Search Results (110)

Titanium dioxide (TiO₂) is a benchmark photocatalyst for environmental applications, but its limited visible-light activity due to a wide band gap and fast charge recombination restricts its practical efficiency. This study presents the development of heterostructured Ag (Au)/MoS₂-TiO₂ inverse opal (IO) films that synergistically integrate photonic, plasmonic, and semiconducting functionalities to overcome these limitations. The materials were synthesized via a one-step evaporation-induced co-assembly approach, embedding MoS₂ nanosheets and plasmonic nanoparticles (Ag or Au) within a nanocrystalline TiO₂ photonic framework. The inverse opal architecture enhances light harvesting through slow-photon effects, while MoS₂ and plasmonic nanoparticles improve visible-light absorption and charge separation. By tuning the template sphere size, the photonic band gap was aligned with the TiO₂-MoS₂ absorption edge and the localized surface plasmon resonance of Ag, enabling optimal spectral overlap. The corresponding Ag/MoS₂-TiO₂ photonic films exhibited superior photocatalytic and photoelectrocatalytic degradation of tetracycline under visible light. Ultraviolet photoelectron spectroscopy and Mott–Schottky analysis confirmed favorable band alignment and Fermi level shifts that facilitate interfacial charge transfer. These results highlight the potential of integrated photonic–plasmonic-semiconductor architectures for efficient solar-driven water treatment. 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

ZnO nanorods are promising nanomaterials for photoelectrochemical photodetectors (PEC PDs). However, the weak photocurrent density, delayed response, and low stability of ZnO are major drawbacks for their applications. To address these challenges, we integrated multilayer MoS₂ nanosheets with ZnO nanorods using a chemical bath deposition method. The resulting ZnO/MoS₂ heterojunction achieved a photocurrent density of 1.02 mA/cm² (~20 times higher than that of bare ZnO), ultrafast response times (90/150 ms), and 92% stability retention over 3600 s. These enhancements originated from suppressed charge recombination and accelerated water oxidation kinetics. Our work provides another possible energy-saving route toward developing high-efficiency and stable ZnO-based photoanodes for practical applications in PEC PDs. Full article

The widespread presence of pesticides—especially malathion—in aquatic environments presents a major obstacle to conventional remediation strategies, while the ongoing global energy crisis underscores the urgency of developing renewable energy sources such as hydrogen. In this context, photocatalytic water splitting emerges as a promising approach, though its practical application remains limited by poor charge carrier dynamics and insufficient visible-light utilization. Herein, we report the design and evaluation of a series of TiO₂-based ternary nanocomposites comprising commercial P25 TiO₂, reduced graphene oxide (rGO), and molybdenum disulfide (MoS₂), with MoS₂ loadings ranging from 1% to 10% by weight. The photocatalysts were fabricated via a two-step method: hydrothermal integration of rGO into P25 followed by solution-phase self-assembly of exfoliated MoS₂ nanosheets. The composites were systematically characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Photocatalytic activity was assessed through two key applications: the degradation of malathion (20 mg/L) under simulated solar irradiation and hydrogen evolution from water in the presence of sacrificial agents. Quantification was performed using UV-Vis spectroscopy, gas chromatography–mass spectrometry (GC-MS), and thermal conductivity detection (GC-TCD). Results showed that the integration of rGO significantly enhanced surface area and charge mobility, while MoS₂ served as an effective co-catalyst, promoting interfacial charge separation and acting as an active site for hydrogen evolution. Nearly complete malathion degradation (~100%) was achieved within two hours, and hydrogen production reached up to 6000 µmol g⁻¹ h⁻¹ under optimal MoS₂ loading. Notably, photocatalytic performance declined with higher MoS₂ content due to recombination effects. Overall, this work demonstrates the synergistic enhancement provided by rGO and MoS₂ in a stable P25-based system and underscores the viability of such ternary nanocomposites for addressing both environmental remediation and sustainable energy conversion challenges. Full article

