Molecular Passivation of Cu via Spontaneous Aryl Diazonium Grafting

Copper is among the most-used metals in our daily life and in industry, but its thermal and electronic conductivities may be affected by the corrosion occurring in practical use. Molecular passivation represents a promising method to enhance the corrosion resistance of copper, but so far, it remains challenging to passivate the surface of copper with a robust nanolayer of small molecules. Here, we apply aryl diazonium grafting as a facile and efficient method to enhance the chemical resistance of copper materials of different sizes and shapes under mild conditions. We take advantage of the instability of aryl diazonium salts to passivate the surface of copper with a nanolayer of aryl groups, which endows copper not just with enhanced thermostability but also with improved corrosion resistance against solutions of alkali, hydrogen peroxide, sulfide, and salt. With an auxiliary ligand, the corrosion rate of aryl-modified copper foil can be as low as 3.12 μm yr^-1 in alkaline media, corresponding to an inhibition efficiency of 95.9%. We expect that the ease of operation, the versatility of diazonium chemistry, and the high inhibition efficiency of aryl passivation nanolayers will make our protocol applicable for Cu passivation in practical uses.