Nanoscale Materials Synthesis. 1. Solvent Effects on Hydridoborate Reduction of Copper Ions

Abstract

The reduction of CuBr2 by NaBH4 in a variety of solvents yields nanoscale metallic copper as the primary product. Although the product of this reaction is largely solvent independent, the studies show that reaction times, the total volume of gaseous products, and nanoscale particle sizes are dependent on solvent properties. The reaction occurred instantaneously in polar, protic, and acidic solvents such as methanol and ethanol. In contrast, in polar, aprotic, and coordinating solvents such as tetrahydrofuran and acetonitrile, the reaction was slow. Particle sizes increased as the rate of reaction decreased. For solvents in which similar reaction times were observed, the reaction carried out in polar, aprotic, and coordinating solvents yielded copper samples with larger particle sizes. The acid properties of the solvent controlled the amount of gas evolved in these experiments.

Copper: Synthesis Techniques in Nanoscale and Powerful Application as an Antimicrobial Agent

“…Ablation [85][86][87] Colloidal microemulsion [48,49] Physical Vapor Deposition (PVD) [88] Sonochemical [52,[89][90][91] Wire discharge [83,92] Electrochemical [25,40,82,93] Grinding [94] Microwave [43,[95][96][97] Radiolysis [98] Hydrothermal [46,82,99] Aerosol [100] Mechanical attrition [101] obtaining nanoparticles with low quality. Several physical techniques are incorporated during or after a chemical process, for example, the laser ablation requires a colloidal solution, which minimizes the chances of oxidation on the surface of the nanoparticles, and it must be placed in a vacuum chamber in order to remove or extract atoms from a bulk surface through emission of laser beam; this method is not feasible due to the complexity of the equipment and the use of high energy for the laser [26].…”

“…Regardless of the technique chosen for the synthesis of Cu PN, conditions should be controlled to adjust the particle size (lower than 100 nm) and shape of the nanoparticles (nanofibers, nanotriangles, and nanospheres), because the wide distribution particle size modified their properties [48][49][50]. Shankar and Rhim found that nanofibers and triangle and spherical nanoparticles can be obtained by using basic or acidic solution, respectively, which presented different absorbing bands, the first in the range of 280-360 nm and the second from 240 to 280 nm [51].…”

“…Cu NPs have been physically and chemically characterized in order to obtain the great amount of data to establish the physical and biological characteristics ( Table 3). The diminutive sizes of Cu NPs are also their main disadvantage because it represents a challenge for the scientific community to achieve adequate physical and chemical characterization [49,52].…”

Synthesis and Thermal Behavior of Metallic Cobalt Micro and Nanostructures

“…of stirring, NaBH 4 (Aldrich ≥ 96%) 0.0189 g dissolved in 20 ml of deionized water were introduced drop by drop. The molar ratio of NaBH 4 :CoCl 2 was purposely made larger than two in orders to ensure complete reduction of CoCl 2 [15]. The solution color changes from pale pink into black after approximately 10 min.…”

Study of Pt-M (M=Au and Co) nano-catalysts with low Pt loading for PEMFC applications

“…229 That is why in this experiment the molar ratio between NaBH 4 and CoCl 2 was just slightly higher than 2. Moreover, it was already proposed by Glavee et al, 230 final product will be as of a porous structure due to two Co atoms will be replaced by one Pt 4+ ion. show the same intensity and the same absorption peak which is located at ~510 nm.…”