In this work, WO3 nanorods were successfully synthesized by thermal oxidation method and further investigated for gas sensing application. For WO3 nanorods synthesis, tungsten film was deposited on ...oxidized Si substrate by sputtering method and subsequently subjected to thermal oxidation process at 500 °C in atmospheric environment. The synthesized nanorods were analyzed using SEM, XRD, Raman, and XPS. A chemiresistive type MEMS-based sensing device was fabricated incorporating these nanorods. The sensor was tested for different gases and VOCs over operating temperatures ranging from 75 to 300°C. It showed high selectivity towards NO2 gas over H2S, NH3, acetone, methanol, and ethanol. The excellent sensing performance and sophisticated method of synthesis make this a promising candidate for gas sensing applications.
The development of photocatalysts with superior activity and stability to produce organic fuels through CO2 reduction under renewable sunlight is of great significance due to the depletion of fossil ...fuels and severe environmental problems. In this study, we presented a “hitting three birds with one stone” strategy to synthesize carbon layer coated cuprous oxide (Cu2O) mesoporous nanorods on Cu foils via a facile chemical oxidation and subsequent carbonization method. The thin carbon layer not only works as a protective layer to quench the common photocorrosion problem of Cu2O but also endows the sample a mesoporous and one-dimensional nanorod structure, which can facilitate reactant molecule adsorption and charge carrier transfer. Substantially, the coated samples exhibited remarkably improved stability as well as decent activity for CO2 reduction under visible light irradiation. The optimized sample attained an apparent quantum efficiency of 2.07% for CH4 and C2H4 at λ0 400 nm, and 93% activity remained after six photoreduction cycles under visible light. This work provides a facile strategy to address the stability and activity issues of Cu2O under visible light irradiation, which is presumably suitable for other semiconductors as promising candidates for CO2 reduction in artificial photosynthesis.
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The piezo-/photocatalytic effects of ZnO have been in the limelight because of their great potential in environmental remediation and energy conversion. However, the poor ...recyclability of the suspended catalysts can cause inevitable secondary pollution, which is one of the major issues that limit the practical application of these materials. To address this problem, a magnetically retrievable Fe3O4@SiO2@ZnO nanocomposite was designed and successfully synthesized by multi-step reactions. The ZnO nanorods were vertically grown on the surface of the magnetic Fe3O4@SiO2 microspheres, while SiO2 served as an insulator to protect the inner core and to inhibit charge transfer across the core/shell interface. The Fe3O4@SiO2@ZnO nanocomposite can be easily collected and separated by using a magnetic field. Along with the good recyclability, the material also exhibited high efficiencies in piezocatalytic, photocatalytic and piezo-photocatalytic dye degradation processes. The rate constant of piezo-photocatalysis reached 95.9 × 10−3 min−1, which was 2.2 and 6.1 times that of the individual piezocatalysis and photocatalysis, respectively. The present result confirmed the existence of a synergetic effect between piezo- and photocatalytic processes. Hereby, we demonstrated that incorporation of a magnetic carrier is a feasible strategy to achieve retrievable and highly efficient piezo-/photocatalyst.
Single-atom Pt decorated g-C3N5 nanorods (Pt SA/C3N5) were synthesized that exhibit highly efficient photocatalytic performance toward H2 evolution and wastewater purification. Implanting single Pt ...atoms into rod-like g-C3N5 through Pt–N coordination bonds could not only optimize its band structure, but also improve its specific surface area and promote the charge transfer. Therefore, the photocatalytic H2 evolution of Pt SA/C3N5 (444.2 μmol g−1 h−1) is about 4.4 times higher than that of C3N5 (102.0 μmol g−1 h−1), and its apparent quantum efficiency can reach 0.47 % at 420 nm. Furthermore, the degradation efficiency of Pt SA/C3N5 for Rhodamine B, Methylene blue and Malachite green is about 2.5, 1.6 and 1.5 times higher than that of C3N5, respectively. Moreover, Pt SA/C3N5 exhibits excellent stability on both the H2 evolution and wastewater purification. This research provides a neoteric way to build efficient photocatalysts that can be applied to energy and environment.
Single-atom Pt decorated g-C3N5 nanorods were synthesized that exhibit highly efficient photocatalytic performance toward H2 evolution and wastewater purification. Display omitted
•Single-atom Pt decorated g-C3N5 nanorods (Pt SA/C3N5) through Pt–N coordination bonds were successfully synthesized.•Larger specific surface area, optimized band structure and rapid charge transfer were achieved for Pt SA/C3N5.•Highly efficient photocatalytic activity toward H2 evolution and wastewater purification.•Super stability even after five repeated cycles.
