Solution-phase Approach Research Articles

Hierarchical bismuth vanadate/reduced graphene oxide composite photocatalyst for hydrogen evolution and bisphenol A degradation

Bismuth vanadate (BiVO4) is a widely studied photocatalyst for the depollution of contaminated wastewater, production of hydrogen by water splitting, and organic synthesis. The photophysical properties of BiVO4 are sensitive to morphology and quantum confinement effects, and can exhibit enhanced photocatalytic performance in nanocomposites with graphene. Synthesis of hierarchical BiVO4 plates decorated by nanoparticles (h-BiVO4) in contact with reduced graphene oxide (RGO) is reported via a facile one-pot solution phase approach using ethanolamine and a polyethylene glycol stabilizer. The resulting h-BiVO4/RGO photocatalyst exhibited superior photoactivity for bisphenol A (BPA) degradation and hydrogen evolution under visible light irradiation compared to single component h-BiVO4 or a μm-sized block-like BiVO4 morphology. Rates of BPA photocatalytic degradation and apparent quantum efficiency (AQE) decreased in the order h-BiVO4/RGO (4.5 × 10−2 mmol.g−1.min−1; 15.1% AQE) > h-BiVO4 (3.5 × 10−2 mmol.g−1.min−1; 11.7% AQE) > BiVO4 (1 × 10−2 mmol.g−1.min−1; 3.4% AQE), representing a 4.5 fold enhancement for h-BiVO4/RGO versus BiVO4. Liquid phase photodegradation products included benzene-1,4-diol, cyclohexa-2,5-diene-1,4-dione and (2Z)-but-2-enedioic acid. The rate of photocatalytic hydrogen production under visible light was 11.5 µmol.g−1.h−1 for h-BiVO4/RGO, ~383.3 times greater than for BiVO4 (0.03µmol.g−1.h−1). The superior photocatalytic performance of h-BiVO4/RGO is largely attributed to its higher surface area, aided by enhanced visible light absorption and charge separation across the semiconductor-RGO interface, which together confer a higher density and lifetime of photoexcited charge carriers.

Ultrathin Ni(OH)2 nanosheets decorated with Zn0.5Cd0.5S nanoparticles as 2D/0D heterojunctions for highly enhanced visible light-driven photocatalytic hydrogen evolution

Designing and fabricating highly efficient photocatalysts for water splitting is a promising strategy to address energy and environmental issues. Cadmium sulfide (CdS) has received significant interest as a photocatalyst for visible-light-induced hydrogen (H2) generation. However, the severe photocorrosion, high overpotential, rapid charge recombination, and sluggish surface reaction kinetics drastically hinder its practical application in water splitting. Herein, uniform zinc cadmium sulfide (Zn0.5Cd0.5S) nanoparticles were anchored on ultrathin Ni(OH)2 nanosheets via a facile solution-phase approach to form an intimate two-dimensional (2D)/zero-dimensional (0D) heterojunction. Under visible light irradiation, the 7%Ni(OH)2/Zn0.5Cd0.5S composite exhibited the highest H2 production rate of 6.87 mmol·h−1·g−1 with an apparent quantum yield of 16.8% at 420 nm, which is almost 43 times higher than that of pristine Zn0.5Cd0.5S and considerably higher than that of the Pt/Zn0.5Cd0.5S photocatalyst. The high photoactivity of the 2D/0D Ni(OH)2/Zn0.5Cd0.5S heterojunction can be ascribed to its unique and robust structure, wherein the ultrathin Ni(OH)2 nanosheets not only provide an excellent platform for the incorporation of Zn0.5Cd0.5S nanoparticles but also serve as an effective cocatalyst to promote photoinduced electron transfer and offer more active sites for photocatalytic H2 generation. This work paves the way toward the development of versatile, low-cost, and highly efficient 2D/0D heterojunction photocatalysts for solar energy conversion.

