Cu2O nanoparticles with morphology-dependent peroxidase mimic activity: a novel colorimetric biosensor for deoxynivalenol detection.

Different morphological Cu2O nanoparticles including cube, truncated cube, and octahedron were successfully prepared by a selective surface stabilization strategy. The prepared cube Cu2O exhibited superior peroxidase-like activity over the other two morphological Cu2O nanoparticles, which can readily oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to form visually recognizable color signals. Consequently, a sensitive and simple colorimetric biosensor was proposed for deoxynivalenol (DON) detection. In this biosensor, the uniform cube Cu2O was employed as the vehicle to label the antibody for the recognition of immunoreaction. The sensing strategy showed a detection limit as low as 0.01 ng/mL, and a wide linear range from 2 to 100 ng/mL. Concurrently, the approximate DON concentration can be immediately and conveniently observed by the vivid color changes. Benefiting from the high sensitivity and selectivity of the designed biosensor, the detection of DON in wheat, corn, and tap water samples was achieved, suggesting the bright prospect of the biosensor for the convenient and intuitive detection of DON in actual samples.

Integrating Cu2O Colloidal Mie Resonators in Structurally Colored Butterfly Wings for Bio-Nanohybrid Photonic Applications.

Colloidal Cu2O nanoparticles can exhibit both photocatalytic activity under visible light illumination and resonant Mie scattering, but, for their practical application, they have to be immobilized on a substrate. Butterfly wings, with complex hierarchical photonic nanoarchitectures, constitute a promising substrate for the immobilization of nanoparticles and for the tuning of their optical properties. The native wax layer covering the wing scales of Polyommatus icarus butterflies was removed by simple ethanol pretreatment prior to the deposition of Cu2O nanoparticles, which allowed reproducible deposition on the dorsal blue wing scale nanoarchitectures via drop casting. The samples were investigated by optical and electron microscopy, attenuated total reflectance infrared spectroscopy, UV-visible spectrophotometry, microspectrophotometry, and hyperspectral spectrophotometry. It was found that the Cu2O nanoparticles integrated well into the photonic nanoarchitecture of the P. icarus wing scales, they exhibited Mie resonance on the glass slides, and the spectral signature of this resonance was absent on Si(100). A novel bio-nanohybrid photonic nanoarchitecture was produced in which the spectral properties of the butterfly wings were tuned by the Cu2O nanoparticles and their backscattering due to the Mie resonance was suppressed despite the low refractive index of the chitinous substrate.

Cu2O Nanoparticles as Nanocarriers and Its Antibacterial Efficacy.

In this study, Cu2O nanoparticles were synthesized using the sol-gel technique and subsequently functionalized with extracts from plants of the Rauvolfioideae subfamily and citrus fruits. Comprehensive characterization techniques, including UV-Vis spectroscopy, FT-IR, XRD, BET, SEM, and TEM, were employed to evaluate the structural and surface properties of the synthesized nanoparticles. The results demonstrated that both functionalized Cu2O nanoparticles exhibit mesoporous structures, as confirmed by nitrogen adsorption-desorption isotherms and the pore size distribution analysis. The green extract functionalized nanoparticles displayed a more uniform pore size distribution compared to those functionalized with the orange extract. The study underscores the potential of these functionalized Cu2O nanoparticles for applications in drug delivery, catalysis, and adsorption processes, highlighting the influence of the functionalization method on their textural properties and performance in antibacterial efficacy.

Improved Synthesis of Cu2O NPs and Ascorbic Acid-Modified Derivatives for Adsorption of Brilliant Cresyl Blue: Surface and Reusability Studies.

