Facile Gram-Scale Synthesis of Co₃O₄ Nanocrystal from Spent Lithium Ion Batteries and Its Electrocatalytic...

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.