A novel finding: cubic particles of CuCl can be prepared on the surface of the commercial copper foil via an immersion method at room temperature in which the preparing solution only contained the commercial copper foil, CuSO₄ solution and an ionic liquid of 1-butyl-3-methylimidazole chloride. To our knowledge, this is a novel finding which has never been reported previously.  Please refer to the web site of Journal of Alloys and Compounds 835 (2020) 155302