Even if limited amount of fluoride is vital, excessive accumulation of it has a serious health effect to human. Thus fluoride ions need to be removed using an environmentally friendly method and ...cost-effective material. Bismuth-doped hydroxyapatite nanorod was synthesized using co-precipitation technique and characterized by XRD, FT-IR, FE-SEM and EDS. XRD data revealed that the synthesized materials are hydroxyapatite having hexagonal structure with a space group of P63/m. Crystallite size and degree of crystallinity were increased as the amount of bismuth doped increased. Characteristics peaks of hydroxyapatite were observed in the FT-IR analysis. Energy dispersive spectroscopic analysis indicates that calcium, phosphorous, oxygen and bismuth are available in the synthesized product. In addition, the result indicates that the molar ratio of calcium to phosphorous reduced due to substitution of calcium by bismuth. Morphology analysis shows the presences of an aggregates of rod-like structure having diameters in the range of 10.06 – 31.93 nm. Batch adsorption experimental data were well fitted to pseudo-second order and Langmuir models, which implies that the sorption process is chemisorption through a monolayer on homogenous surface. The maximum adsorption capacity of bismuth doped hydroxyapatite nanorod was 60.67 mg/g using Langmuir model at room temperature. Thermodynamic data revealed that the adsorption process is endothermic and spontaneous. Regeneration and reuse analysis insured that the materials have good potential for reuse. The adsorption mechanism was inferred as chemisorption through electrostatic interaction and ion exchange. The modification of hydroxyapatite with bismuth can be considered a competent sorbent for removing fluoride ions.
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•Ferrous selenide nanorods on carbon cloth was prepared via in situ synthesis.•The self-supported nitrite sensor displays high sensitivity and low detection limit.•The proposed sensor ...detected nitrite in real samples with acceptable results.
In this paper, a self-supported electrode for nitrite detection was obtained by loading ferrous selenide nanorods on carbon cloth (FeSe NR/CC) via in situ synthesis. The morphology and chemical composition of the FeSe NR/CC were characterized using scanning electron microscope (SEM), X-ray diffractogram (XRD), and X-ray photoelectron spectroscopy (XPS). Owing to the synergistic effect between FeSe nanorods and carbon cloth, the rich redox active sites, and the lower transferring resistance, the binder-free and self-supported sensor based on FeSe NR/CC exhibits a wide linear relationship from 0.625 μM to 6775.5 μM, a fast-current response of 3 s, and a high sensitivity of 1107.7 μA mM−1 cm−2. The detection limit of the FeSe NR/CC was evaluated as 0.07 μM and the developed sensor displays excellent selectivity, stability, and reproducibility. Additionally, the as-prepared sensor has been successfully applied to detect nitrite in pickled vegetable samples, proving its feasibility for practical applications. Therefore, the self-supported and binder-free electrode proposed in this study could be used as a highly efficient and cost-effective electrochemical nitrite sensing device to achieve rapid quantitative detection of nitrite in food samples.
Pro-oxidant drug-loaded piezoelectric ZnO NRs-based nanocatalysts are developed for combined chemo-piezocatalytic cancer therapy. Under US irradiation, piezoelectric Au NPs-deposited ZnO NRs generate ...ROS via piezocatalytic processes, leading to apoptosis in breast cancer cells. Pro-oxidant PL also increases intracellular ROS in cancer cells, leading to cancer-specific apoptosis. PL-loaded Au-decorated ZnO NRs-based nanocatalysts enable combined cancer-specific chemotherapy and US-triggered piezocatalytic therapy.
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•Au-coated ZnO nanorods (Au@P-ZnO NRs) were developed for efficient piezocatalytic cancer therapy.•Piezoelectric Au@P-ZnO NRs catalyzed the generation of ROS under ultrasound (US) irradiation.•Au NPs, as sites of oxygen reduction, acted as Fenton-like catalysts on the ZnO NRs.•A pro-oxidant piperlongumine (PL) was loaded into Au@P-ZnO NRs to enhance their cancer-specificity.•PL-loaded Au@P-ZnO NRs achieved cancer-specific chemo-piezocatalytic combination therapy.
Nanocatalytic cancer therapy that triggers catalytic reactions to generate cytotoxic reactive oxygen species (ROS) in target cancer cells has recently emerged as an effective therapeutic modality. In this study, piezoelectric, Au-decorated, poly(ethylene glycol)-coated zinc oxide nanorods (Au@P-ZnO NRs), a new class of nanoscale piezocatalysts, were developed for efficient cancer treatment via US-triggered piezocatalytic generation of ROS. The detailed piezocatalytic mechanism of Au@P-ZnO NRs was also proposed. Under US exposure, thermally excited electrons and holes that are produced in ZnO NRs are separated and accumulated at the surface by piezoelectric polarization, which subsequently catalyzes the generation of ROS for piezocatalytic cancer therapy. Au NPs, as Fenton-like catalysts, were deposited on the surface of the P-ZnO NRs to enhance the piezocatalytic generation of ROS. A pro-oxidant drug, piperlongumine (PL), was loaded into Au@P-ZnO NRs to enhance their cancer-specificity and anticancer effects. The variation in piezoelectric potential with respect to the size of the ZnO NRs and the pressure applied by US were calculated using COMSOL Multiphysics®. Under US irradiation, the piezocatalytic Au@P-ZnO NRs considerably amplified intracellular ROS levels in MCF-7 human breast cancer cells. PL-loaded Au@P-ZnO NRs (PL-Au@P-ZnO NRs) revealed efficient and cancer-specific cytotoxicity in MCF-7 cells under US irradiation, thereby confirming effective chemo-piezocatalytic combination cancer therapy. Notably, a single intravenous injection of PL-Au@P-ZnO NRs with US exposure significantly suppressed tumor growth without resulting in systemic toxicity in mice. This study demonstrates the feasibility of PL-Au@P-ZnO NRs as US-triggered piezocatalytic agents that can selectively and effectively eradicate tumors via chemo-piezocatalytic combination therapy.
