Gold, Silver Nanoparticles And C-dots

The study of nanoparticles could be traced back to Michael Faraday’s erawhen the great physicist noticed the transmittance of green light through thingold leaf. He then introduced several methods of nanomaterial synthesis, andfound an interesting phenomenon that Au nano-particles would aggregate afterthe addition of nonorganic salt which was explained latterly that nonorganic saltdestroys the electric balance on the surface of metal nano-particles which plays akey role in the resistance of aggregating. And this is well known now amongnano-tech researchers.This article contains two parts and will respectively introduce micro-plasmasreduction of silver or gold nano-particles and micro-plasma induced synthesismethod of quantum carbon dots, as well as chemical method.The first half of this article is related to Au/Ag nanoparticles which has beenunder abundant researches in both application, e.g. working as chemical catalystor environmental&biology sensors, and synthesis methods for decades. Thefirst part mainly focuses on the synthesis of Ag/Au nano-particles. Typically, allthe methods could be concluded by the preparing precursor: Ag+or Au+plays as precursor named small to big (STB) route and larger Ag or Au particles plays asprecursor named big to small (BTS) route. Of the two routes, STB is a muchmore common one, since many methods belong to this route, such as sodiumborohydride reduction and sodium citrate etc. The micro-plasma reductionmethod is also a variation of this route, which was first reported by R. MohanSankaran in2008. I will describe how the relevant factors, e.g. current,temperature, concentration and helium flow etc. influence the final Ag or Aunano-particles.The second half of this article will introduce two new methods of carbonquantum dots (or c-dots) synthesis after a brief review of reported methods.Similarly, all the methods belong to two routes: small to big (STB) whichindicates that carbon atoms of c-dots are from small or big organic molecularand big to small (BTS) which indicates carbon atoms from large carbon crystals,such as graphite and carbon tubes. My methods both belong to STB, and theyare micro-plasma induced method (MPIM) and chemical method (CM) whichwas found in the study of MPIM coincidently. Both of them are fast and greenways, especially the CM which is an auto chemical process and don’t need anyenergy input.