CuO Nanoclusters Research Articles

Ultra-facile synthesis of CuO nanoclusters with excellent antibacterial activity and their antimicrobial mechanism study

Ultra-facile synthesis of CuO nanoclusters with excellent antibacterial activity and their antimicrobial mechanism study

Acetate Ions Facilitated Immobilization of Highly Dispersed Transition Metal Oxide Nanoclusters in Mesoporous Silica.

The immobilization of tiny active species within inert mesoporous silica imparts a range of functions, enhancing their applicability. A significant obstacle is the spontaneous migration and aggregation of these species within the mesopores, which threaten their uniform distribution. To address this, we propose a postmodification method that involves grafting transition metal oxide nanoclusters into silica mesopores via interfacial condensation, catalyzed by acetate ions. Specifically, CuO nanoclusters, in the form of oligomeric [O1-x-Cu2-(OH) 2x]n2+, have a strong interaction with the silica framework. This interaction inhibits their growth and prevents mesopore blockage. Theoretical calculation results reveal that the acetate ion promotes proton transfer among various hydroxy species, lowering the free energy and thereby facilitating the formation of Cu-O-Si bonds. This technique has also been successfully applied to the encapsulation of four other types of transition metal oxide nanoclusters. Our encapsulation strategy effectively addresses the challenge of dispersing transition metal oxides in mesoporous silica, offering a straightforward and widely applicable method for enhancing the functionality of mesoporous materials.

Formation and Electrochemical Properties of Heterostructured Electrodes Based on Cu2O and CuCo2O4

Individual (FTO/Cu2O and FTO/CuCo2O4) and heterostructured (FTO/BiVO4/Cu2O, FTO/BiVO4/CuCo2O4, and FTO/CuCo2O4/Cu2O) electrodes were successfully formed using the electrodeposition method on copper-containing compounds. The morphology of the synthesized electrode systems, which affect the electrochemical properties, was determined. A comparative study of the electrochemical and photoelectrochemical properties of the individual and heterostructured electrodes showed that the modification of the BiVO4 electrode surface with Cu2O and CuCo2O4 oxides led to a significant increase in its efficiency as a photoanode. The deposition of Cu2O nanoclusters onto CuCo2O4 nanoflakes increased the electrochemical stability of the electrode while maintaining its high capacitance.

Antibacterial efficacy of NiO composites with CuO nanoclusters via co-precipitation method

Antibacterial efficacy of NiO composites with CuO nanoclusters via co-precipitation method

Strong ectopic adsorption on single cobalt site accelerates the direct catalytic oxidation of low concentration acetonitrile on CuO nanoparticles embedded in SAPO-34

It is usually inevitable for the usage of zeolite rotor concentrator to increase the level of volatile organic compounds (VOCs) concentration, which in turn enables the regenerative catalytic oxidation of VOCs with large gas flow rate to achieve autothermal operation. Herein, we present a new strategy for the preparation of autothermal oxidation catalyst (AOC) with strong ectopic adsorption ability for VOCs molecules by the on-site doping of single cobalt sites on CuO nanoclusters confined in zeolitic materials SAPO-34, which exhibits a strong enrichment ability for low concentration acetonitrile even at 300 °C. Meanwhile, a distinguished enhancement on the catalytic oxidation activities has also been achieved according to the formation of CoⅡ-oxo and/or Co-Ovac sites on CuO nanoparticles.

Formation of large-scale MoS2/Cu2O/ZnO heterostructure arrays by in situ photodeposition and application for ppb-level NO2 gas sensing