The usage of a ytterbium oxide nanorod/carbon nanofiber (Yb2O3/f-CNF) hybrid nanocomposite for the electrochemical detection of carbendazim (CBZ) fungicide is demonstrated for the first time in this ...study. Various physicochemical methods such as Field Emission Scanning Electron Microscopy (FE-SEM), Transmission electron microscopy (TEM), and X-ray diffraction (XRD) spectroscopy have been used to confirm the formation of Yb2O3, f-CNF, and Yb2O3/f-CNF composite. Different electrode electrochemical characteristics for the detection of CBZ were investigated using cyclic voltammetry and differential pulse voltammetry. Compared to Yb2O3 and f-CNF, the Yb2O3/f-CNF nanocomposite had the most significant electrocatalytic activity for CBZ oxidation. The designed sensor has a low detection limit (6 nM) and an extensive linear range (50 nM to 3035 µM) with excellent sensitivity (0.2899 µA µM−1 cm−2). Furthermore, the sensor has shown outstanding stability, anti-interference ability, reproducibility, repeatability, and practicability. In addition, these sensor electrodes are simple to make, inexpensive, portable, and effective in detecting CBZ fungicide residues in food and the environment.
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•Syntheis of a novel composite of Yb2O3/f-CNF using coprecipitation and sonochemical methods.•Yb2O3/f-CNF composite was used for carbendazim detection for the first time.•The fabricated sensor has low limit of detection and good sensitivity with a comprehensive linear response range.•The practicality of the sensor was evaluated for the detection of CBZ in vegetables and water samples.
Well-aligned ZnO nanorods (NRs) arrays were grown on ZnO seed layer/ITO substrate using chemical bath deposition (CBD) technique and then fabricating ultraviolet (UV) photodetectors (PDs). The effect ...of precursor concentration of sols on the properties of ZnO seed layer was investigated, and indicated that the crystallinity and growth orientation of samples depend significantly on precursor concentration. ZnO NRs deposited on seed layer exhibit hexagonal wurtzite structure and found that changing the concentration not only affects seed layer, but also influence the rods growth, making it possible to improve the aspect ratio and crystallinity of ZnO NRs. Moreover, the performance of PDs was further discussed and suggested that the maximum signal-to-noise ratio (SNR) and sensitivity (S) of PDs are 67 dB and 2348, when the concentration is 0.5 mol/L, also the shortest rise time of 0.993 s and fall time of 2.036 s can be obtained in such preparation conditions, which is related to larger aspect ratio and higher crystal quality of ZnO NRs. The fabricated UV PDs with high performance are helpful to its application in ultraviolet astronomy, fire detection, especially in military fields, and also are promising for large-scale production.
•Vertically aligned ZnO nanorods arrays were prepared by hydrothermal method.•The aspect ratio of obtained ZnO nanorods is up to 14.69•UV detectors based on ZnO NRs show high response performance.•The signal-to-noise ratio (SNR) and sensitivity of device are 67 dB and 2348.
With the increasing demand for smart wearable clothing, the textile piezoelectric pressure sensor (T-PEPS) that can harvest mechanical energy directly has attracted significant attention. However, ...the current challenge of T-PEPS lies in remaining the outstanding output performance without compromising its wearing comfort. Here, a novel structural hierarchy T-PEPS based on the single-crystalline ZnO nanorods are designed. The T-PEPS is constructed with three layers mode consisting of a polyvinylidene fluoride (PVDF) membrane, the top and bottom layers of conductive rGO polyester (PET) fabrics with self-orientation ZnO nanorods. As a result, the as-fabricated T-PEPS shows low detection limit up to 8.71 Pa, high output voltage to 11.47 V and superior mechanical stability. The sensitivity of the sensor is 0.62 V·kPa
−1
in the pressure range of 0–2.25 kPa. Meanwhile, the T-PEPS is employed to detect human movements such as bending/relaxation motion of the wrist, bending/stretching motion of each finger. It is demonstrated that the T-PEPS can be up-scaled to promote the application of wearable sensor platforms and self-powered devices.