Investigation of a Single Tail Lysine Rich Peptide Amphiphile with an Ultra Short Peptide Head for its Nano Scale Self-assembly and Drug Loading Potential

Peptide amphiphiles (PA) are highly biocompatible, unique designer molecules capable of self-assembling into nanostructures of diverse morphologies. They are attracting wider scientific interest for lipophilic drug’s solubilization and delivery owing to their amphiphilicity. This study reports the synthesis of a lysine containing PA with an ultra-short peptide head and its investigation for self-assembling into nanostructures and drug loading. The PA was synthesized through solution phase approach followed by characterization through mass spectrometry and 1H NMR and 13C NMR spectroscopy. Self-assembling behavior of the synthesized PA was investigated through circular dichroism spectroscopy followed by authentication through Atomic Force microscopy (AFM). UV visible spectrophotometer was used for determination of its critical micelle concentration (CMC). The amphiphile was evaluated for its drug loading potential using cefixime as a hydrophobic drug. Results show that the synthesized PA bearing an ultra-short peptide head has a CMC value of 0.061 mM and was capable of self-assembling into predominantly cylindrical nanostructures in aqueous medium having a size of 12.5 nm. Furthermore, PA loaded 52.26 ± 2.50% of the model hydrophobic drug in its nanostructures without altering its chemical identity. The results suggest that the synthesized PA with an ultra-short peptide backbone could be a promising vehicle for nanoscale drug delivery.

FACILE SYNTHESIS AND GROWTH MECHANISM OF TRIGONAL SELENIUM NANOWRIES

Trigonal selenium (t-Se) nanowires were fabricated via a facile solution-phase approach at room temperature. Time-dependent experiments were designed to explore the mechanism of the transition of a-Se to t-Se both in solution and in solid phases. It was found that the extended spiral chains of selenium atoms in the trigonal phase provided a natural template to define and guide the growth direction. The transition of a-Se to t-Se nanowire can happen not only in a solid-solution-solid process, but also in a solid to solid process. The synthesis method will provide a new approach for research on its performance.

Electro-enhanced solid-phase microextraction with covalent organic framework modified stainless steel fiber for efficient adsorption of bisphenol A

In this work, electro-enhanced solid-phase microextraction (EE-SPME) and covalent organic framework (COF) were adopted to improve the extraction efficiency. A conductive COF synthesized of 2,6-diaminoanthraquinone (DQ) and 1,3,5-triformylphloroglucinol (TP) was in situ bonded to the stainless steel wire via facile solution-phase approach and used as the EE-SPME fiber coating to preconcentrate a typical endocrine disruptor bisphenol A (BPA). Compared with conventional SPME, the DQTP bonded fiber coupled with EE-SPME device exhibited higher extraction efficiency and achieved extraction equilibrium within 10 min. The proposed approach based on EE-SPME and gas chromatography coupled with flame ionization detector gave a linear range of 0.05–10 μg mL−1 and detection limit of 3 μg L−1 (S/N = 3) with good precision (<6.7%) and reproducibility (<7.1%) spiked with 0.1, 0.5, 1.0 μg mL−1 BPA. Quantitative determination of BPA in extracts of food packagings (mineral water bottles, milk boxes and milk tea cups) was achieved with recoveries from 88.6 to 118.0%.

Synthesis of Bacterial-Derived Peptidoglycan Cross-Linked Fragments.

Peptidoglycan (PG) is the core structural motif of the bacterial cell wall. Fragments released from the PG serve as fundamental recognition elements for the immune system. The structure of the PG, however, encompasses a variety of chemical modifications among different bacterial species. Here, the applicability of organic synthetic methods to address this chemical diversity is explored, and the synthesis of cross-linked PG fragments, carrying biologically relevant amino acid modifications and peptide cross-linkages, is presented using solution and solid phase approaches.

Affinity selection-mass spectrometry for the discovery of pharmacologically active compounds from combinatorial libraries and natural products.

Invented to address the high-throughput screening (HTS) demands of combinatorial chemistry, affinity selection-mass spectrometry (AS-MS) utilizes binding interactions between ligands and receptors to isolate pharmacologically active compounds from mixtures of small molecules and then relies on the selectivity, sensitivity, and speed of mass spectrometry to identify them. No radiolabels, fluorophores, or chromophores are required. Although many variations of AS-MS have been devised, three approaches have emerged as the most flexible, productive, and popular, and they differ primarily in how ligand-receptor complexes are separated from nonbinding compounds in the mixture. These are pulsed ultrafiltration (PUF) AS-MS, size exclusion chromatography (SEC) AS-MS, and magnetic microbead affinity selection screening (MagMASS). PUF and SEC AS-MS are solution-phase screening approaches, and MagMASS uses receptors immobilized on magnetic microbeads. Because pools of compounds are screened using AS-MS, each containing hundreds to thousands of potential ligands, hundreds of thousands of compounds can be screened per day. AS-MS is also compatible with complex mixtures of chemically diverse natural products in extracts of botanicals and fungi and microbial cultures, which often contain fluorophores and chromophores that can interfere with convention HTS. Unlike conventional HTS, AS-MS may be used to discover ligands binding to allosteric as well as orthosteric receptor sites, and AS-MS has been useful for discovering ligands to targets that are not easily incorporated into conventional HTS such as membrane-bound receptors.

