Nanocomposite Heterostructure Research Articles

Biosynthesis of ZnO/Ag nanocomposites heterostructure for efficient photocatalytic degradation of antibiotics and synthetic dyes

Abstract This study addresses the pressing issue of environmental pollution caused by antibiotics and synthetic dyes in aquatic ecosystems, presenting a novel approach for their efficient photocatalytic degradation. Zinc oxide (ZnO)-based nanoscale photocatalysts, including ZnO nanoparticles (NPs) and ZnO/Ag nanocomposite heterostructure (NCH), were synthesized through an innovative and eco-friendly method utilizing an extract derived from discarded lemon peels as a biogenic reducing agent. The synthesized materials were extensively characterized through UV spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results confirmed the different morphologies of ZnO NPs and ZnO/Ag NCH, with average sizes of 20 nm and 42 nm, respectively. Notably, the ZnO NPs and ZnO/Ag NCH exhibited optical bandgap energies of 3.2 eV and 2.85 eV, respectively, signifying their potential as efficient photocatalysts. Under natural sunlight irradiation, these materials demonstrated exceptional photocatalytic activity, achieving a remarkable 98.8 % degradation rate for metronidazole and 90 % for ciprofloxacin in just 12 min. Furthermore, the ZnO NPs effectively removed 84 % of Toluidine Blue and 77 % of Congo red after 120 min, while ZnO/Ag NCH enhanced degradation rates to approximately 90.5 % for Toluidine Blue and 86 % for Congo Red. This research highlights the significant physicochemical properties and novel synthesis methods employed, positioning these sustainable nanomaterials as promising solutions for mitigating environmental pollution effectively.

Optimizing Gas Sensing Properties of Fe-Loaded Indium Zinc Oxide Nanocomposite for Efficient Detection of Ammonia Gas

The current study delineates the role of gas sensing properties of Fe-IZO (Iron loaded Indium Zinc oxide) a mixed metal oxide nanocomposite. The heterostructured Fe-IZO nanocomposite (NC) was synthesized via the facile co-precipitation method. The Fe-IZO NC was characterized by various experimental techniques and the results attained allowed us to suggest the mechanism for considering the connection between morphological variations and gas-sensing characteristics of Fe-IZO NC. One of the cutting-edge circumstances now-a-days is the prime use of gas sensors for environmental applications. The NC has a good selectivity for NH3 gas that has shown good stability up to 80 d. The response time (ℸres) is 64 s, recovery time (ℸrec) is 72 s for 50 ppm (parts per million) and obtained a highest response of 87% at room temperature. The Fe-IZO NC heterostructure with efficient charge transfer can enable the subsequent reaction mechanism with NH3 gas and the adsorbed oxygen ions leading to an increased response. Consequently, the results attained in this work has shown that the synthesized heterostructured NC sensor is suitable for room temperature NH3 sensing with high performance.

Ruthenium decorated V@WO3 nanocomposites heterostructures for selective detection of sulfonamide in honey samples

In the current study, V@WO3 nanocomposite heterostructures were synthesized by a facile hydrothermal method having 1D highly stable and uniform morphology. The designed nanostructures were decorated with ruthenium nanoparticles through a microwave-assisted fabrication method. The physiochemical attributes of Ru/V@WO3 were confirmed by applying various analytical as well as spectroscopic techniques; including, XRD, SEM, FTIR, Raman spectroscopy, and UV–vis spectroscopy. The Ru/V@WO3 modified glassy carbon electrode was utilized for the detection of sulfonamide. The fabricated electrode exhibited fantastic electrochemical properties for the highly selective and sensitive detection of sulfonamide with a desirable and well-defined reduction peak (39 µA) at − 0.6 V. The designed sensor was used for the detection of sulfonamide in honey samples with 0.006 nM LoD and the regression value was 0.997 indicating a good linear relationship between composite and analyte. To study the selectivity of the designed sensor, interfering substances; trimethoprim (TMP), metronidazole (MTD), cephalosporin (CEP), and dihydroartemisinin (DHA) were used and no response was recorded against these drugs. Furthermore, the modified GCE showed excellent stability and life span.

