Phase transfer-assisted indium recovery from spent liquid crystal display panels and its extension in preparing indium-based electrocatalysts for CO2 reduction

Abstract

Transforming discarded electronic devices into low-cost and high-efficiency catalysts presents a win–win approach to address the scarcity of rare resources and sustainable energy challenges. Herein, we report an effective strategy that combines an ethanol-mediated dodecylamine (DDA) phase transfer with hydrothermal methods for facilitating the facile synthesis of indium (In)-based nanomaterials from the leachates of liquid crystal display panels (LCDPs) toward high-efficiency electrochemical CO2 reduction reaction (eCO2RR). In this strategy, the rapid formation of coordinating compounds between the –NH2 group of DDA and metal ions facilitates the separation of In3+ cations from the acidic LCDPs leach solution by transferring them into an organic phase, which are then converted into InOOH nanoparticles with abundant oxygen vacancies (denoted as In-LCDPs and hereafter) through a low-temperature hydrothermal process. The eCO2RR evaluations confirm the superior electrocatalytic performance of the In-based nanoparticles produced from the LCDPs. In specific, within a broad potential range (−0.77 to −1.17 V vs RHE), the In-LCDPs show a Faradaic efficiency for formate (FEformate) of 85 %, with the highest FEformate of 90.23 % at −0.97 V vs RHE, which is comparable to the FEformate (93.8 % at −0.97 V vs RHE) of In-based catalyst prepared from pure In precursors using the same method. Further investigations reveal that the Sn and Al impurities have minimal impact on the catalytic performance of In-LCDPs, while the presence of Fe3+ impurities significantly enhance the production of hydrogen during the eCO2RR. This work might have provided a scalable pathway to transform LCDPs into value-added electrocatalysts for eCO2RR.