Synthesis and Evaluation of Antimycobacterial and Antiplasmodial Activities of Hirsutellide A and Its Analogues.

Hirsutellide A is nature-derived cyclic hexadepsipeptide with reported antimycobacterial and antiplasmodial activities. To verify its structure, hirsutellide A was synthesized following a solution-phase peptide synthesis approach. A detailed analysis of the 1H and 13C NMR spectra of the synthesized compound revealed structural variation from what had been originally assigned for hirsutellide A, despite the use of identical building blocks. This variation occurred at the two allo-Ile moieties. To investigate the structure–activity relationship, the depsipeptide and peptide analogues of hirsutellide A were prepared and tested for antimycobacterial and antiplasmodial activities. The compounds displayed antiplasmodial potency against Plasmodium falciparum 3D7 while showing weak or no activity against Mycobacterium tuberculosis H37Rv. The drug-likeness of the series was assessed through in vitro absorption, distribution, metabolism, and excretion (ADME) profiling, revealing systematic differences between the pharmacokinetic properties of cyclic hexapeptides and hexadepsipeptides.

The Functionalization of Low Dimensional Materials for a Multi-Functional Gas Sensor Platform

Presently, most space missions rely on large, heavy, and high-power instrumentation such as mass spectrometers for chemical analysis on planetary bodies. The weight of these payloads is prohibitive to mission cost, and ultimately hinders scientific advancement. This hindrance has driven us to develop a multi-functional gas sensor platform based on the additive manufacturing of low-dimensional materials. The discovery of low-dimensional materials such as graphene and carbon nanotubes (CNTs) has instigated a push to apply these materials in device design. The unique electrical and physical properties of these materials coupled to their high surface area to volume ratio make them outstanding candidates as extremely sensitive gas sensing elements for both chemiresistive and field effect transistor (FET) based devices. The detection of gases using low-dimensional materials as sensing elements relies on change in the resistance of the sensing element associated with electron donation or extraction by the gas to be detected. For most low-dimensional materials, this mechanism is not especially selective. This lack of selectivity necessitates the functionalization of said materials with catalytically appropriate functional units to promote device selectivity while maintaining the high sensitivity of the low-dimensional materials. We will present our efforts on the functionalization of chemiresistive and FET gas sensors using CNTs, graphene and transition metal dichalcogenides with both physical vapor deposition and solution phase approaches. This functionalization will ultimately allow for the fabrication of an array of gas sensors with each sensor demonstrating varied selectivity for the gases of interest. Our functional group choice, process optimization and ultimately sensor performance will be demonstrated.

Morphology-Graded Silicon Nanowire Arrays via Chemical Etching: Engineering Optical Properties at the Nanoscale and Macroscale.

We report on a quick, simple, and cost-effective solution-phase approach to prepare centimeter-sized morphology-graded vertically aligned Si nanowire arrays. Gradients in the nanowire diameter and shape are encoded through the macroscale substrate via a “dip-etching” approach, where the substrate is removed from a KOH etching solution at a constant rate, while morphological control at the nanowire level is achieved via sequential metal-assisted chemical etching and KOH etching steps. This combined approach provides control over light absorption and reflection within the nanowire arrays at both the macroscale and nanoscale, as shown by UV–vis spectroscopy and numerical three-dimensional finite-difference time-domain simulations. Macroscale morphology gradients yield arrays with gradually changing optical properties. Nanoscale morphology control is demonstrated by synthesizing arrays of bisegmented nanowires, where the nanowires are composed of two distinct segments with independently controlled lengths and diameters. Such nanowires are important to tailor light–matter interactions in functional devices, especially by maximizing light absorption at specific wavelengths and locations within the nanowires.

