Green approach to fabrication of a super-hydrophobic film on copper and the consequent corrosion resistance

•Green approach is proposed to fabricate super-hydrophobic film on copper.•The most possible bonding sites between Cu(II) and capsaicin are proposed.•The dependence of wettability on morphology is clarified with binarisation method.•Film acts as super-barrier to corrosion within a wide potential range.

A green approach was used to fabricate super-hydrophobic film with capsaicin (N-(4-hydroxy-3-methoxybenzyl)-8-methylnon-trans-6-enamide), pungent ingredient of cayenne. The film is composed of capsaicin that coordinates with Cu(II) through π orbital of benzene ring. Super-hydrophobic property of film can be attributed to nanospherical pores of its structure and low surface energy of its hydrocarbon chain. Super-hydrophobic film shows >99.9% efficiency as a barrier that inhibits corrosion of underlying Cu without losing its stability within a wide potential range. This performance can be attributed to isolating action and insulating property of air trapped in film.