Anode for Nanoparticles, Cathode for Alloy: A Dual-Functional Electrochemical Strategy for Spent ITO Upcycling

The production and disposal of indium tin oxide (ITO) targets are rapidly increasing with the expansion of cutting-edge optoelectronic and display technologies. To reduce reliance on indium (In) resources, there is an urgent need to develop efficient recycling strategies for spent ITO (s-ITO). Here, we propose a facile electrochemical recovery approach in which s-ITO serves as both the anode and cathode in Na₂SO₄ solution. This dual-function system enables selective anode conversion of s-ITO into nanoscale Sn-doped In₂O₃ particles and cathode electro-deoxidation into an In-Sn alloy, delivering an overall current-utilization efficiency exceeding "120%." Combined experiments and density functional theory (DFT) reveal fundamentally differentiated electrode pathways: anodic conversion proceeds through lattice oxygen mechanism (LOM) deconstruction with oxygen-vacancy formation and structural destabilization, whereas cathodic recovery is governed by oxygen removal and in situ alloying. The process remains stable under 150 A scale-up electrolysis over eight cycles, with the anode enabling parallel recovery and the cathode enabling recovery toward the In-Sn alloy. These findings establish a mechanism-informed, acid-free, and dual-functional route for the closed-loop upcycling of s-ITO.