In this study, Bi₂MoO₆ nanoflowers with different molybdenum sources were in situ grown on the surface of g-C₃N₄ nanosheets (OCN) by a simple one-step solvothermal method. The effects of doping and different molybdenum sources on the photocatalytic degradation and bactericidal activity of Bi₂MoO₆/OCN were discussed. Among them, the solvothermal preparation of P-Bi₂MoO₆/OCN using phosphomolybdic acid as molybdenum source can make up for the shortcomings caused by the destruction of OCN structure by generating more lattice defects to promote charge separation and constructing Lewis acid/base sites to effectively improve the photocatalytic performance. In addition, by adding phosphoric acid to increase the P-doped content, more exposed alkaline active sites are induced on the surface of P-Bi₂MoO₆/OCN, as well as larger specific surface area and charge transfer efficiency, which further improve the photocatalytic performance. Finally, the optimized 16P-Bi₂MoO₆/OCN showed a degradation rate of 99.7% for 20 mg/L rhodamine B (RhB) within 80 min under visible light, and the antibacterial rates against E. coli, S. aureus and P. aeruginosa within 300 min were 99.58%, 98.20% and 97.48%, respectively. This study provides a reference for optimizing the synthesis of environmentally friendly, solar-responsive, photocatalytic sterilization materials from the perspective of preparation, raw materials and structure. Full article

Monitoring trace toluene exposure is critical for early-stage lung cancer screening via breath analysis, yet conventional chemiresistive sensors face fundamental limitations, including compromised selectivity in complex VOC matrices and humidity-induced signal drift, with prevailing p–n heterojunction architectures suffering from inherent charge recombination and environmental instability. Herein, we pioneer a 2D core–shell n–n heterojunction strategy through rational design of TiO₂@MoS₂ heterostructures, where vertically aligned MoS₂ nanosheets are epitaxially grown on 2D TiO₂ derived from graphene-templated synthesis, creating built-in electric fields at the heterojunction interface that dramatically enhance charge carrier separation efficiency. At 240 °C, the TiO₂@MoS₂ sensor exhibits a superior response (R_a/R_g = 9.8 to 10 ppm toluene), outperforming MoS₂ (R_a/R_g = 2.8). Additionally, the sensor demonstrates rapid response/recovery kinetics (9 s/16 s), a low detection limit (50 ppb), and excellent selectivity against interfering gases and moisture. The enhanced performance is attributed to unidirectional electron transfer (TiO₂ → MoS₂) without hole recombination losses, methyl-specific adsorption through TiO₂ oxygen vacancy alignment, and steric exclusion of non-target VOCs via size-selective MoS₂ interlayers. This work establishes a transformative paradigm in gas sensor design by leveraging n–n heterojunction physics and 2D core–shell synergy, overcoming long-standing limitations of conventional architectures. Full article

In the current study, the Prussian blue analog decorated with zinc oxide (PBA@ZnO) was produced using a simple chemical co-precipitation method. The nanohybrid was examined using XRD, EDX, SEM, and TEM techniques, where it exhibited a polycrystalline structure with highly intense broadening peaks. The surface morphology was observed as thin nanosheets decorated with tiny spheres. Following excitation at 360 nm, the fluorescence spectra of PBA@ZnO showed fluorescence emission at 455 nm. The developed PBA@ZnO was used to qualitatively and quantitatively assess sunset yellow (SY), where its native fluorescence was selectively quenched as SY concentrations increased. For the first time, PBA@ZnO was used as a turn-off nano-sensor for the spectrofluorimetric measurement of SY. The method’s markable sensitivity was demonstrated within an SY linearity range of 50–500 ng/mL, where the limit of detection was calculated as 9.77 ng/mL. Real sample analysis in the food industry, including samples from real food, soft drinks, and sun cream, was made possible by the detection of tiny amounts of SY. Analytical Greenness (AGREE), AGREEprep, and the complementing Green Analytical Procedure Index (Complex MoGAPI) were used to illustrate the new approach’s exceptional eco-friendliness and greenness. The RGB 12 algorithm worked to demonstrate that the suggested approach is less costly, more environmentally friendly, more sustainable, analytically sound, and whiter than the ones that were previously published. In accordance with ICH principles, the suggested method was validated. This approach offers a promising way to rapidly and accurately identify and measure SY in the food industry, helping to guarantee food safety and maintain the health of customers. Full article