Photodeposition has been used extensively for nanomaterial growth on a substrate, but direct photodeposition of 2D transition metal dichalcogenides (TMDs) remains challenging. An alternative approach is to deposit 2D TMDs on a suitable nanomaterial template. In this work, large-scale MoS2/Cu2O/ZnO heterostructure arrays are formed by low-temperature in situ photodeposition and the nanocomposites are used for chemiresistive gas sensing at room temperature. Using 254 nm UV irradiation, Cu2O nanoclusters are photodeposited in solution on hydrothermally grown ZnO nanorod arrays and Cu2O/ZnO heterostructure arrays are first formed. MoS2 nanoparticles are subsequently photodeposited on Cu2O and MoS2/Cu2O/ZnO heterostructure arrays with good uniformity on a sub-millimeter scale are consequently produced. The ternary nanocomposite with a 45 min MoS2 photodeposition time shows the highest response of 890% toward 500 ppb NO2 under UV-activated sensing. An excellent linear sensitivity of 18.7 ppm–1 has been achieved and the estimated lowest detection limit is 1.3 ppb, exhibiting good potential for monitoring of environmental NO2 content. The outstanding performance is attributed to the combined chemical and electronic sensitization effects of the abundant heterojunctions in the nanocomposite. The present work reveals that facile in situ photodeposition is suitable for synthesis of large-scale MoS2/Cu2O/ZnO heterostructure arrays with remarkable gas sensing performance.

Enhanced the combustion performance of DAP-4 with assembled Cu2O nanoclusters

In this work, the catalytic combustion performance of molecular perovskite energetic material DAP-4 with assembled Cu2O nanoclusters added was studied. Results showed that aggregated spherical Cu2O clusters with the size of ∼1 μm were assembled by nano particles with ∼50 nm diameter by the high-temperature reduction method. Assembled Cu2O nanoclusters have intrinsic catalysis combustion characteristics on DAP-4. With 5 wt% Cu2O added, the combustion time of DAP-4 had reduced by ∼70 ms from raw DAP-4 (∼90 ms) to DAP-4/Cu2O (20 ms). The combustion pressurization rate of DAP-4/Cu2O is ∼4 times of DAP-4. The catalysis combustion mechanism of DAP-4 with assembled Cu2O nanoclusters as an additive was proposed. The work offered a new idea to utilize novel catalysts for enhancing the combustion performance of DAP-4.

Photocatalytic activities of TiO2 nanoparticles modified by nanoclusters of copper oxides prepared by atomic layer deposition

We employed atomic layer deposition to deposit nanoclusters of Cu2O on TiO2 nanoparticles to produce TiO2/Cu2O photocatalysts with the Cu concentration in the range of 0.4 - 4.6%. By annealing the TiO2/Cu2O photocatalysts in the air at 400 °C for 4 h, the oxidation of Cu2O resulted in the formation of TiO2/CuO photocatalysts having the same Cu concentration. Transmission electron microscopy and X-ray diffraction characterizations demonstrated the successful deposition of Cu2O nanoclusters with an average diameter in the range of 1.3 - 2.0 nm and a face-centered cubic crystalline structure, whereas a weak signal of the monoclinic structure of CuO was detected for the TiO2/Cu2O catalysts. The photocatalytic activity of the TiO2/Cu2O and the TiO2/CuO photocatalysts was investigated by the degradation of RhB under UV radiation. The results show that the presence of Cu2O and CuO nanoclusters could improve the photocatalytic activity of TiO2, and for the same Cu concentration, the TiO2/Cu2O photocatalyst provided higher catalytic activity than the TiO2/CuO counterpart.

Molecular dynamics simulation on surface modification of quantum scaled CuO nano-clusters to support their experimental studies

Interest in nanoparticle modification using functional chemicals has increased rapidly, as it allows more freedom of physiochemical tuning of the nanoparticle’s surface into biomedically oriented and designated properties. However, the observation and detection of the thin molecular layers on the nanoparticle surface are very challenging under current analytical facilities. The focus of this research is to demonstrate fundamental interactions between the surface treated nanoparticles and their host liquid media using lab-based experimentation and simulation. In this research, investigation has been carried out on analyzing the surface compatibility and the diffusivity of modified CuO nanoparticles (CuONPs) with short-chain carboxylate-terminated molecules in biofluids. Moreover, during the current Covid-19 pandemic, the Cu/CuONPs have proved effective in killing SARS-CoV1/2 and other airborne viruses. This research was conducted at the molecular level with joint consideration of experimental and simulation studies for characterization of variables. Experimental tests conducted using Fourier Transform Infrared (FTIR) spectroscopy demonstrated several spectral ranges of interest, specifically, detection of three major carboxylate attachments (i.e., 1667–1609 cm−1, 1668–1557 cm−1, etc.) were found. From simulation, similar attachment styles were observed by the LAMMPS simulation package that mimicked similar agglomerations with a predicted diffusion coefficient as recorded to be 2.28E−9 m2/s. Viscosities of modified nanofluids were also compared with unmodified nanofluids for defining aggregation kinetics.

