Achieving Full Redispersion of Dried MXene Monoliths via Trace Metal Cation Intercalation.

Abstract

MXenes, a class of 2D transition metal carbides and nitrides, exhibit exceptional electrical conductivity and solution dispersibility, making them promising materials for various applications. However, their long-term stability remains a critical challenge due to oxidation in aqueous dispersions. While the transformation of these dispersions into water-redispersible dry monoliths is highly desirable, achieving this has proven difficult. This study introduces a facile approach to enhance the redispersion yield of dried MXene monoliths by incorporating trace amounts of metal cations (Li⁺, Mg²⁺, and Al³⁺) into aqueous dispersions prior to lyophilization. These cations intercalate between MXene sheets, acting as atomic pillars that inhibit face-to-face restacking and facilitate water infiltration during redispersion. Systematic investigations reveal that optimal cation concentrations significantly improve redispersion efficiency without inducing flocculation, achieving yields of up to 100% for Li⁺-modified MXenes. Characterization of redispersed MXene nanosheets confirms preserved morphology and structural integrity. Furthermore, compared to the pristine MXene counterparts, MXene films made from cation-aided redispersions show higher electrical conductivity and electromagnetic interference shielding performances. This simple yet effective strategy addresses key challenges in MXene storage and processing, enabling reliable solution-based fabrication for energy storage, sensing, and electronic applications.