Without the use of a template, sub-micron scaled cobalt-aluminum (Co-Al) net (mesh) sheets can be obtained via a double-potential step electrodeposition method from a Lewis acidic aluminum chloride/trimethylamine hydrochloride (AlCl3-TMHC) room temperature ionic liquid containing cobalt chloride (CoCl2). During the electrodeposition, the electrode potential was repeatedly stepped between a more negative potential E-1 for a time period of t(1) and a less negative potential E-2 for a time period of t(2). The step potentials and step durations controlled the growth of the Co-Al sheet, and therefore, the physical dimensions of the net-like Co-Al. The electrodeposited Co-Al nets were characterized by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). However, due to the high sensitivity of aluminum and cobalt toward oxygen, the electrodeposited Co-Al micro nets quickly turned into the corresponding metal oxides when exposed to the air. (C) 2018 The Electrochemical Society.