This study addresses the critical need for efficient and recyclable photocatalysts for water treatment applications by presenting a novel approach for the synthesis and characterization of copper (I) oxide (Cu2O) nanoparticles modified with ascorbic acid (Cu2O/AA). The motivation for this research stems from the increasing concern about environmental pollution caused by organic pollutants, such as Brilliant Cresyl Blue (BCB), and the necessity for sustainable solutions to mitigate this issue. Through comprehensive characterization techniques including Ultraviolet-Visible spectroscopy (UV-Vis), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), zeta potential measurements, and Brunauer-Emmett-Teller (BET) analysis, we demonstrate a significant modification to the electronic structure, enhancing the photocatalytic activity of Cu2O/AA. BET analysis revealed a mesoporous structure with a specific surface area of 2.7247 m2/g for Cu2O/AA, further emphasizing its potential for enhanced catalytic performance. The photocatalytic degradation studies showcased remarkable efficiency improvements, with degradation coefficients of 30.8% and 73.12% for Cu2O NPs and Cu2O/AA NC, respectively, within a 120 min timeframe. Additionally, recyclability experiments indicated sustained efficiency over five consecutive cycles, with both catalysts retaining crystalline integrity. These findings underscore the promising potential of Cu2O/AA nanoparticles as highly efficient and recyclable photocatalysts for the degradation of organic pollutants, offering superior performance compared to pure Cu2O NPs and addressing the pressing need for sustainable water treatment solutions.

Highly stable Ag-doped Cu2O immobilized cellulose-derived carbon beads with enhanced visible-light photocatalytic degradation of levofloxacin.

Ag-doped Cu2O immobilized carbon beads (Ag/Cu2O@CB) based composite photocatalysts have been prepared for the removal of levofloxacin, an antibiotic, from water. The photocatalysts were prepared by the processes of chemical reduction and in-situ solid-phase precipitation. The composite photocatalyst was characterized by a porous and interconnected network structure. Ag nanoparticles were deposited on Cu2O particles to develop a metal-based semiconductor to increase the catalytic efficiency of the system and the separation efficiency of the photogenerated carriers. Cellulose-derived carbon beads (CBs) can also be used as electron storage libraries which can capture electrons released from the conduction band of Cu2O. The results revealed that the maximum catalytic degradation efficiency of the composite photocatalyst for the antibiotic levofloxacin was 99.02 %. The Langmuir-Hinshelwood model was used to study the reaction kinetics, and the process of photodegradation followed first-order kinetics. The maximum apparent rate was recorded to be 0.0906 min-1. The mass spectrometry technique showed that levofloxacin degraded into carbon dioxide and water in the presence of the photocatalyst. The results revealed that the easy-to-produce photocatalyst was stable and efficient in levofloxacin removing.

Fracture load in double keyhole notch PLA-Cu2O nanocomposites manufactured via compression molding and 3D printing: An experimental and numerical study.

Polylactic acid (PLA) polymer has garnered significant attention due to its biocompatibility. The incorporation of copper oxide (Cu2O) nanoparticles into this polymer is expected to enhance its antibacterial, electrical, and thermal properties. This modification can potentially improve the performance of PLA in the fields of prosthetics manufacturing or printed circuit fabrication. However, the current research is rather focused on the mechanical properties of the PLA-Cu2O nanocomposites. This research is thus aimed to analyze PLA-Cu2O (97-3 wt%) nanocomposites with a double keyhole notch configuration both experimentally and numerically. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray mapping of elemental distribution(X-map), and thermogravimetric analysis (TGA) were employed to explore the morphology, crystallinity, homogeneity, purity, and thermal stability of the nanocomposite. The specimens were fabricated through two different processes: the classical method of compression molding and the innovative method of 3D printing. The results revealed the superior mechanical performance of the 3D-printed nanocomposite at a 0° raster angle, while the mechanical properties gradually decreased for raster angles of 45° and 90°. The experimental test also indicated a decline in the maximum fracture load of specimens with a double keyhole notch and constant notch inclination angle by raising the notch radius. This behavior was also observed by increasing the notch inclination angle at constant notch radius. The numerical results were similar to the experimental findings. Moreover, the nanocomposite manufactured through the classical method exhibited higher critical fracture load compared to their 3D-printed counterparts with the same geometry.

Catalytic activity of Cu2O nanoparticles supported on cellulose beads prepared by emulsion-gelation using cellulose/LiBr solution and vegetable oil.