Facile synthesis of an aminopropylsilane layer on Si/SiO2 substrates using ethanol as APTES solvent

(3-aminopropyl)triethoxysilane (APTES) is a commonly used organosilane on surface functionalization of silicon oxide surfaces. However, its deposition process from solution-phase usually involves the use of toluene, which has often been identified as crucial for the formation of an aminopropylsilane monolayer. Toluene is ranked as a problematic solvent in the guide developed by a group referred to as the solvent sub-team of CHEM21. In this work, we propose a facile synthetic route for functionalizing a silicon substrate with APTES via solution-phase approach using only solvents that are classified as recommended. The influence of the APTES concentration, reaction times and different post-deposition conditions using acetic acid and methanol were studied in order to evaluate the quality and thickness of the organosilane layers.•The method uses ethanol as APTES solvent for functionalizing silicon dioxide surfaces and only uses solvents classified as recommended.•The method uses a solution phase approach, does not require complicated equipment and can be prepared at room temperature.

Fabrication of Customized Nanogel Carriers From a UV-Triggered Dynamic Self-Assembly Strategy.

Recent advances in self-assembled nanogel carriers have allowed precise design of hierarchical structures by a low-cost solution-phase approach. Typically, photochemical strategy on the tailor of morphology and dimension has emerged as a powerful tool, because light-trigger has exceptional advantages of an instant “on/off” function and spatiotemporal precision at arbitrary time. Herein, we report a tunable manipulation of sequentially morphological transition via a “living” thiol-disulfide exchange reaction from a UV-tailored hierarchical self-assembly strategy. By varying the irradiation time, the photochemical method can easily fabricate and guide a series of attractively architectural evolution in dilute aqueous solutions, by which the improving hydrophobicity and sensitive redox-responsiveness endowed these disulfide-linked nanoparticles with remarkable capacities of abundant encapsulation, effective separation, and controlled release of hydrophobic cargoes. Notably, once the exchange reaction is suspended at any point of time by removing the UV lamp, these active sites within the nanogel carriers are instantaneous deactivated and the correspondingly structural transformations are also not conducted any more. However, if the stable inert sites are reactivated as needed by turning on the UV light, the interrupting morphology evolution can continue its previous steps, which may provide a simple and novel approach to fabricating the desired self-assemblies in solutions. With regard to this advanced functionality, various nanogel carriers with customizable structures and properties have been yielded and screened for cancer therapy. Thus, this “living” controlled self-assembled method to program morphology evolution in situ is a universal strategy that will pave novel pathways for creating sequential shape-shifting and size-growing nanostructures and constructing uniform nanoscopic functional entities for advanced bio-applications.

Automated solution-phase syntheses of alpha 1 → 2, 1 → 3 type rhamnans and rhamnan sulfate fragments

Rhamnan and rhamnan sulfate are naturally occurring carbohydrates that have important biological functions and possible therapeutic applications, but studies are limited to the microheterogeneous mixtures from natural sources. This work reports the first synthesis of any sulfated rhamnan fragments and successful automation of the process with a recently developed automated solution-phase approach using N-iodosuccinimide/trimethylsilyl triflate (NIS/TMSOTf) promotor and levulinoyl ester deprotection conditions. The automated solution-phase activation/deprotection approach was initially able to create alpha 1 → 2, 1 → 3 type rhamnan di- and trisaccharide in moderate yields. Once these targets were achieved, a process to use SO3•pyridine complex in DMF for sulfation compatible with an automated solution-phase liquid handling system was developed and successfully applied to carbohydrate sulfation to create two rhamnan sulfate fragments with differing monosulfation patterns.

Facile room-temperature synthesis of a spherical mesoporous covalent organic framework for ultrasensitive solid-phase microextraction of phenols prior to gas chromatography-tandem mass spectrometry

High-performance extraction of polar phenols from aqueous samples is challenging because of their hydrophilicity, extremely low concentration, and complicated matrices. Covalent organic frameworks (COFs) are new types of porous organic materials. In this work, spherical TPB-DMTP-COF was fabricated via a simple room-temperature solution-phase approach. The material exhibited high acid/base stability, remarkable thermostability, high crystallinity, and large surface area of 1560 m2 g−1 and thus could be an excellent coating for solid-phase microextraction (SPME) of phenols. This coating provided superior adsorption affinity toward phenols over commercial coatings. TPB-DMTP-coated fiber showed high enhancement factors (EFs, 1741–4265), and EFs increased with the number of chlorine or methyl substituents and high hydrophobicity of phenols. Hence, the strong adsorption affinity could be derived from hydrophobic and steric hindrance effects together with π−π affinity, H-bonding, van der Waals forces, and size-matching effect. The proposed approach based on TPB-DMTP-COF-coated fiber and gas chromatography-tandem mass spectrometry achieved low limits of detection (0.0048–0.015 ng L−1), wide linearity (0.05–1000 ng L−1), good precision (<8.87%), and reproducibility (<10.0%). The actual amounts of phenols ranged from 0.6 ng L−1 to 22.7 ng L−1 in underground water and reservoir water. The satisfactory recoveries (81.3–116.3%) for simultaneous analysis of five phenols were obtained. Therefore, TPB-DMTP-COF coating could be an excellent alternative for sensitive analysis of phenols at ultra-trace level in complex samples.