STRUCTURAL INVESTIGATION OF HETERO-STRUCTURED CORE-SHELL SILVER-SILICA HYBRID AS A POTENTIAL AGRO-SENSOR MATERIAL

Investigation into the novel synthesis and structural properties of Heterostructured core shell Silver-Silica (AgSiO2) Nanohybrid is reported herein, for possible utilization as humidity sensing material in Agricultural post-harvest humidity monitoring system and greenhouse farming. The Heterostructured nanoparticles (Ag and SiO2) were synthesized via a chemical reduction method. Structural characterizations were done using X-ray Diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM), Scanning Electron Microscopy (SEM), UV-Visible spectroscopy, Energy Dispersive X-ray (EDX) spectroscopy and N2 adsorption-desorption techniques. The XRD diffractogram of Ag-SiO2 showed distinct peaks at 2? values of 390, 430, 660 and 790 which was corroborated by the SEM and HRTEM results. EDX convincingly confirmed Ag and SiO2 incorporation into the Ag-SiO2 nanocomposite hetero-structure at 16.7 % and 83.3 % respectively. A Surface Plasmon Resonance absorption peak of 421 nm of Ag was revealed by UV-Visible spectroscopic analysis. An effective and relatively narrow pore size distributions of 3 – 8 nm was revealed by N2 adsorption-desorption for the Ag-SiO2 Nanocomposite. Overall, these properties are promising for effective use as humidity sensing material.

GQD@NiFe-LDH Nanosheets for Photocatalytic Activity towards Textile Dye Degradation via Lattice Contraction.

The functionalized NiFe-LDH with photosensitized GQDs were synthesized through the hydrothermal route by differing the amount of GQDs solution and studied its efficacy towards the mineralization of textile dyes under visible light. The synthesized samples were characterized by XRD, FESEM, HRTEM, DRUV-Vis, RAMAN, XPS, and BET. The combined effect of the hexagonal carbon lattice in GQD and open layered porous structure of NiFe-LDH nanosheets results in the contraction of the lattice. Different reactive and conventional dyes were taken as representative dyes to evaluate the activity of the as-synthesized photocatalysts. The enhanced electron absorption/donor effect between GQDs and NiFe-LDH, and the growth of oxygen-bridged Ni/Fe-C moieties enable the composite to exhibit better photocatalytic activity. Both photocatalytic activity and characterization results confirmed that the GQD@NiFe-LDH nanocomposite heterostructure synthesized at 160 °C by taking 10 mL of GQDs aqueous solution named GNFLDH10 has a higher degree of crystallinity and has the best photocatalytic efficiency compared to other reported visible light catalysts. Specifically, the above optimized GQD@NiFe-LDH photocatalyst is capable of photo-mineralizing 50 ppm of Reactive Green in 20 min, Reactive Red in 20 min, and Congo Red in 25 min respectively following a direct Z-scheme mechanism with substantial reusability.

Synthesis of Pt/FeVO4: A novel heterostructure for efficient photocatalysis

In this work, a unique platinum-loaded iron vanadate (Pt/FeVO4) composite for escalating the photocatalytic performance via the facile sonicated assisted hydrothermal method was synthesized. Morphological results revealed that the FeVO4 and well-dispersed Pt/FeVO4 particle is in the range of 150–200 nm size, which developed transportation of the photogenerated electrons into FeVO4, resulting in efficient separation of the photogenerated carriers in coupled Pt/FeVO4 nanocomposite heterostructure. The multi-characterizations results indicate an excellent adsorption ability and enhanced surface plasmon resonance (SPR) of Pt/FeVO4 composites as these composites are strongly associated with Pt loading. The induced impedance spectroscopy and photoluminance results demonstrated that Pt enhances separation efficiency as well as transferring rates for photogenerated charges. The ESR data suggests that the reactive oxygen species (OH•) was the most reactive specie agent with h+, •O2¯ having a minor role in methylene blue (MB) degradation.