Nanocatalysts tend to aggregate and are difficult to recycle, limiting their practical applications. In this study, an environmentally friendly method was developed to produce cellulose beads for use as supporting materials for Cu-based nanocatalysts. Cellulose beads were synthesized from a water-in-oil emulsion using cellulose dissolved in an LiBr solution as the water phase and vegetable oil as the oil phase. Upon cooling, the gelation of the cellulose solution produced spherical cellulose beads, which were then oxidized to introduce surface carboxyl groups. These beads (diameter: 95-105 µm; specific surface area: 165-225 m2 g-1) have a three-dimensional network of nanofibers (width: 20-30 nm). Furthermore, the Cu2O nanoparticles were loaded onto oxidized cellulose beads before testing their catalytic activity in the reduction of 4-nitrophenol using NaBH4. The apparent reaction rate constant increased with increasing loading of Cu2O nanoparticles and the conversion efficiency was >90 %. The turnover frequency was 376.2 h-1 for the oxidized cellulose beads with the lowest Cu2O loading, indicating a higher catalytic activity compared to those of other Cu-based nanoparticle-loaded materials. In addition to their high catalytic activity, the cellulose beads are reusable and exhibit excellent stability.

Bioengineering of Cu2O structured macro-biotemplate for the ultra-efficient and selective hand-retrieval of glyphosate from agro-farms.

Glyphosate (Gly) is a massively utilized toxic herbicide exceeding its statutory restrictions, causing adverse environmental and health impacts. Engineered nanomaterials, even though are integral to remediate Gly, their practical use is limited due to time and energy driven purifications, and negative environmental impacts. Here, a 3D wide area (~1.6 ± 0.4 cm2) Cu2O nanoparticle supported biotemplate is designed using fish-scale wastes as a sustainable approach for the ultra-efficient and selective hand-remediation of Gly from real-time samples from agro-farms. While the innate metal binding and reducing ability of collagenous scales aided self-synthesis cum grafting of Cu2O, the selective binding potential of Cu2O to Gly facilitated its hand-retrieval; as assessed using optical characterizations, Fourier transform infrared spectroscopy, thermogravimetric analysis and liquid chromatography mass spectrometry. Optimization studies revealed extractions of diverse pay-loads of Gly between 0.1 µg/mL to 40 µg/mL per 80 mg biotemplate grafted with ~6.354 µg of sub-5 nm Cu2O and was exponential to the number of Cu2O@biotemplates. Even though pH and surfactant didn't have any impact on the adsorption of Gly to the Cu2O@biotemplates, increase in the ionic strength led to a drastic increase in the adsorption. Density function theory simulations unveiled the involvement of phosphonic and carboxylic groups of Gly for interaction with Cu2O with a bond length of 1.826 Å and 1.833 Å, respectively. Overall, our sustainably generated, cost-efficient, hand-retrievable Cu2O supported biotemplate can be generalized to extract diverse organophosphorus toxins from agro-farms and other sewage embodiments. SYNOPSIS: Glyphosate is an excessively applied herbicide with potent health hazards and carcinogenicity. Thus, a hand removable Cu2O-supported biotemplate to selectively and efficiently remediate glyphosate from irrigation water is developed.

Fabrication of Ultrafine Cu2 O Nanoparticles on W18 O49 Ultra-Thin Nanowires by In-Situ Reduction for Highly Efficient Photocatalytic Nitrogen Fixation.

Photocatalytic ammonia synthesis technology is one of the important methods to achieve green ammonia synthesis. Herein, two samples of Cu ion-doped W18 O49 with different morphologies, ultra-thin nanowires (Cu-W18 O49 -x UTNW) and sea urchin-like microspheres (Cu-W18 O49 -x SUMS), are synthesized by a simple solvothermal method. Subsequently, Cu2 O-W18 O49 -x UTNW/SUMS is synthesized by in situ reduction, where the NH3 production rate of Cu2 O-W18 O49 -30 UTNW is 252.4 µmol g-1  h-1 without sacrificial reagents, which is 11.8 times higher than that of the pristine W18 O49 UTNW. The Cu2 O-W18 O49 -30 UTNW sample is rich in oxygen vacancies, which promotes the chemisorption and activation of N2 molecules and makes the N≡N bond easier to dissociate by proton coupling. In addition, the in situ reduction-generated Cu2 O nanoparticles exhibit ideal S-scheme heterojunctions with W18 O49 UTNW, which enhances the internal electric field strength and improves the separation and transfer efficiency of the photogenerated carriers. Therefore, this study provides a new idea for the design of efficient nitrogen fixation photocatalysis.

