LAUSR

In this study, we demonstrate a new approach to easily prepare spinel Co3O4 nanoparticles (s-Co3O4 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-Co3O4 NPs showed better electrocatalytic properties toward the oxygen evolution reaction (OER) in comparison to previously reported Co3O4 NPs and nanowires, which could be due to the more exposed electrocatalytic active sites on the s-Co3O4 NPs. Moreover, the electrocatalytic activity of the s-Co3O4 NPs was comparable to the previously reported RuO2 catalysts. By taking advantage of the proposed recycling route, we would expect that various valuable transition metal oxide NPs could be prepared from SLIBs.