Z-scheme heterojunction photocatalyst: Deep eutectic solvents-assisted synthesis of Cu2O nanocluster improved hydrogen production of TiO2

The development of nanocluster scale heterojunction catalysts using a green method for solar energy conversion applications is an important challenge. In this study, deep eutectic solvents (DESs)-assisted process was employed as a green approach to synthesize size-controlled Cu2O nanoclusters on TiO2 surfaces without using any size-controlling agent. The Cu2O nanoclusters (1.5 nm) interact with the subdomain surface of TiO2 nanoparticles, forming Z-scheme heterojunction, resulting in the effective separation of photogenerated charge carriers. Also, the surface chemical environment of the Cu2O/TiO2 composite was altered by the formation of defects during the in-situ Cu2O synthesis, which generated oxygen vacancies. The optimized Cu2O/TiO2 catalyst has a high charge density (16.3 ×1019 cm−3) and 2.38 times less charge transfer resistance compared to pristine TiO2. The optimized Cu2O/TiO2 photocatalysts had a 1.32 times higher H2 production rate (24.21 mmol g−1 h−1) than pristine TiO2. This study provides new insight into the development of monosized Cu2O nanoclusters on TiO2 by DESs assisted process as a green synthesis approach for photocatalytic hydrogen production.

Size Effect of (CuO)n (n = 1–6) Clusters on the Modification of Rutile–TiO2 Photocatalysts

The modification of different-size CuO nanoclusters on rutile-TiO2 photocatalysts can lead to an enhanced light-absorption ability and a remarkable improvement in the photocatalytic hydrogen evolution reaction. This work presents a theoretical and quantitative study on the size effects of (CuO)n (n = 1∼6) clusters supported on rutile-TiO2 photocatalysts, which conforms to previous as-prepared CuO/TiO2 photocatalysts. More details can be found in article number 2100161, Haibo Zhao and co-workers.

Controlled growth of ultrasmall Cu2O clusters on TiO2 nanoparticles by atmospheric-pressure atomic layer deposition for enhanced photocatalytic activity

This work presents a gas-phase approach for the synthesis of Cu2O/TiO2 powder-based photocatalysts using atomic layer deposition (ALD). The process is carried out in a fluidized bed reactor working at atmospheric pressure using (trimethylvinylsilyl)-hexafluoroacetulacetonate copper(I) as the Cu-precursor and H2O vapor as the oxidizer. The saturating regime of the chemical reactions and the linear growth of ALD are achieved. In combination with the unsaturated regime, the ALD approach enables the deposition of ultrasmall Cu2O clusters with average diameters in the range of 1.3–2.0 nm, narrow particle size distributions and tunable Cu2O loadings on P25 TiO2 nanoparticles. The photocatalytic performance of Cu2O/TiO2 photocatalysts is investigated by the degradation of organic dyes, including Rhodamine B (RhB), methyl orange, and methylene blue; the results demonstrate that the surface modification of TiO2 nanoparticles by Cu2O nanoclusters significantly enhances the photocatalytic activity of TiO2. This is attributed to the efficient charge transfer between Cu2O and TiO2 that reduces the charge recombination. The photocatalytic reaction mechanism is further investigated for the degradation of RhB, revealing the dominating role of holes, which contribute to both direct hole oxidation and indirect oxidation (i.e. via the formation of hydroxyl radicals). Our approach provides a fast, scalable and efficient process to deposit ultrasmall Cu2O clusters in a controllable fashion for surface engineering and modification.