A boron-doped BiOBr photocatalytic nanosheet was synthesized using a one-step hydrothermal method. The effects of solvent, temperature, and boron doping content on the morphology and photocatalytic performance were investigated. The boron-doped samples synthesized with acetic acid at 180 °C (1B-AB) showed optimal photocatalytic performance, achieving 80% efficiency in degrading sulfanilamide (SN) within 6 h. After five cycles, the degradation rate decreased by 21%. The 10% boron doping reduced BiOBr’s bandgap (from 2.90 to 2.88 eV), improving visible light utilization and reducing electron–hole pair recombination. The 1B-AB photocatalyst also demonstrated excellent activity against anionic dyes like methyl orange (MO) and malachite green (MG). Hydroxyl radicals (·OH) and superoxide anions (·O₂⁻) were identified as the main active species in the SN degradation process. Full article

A double-layer core–shell photocatalytic coating was engineered on carbon fibers (CFb) derived from bamboo pulp precursors, employing a sequential process involving seed pre-loading, solvothermal treatment, and impregnation. XRD, SEM, and SEM-EDS analyses revealed that g-C₃N₄ and Bi₂O₃ nanosheets were co-assembled on the carbon fiber skeleton, and 50 nm MoS₂ particles were successfully loaded, resulting in the fabrication of MoS₂/g-C₃N₄/Bi₂O₃/CFb photocatalytic fibers. UV–vis spectroscopy, transient photocurrent response, and EIS tests demonstrated that the introduction of narrow-bandgap visible-light photocatalysts (g-C₃N₄ and MoS₂) enhanced light absorption and improved the separation and migration efficiency of photogenerated electron hole pairs. Photocatalytic degradation experiments of MB showed that MoS₂/g-C₃N₄/Bi₂O₃/CFb significantly outperformed g-C₃N₄/Bi₂O₃/CFb and Bi₂O₃/CFb, achieving a degradation efficiency of 92% within 60 min. Band structure calculations and analysis confirmed the formation of Z-scheme heterojunctions between g-C₃N₄ and Bi₂O₃, as well as between MoS₂ and Bi₂O₃. This dual Z-scheme heterojunction endowed MoS₂/g-C₃N₄/Bi₂O₃/CFb with enhanced redox capabilities, providing a novel strategy for developing efficient photocatalytic materials. 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

Constructing an S-type heterojunction to promote photogenerated carrier separation is a valid method to ameliorate this problem. In this work, self-assembled perylenetetracarboxylic diimide (PDI) was modified on the surface of two-dimensional (2D) BiOBr nanosheets using a continuous ion layer adsorption method. To explore its microstructure, photoelectric properties, and other characteristics, the electron transport channel constructed between self-assembled PDI and BiOBr hinders photogenerated electron-hole recombination. Under visible light irradiation, when the rhodamine B (RhB) was 50 mg/L, the removal rate over 1/3 PDI/BiOBr reached 98% in 60 min, and the rate constant was 15.9 times that over self-assembled PDI and 13 times that over BiOBr. In degrading methyl orange (MO), the removal rate over 1/3 PDI/BiOBr was 65.8% in 60 min, and the rate constant was 5.7 times that over self-assembled PDI and 3.4 times over BiOBr. After the ESR test, O₂⁻ is proved to be the main active species in the reaction. Full article

The design and preparation of advanced hybrid nanofibers with controllable microstructures will be interesting because of their potential high-efficiency applications in the environmental and energy domains. In this paper, a simple and efficient strategy was developed for preparing hybrid nanofibers of zinc oxide–molybdenum disulfide (ZnO–MoS₂) grown on polyimide (PI) nanofibers by combining electrospinning, a high-pressure hydrothermal process, and in situ growth. Unlike simple composite nanoparticles, the structure is shown in PI–ZnO to be like the skeleton of a tree for the growth of MoS₂ “leaves” as macro-materials with controlled microstructures. The surface morphology, structure, composition, and photocatalytic properties of these structures were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV–vis spectroscopy. The ultra high-volume fraction of MoS₂ can be grown on the brush-shaped PI–ZnO. Decorating ZnO with nanosheets of MoS₂ (a transition metal dichalcogenide with a relatively narrow band gap) is a promising way to increase the photocatalytic activity of ZnO. The hybrid nanofibers exhibited high photocatalytic properties, which decomposed about 92% of the methylene blue in 90 min under visible light irradiation. The combination of MoS₂ and ZnO with more abundant surface-active sites significantly increases the spectral absorption range, promotes the separation and migration of carriers, and improves the photocatalytic characteristics. Full article

