Zero-valence light transition metal

Nanoparticles of light transition metals are more difficult to prepare because of lower redox potential of the metal ions than those of the precious metal ions. In other words, light transition metal ions are difficult to reduce to zero valence, and zero-valence light transition metals are easily oxidized to ions. 

Hydroborate Reduction. Lithium or sodium tetrahydroborate and diborane can be used for reduction of metal ions, especially light transition metal ions, to produce colloidal metals. For example, colloidal copper protected by polymer was prepared by reduction of copper(II) sulfate by a large excess of sodium tetrahydroborate in the presence of PVP or other polymers (12). A similar procedure for nickel(III) chloride produced nickel boride, not zero-valence nickel metal particles. 

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