Colloids are a classic example of chemically controlled nanostructures.
More recently, electrochemical procedures have been developed as have numerous sol-gel synthetic procedures. Reduction Method Inorganic salts of metal ions can be reduced in solution to form nanocrystals of the metal. A common reductant comes from the family of reactants known as alkali metal hydrotriorganoborates. A related process uses polyols, such as ethylene glycol, as both solvent and reductant. Alkalids and electrides have also been obtained, allowing the reducing processes to occur at quite low temperatures.