A hydrothermal reacting approach to prepare few-layer graphene from bulk graphite

The paper presents a simple, efficient and high-quality method for preparing few-layer graphene during the hydrothermal synthesis of magnesium silicate hydroxide (MSH) using bulk graphite as initial material. This type of graphene was characterized by high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Results show that the graphene obtained using this method is coated on the outer surface of MSH nanoparticles and stacked by 8–12 single graphene sheets with an approximate interlayer spacing of 0.34 nm. The graphene-MSH interface connects via chemical bonds of C-OH, CO and CH that formed between carbon atoms in graphene and active oxygen atoms and/or hydroxyl groups in MSH. This simple solution-phase approach offers a greater possibility in the large-yield, environmental and lattice-perfect produce of graphene using only bulk graphite as the raw material.

Novel defect-fluorite pyrochlore sodium niobate nanoparticles: solution-phase synthesis and radiation tolerance analysis.

Materials possessing a defect-fluorite pyrochlore structure can have a range of useful properties that are sought after, which include their radiation tolerance, nuclear waste immobilization, and phase stability at elevated temperatures. In this study, we demonstrate for the first time the synthesis and a detailed analysis of defect-fluorite pyrochlore sodium niobate (NaNbO3) nanoparticles. This analysis included an investigation into their stability to elevated temperatures and neutron irradiation. A surfactant-assisted solvothermal method is used to prepare nanoparticles of NaNbO3. This solution-phase approach results in the formation of crystalline nanoparticles of a defect-fluorite pyrochlore NaNbO3 at relatively low temperatures. The products had an average diameter of ∼74 ± 11 nm. The nanoparticles adopted a defect-fluorite pyrochlore phase and matched the cubic Fm3[combining macron]m space group. This pyrochlore form of NaNbO3 was found to be stable up to 500 °C. The nanoparticles transformed into the orthorhombic and rhombohedral perovskite phases of NaNbO3 along with the introduction of a pseudo-hexagonal Nb2O5 at higher temperatures. These defect-fluorite pyrochlore nanoparticles of NaNbO3 also exhibited a resistance to radiation induced amorphization. The dimensions, phase, and crystallinity of the defect-fluorite pyrochlore nanoparticles after exposure to a flux of neutrons were comparable to those of the as-synthesized product. The thermal stability and radiation tolerance of these pyrochlore nanoparticles could be useful in the design of thermally resilient materials, high temperature catalysts, and durable materials for the handling and storage of radioactive waste.

Observation of n-type behavior in Fe-doped tetrahedrite at low temperature

Tetrahedrite exhibits favorable thermoelectric properties, while also being composed of non-toxic and earth-abundant elements. Although tetrahedrite has been studied extensively as a p-type thermoelectric, n-type behavior in this material has not yet been observed. We report the first findings of n-type conductivity in tetrahedrite observed over a temperature range of 80 to 310 K, with typical p-type conductivity found at higher temperatures. Herein, we characterize electrical and thermal transport properties on these samples from 80 to 673 K. Mechanical alloying and modified polyol synthesis methods were used to synthesize Fe-doped samples (Cu12-xFexSb4S13 with x = 1, 1.3, and 1.5) by solid-state and solution-phase approaches, respectively. Elemental analysis by energy-dispersive X-ray spectroscopy was conducted to investigate the relationship between thermoelectric properties and chemical composition. A maximum ZT = 0.67 at 673 K was obtained for Cu10.5Fe1.5Sb4S13 synthesized by the modified polyol process. Our observation of negative Seebeck coefficient values in the low-temperature regime should serve as a foundation for further study of n-type behavior in tetrahedrite materials.

Peroxidase-Mimicking Nanoassembly Mitigates Lipopolysaccharide-Induced Endotoxemia and Cognitive Damage in the Brain by Impeding Inflammatory Signaling in Macrophages.

