Sonochemical synthesis of Cu2O nanocubes for enhanced chemiluminescence applications

Sonochemically synthesized mesoporous cobalt oxide nanoparticles for luminol-enhanced chemiluminescence sensing

In recent years, mesoporous cobalt oxides have attracted more attention due to their exceptional physical and chemical properties and their important applications in various fields. The synthesis of cobalt oxides of various sizes, morphologies, and porosity is still a challenging process. In this report, mesoporous Co₃O₄NPs with different porosity were synthesized through facile, one-step, and cost-effective routes, without using any complicated materials or instruments, via the sonochemical process. X-ray powder diffraction (XRD), BET, and transmission electron microscopy (TEM) were used to characterize the as-synthesized NPs. XRD technique was used to determine the crystal structure and phase of the NPs, BET to describe the porous nature of the NPs, and TEM to investigate the structure and morphology of the NPs. Next, the effect of as-synthesized Co₃O₄NPs as a catalyst for the luminol-H₂O₂chemiluminescence system was studied. Co₃O₄NPs were chosen since they have nanoscale size, high specific surface area, and mesoporous nature. Therefore, these NPs can form more active sites and thus show unique catalytic activity than common ionic catalysts such as Co²⁺, Fe³⁺, Cu²⁺used in the luminol-H₂O₂CL system. Finally, this system was used to detect and measure H₂O₂and glucose under optimal conditions. A good linear relationship was observed between the chemiluminescence intensity of the designed system and the concentration of H₂O₂and glucose. A linear range like 0.25-10 pM for H₂O₂and 1-30 nM for glucose was obtained. The excellent LOD of the proposed method for measuring H₂O₂was about 0.07 pM, and for measuring glucose was about 0.14 nM.

An S-scheme α-Fe2O3/Cu2O photocatalyst for an enhanced primary amine oxidative coupling reaction under visible light

Photoredox catalysis under visible light has been recorded as a potential and reassuring recipe for organic synthesis. More and more heterojunction catalysts have appeared in people's fields of vision, especially those with S-scheme heterojunction structures. The S-scheme heterojunction structure of a photocatalyst can remarkably improve its photocatalytic efficiency. Here, an S-scheme α-Fe₂O₃/Cu₂O heterojunction photocatalyst was designed and fabricated for the primary amine oxidative coupling reaction. On account of that, the S-scheme structure effectively separated the photogenerated electron-hole pairs and enhanced the photoredox ability of the photocatalytic system. The α-Fe₂O₃/Cu₂O composite could also enhance the reactivity to a large extent. This work will provide new insight into the design of photocatalysts with a more reasonable structure and higher performance.

Facile synthesis of nanocellulose-based Cu2O/Ag heterostructure as a surface-enhanced Raman scattering substrate for trace dye detection

Semiconductor metal-oxide/metal heterostructures with synergetic properties have potential applications in photocatalysis and optical sensors. Here, Cu₂O sub-micro cubes were synthesized under environmentally benign conditions using 2, 2, 6, 6-tetramethylpyperdine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils as a reducing and stabilizing agent. Then the surface of the Cu₂O cubes was decorated with silver nanoparticles (AgNPs) by a substitution reaction. The Cu₂O/Ag heterostructures within the cellulose nanofibrils (CNFs) network were employed as a promising surface-enhanced Raman scattering (SERS) assay for efficient sensing of methylene blue (MB), reaching a maximum enhancement factor (EF) of 4.0 × 10⁴. Their SERS intensities depended on the coverage density of AgNPs and the wavelength of the excitation laser. The excellent SERS performance may result from the charge transfer between Ag and Cu₂O molecules and the strong electromagnetic field at the interface. The CNF-Cu₂O/Ag substrates were capable of detecting MB dye down to 10^-8 M level with a relative standard deviation of 10-15%, demonstrating great sensitivity and reproducibility.

