Facile Gram-Scale Synthesis of Co 3 O 4 Nanocrystal from Spent Lithium Ion Batteries and Its Electrocatalytic Application toward Oxygen Evolution Reaction.

In this study, we demonstrate a new approach to easily prepare spinel Co 3 O 4 nanoparticles ( s -Co 3 O 4 NPs) in the gram-scale from the cathode of spent lithium ion batteries (SLIBs) by the alkali leaching of hexaamminecobalt(III) complex ions. As-obtained intermediate and final products were characterized with powder X-ray diffraction (PXRD), Ultraviolet-Visible (UV-Vis), Fourier transform infrared (FTIR), and Transmission electron microscopy (TEM). Additionally, the synthesized s -Co 3 O 4 NPs showed better electrocatalytic properties toward the oxygen evolution reaction (OER) in comparison to previously reported Co 3 O 4 NPs and nanowires, which could be due to the more exposed electrocatalytic active sites on the s -Co 3 O 4 NPs. Moreover, the electrocatalytic activity of the s -Co 3 O 4 NPs was comparable to the previously reported RuO 2 catalysts. By taking advantage of the proposed recycling route, we would expect that various valuable transition metal oxide NPs could be prepared from SLIBs.