Oxidative stress during sepsis pathogenesis remains the most-important factor creating imbalance and dysregulation in immune-cell function, usually observed following initial infection. Hydrogen peroxide (H2O2), a potentially toxic reactive oxygen species (ROS), is excessively produced by pro-inflammatory immune cells during the initial phases of sepsis and plays a dominant role in regulating the pathways associated with systemic inflammatory immune activation. In the present study, we constructed a peroxide scavenger mannosylated polymeric albumin manganese dioxide (mSPAM) nanoassembly to catalyze the decomposition of H2O2 responsible for the hyper-activation of pro-inflammatory immune cells. In a detailed manner, we investigated the role of mSPAM nanoassembly in modulating the expression and secretion of pro-inflammatory markers elevated in bacterial lipopolysaccharide (LPS)-mediated endotoxemia during sepsis. Through a facile one-step solution-phase approach, hydrophilic bovine serum albumin reduced manganese dioxide (BM) nanoparticles were synthesized and subsequently self-assembled with cationic mannosylated disulfide cross-linked polyethylenimine (mSP) to formulate mSPAM nanoassembly. In particular, we observed that the highly stable mSPAM nanoassembly suppressed HIF1α expression by scavenging H2O2 in LPS-induced macrophage cells. Initial investigation revealed that a significant reduction of free radicals by the treatment of mSPAM nanoassembly has reduced the infiltration of neutrophils and other leukocytes in a local endotoxemia animal model. Furthermore, therapeutic studies in a systemic endotoxemia model demonstrated that mSPAM treatment reduced TNF-α and IL-6 inflammatory cytokines in serum, in turn circumventing organ damage done by the inflammatory macrophages. Interestingly, we also observed that the reduction of these inflammatory cytokines by mSPAM nanoassembly further prevented IBA-1 immuno-positive microglial cell activation in the brain and consequently improved the cognitive function of the animals. Altogether, the administration of mSPAM nanoassembly scavenged H2O2 and suppressed HIF1α expression in LPS-stimulated macrophages and thereby inhibited the progression of local and systemic inflammation as well as neuroinflammation in an LPS-induced endotoxemia model. This mSPAM nanoassembly system could serve as a potent anti-inflammatory agent, and we further anticipate its successful application in treating various inflammation-related diseases.

Conversion Mechanism of Soluble Alkylamide Precursors for the Synthesis of Colloidal Nitride Nanomaterials.

There are few molecular precursors that chemically convert to nitride nanomaterials, which severely limits the development of this important class of materials. Alkylamides are soluble and stable nitride precursors that can be based on the same primary amines that are often used in colloidal nanomaterial synthesis, but their conversion involves the breaking of stable C-N bonds through a mechanism that remained unknown up to now. A critical aspect of this conversion mechanism is uncovered here, involving a prelimary step whereby alkylamides are oxidized to N-alkylimines to yield NH2- amide species that are postulated to be the actual reactive precursors in the formation of indium nitride nanomaterials. Interestingly, this step also involves the concomitant reduction of indium(III) to In(0) nanodroplets, which consequently catalyze the growth of InN nanomaterials. The elucidation of the origin of the surprising reactivity of otherwise stable molecular precursors opens the door to the development of new solution-phase approaches for the synthesis of nitride materials.

Synthesis, Spray Deposition, and Hot-Press Transfer of Copper Nanowires for Flexible Transparent Electrodes.

We report a solution-phase approach to the synthesis of crystalline copper nanowires (Cu NWs) with an aspect ratio >1000 via a new catalytic mechanism comprising copper ions. The synthesis involves the reaction between copper(II) chloride and copper(II) acetylacetonate in a mixture of oleylamine and octadecene. Reaction parameters such as the molar ratio of precursors as well as the volume ratio of solvents offer the possibility to tune the morphology of the final product. A simple low-cost spray deposition method was used to fabricate Cu NW films on a glass substrate. Post-treatment under reducing gas (5% H2 + 95% N2) atmosphere resulted in Cu NW films with a low sheet resistance of 24.5 Ω/sq, a transmittance of T = 71% at 550 nm (including the glass substrate), and a high oxidation resistance. Moreover, the conducting Cu NW networks on a glass substrate can easily be transferred onto a polycarbonate substrate using a simple hot-press transfer method without compromising on the electrical performance. The resulting flexible transparent electrodes show excellent flexibility ( R/ Ro < 1.28) upon bending to curvatures of 1 mm radius.