Cu2O Nanoparticles Wrapped by N-Doped Carbon Nanotubes for Efficient Electroreduction of CO2 to C2 Products.

Electroreduction of carbon dioxide (CO2) to C2 products (ethylene and ethanol) using efficient catalysts is a feasible approach to alleviate the climate crisis. Cuprous oxide nanoparticles (Cu2O NPs) are a promising catalyst for C2 production but suffer from inherent selectivity and durability. To address this challenge, a Cu2O NPs-nitrogen-doped carbon nanotube (Cu2O NPs-NCNT) composite was prepared with carbon nanotubes (CNTs), Cu2O NPs, and phthalocyanine (Pc). The results indicate that Cu2O NPs-NCNT has excellent Faradic efficiency of C2 products (77.61%) at -1.1 V vs RHE, which is 103.43% higher than that of Cu2O NPs. In the potentiostatic electrolysis combined with Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements, Cu2O NPs-NCNT exhibited structural and catalytic current stability over 10 h. Finally, density functional theory calculations combined with XPS demonstrated that the NCNT in Cu2O NPs-NCNT can selectively absorb CO2 through specific N-CO2 interactions. Our work provides a unique strategy to promote the selectivity of Cu2O NPs for C2 production by introducing N-doped linear carbon materials to fabricate composite.

Spectral Engineering of Hybrid Biotemplated Photonic/Photocatalytic Nanoarchitectures.

Solar radiation is a cheap and abundant energy for water remediation, hydrogen generation by water splitting, and CO2 reduction. Supported photocatalysts have to be tuned to the pollutants to be eliminated. Spectral engineering may be a handy tool to increase the efficiency or the selectivity of these. Photonic nanoarchitectures of biological origin with hierarchical organization from nanometers to centimeters are candidates for such applications. We used the blue wing surface of laboratory-reared male Polyommatus icarus butterflies in combination with atomic layer deposition (ALD) of conformal ZnO coating and octahedral Cu2O nanoparticles (NP) to explore the possibilities of engineering the optical and catalytic properties of hybrid photonic nanoarchitectures. The samples were characterized by UV-Vis spectroscopy and optical and scanning electron microscopy. Their photocatalytic performance was benchmarked by comparing the initial decomposition rates of rhodamine B. Cu2O NPs alone or on the butterfly wings, covered by a 5 nm thick layer of ZnO, showed poor performance. Butterfly wings, or ZnO coated butterfly wings with 15 nm ALD layer showed a 3 to 3.5 times enhancement as compared to bare glass. The best performance of almost 4.3 times increase was obtained for the wings conformally coated with 15 nm ZnO, deposited with Cu2O NPs, followed by conformal coating with an additional 5 nm of ZnO by ALD. This enhanced efficiency is associated with slow light effects on the red edge of the reflectance maximum of the photonic nanoarchitectures and with enhanced carrier separation through the n-type ZnO and the p-type Cu2O heterojunction. Properly chosen biologic photonic nanoarchitectures in combination with carefully selected photocatalyst(s) can significantly increase the photodegradation of pollutants in water under visible light illumination.

Cuprous Oxide Nanoparticles Decorated Fabric Materials with Anti-biofilm Properties.

