controlled-variable approach, the reaction parameters were systematically optimized. The refined CoP-3 system achieved 90.7% TC removal within 6 min, with the optimal degradation parameters determined as 0.1 g/L CoP-3 and 0.2 g/L PMS. Based on liquid chromatography–tandem mass spectrometry (LC-MS/MS) analysis, three degradation pathways were inferred. The toxicity of TC and its intermediates was assessed using quantitative structure–activity relationships (QSARs) via the Toxicity Estimation Software Tool (T.E.S.T). The results demonstrated reduced acute toxicity in intermediates compared to the parent compound. In practical applications, the catalyst achieved 64.7% and 80.8% TC removal rates in livestock wastewater and river water, respectively, while maintaining stable activity over four cycles. This demonstrates significant potential for engineering applications. The results were verified by free radical quenching experiments and were attributed to enhanced charge separation and an h⁺-dominated non-free radical pathway. This work provides a sustainable strategy for antibiotic remediation based on transition metal phosphonates. Full article

Hydrogen energy holds great promise for alleviating energy and environmental issues, with alkaline electrochemical water splitting being a key approach for hydrogen production. However, the high cost and limited availability of noble-metal catalysts hinder its widespread application. This study presents a novel method to fabricate a NiFeP-CoP/CF electrode. By growing CoOOH nanosheets on Co foam at low temperatures and filling the gaps between nanosheets with Ni and Fe phosphides, the prepared electrode exhibits outstanding electrocatalytic performance. For the oxygen evolution reaction (OER) in alkaline media, it requires overpotentials of only 235 mV and 290 mV to reach current densities of 10 mA cm⁻² and 100 mA cm⁻², respectively. In the case of the hydrogen evolution reaction (HER), overpotentials of 89 mV and 172 mV are needed to achieve current densities of −10 mA cm⁻² and −100 mA cm⁻². The NiFeP-CoP/CF-based electrolytic cell requires a cell voltage of only 1.70 V to achieve a current density of 100 mA cm⁻² for overall water splitting. Moreover, during long-term continuous operation at 100 mA cm⁻², the overpotential for OER remains constant while that for HER decreases. The low-temperature growth of CoOOH nanosheets on Co foam provides a new strategy for large-scale electrode production applicable in electrochemical processes and pollutant degradation. Significantly, filling the nanosheet gaps with phosphides effectively enhances the electrocatalytic performance of the system. This work offers a facile and cost-effective technique for the large-scale production of metallic (oxyhydr)hydroxides for electrocatalytic water splitting, showing great potential for industrial applications. Full article

A Yb³⁺-doped BiOI 3D nanosheet array composite was successfully fabricated through a solvothermal deposition strategy on flexible carbon cloth (CC). This composite was subsequently integrated with high-chlorine fly ash (FA) blocks to form the Yb-BiOI/CC/FA hybrid material. Comprehensive characterization was performed using multiple analytical techniques for crystalline phase identification, morphological analysis, valence state, band structure evaluation, and charge carrier separation assessment. Electrochemical measurements were conducted to evaluate the material’s electronic properties. Experimental results demonstrated superior photocatalytic performance under visible light irradiation, with the Yb-BiOI/CC/FA composite achieving 52.87% methylene blue degradation efficiency. The reaction rate constant of this modified nanomaterial was approximately 2.1 times higher than that of pristine BiOI/CC/FA. Radical trapping experiments revealed that superoxide radicals (·O₂⁻) served as the predominant oxidative species. This study presents a dual-benefit strategy for environmental remediation by simultaneously achieving sustainable waste valorization of industrial byproducts (FA) and developing high-efficiency photocatalytic materials. The successful integration of rare-earth metal modification with substrate engineering provides valuable insights for designing advanced photocatalytic systems for pollutant degradation. Full article

The persistent threat of heavy metal ions (e.g., Pb²⁺, Hg²⁺, Cd²⁺) in aqueous environments to human health underscores an urgent need for advanced sensing platforms capable of rapid and precise pollutant monitoring. Graphitic carbon nitride (g-C₃N₄), a metal-free polymeric semiconductor, has emerged as a revolutionary material for constructing next-generation environmental sensors due to its exceptional physicochemical properties, including tunable electronic structure, high chemical/thermal stability, large surface area, and unique optical characteristics. This review systematically explores the integration of g-C₃N₄ with functional nanomaterials (e.g., metal nanoparticles, metal oxide nanomaterials, carbonaceous materials, and conduction polymer) to engineer high-performance sensing interfaces for heavy metal detection. The structure-property relationship is critically analyzed, emphasizing how morphology engineering (nanofibers, nanosheets, and mesoporous) and surface functionalization strategies enhance sensitivity and selectivity. Advanced detection mechanisms are elucidated, including electrochemical signal amplification, and photoinduced electron transfer processes enabled by g-C₃N₄’s tailored bandgap and surface active sites. Furthermore, this review addresses challenges in real-world deployment, such as scalable nanomaterial synthesis, matrix interference mitigation, and long-term reliable detection. This work provides valuable insights for advancing g-C₃N₄-based electrochemical sensing technologies toward sustainable environmental monitoring and intelligent pollution control systems. Full article