Green synthesis of starch-capped Cu2O nanocubes and their application in the direct electrochemical detection of glucose

Glucose determination is an essential procedure in different fields, used in clinical analysis for the prevention and monitoring of diabetes. In this work, modified carbon paste electrodes with Cu₂O nanocubes (Cu₂O NCs) were developed to test electrochemical glucose detection. The synthesis of the Cu₂O NCs was achieved by a green method using starch as the capping agent, obtaining cubic-like morphologies and particle sizes from 227 to 123 nm with increasing amounts of the capping agent, as corroborated by electron microscopy analysis. Their crystalline structure and purity were determined by X-ray diffraction. The capability of starch as a capping agent was verified by Fourier-transform infrared spectroscopy, in which the presence of functional groups of this biopolymer in the Cu₂O NCs were identified. The electrochemical response to glucose oxidation was determined by cyclic voltammetry, obtaining a linear response of the electrical current as a function of glucose concentration in the range 100–700 μM, with sensitivities from 85.6 to 238.8 μA mM⁻¹ cm⁻², depending on the amount of starch used in the synthesis of the Cu₂O NCs.

Starch-capped Cu₂O nanocubes were used as an active electrochemical element to directly detect glucose.

In-situ synthesis of Cu2O on cotton fibers with antibacterial properties and reusable photocatalytic degradation of dyes

In this study, the cotton fabrics/cuprous oxide-nanocellulose (Cu₂O-NC) flexible and recyclable composite material (COCO) with highly efficient photocatalytic degradation of dyes and antibacterial properties was fabricated. Using flexible cotton fabrics as substrates, Cu₂O were in-situ synthesized to make Cu₂O uniformly grew on cotton fibers and were wrapped with NC. The photocatalytic degradation ability of COCO-5 was verified by use methylene blue (MB), the degradation rate was as high as 98.32%. The mechanism of COCO-5 photocatalysis and the process of dye degradation were analyzed by using electron paramagnetic resonance (EPR) spectrum, transient photocurrent response (TPR) spectrum, Fourier transform infrared (FTIR) spectroscopy and ion chromatography (IC). This study analyzed the complete path from electron excitation to dye degradation to harmless small molecules. Qualitative and quantitative experiments demonstrate that COCO-5 has high antibacterial activity against S. aureus and E. coli, the highest antibacterial rate can reach 93.25%. Finally, the stability of COCO-5 was verified by recycling and mechanical performance tests. The textile-based Cu₂O functionalized material has photocatalytic degradation and antibacterial properties, and the preparation process is simple and convenient for repeated use, so it has great potential in wastewater treatment containing dyes and bacteria.

Surface-Engineered Sponge Decorated with Copper Selenide for Highly Efficient Gas-Phase Mercury Immobilization

The paramount challenge in design and synthesis of materials for vapor-phase elemental mercury (Hg⁰) immobilization is to achieve a balance between performance and economy for practical applications. Herein, a newly designed electroless plating coupled with an in situ selenization method was developed to construct a copper selenide (Cu₂Se)-functionalized commercial polyurethane sponge (PUS) as an efficient Hg⁰ trap. Intrinsic features such as easy availability of the raw material, facile preparation, and excellent performance guarantee the Cu₂Se/PUS to be applicable in industrial uses. The Cu₂Se/PUS exhibits a maximum adsorption capacity (Q_m,Cu2Se/PUS) of 25.90 mg·g^-1, while this value is 758.80 mg·g^-1 when normalized to the Cu₂Se coating amount. This value of Q_m,Cu2Se is equal to 79.7% of its corresponding theoretical value (Q_t,Cu2Se), far exceeding the availability of Cu₂Se anchored on other supports. Meanwhile, the Cu₂Se/PUS exhibited a quick response for Hg⁰, with an extremely high uptake rate of 1275.84 μg·g^-1·min^-1. Even under harsh conditions, the Cu₂Se/PUS still immobilizes Hg⁰ effectively, which is crucial for real-world applications. This work not only provides a promising trap for permanent Hg⁰ sequestration from industrial sources but also illustrates a versatile platform for the economic fabrication and practical application of advanced functional sponges in diverse environmental remediation.