Biothermodynamic, antiproliferative and antimicrobial properties of synthesized copper oxide nanoparticles

Nanoparticles (NPs) have been widely used as anticancer and antibacterial agents. However, before their use in biomedical applications, some in vitro assays should be carried out to investigate their interaction with biological systems. The copper oxide NPs (CuO NPs) were synthesized by hydrothermal method and their interaction with human serum albumin (HSA), leukemia K562 cells and three strains of bacteria was explored by spectroscopic, docking, cellular, and antibacterial investigations. The TEM, DLS, XRD, FTIR, Raman, and UV–visible techniques revealed that synthesized CuO NPs provide a crystalline structure corresponding to CuO nanoclusters with good colloidal stability. Biothermodynamic studies showed that CuO NPs formed a static complex with HSA molecules through hydrogen bonds which was further confirmed by docking analysis. UV–Vis spectroscopy results exhibited that the melting temperature (Tm) of HSA was slightly changed in the presence of CuO NPs. Cellular studies displayed that CuO NPs selectively resulted in the mortality of K562 cells through cell membrane leakage, caspase-9 and -3 activation, and apoptosis. Finally, antibacterial assays depicted that CuO NPs can induce an inhibitory effect in the case of both Gram-negative and Gram-positive bacteria. In conclusion, this study may provide useful data regarding the protein binding and biomedical applications of NPs.

Peptide-inspired green synthesis of hedgehog-like CuO nanoclusters on reduced graphene oxide for non-enzymatic hydrogen peroxide sensor

Bioinspired synthesis provides a potential green method for creating functional nanomaterials on graphene supports. In this study, we demonstrate the preparation of hedgehog-like cupric oxide nanoclusters (CuONCs) on peptide-modified reduced graphene oxide (RGO-Pep) nanohybrids through a solution-phase synthesis in which the bound peptide molecules (GNNQQNYEE) mediate the non-covalent modification of GO and provide the adsorption of Cu[Formula: see text] ions and the nucleation sites for the growth of CuONCs. The synthesized RGO-Pep-CuONCs hybrids were further utilized for the modification of a glass carbon electrode to fabricate a non-enzymatic electrochemical sensor for hydrogen peroxide (H2O2). It was found that the fabricated H2O2 sensor exhibited good performances for sensing H2O2 with a detection limit of [Formula: see text]M and two wide linear detection ranges. In addition, this sensor revealed good selectivity and stability. It is expected that the strategies used in this study will be valuable to inspire the creation of various functional biomolecule- and graphene-based hybrid bionanomaterials for the applications in materials science, sensors, biomedical engineering, tissue engineering, nanotechnology, and other fields.

Flame spray pyrolysis synthesis and H2S sensing properties of CuO-doped SnO2 nanoparticles

In this work, CuO-doped SnO2 (CuO/SnO2) nanoparticles with different CuO mass fractions (0–1.0 wt%) are synthesized by a flame spray pyrolysis (FSP) route and applied to fabricate thin-film gas sensors for H2S detecting. The nanoparticles are characterized by X-ray diffraction (XRD), N2-physisorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Within the 0–1.0 wt% CuO-doping concentrations, all of the nanoparticles predominantly exhibit a spherical structure with a diameter of 5–15 nm, and possess a quite large specific surface area (110–125 m2/g). These textural characterizations suggest that Cu atoms form substitution doping in polycrystalline SnO2 nanoparticles at low CuO levels (< 0.5 wt%), and they are segregated as CuO nanoclusters at high CuO concentrations (0.5–1.0 wt%). From gas-sensing measurements, the CuO doping significantly improves the H2S sensing performance of SnO2 nanoparticles, especially at the optimal CuO-doping mass fraction of 0.5 wt%. The optimal CuO-doped SnO2 gas sensor exhibits a highest response (Ra/Rg = 1056) under a condition of 10 ppm H2S atmosphere at 125 °C. This is probably because a large number of highly dispersed small CuO nanoclusters are supported on the surface of the nanoparticle for 0.5 wt% doping, forming abundant p-n junctions with SnO2. When the CuO/SnO2 composite is exposed to H2S, semiconducting CuO is converted to metallic-like CuS, thereby increasing electrical conductivity and resulting in a high response. In addition, the optimal sensor displays good cycle performance and high H2S selectivity against other toxic and flammable gases including NH3, H2 and CO. Therefore, the gas sensor of 0.5 wt% CuO-doped SnO2 made by the FSP shows a large potential for H2S detecting in practical industrial application.