Gate-All-Around (GAA) Nanosheet (NS) transistors have been identified as the device architecture for 3 nm and beyond as they provide additional scaling benefits. The Hot Carrier (HC) effect cannot be ignored in the development of metal oxide semiconductor field effect transistors (MOSFETs). In this article, we present a comprehensive review of Hot Carrier Degradation (HCD) studies on GAA NS transistors including geometry dependencies, surface orientation impacts, corner effects, characterization methodologies, process impacts and self-heating impacts from different researchers, together with the challenges and outlook, providing an insightful and valuable HCD reliability discussion and review on the cutting-edge technology in continuous MOSFET scaling. Full article

With the rapid development of the Internet of Things (IoT), there is an increasing demand for batteries with high energy and power densities. Three-dimensional microstructures present a promising approach for achieving high areal mass loading and an expanded electrochemical reaction surface. However, their high cost and complexity have hindered their widespread adoption. In this study, hierarchical porous electrodes integrated with conformal ultrathin nanosheets were fabricated to enhance reaction kinetics. The hierarchical porous skeleton provides a continuous pathway for electron transport and electrolyte diffusion, while the amorphous vanadium oxide (α-VO_x) nanosheets offer short ion diffusion channels and a large electrochemical surface area. Additionally, the internal space of the hierarchical structure accommodates substantial growth of the α-VO_x nanosheets, thereby supporting high mass loading and preserving areal capacity. The resulting hierarchical electrode structure demonstrates a high energy density of 0.49 mAh cm⁻² at 1 mA cm⁻² and an ultrahigh power density of 410 mW cm⁻² at 250 mA cm⁻². The assembled microbattery, using lithium metal as the anode, is encapsulated with a novel packaging process. This microbattery can power an electronic clock for up to 18 h on a single charge, retaining 75% of its initial capacity after 180 cycles. Full article

Water molecules from the environment or human breath are one of the main factors affecting the accuracy, efficiency, and long-term stability of electronic gas sensors. In this contribution, yttrium (Y)-doped La₂Ti₂O₇ (LTO) nanosheets were synthesized by a hydrothermal reaction, demonstrating improved proton conductivity compared to their non-doped counterparts. The response of Y-doped LTO with the optimal doping concentration to 100 ppm NO₂ at 43% relative humidity (RH) was −21%, which is four times higher than that of bare La₂Ti₂O₇. As the humidity level increased to 75%, the response of Y-doped LTO further increased to −64%. Unlike the gas doping effect observed in previous studies of semiconducting metal oxides, the sensing mechanism of Y-doped LTO nanosheets is based on the enhanced dissociation of H₂O in the presence of target NO₂ molecules, leading to the generation of more protons for ion conduction. This also resulted in a greater resistance drop and thus a larger sensing response at elevated humidity levels. Our work demonstrates that proton-conductive oxide materials are promising gas-sensing materials under humid conditions. Full article

The development of functional materials and the use of nanotechnology are ongoing projects. These fields are closely linked, but there is a need to combine them more actively. Nanoarchitectonics, a concept that comes after nanotechnology, is ready to do this. Among the related research efforts, research into creating functional materials through the formation of thin layers on surfaces, molecular membranes, and multilayer structures of these materials have a lot of implications. Layered structures are especially important as a key part of nanoarchitectonics. The diversity of the components and materials used in layer-by-layer (LbL) assemblies is a notable feature. Examples of LbL assemblies introduced in this review article include quantum dots, nanoparticles, nanocrystals, nanowires, nanotubes, g-C₃N₄, graphene oxide, MXene, nanosheets, zeolites, nanoporous materials, sol–gel materials, layered double hydroxides, metal–organic frameworks, covalent organic frameworks, conducting polymers, dyes, DNAs, polysaccharides, nanocelluloses, peptides, proteins, lipid bilayers, photosystems, viruses, living cells, and tissues. These examples of LbL assembly show how useful and versatile it is. Finally, this review will consider future challenges in layer-by-layer nanoarchitectonics. Full article