Considering the global spread of bacterial infections, the development of anti-biofilm surfaces with high antimicrobial activities is highly desired. This work unraveled a simple, sonochemical method for coating Cu2O nanoparticles (NPs) on three different flexible substrates: polyester (PE), nylon 2 (N2), and polyethylene (PEL). The introduction of Cu2O NPs on these substrates enhanced their surface hydrophobicity, induced ROS generation, and completely inhibited the growth of sensitive (Escherichia coli and Staphyloccocus aureus) and drug-resistant (MDR E. coli and MRSA) planktonic and biofilm. The experimental results confirmed that Cu2O-PE exhibited complete biofilm mass reduction ability for all four strains, whereas Cu2O-N2 showed more than 99% biomass inhibition against both drug-resistant and sensitive pathogens in 6 h. Moreover, Cu2O-PEL also indicated a 99.95, 97.73, 98.00, and 99.20% biomass reduction of MRSA, MDR E. coli, E. coli, and S. aureus, respectively. All substrates were investigated for time-dependent inhibitions, and the associated biofilm mass and log reduction were evaluated. The mechanisms of Cu2O NP action against the mature biofilms include the generation of reactive oxygen species (ROS) as well as electrostatic interaction between Cu2O NPs and bacterial membranes. The current study could pave the way for the commercialization of sonochemically coated Cu2O NP flexible substrates for the prevention of microbial contamination in hospitals and industrial environments.

Cuprous Oxide Nanoparticles: Synthesis, Characterization, and Their Application for Enhancing the Humidity-Sensing Properties of Poly(dioctylfluorene).

In this paper, we report on the synthesis-via the wet chemical precipitation route method-and thin film characteristics of inorganic semiconductor, cuprous oxide (Cu2O) nanoparticles, for their potential application in enhancing the humidity-sensing properties of semiconducting polymer poly(9,9-dioctylfluorene) (F8). For morphological analysis of the synthesized Cu2O nanoparticles, transmission electron microscope (TEM) and scanning electron microscope (SEM) micrographs are studied to investigate the texture, distribution, shape, and sizes of Cu2O crystallites. The TEM image of the Cu2O nanoparticles exhibits somewhat non-uniform distribution with almost uniform shape and size having an average particle size of ≈24 ± 2 nm. Fourier transformed infrared (FTIR) and X-ray diffraction (XRD) spectra are studied to validate the formation of Cu2O nanoparticles. Additionally, atomic force microscopy (AFM) is performed to analyze the surface morphology of polymer-inorganic (F8-Cu2O) nanocomposites thin film to see the grain sizes, mosaics, and average surface roughness. In order to study the enhancement in sensing properties of F8, a hybrid organic-inorganic (F8-Cu2O) surface-type humidity sensor Ag/F8-Cu2O/Ag is fabricated by employing F8 polymer as an active matrix layer and Cu2O nanoparticles as a dopant. The Ag/F8-Cu2O/Ag device is prepared by spin coating a 10:1 wt% solution of F8-Cu2O nanocomposite on pre-patterned silver (Ag) electrodes on glass. The inter-electrode gap (≈5 µm) between Ag is developed by photolithography. To study humidity sensing, the Ag/F8-Cu2O/Ag device is characterized by measuring its capacitance (C) as a function of relative humidity (%RH) at two different frequencies (120 Hz and 1 kHz). The device exhibits a broad humidity sensing range (27-86%RH) with shorter response time and recovery time, i.e., 9 s and 8 s, respectively. The present results show significant enhancement in the humidity-sensing properties as compared to our previously reported results of Ag/F8/Ag sensor wherein the humidity sensing range was 45-78%RH with 15 s and 7 s response and recovery times, respectively. The improvement in the humidity-sensing properties is attributed to the potential use of Cu2O nanoparticles, which change the hydrophobicity, surface to volume ratio of Cu2O nanoparticles, as well as modification in electron polarizability and polarity of the F8 matrix layer.

Experimental and Theoretical Studies of Green Synthesized Cu2O Nanoparticles Using Datura Metel L.

In biomedical applications, Cu2O nanoparticles are of great interest. The bioengineered route is eco-friendly for the synthesis of nanoparticles. Therefore, in the present study, there is an attempt to synthesis Cu2O nanoparticles using Datura metel L. The synthesized nanoparticles were characterized by UV-Vis, XRD, and FT-IR. UV-Vis results suggest the presence of hyoscyamine, atropine in Datura metel L, and also, nanoparticles formation has been confirmed by the presence of absorption peak at 790 nm. The average crystallite size (19.56 nm) was obtained by XRD. FT-IR was also used to confirm the different functional groups. Fourier Power Spectrum was also employed to examine the synthesized nanomaterials spectrum data to emphasize the peak of the prominent frequencies. Density functional theory (DFT) was also utilized to assess the energy of the substance over time, which appears to indicate a stable molecule. Furthermore, calculated energies, thermodynamic properties (such as enthalpies, entropies, and Gibbs-free energies), modeled structures of complexes, crystals, and clusters, and predicted yields, rates, and regio- and stereospecificity of reactions were all in good agreement with experimental results. Overall, the results show that the successful production of Cu2O nanoparticles with Datura metel L. corresponds to theoretical research.