Development of luminol-fluorescamine-PVP chemiluminescence system and its application to sensitive tyrosinase determination

Fluorescamine is a popular fluorescent probe. We report for the first time that luminol chemiluminescence (CL) can be enhanced by fluorescamine in the presence of PVP. The CL intensity of luminol-fluorescamine-PVP is about 26 times stronger than that of luminol. Both the removal of oxygen and the addition of superoxide dismutase (SOD) decrease CL intensity, thiourea and NaN₃ have little effect on CL intensities, indicating that O₂^•- is critical for CL. Interestingly, o-quinone generated from phenol by tyrosinase obviously inhibited the CL intensity. Inspired by such quenching effect on the luminol-fluorescamine-PVP CL system, a sensitive CL sensing for the determination of tyrosinase activity was developed. The method can detect tyrosinase in the range of 0.07-1.5 μg mL^-1 (0.19-4.02 U mL^-1) with the detection limit of 0.035 μg mL^-1 (0.094 U mL^-1). Moreover, this method exhibits satisfied recoveries for the spiked human serum samples.

Sub 1 nm Poly(acrylic acid)-Capped Copper Nanoparticles for the Synthesis of 1,2,3-Triazole Compounds

The stable, water-soluble, and fluorescent sub 1 nm sized poly(acrylic acid)-capped copper nanoparticles (PAACC NPs) were synthesized using a high-intensity ultrasound sonication (30 KHz) method. The reduction of copper NPs from copper(II) salt by mild reducing agent l-ascorbic acid in an aqueous medium was achieved in the presence of poly(acrylic acid). The PAACC NPs were characterized by DRS UV-visible, XPS, PL, FESEM, and HRTEM techniques. The resulting PAACC NPs show orange fluorescence with a peaking center at 560 nm. The PAACC NPs serve as effective catalysts for the synthesis of 1,2,3-triazoles via click reaction in good yields under mild reaction conditions.

Application of CuxO-FeyOz Nanocatalysts in Ethynylation of Formaldehyde

Composite nanomaterials have been widely used in catalysis because of their attractive properties and various functions. Among them, the preparation of composite nanomaterials by redox has attracted much attention. In this work, pure Cu₂O was prepared by liquid phase reduction with Cu(NO₃)₂ as the copper source, NaOH as a precipitator, and sodium ascorbate as the reductant. With Fe(NO₃)₃ as the iron source and solid-state phase reaction between Fe³⁺ and Cu₂O, Cu_xO-Fe_yO_z nanocatalysts with different Fe/Cu ratios were prepared. The effects of the Fe/Cu ratio on the structure of Cu_xO-Fe_yO_z nanocatalysts were studied by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet confocal Raman (Raman), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS, XAES), and hydrogen temperature-programmed reduction (H₂-TPR). Furthermore, the structure–activity relationship between the structure of Cu_xO-Fe_yO_z nanocatalysts and the performance of formaldehyde ethynylation was discussed. The results show that Fe³⁺ deposited preferentially on the edges and corners of the Cu₂O surface, and a redox reaction between Fe³⁺ and Cu⁺ occurred, forming Cu_xO-Fe_yO_z nanoparticles containing Cu⁺, Cu²⁺, Fe²⁺, and Fe³⁺. With the increase of the Fe/Cu ratio, the content of Cu_xO-Fe_yO_z increased. When the Fe/Cu ratio reached 0.8, a core–shell structure with Cu₂O inside and a Cu_xO-Fe_yO_z coating on the outside was formed. Because of the large physical surface area and the heterogeneous structure formed by Cu_xO-Fe_yO_z, the formation of nonactive Cu metal is inhibited, and the most active species of Cu⁺ are exposed on the surface, showing the best formaldehyde ethynylation activity.

