BS in Materials Engineering
Materials Engineering Department
Katherine C. Chen
Silver nanoparticles were synthesized through the reduction of AgNO3 using NaBH4. The borohydride anions were adsorbed onto silver nanoparticles. The repelling forces of the borohydride anions prevented the aggregation of particles, but the addition of an electrolyte or agitation induced aggregation. A yellow hue was given off by the silver nanoparticle sol that, using a spectrophotometer, had plasmon resonance at 386 nm. The silver nanoparticles were estimated to be 10 to 20 nm in diameter. Gold nanoparticles were synthesized through the reduction of HAuCl4 using Na3C6H5O7. The gold nanoparticle sol gave off a red hue that had plasmon resonance at 515 nm. The gold nanoparticles were estimated to be 10 to 25 nm in diameter. A gold nanoparticle sol was used in informal education demonstrations for pre-middle school children in an open setting, and for middle school children in an organized setting. The older children were much more receptive to the information. The ineffectiveness of the demonstrations for the younger children was attributed to the lack of hands-on interaction involved with the nanoparticle demonstrations. The nanoparticles were also demonstrated during a college-level materials laboratory. The activity allowed the students to synthesize the nanoparticles and alter the color through aggregation. Students attempted adding PVA to the nanoparticles to create 'stained glass' as a takeaway. A list of questions was given to the students to prompt further thinking and evaluate the effectiveness of the activity. The quiz results showed a minimal increase in nanoparticle understanding, but it may have been a factor of an ineffective lab design and not asking the right questions in the quiz. The low cost and learning potential of the reduction of silver nitrate through sodium borohydride could lead to a future addition to current laboratories.