DefinePK

Abstract

The synthesis of nanomaterials have attracted a great deal of attention these recent years due to their wide application in many scientific and technological field. Silver nanoparticles, among all other metals, have been investigated because of their unique optical, electronic and chemical properties that depends on their shape and sizes. The main objective of this work is to study the effect of reducing agent to surfactant ratio on the morphology and optical properties of silver nanoparticles. It is believed that the ratio of reducing agent to surfactant plays a significant roles in controlling the size and shapes of the synthesized nanoparticles. In this work, the silver nanoparticle was firstly synthesized via chemical reduction method of AgNO3 with the help of Sodium Borohydride as a reducing agent and Cetyltrimethylammonium Bromide (CTAB) as a surfactant. Different concentration of CTAB and NaBH4 were used in this study ranging from 0.5mM to 1.0mM and 2mM to 4mM, respectively. From this study, it can be observed that high concentration of NaBH4 to low concentration of CTAB produces a larger particles as the presence of CTAB at low concentration in the solution is not enough to inhibit the rapid growth of AgNPs. Meanwhile, the opposite effect were observed at low concentration of NaBH4 to high concentration of CTAB where the AgNPs formed are much more distributed as the growth of silver atoms were inhibited after the reduction process occurs. The low concentration of NaBH4 causes the reduction of silver ions to be at a slower phase, giving time to the CTAB to form a barrier and inhibit growth of AgNPs and thus, avoiding agglomeration. The different reducing agent and surfactant concentration used give rise to the effect of reducing agent to surfactant ratio towards the morphology and optical properties of as-synthesized AgNPs. The resulting AgNPs were then characterized by X-ray diffraction analysis, Field Emission Microscopy (FESEM)and UV-vis analysis. Results from UV-Vis showed the highest absorbance peak at ~410 nm which indicates the silver nanoparticles formation. From the result obtained, it can be suggested that the best ratio of reducing agent to surfactant is at 2.00 with NaBH4 and CTAB concentration at 3 mM and 1.5 mM respectively. At this ratio, the distribution of AgNPs are more improved with less agglomeration.