Glutathione modulated fluorescence quenching of sulfur quantum dots by Cu2O nanoparticles for sensitive assay.

Sulfur quantum dots (S-dots) show great potential for applications in various field, due to their favorable biocompatibility, high stability, and antibacterial properties. However, the use of S-dots in chemical sensing is limited by the lack of functional groups on the surface. In this work, a fluorescence glutathione (GSH) assay is developed based on the GSH modulated quenching effect of Cu2O nanoparticles (NP) on S-dots. The fluorescence of S-dots is effectively quenched after forming complex with Cu2O NP through a static quenching effect (SQE). Introducing of GSH can trigger the decomposition of Cu2O NP into GSH-Cu(I) complex, which leads to the weaken of SQE and the partial recover of the fluorescence. The intensity of recovered fluorescence shows a positive correlation with the concentration of GSH in the concentration range of 20 to 500 µM. The fluorescence GSH assay shows excellent selectivity and robustness towards various interferences and high concentration salt, which endow the successful detection of GSH in human blood sample. The presented results provide a new door for the design of fluorescence assays, which also provides a platform for the applications in nanomedicine and environmental science.

In situ deposition of nano Cu2O on electrospun chitosan nanofibrous scaffolds and their antimicrobial properties.

In order to obtain a synergistic antimicrobial effect of cuprous oxide nanoparticles (Cu2O NPs) and chitosan (CS) nanofibers, the nano Cu2O/CS nanofibrous scaffolds were synthesized in situ via two subsequent steps of chelation and reduction. The Cu2+ were stably chelated on CS nanofibrous scaffolds through the coordination of amino group (-NH2) and hydroxyl group (-OH) on CS with Cu2+, and then the chelated Cu2+ were reduced to nano Cu2O by Vitamin C under alkaline conditions. And by the measurements of XRD, XPS and FTIR-ATR, the results showed that Cu2O NPs were successfully deposited on the CS nanofibrous scaffolds. SEM clarified that the particle size of Cu2O gradually decreased and the shape changed from cubic to irregular with the increase of CuSO4 concentration. With the CuSO4 concentration of 0.02 and 0.04 mol·L-1, the Cu2O/CS nanofibrous scaffolds presented outstanding hydrophilicity and antibacterial activity against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) comparing to the CS nanofibrous scaffolds, meanwhile, they possessed good biocompatibility. This kind of nanofibrous scaffolds deposited with nano Cu2O would have broad application prospects in the field of antibacterial biomaterials.

Cu2O nanoparticles for the degradation of methyl parathion.

Methyl parathion (MP) is one of the most neurotoxic pesticides. An inexpensive and reliable one-step degradation method of MP was achieved through an aqueous suspension of copper(I) oxide nanoparticles (NPs). Three different NPs sizes (16, 29 and 45 nm), determined with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), were synthesized using a modified Benedict's reagent. 1H nuclear magnetic resonance (NMR) results show that the hydrolytic degradation of MP leads to the formation of 4-nitrophenol (4-NPh) as the main product. While the P=S bond of MP becomes P=O, confirmed by 31P NMR. Although Cu2O is a widely known photocatalyst, the degradation of methyl parathion was associated to the surface basicity of Cu2O NPs. Indirect evidence for the basicity of Cu2O NPs was achieved through UV-vis absorption of 4-NPh. Likewise, it was shown that the surface basicity increases with decreasing nanoparticle size. The presence of CuCO3 on the surface of Cu2O, identified using X-ray photoelectron spectroscopy (XPS), passivates its surface and consequently diminishes the degradation of MP.