Pt-Ag/Ag3PO4-WO3 nanocomposites for photocatalytic H2 production from bioethanol

Crystalline Ag3PO4 and WO3 nanofibers were synthesized by microwave and electrospinning methods. Three different WO3 nanofibers composition (5, 10 and 15 wt%) were used to obtain Ag3PO4/WO3 nanocomposite heterostructures, which are effective visible light active photo catalysts. Further, a simple, enviro-friendly, and cost-effective biogenic synthesis method have been achieved using Salvia officinalis extractto decorate Pt-Ag metal nanoparticles on the surface of Ag3PO4-WO3 composites. Presence of bioactive agents in the extract are responsible for the Pt and Ag3PO4 reduction to obtain Pt-Ag/Ag3PO4-WO3 nanocomposites and for prevention of the Pt nanoparticles from aggregation in aqueous medium. Various analytical techniques such as XRD, SEM, FT-IR, DR UV–vis, XPS and N2 gas physisorption were utilized to characterize the synthesized photocatalysts. The band gap energy values were decreased after decoration of Pt and Ag metal nanoparticles over Ag3PO4-WO3 nanocomposites. The Pt and Ag metal nanoparticles decorated Ag3PO4-WO3 (10 wt%) nanocomposite exhibited highest photo catalytic activity for H2 production from bioethanol due to possession of unique physicochemical properties low band gap and surface area. In addition, presence of plasmonic nanoparticles assisted for the efficient electron trap to decrease the e--h+ recombination rate to enhance the hydrogen production.

Synthesis of MoS2/SnWO4 nanocomposite heterostructures: photocatalytic degradation of tetracycline upon visible-light irradiation

Synthesis of MoS2/SnWO4 nanocomposite heterostructures: photocatalytic degradation of tetracycline upon visible-light irradiation

Production of p-CuO/n-ZnO:Co nanocomposite heterostructure thin films: An optoelectronic study

The p-n junction is the principal mode of optoelectronic semiconductor material. At present, we submit a solution-based attempt at the synthesis of nanostructured p-type CuO and n-type ZnO nanocomposite (NC) heterostructure films. Bare and Cobalt (Co)-doped CuO–ZnO NC films have been produced on glass slides using the SILAR (Successive Ionic Layer Adsorption and Reaction) method. The influence of Co-doping concentration on the physical characteristics of CuO–ZnO NC heterostructure films was investigated. XRD spectrums indicated the phase and structural purity of solution-based synthesized CuO–ZnO NC samples. The surface topographical, as well as optical and electrical properties of heterostructure films were, also investigated. While the bare CuO–ZnO NC film has a ∼38% transmission near 1000 nm wavelength region, the 2.0% Co-doped CuO–ZnO NC film has ∼31% of optical transmission. The sheet resistance value of the grown 2.0% Co:CuO–ZnO NC sample is almost 13 times lower than that of the bare CuO–ZnO NC sample at 400 K temperature. As a consequence, our attempt ensures a novel strategy for the production and performance optimization of CuO–ZnO NC heterostructures in the implementation of optoelectronics.

A new copper molybdate-doped aluminium phosphate nanocomposite heterostructure for photoreduction of aqueous 2-NA and 4-NA

Metal molybdate-doped aluminium phosphate heterostructures have been prepared by a solid solution method and found to be photoluminescence, semiconducting properties and effective catalysts for the photoreduction of o-nitroaniline and p-nitroaniline.

One-Pot Facile Synthesis of CuO-CdWO4 Nanocomposite for Photocatalytic Hydrogen Production.