High-Performance Chlorine-Doped Cu2O Catalysts for the Ethynylation of Formaldehyde

The in situ formed Cu+ species serve as active sites in the ethynylation of formaldehyde. The key problem that needs to be solved in this process is how to avoid excessive reduction of Cu2+ to inactive metallic Cu, which tends to decrease the catalytic activity. In this work, Cl−-modified Cu2O catalysts with different Cl content were prepared by co-precipitation. The characterization results demonstrated that Cl− remained in the lattice structure of Cu2O, inducing the expansion of the Cu2O lattice and the enhancement of the Cu–O bond strength. Consequently, the reduction of Cu+ to Cu0 was effectively prevented in reductive media. Moreover, the activity and stability of Cu2O were significantly improved. The Cl− modification increased the yield of 1,4-butynediol (BD) from 73% to 94% at a reaction temperature of 90 °C. More importantly, the BD yield of Cl− modified Cu2O was still as high as 86% during the ten-cycle experiment, whereas the BD yield of Cu2O in the absence of Cl− decreased sharply to 17% at the same reaction conditions. This work provides a simple strategy to stabilize Cu+ in reductive media.

Preparation, characterization and investigation of sonophotocatalytic activity of thulium titanate/polyaniline nanocomposites in degradation of dyes

Thulium titanate/polyaniline nanocomposites were synthesized to observe the sonophotocatalytic degradation of dyes (widely used as a model pollutant) under ultrasonic irradiation and visible light. Based on our results, the synthesis process can improve sol-gel assisted sonochemical method in the presence of ultrasound and starch. To prepare pure thulium titanate nanostructures, the presence of starch and sonication treatment were concurrently obligatory. Therefore, sol-gel assisted sonochemical method can be used as a successful process for synthesis of thulium titanate nanostructures. According to the BET results, in the presence of ultrasound and starch surface area increased from 9.5305 m₂/g to 40.28 m₂/g. For verification of photacatalytic behavior of nanoparticles, several factors were studied. The nanocomposites/ultrasonic system showed greater photocatalytic activity for the degradation of Rh B rather than separately treatment of nanocomposites under visible light.

Tin oxide nanoparticles modified by copper as novel catalysts for the luminol–H2O2 based chemiluminescence system

Unique catalytic activity was found for SnO₂ nanoparticles modified by copper to enhance the chemiluminescence intensity of the luminol–H₂O₂ system.

Enhanced optical properties of Cu2O anchored on reduced graphene oxide (rGO) sheets

In this report, Cu₂O and Cu₂O/rGO nanocomposites were successfully synthesized through chemical reduction method using glucose as a reducing agent for GO. The x-ray diffraction and field emission scanning electron microscope was used to investigate the phase composition and microstructure of the as-prepared materials. The presence of different functional groups in the as-synthesized sample was analyzed by Fourier transform infrared spectroscopy. Raman spectroscopy was used to confirm structural aspects such as defects of synthesized Cu₂O/rGO nanocomposites. The optical properties of the as-prepared samples were analyzed by UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. Urbach energy is calculated in order to find out the defects in the nanocomposites. Zeta potential analysis was done to study the surface charge and stability of the as-synthesized samples. These results show that the content of rGO introduced into nanocomposite improves the optical properties of Cu₂O thereby enhancing the utilization of visible light.

Ultrasound-assisted synthesis of YbVO4 nanostructure and YbVO4/CuWO4 nanocomposites for enhanced photocatalytic degradation of organic dyes under visible light

YbVO₄ nanostructure and YbVO₄/CuWO₄ nanocomposites were successfully synthesized using sonochemical method, for the first time. In this disquisition, we tried to compare various parameters and reaction conditions on size, morphology, and uniformity of as-obtained samples. To reach optimum condition, some parameters including time, power, temperature, and solvent were investigated. The structural, morphological, optical, and magnetic properties of as-obtained products were characterized by some techniques such as FT-IR, XRD, EDS, SEM, TEM, UV-Vis, and VSM. Furthermore, due to occurrence of red shift in nonanocomposite, during the coupling of CuWO₄ into YbVO₄, photocatalytic and optical properties of final products were improved which lead to improve photo-destruction efficiency for methylene blue from 65% to 100%, during 120 min irradiation. The effect of the ultrasonic radiation on the photocatalytic behavior of YbVO₄/CuWO₄ shows that methylene blue pollutant destruction was about 100% with ultrasonic wave and 61% in the absence of ultrasonic radiation.