Purification of soot particles from automobile exhaust has closely to do with the synergistic effect between catalyst metals. Here, several binary Ni-Fe oxide catalysts were elaborately prepared via a modified solvothermal method. A non-noble-metal (Ni)-modified hexagonal Fe₂O₃ nano-sheet catalyst (Ni−Fe₂O₃) was prepared. The introduced heteroatoms replace some of the Fe atoms, which take up the surface of the [FeO₆] octahedron, and the synergistic effect formed between the heteroatoms which are on the surface and the adjacent Fe atoms promotes the formation of coordination unsaturated ions of the activated reactants. The optimal performance was obtained with the Ni-Fe₂O₃-20 composition, with catalytic soot oxidation resulting in T₅₀, SCO₂^m, E_a and TOF of 366 °C, 99.1%, 72.7 kJ mol⁻¹ and 0.156 min⁻¹ (at 310 °C), respectively. The combination of Ni and Fe₂O₃ cells increases the ratio of Fe³⁺/Fe²⁺, making the interaction among electrons between the Ni, which was proved highly dispersed over the catalyst, and the Fe₂O₃ strong. Both exist on the catalyst surface in the form of NiFe₂O₄. Ni atoms and Fe₂O₃, which demonstrate a synergistic effect, promoting the formation of coordination unsaturated ions of the activated reactants and generating more oxygen vacancies, thus promoting the adsorption of NO and accelerating the ignition of soot in O₂ at a low temperature. The novel Ni-Fe₂O₃-X oxide cocatalyst is an improved noble-free catalyst that promotes the synergistic effect between heteroatoms and metal oxides through surface regulation. This is of great significance for the further development of economic and efficient catalysts for soot particle removal from automobile exhaust. Full article

Emerging pollutants, such as N-acetyl-para-aminophenol, pose significant challenges to environmental sustainability, and Bi₂Fe₂O₂ (BFO) nanomaterials are an emerging class of piezoelectric materials. This study presents a novel piezoelectric-driven Fenton system based on Bi₂Fe₄O₉ nanosheets for the efficient degradation of organic pollutants. BFO nanosheets with varying thicknesses were synthesized, and their piezoelectric properties were confirmed through piezoresponse force microscopy and heavy metal ion reduction experiments. The piezoelectric electrons generated within the BFO nanosheets facilitate the in situ production of hydrogen peroxide, which in turn drives the Fenton-like reaction. Furthermore, the piezoelectric electrons enhance the redox cycling of iron in the Fenton process, boosting the overall catalytic efficiency. The energy band structure of BFO nanosheets is well-suited for this process, enabling efficient hydrogen peroxide generation and promoting Fe³⁺ reduction. The findings demonstrate that thinner BFO nanosheets exhibit superior piezoelectric activity, leading to enhanced catalytic performance. Additionally, the incorporation of gold nanodots onto BFO nanosheets further boosts their piezocatalytic efficiency, particularly in the reduction of Cr (VI). The system exhibited robust oxidative capacity, stability, and recyclability, with reactive oxygen species (ROS) verified via electron paramagnetic resonance spectroscopy. Overall, BFO nanosheets, with their optimal energy band structure, self-supplied hydrogen peroxide, and enhanced Fe³⁺ reduction, represent a promising, sustainable solution for advanced oxidation processes in wastewater treatment and other applications. Full article

Achieving high energy density while maintaining high power density and long cycle life in supercapacitors, particularly in supercapatteries (SCs), through a thermally stable, greener ionic liquid approach remains a significant challenge for an advanced energy storage application. In this work, we prepared high conductive and high charge storage capability bimetallic transition metal molybdate [Ag₂Mo₂O₇ (AgM)], synergistic with reduced graphene oxide (rGO) coated on nickel foam (AgM/rGO/NF). The physio-chemical characterization revealed a ball-like cluster morphology wrapped in rGO nanosheets and a spinel-type cubic structure using scanning electron microscopy (FE-SEM) displays and X-ray diffraction (XRD) analyses. Further, the electrochemical performance of AgM/rGO/NF electrode achieved a remarkable specific C_sp value of 573.63 F/g at a current density of 1.0 A/g in 3 M KOH electrolyte. An asymmetric SCs (ASCs) device was fabricated using AgM/rGO/NF as the positive and rGO as the negative electrodes, achieving a wide potential window of 1.3 V. The ASC demonstrated an energy density of 16.71 Wh/kg at a power density of 642.98 W/kg, highlighting AgM/rGO/NF’s potential as an advanced electrode material for energy storage applications. Full article