Abstract: Provided is a method of making colloidal metal nanoparticles. The method includes the steps of: mixing a metal aqueous solution and a reducing agent to form a mixture solution in a reaction tank; heating the mixture solution and undergoing a reduction reaction to produce a composition containing metal nanoparticles, residues and gas, wherein the amount of the residues is less than 20% by volume of the mixture solution, and guiding the gas out of the reaction tank; dispersing the metal nanoparticles with a medium to obtain colloidal metal nanoparticles. By separating the reduction reaction step and the dispersion step, the method of making colloidal metal nanoparticles is simple, safe, time-effective, cost-effective, and has the advantage of high yield.

Abstract: A method of making the inorganic gold compound, such as tetrachloroauric acid, sodium tetrachloroaurate, potassium tetrachloroaurate, sodium tetracyanoaurate, and potassium tetracyanoaurate, includes the step of: treating gold with a halogen-containing oxidizing agent in a hydrochloric acid to obtain the inorganic gold compound, wherein the halogen-containing oxidizing agent excludes chlorine gas. The method of making the inorganic gold compound is simple, safe, time-effective, cost-effective, and environment-friendly, and has the advantage of high yield.

Abstract: A method of making the inorganic gold compound, such as tetrachloroauric acid, sodium tetrachloroaurate, potassium tetrachloroaurate, sodium tetracyanoaurate, and potassium tetracyanoaurate, includes the step of: treating gold with a halogen-containing oxidizing agent in a hydrochloric acid to obtain the inorganic gold compound, wherein the halogen-containing oxidizing agent excludes chlorine gas. The method of making the inorganic gold compound is simple, safe, time-effective, cost-effective, and environment-friendly, and has the advantage of high yield.