The flame retardancy and smoke suppression effect of a hybrid containing CuMoO4 modified reduced graphene oxide/layered double hydroxide on epoxy resin

The co-precipitation method was used to synthesize a hybrid with MgAl-layered double hydroxide loaded graphene (RGO-LDH). CuMoO₄ was then introduced onto the surface of RGO-LDH to prepare a hybrid with CuMoO₄ modified RGO-LDH (RGO-LDH/CuMoO₄). The composition, structure and morphology of RGO-LDH/CuMoO₄ were characterized by X-ray diffraction, Laser raman spectroscopy and Transmission electron microscope-energy-dispersive X-ray spectroscopy. It was found that the hybrid of RGO-LDH/CuMoO₄ had been successfully prepared. The effects of flame retardancy and smoke suppression of epoxy resin were studied with added RGO-LDH/CuMoO₄. Results showed that the PHRR and THR of the EP composite with RGO-LDH/CuMoO₄ added were decreased dramatically. The char yield, LOI and UL-94 vertical burning rating of the EP composite were increased, with improved flame ratardancy. In addition, the SPR, TSP, and D_s,max of the EP composite were decreased drastically with added RGO-LDH/CuMoO₄. Its improved flame retardancy and smoke suppression performance were due mainly to the physical barrier of graphene and LDH, and the catalytic carbonization function of LDH. Meanwhile, Cu₂O and MoO₃ generated from RGO-LDH/CuMoO₄ in the combustion process helped enhance the production of char residue and raised the compactness of the char layer.

Ultrasound-Assisted Synthesis of Nanostructured Oxide Materials

This chapter is focused on the use of high intensity ultrasound for the preparation of nanostructured materials with an emphasis on recent prominent examples of the production of dense or porous metal oxides through sonochemical and ultrasonic spray pyrolysis routes. Sonochemistry enables the synthesis of oxides that are often unachievable by traditional methods or affords known materials with shape, size, and nano/microstructure control under fast reaction conditions. The fundamental principles of acoustic cavitation, as well as the main ultrasonic parameters affecting the cavitation phenomenon, are first summarized. Next, the applications of ultrasound in the synthesis of nanostructured oxide materials following both preparation methods are reviewed. Particular focus is given to the ultrasound-assisted synthesis of metal oxide nanoparticles for energy applications.

Enhanced photodegradation of dye in waste water using iron vanadate nanocomposite; ultrasound-assisted preparation and characterization

The paper proposes a new approach to Schiff-base ligand assisted sonochemical synthesis of iron vanadate. In this disquisition, we tried to comparing various factors and reaction condition on morphology, size and uniformity of as-obtained samples. Some parameters including Schiff-base capping agent (Bis(acetylacetone) ethylenediamine=H₂acacen), electrolyte (NH₄F), solvent and reaction time were investigated to reach optimum condition. XRD, FT-IR, EDS, SEM and TEM were used in order to determine purity and structural morphology of as-synthesized products. Also, we explore the possibility of coupling vanadium pantaoxide into iron vanadate that improves optical properties and photocatalytic activity. With this in mind, FeVO₄/V₂O₅ nanocomposite was prepared via in-situ ultrasound-assisted procedure by using NH₄F in one step. Influence of different parameters such as type of dye (Rhodamine B=Rh B, Phenol red=Ph R and Methyl violet=MV) and light source (Ultraviolet and visible) on photocatalytic ability of samples were studied.