With the growing severity of air pollution, monitoring harmful gases that pose risks to both human health and the ecological environment has become a focal point of research. Titanium dioxide (TiO₂) demonstrates significant potential for application in SO₂ gas detection. However, the performance of pure TiO₂ is limited. In this study, TiO₂ nanospheres and MoSe₂ nanosheets were synthesized using a hydrothermal method, and the gas-sensing properties of TiO₂/MoSe₂ nanostructures for SO₂ detection were investigated. The TiO₂/MoSe₂ composites (with a TiO₂-to-MoSe₂ volume ratio of 2:1) were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The TiO₂/MoSe₂ sensor exhibited high sensitivity to SO₂; the response to 100 ppm of SO₂ reached as high as 59.3, with a significantly shorter response and recovery time (15 s/13 s), as well as excellent repeatability, selectivity, and long-term stability. The experimental results suggest that the enhanced SO₂ adsorption capacity of the TiO₂/MoSe₂ composite can be attributed to the formation of an n-n heterojunction and the unique microstructural features of TiO₂/MoSe₂. Therefore, the TiO₂/MoSe₂ sensor represents a promising candidate for rapid SO₂ detection, providing a theoretical foundation for the development and application of high-performance SO₂ sensors. Full article

In order to utilize the longer wavelength light, the surface sulfurization of MoO₃ was carried out. The photocurrent responses to typical 650, 808, 980, and 1064 nm light sources with Au gap electrodes were investigated. The results showed that the surface S–O exchange of MoO₃ improved the interfacial charge transfer in the range of the broadband light spectrum. The S and O can be exchanged on the surface of MoO₃ nanosheets under the hydrothermal condition, leading to the formation of a surface MoO_x/MoS₂ heterojunction. The interfacial interaction between the MoO₃ nanosheets and MoS₂ easily generated free electrons and holes, and it effectively avoided the recombination of photogenerated carriers. Meanwhile, the surface S-doping of MoO₃ also resulted in the generation of an oxygen vacancy and sulfur vacancy on MoO_3−xS_2−y. The plasmonic characteristics of MoO_3−x contributed to the enhancement of the interfacial charge transfer by photoexcitation. Otherwise, even with zero bias applied, a good photoelectric signal was still obtained with polyimide film substrates and carbon electrodes. This indicates that the formation of the heterojunction generates a strong built-in electric field that drives the photogenerated carrier transport, which can be self-powered. This study provides a simple and low-cost method for the surface functionalization of some metal oxides with a wide bandgap. Full article

As the mainstream type of gas sensors, metal oxide semiconductor (MOS) gas sensors have garnered widespread attention due to their high sensitivity, fast response time, broad detection spectrum, long lifetime, low cost, and simple structure. However, the high power consumption due to the high operating temperature limits its application in some application scenarios such as mobile and wearable devices. At the same time, highly sensitive and low-power gas sensors are becoming more necessary and indispensable in response to the growth of the environmental problems and development of miniaturized sensing technologies. In this work, hierarchical indium oxide (In₂O₃) sensing materials were designed and the pulse-driven microelectromechanical system (MEMS) gas sensors were also fabricated. The hierarchical In₂O₃ assembled with the mass of nanosheets possess abundant accessible active sites. In addition, compared with the traditional direct current (DC) heating mode, the pulse-driven MEMS sensor appears to have the higher sensitivity for the detection of low-concentrations of nitrogen dioxide (NO₂). The limit of detection (LOD) is as low as 100 ppb. It is worth mentioning that the average power consumption of the sensor is as low as 0.075 mW which is one three-hundredth of that in the DC heating mode. The enhanced sensing performances are attributed to loose and porous structures and the reducing desorption of the target gas driven by pulse heating. The combination of morphology design and pulse-driven strategy makes the MEMS sensors highly attractive for portable equipment and wearable devices. Full article