In silico studies to understand the adsorbent properties of CuO nano-clusters for toxic water soluble dyes

In silico studies to understand the adsorbent properties of CuO nano-clusters for toxic water soluble dyes

Heterojunction of CuO nanoclusters with TiO2 for photo-oxidation of organic compounds and for hydrogen production.

Heterojunctions of small CuO nanoclusters (synthesized by radiolysis) with TiO2 (commercial P25) induced a photocatalytic activity under visible light irradiation in a wide range of wavelengths due to the narrow bandgap of CuO nanoclusters of around 1.7 eV. The optical, chemical, and electrical properties of these composite nanomaterials were studied. The photocatalytic properties of bare and modified TiO2-P25 were studied for water purification (photooxidation of organic compounds such as phenol and 2-propanol) and for hydrogen generation under visible light irradiation. Time resolved microwave conductivity signals showed activation of TiO2 under visible light, proving the injection of electrons from CuO nanoclusters to the conduction band of TiO2-P25. The modified materials showed high photocatalytic activity under visible light. The important role of charge-carriers was demonstrated for both photoreduction and photooxidation reactions.

Experimental and mechanistic understanding of photo-oxidation of methanol catalyzed by CuO/TiO2-spindle nanocomposite: Oxygen vacancy engineering

We report experimental and mechanistic understanding of methanol oxidation to produce methyl formate using CuO/TiO2-spindle composite as a promising photocatalyst under mild conditions with over 97% conversion and 83% selectivity. The catalysts are obtained via precise depositing of CuO nanoclusters (size: ~ 3.5 nm) at the {101} facet of the TiO2 to optimally tune exciton recombination through oxygen vacancies generation, evidenced by photoluminescence and Raman spectroscopy measurements. The turnover frequency (TOF) and the apparent quantum efficiency (AQE) of the 7%CuO/TiO2-spindle composites reach up to 23.8 molmethanol·gcat−1·h−1 and 55.2% at 25 °C, respectively, which are substantially higher than these previously reported photocatalysts. Further, the in-situ attenuated total reflection infrared spectroscopy analysis reveals that the methanol oxidation most likely takes place through the conversion of adsorbed methoxy (CH3O*) to formaldehyde (CHO*) intermediate, a subject of major debate for a long time. The adsorbed formaldehyde (CHO*) thus produced reacts with another CH3O* species in its close proximity to form the final product of methyl formate. Results of this study provide insights into the reaction mechanism, and offer guidelines to systematically develop and apply photocatalysts for methanol conversion and related reactions via surface engineering.

Inhibition of Fungal Growth Using Modified TiO2 with Core@Shell Structure of Ag@CuO Clusters.

The photocatalytic disinfection (PCD) properties of TiO2 have attracted attention in the research communities because the produced reactive oxygen species (ROS) allow destruction of different types of microbes, such as fungi, bacteria, viruses, algae, unicellular organisms, etc. on surfaces, in water, and in air. However, TiO2 requires UV irradiation to produce the ROS, which limits its photoactivity in indoor environments. Surface-modified TiO2 with small Ag and CuO nanoclusters in a core-shell structure exhibits antifungal properties under dark and visible conditions, possibly because of the interaction between Ag-CuO nanoclusters in the fungi membrane and their penetration, and the co-presence of Cu2+ and Ag+ ions. Therefore, a synergetic effect is obtained with co-modification of TiO2 with silver and copper, and the sample Ag@CuO/TiO2 (core-shell structure of Ag-Cu in a ratio of 1:3) exhibits the highest antifungal activity; that is, fungi growth inhibition is observed for Aspergillus melleus and Penicillium chrysogenum. Moreover, significant inhibitions of the sporulation and generation of droplets, possibly containing mycotoxins and sclerotia under dark and visible exposure, are also obtained.

Formation of Highly Active Superoxide Sites on CuO Nanoclusters Encapsulated in SAPO-34 for Catalytic Selective Ammonia Oxidation

Generation of surface active sites with tailor-made structure is a promising way to enhance catalytic properties of inexpensive metal oxides, as a replacement to noble metals. In the abatement of N...