Metal-Organic Framework-Derived p-Cu2O/n-Ce-Fe2O3 Heterojunction Nanorod Photoanode Coupling with a FeOOH Cocatalyst for High-Performance Photoelectrochemical Water Oxidation.

Rapid charge recombination and slow water oxidation kinetics are key drawbacks that limit the photoelectrochemical water splitting efficiency of Fe2O3. In this work, we designed and fabricated for the first time that a metal-organic framework (MOF)-derived p-Cu2O/n-Ce-Fe2O3 nanorod array photoanode for the photogenerated charge effectively separated and transported at the Cu2O/Ce-Fe2O3 p-n heterojunction interface through a built-in electric field. In addition, the MOF-derived porous Cu2O nanoparticles have a large surface area, and thus, can offer more surface active sites for water oxidation. As anticipated, the novel structure Cu2O/Ce-Fe2O3 photoanode showed superior photocurrent density (3.2 mA cm-2), excellent bulk charge separation efficiency (38.4%), and surface charge separation efficiency (77.2%). After further modification with the FeOOH cocatalyst, the photocurrent density of the FeOOH/Cu2O/Ce-Fe2O3 photoanode reached 4.2 mA cm-2 at 1.23 VRHE (V vs reversible hydrogen electrode), having a low onset potential of 0.63 VRHE.

Andean Sacha Inchi (Plukenetia Volubilis L.) Leaf-Mediated Synthesis of Cu2O Nanoparticles: A Low-Cost Approach.

In this work, Andean sacha inchi (Plukenetia volubilis L.) leaves were used to prepare monodispersed cuprous oxide (Cu2O) nanoparticles under heating. Visual color changes and UV-visible spectroscopy of colloidal nanoparticles showed λmax at 255 nm, revealing the formation of copper oxide nanoparticles. Transmission electron microscopy and dynamic light scattering analysis indicated that the prepared nanoparticles were spherical with an average size of 6-10 nm. The semi-crystalline nature and Cu2O phase of as-prepared nanoparticles were examined by X-ray diffraction. Fourier-transform infrared spectroscopy confirmed the presence of polyphenols, alkaloids and sugar in the sacha inchi leaf, allowing the formation of Cu2O nanoparticles from Cu2+. Additionally, as-synthesized Cu2O nanoparticles exhibited good photocatalytic degradation activity against methylene blue (>78%, 150 min) with rate constant 0.0219106 min-1. The results suggested that the adopted method is low-cost, simple, ecofriendly and highly selective for the synthesis of small Cu2O nanoparticles and may be used as a nanocatalyst in the future in the efficient treatment of organic pollutants in water.

Mixed Copper/Copper-Oxide Anchored Mesoporous Fullerene Nanohybrids as Superior Electrocatalysts toward Oxygen Reduction Reaction.

Developing a highly active, stable, and efficient non-noble metal-free functional electrocatalyst to supplant the benchmark Pt/C-based catalysts in practical fuel cell applications remains a stupendous challenge. A rational strategy is developed to directly anchor highly active and dispersed copper (Cu) nanospecies on mesoporous fullerenes (referred to as Cu-MFC60 ) toward enhancing oxygen reduction reaction (ORR) electrocatalysis. The preparation of Cu-MFC60 involves i) the synthesis of ordered MFC60 via the prevalent nanohard templating technique and ii) the postfunctionalization of MFC60 with finely distributed Cu nanospecies through incipient wet impregnation. The concurrence of Cu and cuprous oxide nanoparticles in the as-developed Cu-MFC60 samples through relevant material characterizations is affirmed. The optimized ORR catalyst, Cu(15%)-MFC60 , exhibits superior electrocatalytic ORR characteristics with an onset potential of 0.860 vs reversible hydrogen electrode, diffusion-limiting current density (-5.183 mA cm-2 ), improved stability, and tolerance to methanol crossover along with a high selectivity (four-electron transfer). This enhanced ORR performance can be attributed to the rapid mass transfer and abundant active sites owing to the synergistic coupling effects arising from the mixed copper nanospecies and the fullerene framework.