Electrochemical upcycling of indium-gallium-zinc oxide scraps

At present, the processes of recovering indium-gallium-zinc oxide (IGZO) scraps through hydrometallurgy, pyrometallurgy, or molten salt electro-deoxidation are cumbersome, impurities cannot well be effectively removed, and the environmental benefits are inferior. We herein firstly propose a facile electrochemical method for upcycling of IGZO scraps in ammonium salt aqueous solution at ambient temperature. The feasibility of electrodeoxidation of IGZO in aqueous solution has been verified, using IGZO scraps without further crushing as the cathode and anode. The electro-deoxidation behavior of various oxides exhibits differentiation, among which indium oxide is the most easily deoxidized. This difference hinders the formation of a dense alloy layer on the surface of the IGZO substrate, facilitating the transfer of oxygen ions and enabling continuous electrodeoxidation. Impurities such as aluminum and silicon can be significantly removed, with removal rates of 95.8 % and 75.7 %, respectively, which is also attributed to the difference in electrochemical reduction ability between impurity oxides and IGZO, as well as the solid-state existence of cathode products. The process of upcycling IGZO scraps contributes to recovery with straightforward operation and more adaptable implementation environment, which endows it with optimistic application potential.