Hydrogen (H2) is a well-known renewable energy source that produces water upon its burning, leaving no harmful emissions. Nanotechnology is utilized to increase hydrogen production using sacrificial reagents. It is an interesting task to develop photocatalysts that are effective, reliable, and affordable for producing H2 from methanol and acetic acid. In the present study, CuO, CdWO4, and CuO-CdWO4 nanocomposite heterostructures were prepared using a cost-efficient, enviro-friendly, and facile green chemistry-based approach. The prepared CuO, CdWO4, and CuO-CdWO4 nanocomposites were characterized using X-ray diffraction pattern, Fourier-transform infrared spectroscopy, diffuse reflectance ultraviolet-visible spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction (SAED) pattern, N2 physisorption, photoluminescence, and X-ray photoelectron spectroscopy techniques. The synthesized photocatalysts were utilized for photocatalytic H2 production using aqueous methanol and acetic acid as the sacrificial reagents under visible light irradiation. The influence of different variables, including visible light irradiation time, catalyst dosage, concentration of sacrificial reagents, and reusability of catalysts, was studied. The maximum H2 was observed while using methanol as a sacrificial agent over CuO-CdWO4 nanocomposite. This enhancement was due to the faster charge separation, higher visible light absorption, and synergistic effect between the CuO-CdWO4 nanocomposite and methanol.

Development of Bi2WO6 and Bi2O3 - ZnO heterostructure for enhanced photocatalytic mineralization of Bisphenol A.

Present study proposed the synthesis of mixed p-type and n-type nanocomposite heterostructures by co-precipitation method. The as-synthesized heterostructures were characterized through different characterization techniques. The as-synthesized Bi2WO6 and Bi2O3-ZnO heterostructures were tested as photocatalysts during the photodegradation of Bisphenol A (BPA). The Bi2O3-ZnO heterostructure nanocomposite was found to be a more effective photocatalyst than Bi2WO6. The effect of operating parameters including catalytic dose (0.02-0.15 gL-1), initial BPA concentration (5-20 mgL-1), temperature change (5-20 °C) and solution pH changes (4, 5, 7, and 8) were evaluated with Bi2O3-ZnO under UV-light irradiation by selecting a 300 W Xe lamp. More than 90% BPA was degraded with 0.15 gL-1 Bi2O3-ZnO, keeping 1.0 mM H2O2concentration fixed in 250 mL of reaction suspension. The HPLC and GC-MS were used to detect the reaction intermediates and final products. A plausible degradation pathway was proposed on the basis of the identification of reaction intermediates. Repeatability test analysis confirmed that the as-synthesized catalyst showed superb catalytic performance on its removal trend. The kinetics of degradation of BPA were well fitted by the power laws model. With the order of reaction being 0.6, 0.9, 1.2, and 1.3 for different operating parameters, i.e., catalyst dose, initial pH, temperature, and initial BPA concentration.

Heterostructure of MnCo2O4 intercalated graphene oxide coated with Ni-V-Se nanoparticles for supercapacitors with high rate capability

A new approach was proposed to construct a novel 3D hybrid nanocomposite heterostructure GO/MnCo2O4/Ni-V-Se as a hybrid supercapacitor electrode. Electrons can easily migrate from Mn ions to Ni ions, thereby increasing the electron energy of the metal orbital, and this inductive effect can effectively improve the electron transfer efficiency. In addition, the application of surface/interface control method also enables this electrode material to exhibit unique advantages. In this heterostructure, graphene serves as the extended conductive framework, cube-like MnCo2O4 and flower-like Ni-V-Se spheres derived from MOFs as spacers separate the sheets to avoid the layer-by-layer stacking of graphene. Complemented by Ni-V-Se coating, the formed composite heterostructure exhibits excellent electrochemical performance. The as-prepared GO/MnCo2O4/Ni-V-Se delivers ultra-high specific capacity (1292.3 C·g−1 at 1 A·g−1), rate capability (94.87%) and cycling stability. Finally, the hybrid supercapacitor assembled by GO/MnCo2O4/Ni-V-Se and activated carbon also shows good electrochemical performance.

Development of a Core-Shell Heterojunction TiO2 /SrTiO3 Electrolyte with Improved Ionic Conductivity.

The front cover artwork is provided by Prof. Faze Wang's group at the Southeast University. The built-in electric field created by the semiconductor heterostructure confines the proton transport on the surface layer of the nanocomposite core-shell heterostructure imparting faster ion transport and lower activation energy. Read the full text of the Research Article at 10.1002/cphc.202200170.

