Electrochemical upcycling of spent ITO via charge-induced deconstruction

Abstract

Abstract Spent indium tin oxide (s-ITO, the mass ratio of In 2 O 3 to SnO 2 is approximately 9:1) represents the main secondary resource for the rare metal indium, possessing exceptionally potential for reutilization. However, traditional hydrometallurgical or pyrometallurgical recycling methods grapple with substantial challenges, including low product purity, lengthy processes, and environmental pollution. This paper presents an electrochemical upcycling strategy for spent ITO based on charge-induced deconstruction, effectively addressing the aforementioned issues. In this approach, spent ITO serves as the anode in an aqueous electrolysis system. The number of oxygen vacancies on the ITO surface increases drastically under charge excitation, leading to weakened metal-oxygen bonds and the subsequent release of indium and tin ions into the electrolyte. These ions then migrate to the cathode, where high-purity indium tin alloy is obtained by leveraging the differences in electrochemical properties between impurity ions and the target metal ions. Notably, the electrolyte employed in this process can be reused, which significantly reduces wastewater generation. Through systematic optimization of electrolysis parameters, a cathode current efficiency of 71.12% and an energy consumption of 4.87 kWh kg −1 are achieved in a hundred-ampere scale trial, fully demonstrating the industrial applicability of this method.