This paper reports the influence of halide ions on the morphology-controlled synthesis of Cu nanocrystals in the aqueous phase. Cu nanocrystals with controlled shapes, including 2D plates, 1D wires, and 3D polyhedral particles were obtained by a reduction reaction between Cu-halide and ascorbic acid, and branched polyethyleneimine (BPEI) was used as a stabilizing agent in the process. Density functional theory (DFT) calculations showed that this morphological control was caused by the selective adsorption of halide ions depending on the facets of the Cu nanocrystals. The thickness and lateral size of the Cu nanoplates were tuned easily using a co-stabilizer, the addition of Br À ions, and varying the pH of the reaction solution. Furthermore, the resulting Cu nanocrystals possessed great stability, showing very little change after exposure to the ambient atmosphere for 40 days. Overall, this synthetic procedure could be a potential method for the mass synthesis of morphology-controlled Cu nanocrystals for industrial applications because of the superior reaction conditions, such as the air atmosphere, low reaction temperature, water-phase-based synthetic condition as well as the use of nontoxic and inexpensive reagents.
Ag–Cu–Pt–Pd quadrometallic nanoparticles which small Pt and Pd nanoparticles were attached on the surface of AgCu Janus nanoparticles were firstly synthesized by sequential reduction of Pt and Pd precursor in the presence of Janus AgCu bimetallic nanoparticles as seeds in an aqueous solution. Even though there was a small amount of Cu2O on the surface, the synthesized nanoparticles were mainly composed of four independent metallic part, not alloy parts. By theoretical calculation and growth mechanism study, we found that different reducing rate between Ag+ and Cu2+ and sequential reduction of Pt and Pd precursors would be key roles for the formation of the quadrometallic nanoparticles.
This work describes a simple and aqueous-phase route for synthesis of Cu nanowires (Cu NWs) having a long length of 140−180 µm, a high aspect ratio of more than 350, and long-term stability. High-quality Cu NWs were synthesized by reduction of CuCl 2 with ascorbic acid in the presence of branched polyethyleneimine (BPEI) in an aqueous solution at 90 °C. The synthesized uniform Cu NWs showed long-term stability without the formation of Cu oxides on the surface of the NWs after being stored at room temperature for 40 days. Interestingly, we found that Cl − in the reacting solution played a key role in the formation of long Cu NWs. We also investigated the influence of various experimental conditions including the weight ratio of BPEI/CuCl 2 , the pH of the reacting solution, and the reaction temperature on the length, morphology, and stability of Cu NWs.branched polyethyleneimine (BPEI) in an aqueous-phase at 90 °C. The synthesized uniform Cu NWs showed long-term stability without formation of Cu oxides on the surface of the NWs after being stored at room temperature for 40 days. Interestingly, we found that Cl − in the reacting solution played a key role in the formation of long Cu NWs. We also investigated the influence of various experimental conditions including the weight ratio of BPEI/CuCl 2 , the pH of the reacting solution, and the reaction temperature on the length, morphology, and stability of Cu NWs. Experimental SectionMaterials. BPEI (MW = 750,000, 50 wt.% solution in water), cupric chloride (CuCl 2 , ≥99%), copper(II) nitrate (Cu(NO 3 ) 2 ), ascorbic acid (C 6 H 8 O 6, purity ≥99%), sodium hydroxide (NaOH, ≥98%),and nitric acid (HNO 3 , ~ 70 %) were purchased from Aldrich and were used without further purification. Synthesis of Cu NWs.In a typical synthesis, 0.135g of CuCl 2 and 0.04g of BPEI were dissolved in 2 mL of deionized water in air under magnetic stirring at room temperature. Meanwhile, 3mL of 0.167 M aqueous ascorbic acid was added to the reaction solution using a micropipette (final volume of the solution was 5 ml and the weight ratio of BPEI/CuCl 2 was 0.3). The pH of the resulting solution was 2.9. The resulting mixture was aged at 90°C for 3 h, and was then cooled down to room temperature. The product was collected by repeated centrifugation and washing with water three times to remove the excess reagents.Characterization. TEM and high-resolution TEM (HRTEM) images were captured using a JEM-2100F microscope operating at 200 kV. Scanning electron microscopy (SEM) images were obtained using a LEO SUPRA 55 microscope. Powder X-ray diffraction (XRD) patterns were obtained using a Rigaku D-MAX/A diffractometer at 35 kV and 35 mA. Fourier transform infrared spectroscopy (FTIR) analysis was performed using a Jasco FTIR-6100 equipped with an ATR assembly in transmission mode. X-ray photoelectron spectroscopy (XPS) data was obtained using a Thermo Scientific K-Alpha spectrometer. Results and Discussion 5We observed a growth behavior of the Cu NWs by taking samples at various reaction stages and a...
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