Development of a Core-Shell Heterojunction TiO2 /SrTiO3 Electrolyte with Improved Ionic Conductivity.

Lately, semiconductor-membrane fuel cells (SMFCs) have attained significant interest and great attention due to the deliverance of high performance at low operational temperatures, <550 °C. This work has synthesized the nanocomposite core-shell heterostructure (TiO2 -SrTiO3 ) electrolyte powder by employing the simple hydrothermal method for the SMFC. The SrTiO3 was grown in situ on the surface of TiO2 to form a core-shell structure. A heterojunction mechanism based on the energy band structure is proposed to explain the ion transport pathway and promoted protonic conductivity. The core-shell heterostructure (TiO2 -SrTiO3 ) was utilized as an electrolyte to reach the peak power density of 951 mW cm-2 with an open-circuit voltage of 1.075 V at 550 °C. The formation of core-shell heterostructure among TiO2 and SrTiO3 causes redistribution of charges and establishes a depletion region at the interface, which confined the protons' transport on the surface layer with accelerated ion transport and lower activation energy. The current work reveals novel insights to understand enhanced proton transport and unique methodology to develop low-temperature ceramic fuel cells with high performance.

Nanostructured DyCrO3-rGO for efficient photocatalytic dye degradation and hydrogen generation

Dysprosium chromite (DyCrO3) nanoparticles and dysprosium chromite-reduced graphene oxide (DyCrO3-rGO) nanocomposite were synthesized by using a hydrothermal technique. The rGO incorporated DyCrO3-rGO photocatalyst demonstrated up to 87% efficiency to degrade rhodamine B dye which is higher than those of DyCrO3 and commercial Degussa P25 titania nanoparticles. DyCrO3-rGO also generated approximately 3 times greater amounts of hydrogen via water splitting compared to that produced by the P25 titania nanoparticles. The outcome of this investigation might be helpful for synthesizing rGO-based nanocomposite heterostructures for superior solar energy-driven applications.

Effect of laser annealing on the properties of Ag/ZnO nanostructures

Ag/ZnO nanostructures were synthesized using pulsed laser deposition (PLD) in open air (at atmospheric pressure). The deposition was carried out by a Nd:YAG laser, with the Ag layer composed of nanoparticles grown on SiO2 (001) substrates by the laser wavelength of 355 nm; this layer was covered by ZnO deposited by using the laser wavelength of 1064 nm. The samples were laser annealed, which led to a modification of the nanoparticles. The nanocomposites produced were characterized by TEM, UV-Vis and PL spectroscopy. The annealing procedures influence the optical properties of the Ag/ZnO nanocomposites. The laser annealing under certain parameters changes the emission behavior of the Ag/ZnO nanocomposite heterostructures. By employing localized surface plasmon resonance (LSPR), the near band edge (NBE) emission intensity of the ZnO films composed of nanoparticles was varied. An enhancement of the UV emission located at about 383 nm, commonly attributed to an excitonic transition, was registered after laser annealing with one pulse at the wavelength of 355 nm. The results obtained demonstrate that the annealing of Ag/ZnO composite nanostructures plays a key role in tuning the PL performance of a semiconductor material where an LSPR occurs.

Cuprous oxide coated silver/graphitic carbon nitride/cadmium sulfide nanocomposite heterostructure: Specific recognition of carcinoembryonic antigen through sandwich-type mechanism

