Gold chemical reduction

Generally, MPCs are prepared by chemical reduction of gold ions in the presence of thiols. The average core size can be controlled in the range of 2-10 nm by controlling the preparation conditions, such as the molar ratios of gold ions and RSH. However, control of size at an atomic resolution is not feasible by this approach. 

Nanoscale Metallics. Many of the metallization materials previously discussed, such as gold, can be developed into fine particles through either chemical reduction from a metal salt or from vaporization of the bulk metal.89 In fact, metals, such as gold, silver, palladium, and iron, can be harvested in elemental form from vegetation and grains that have been planted... 

Jana, N.R., Gearheart, L., and Murphy, C.J., Evidence for seed mediated nucleation in the chemical reduction of gold salts to gold nanoparticles, Chem. Mater., 13, 2313, 2002. 

It has been established that most cathode metals are to some extent soluble in chromic acid solutions, and ions will enter the solution in the highest available oxidation state [e.g. copper(II), gold(III)]. Polarization of the cathode will then cause reduction to lower oxidation states [kinetic factors will prevent the prior reduction of chromate(VI)], then new low-valent species may then initiate a chemical reduction of the chromium(Vl). Chromium deposition occurs within the potential range for the evolution of dihydrogen and, indeed, the latter is the dominant cathode process with the result that typically cathode current efficiencies of only 10-20% are achieved (see equation 9). 

The study of nanosized particles has its origin in colloid chemistry, which dates back to 1857 when Michael Faraday (1791-1867) set out to systematically investigate the optical properties of thin hhns of gold. Faraday prepared a suspension of ultra-small metaUic gold particles in water by chemically reducing an aqueous solution of gold chloride with phosphorus (Faraday, 1857). To this day, nanoscale metal particles are stiU produced by chemical reduction in aqueous solutions. 

---