Systematic Life Cycle Environmental Impact Comparison of Alternative Synthetic Strategies for Ti₃C₂T_x MXene

Abstract

The need for more environmentally sustainable MXene syntheses was ranked by the MXene community among the top research challenges for the upcoming decades. This means that both well-established synthetic protocols and newly proposed ones need to be assessed and compared in terms of their associated environmental impacts. Despite the various number of existing synthetic methods for MXenes, only one synthesis of Ti 3 C 2 T x has been assessed from an environmental perspective, by applying the life cycle assessment (LCA) methodology. This work proposes for the first time a systematic life cycle environmental impact comparison among seven different synthetic pathways of the same Ti 3 C 2 T x MXene. Starting from the first reported synthesis, the further approaches assessed differ in terms of MAX phase precursors, etching, and delamination procedures adopted. An uncertainty analysis was also performed to determine the reliability of the obtained results, which were also used in conjunction with those related to the measured bulk electrical conductivity of the MXene produced together with the obtained density values of opportunely prepared Ti 3 C 2 T x freestanding films. This allows accounting for the necessary different quality of the obtained products, highlighting the better trade-off solutions between low environmental impacts, high electrical conductivity, and low weight of the potentially developed Ti 3 C 2 T x MXene-based devices.