The development of the effective diagnostic method for the determination of cancer biomarkers is one of the most promising strategies for early clinical diagnosis of cancer. Here, based on the preparation of heterogeneous cuprous oxide coated silver (Ag@Cu2O) nanocomposites/graphitic carbon nitride (g-C3N4)/cadmium sulfide (CdS) nanoarrays structure, a highly sensitive photoelectrochemical (PEC) biosensor for the examination of carcinoembryonic antigen (CEA) has been constructed successfully. The combination of photoactive semiconductor materials g-C3N4 and CdS increases the electron transfer rate between them and enhances their photocurrent response, thus greatly increasing the concentration detection range. At the same time, the specific recognition between antigen and antibody is used to form a sandwich structure secondary antibody (Ab2)/CEA/antibody (Ab1). And because Ag@Cu2O has the function of absorbing light and consuming electron donor. Therefore, the successful measurement of CEA was achieved by labeling Ag@Cu2O on Ab2 and finally immobilizing it on the sensor to correlate the current reduction with the CEA concentration. The sandwich PEC biosensor proposed by this signal amplification strategy under optimal conditions has good analytical performance for CEA, with a wide linear detection range (from 10-5 to 1 ng/mL) and a low detection limit of 0.0011 pg/mL. The PEC biosensor constructed by this method showed high sensitivity, excellent anti-interference ability, favourable repeatability, and good stability.

Ag/Ce0.9Gd0.1O2- δ Based Vertically Aligned Nanocomposite Thin Film Electrodes for Low-Temperature Solid Oxide Cells

Low temperature solid oxide cells (LT-SOCs, 300-500°C) have become the "next generation" technology following the commercialized high temperature SOCs (650–850 °C). The current research is focused on screening new materials and microstructural designs that are ideal for low-temperature operations. This study explores the vertically aligned nanocomposite (VAN) heterostructure design, which has been shown to provide novel properties and new functionalities at the heterointerfaces of two oxide materials.1 In this design, we combine two materials known to show exceptionally fast electrokinetics at low temperatures. However, instead of two oxide materials, we explore a combination of electronically conducting metal and an ionically conducting oxide. The electrode composed of Ag and Ce0.9Gd0.1O2-d (CGO) is deposited epitaxially on oriented yttria-stabilized zirconia substrates by pulsed laser deposition. Silver is a highly active catalyst for oxygen reduction reactions (ORR), exhibits high electrical conductivity at low temperatures and is resistant to oxidation in air, but has a relatively low melting point and agglomerates easily in air. Therefore, it is necessary to prevent Ag agglomeration during operation. Addition of CGO is expected to (i) stabilize Ag by surrounding it through vertically grown columns and (ii) extend the ionically conducting path onto the cathode and share the oxygen ion diffusion pathway with Ag.2 Preliminary results show successful growth of ~40 nm thick oriented Ag/CGO VAN films. The investigations will be complemented with electrochemical performance and stability measurements using impedance spectroscopy. This study will provide insights into enhanced ORR performance at low temperatures by controlling crystal orientation and strain tuning at the metal/oxide VAN heterointerfaces. J. Huang, W. Li, H. Yang and J. L. MacManus-Driscoll, MRS Bull., 2021, 46, 159–167.H. R. Choi, K. C. Neoh, H. J. Choi, G. D. Han, D. Y. Jang, D. Kim and J. H. Shim, J. Power Sources, 2018, 402, 246–251.

The influence of β-Ga2O3 film thickness on the optoelectronic properties of β-Ga2O3@ZnO nanocomposite heterogeneous materials

Nanocomposite heterogeneous nanomaterials excellent optoelectronic properties have been widely used in the field of solar cells. In this research, β-Ga2O3@ZnO composite heterogeneous-material was successfully prepared by combining magnetron sputtering with hydrothermal method. The thickness of the surface β-Ga2O3 was adjusted by controlling the magnetron sputtering time, and the influence of β-Ga2O3 film thickness on the optoelectronic properties of β-Ga2O3@ZnO nanocomposite heterogeneous was systematically investigated. The morphology and microstructure of the samples were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD) and Raman spectroscopy. It is found that the proper thickness of β-Ga2O3 can improve the surface morphology leading to the excellent light absorption performance. Furthermore, the band gap of β-Ga2O3@ZnO nanocomposite heterogeneous is smaller than that of pure ZnO and β-Ga2O3 according to the visible light absorption test. This demonstrates that the β-Ga2O3 coating cam expand the range of light absorption. Thus, the composite material showed excellent photoelectrochemical performance through the photocurrent test in the electrochemical workstation. The results indicate that β-Ga2O3@ZnO nanocomposite heterostructures have broad application potential in the field of optoelectronics.