Bio-inspired reinforcement of MXene composites: tannic acid and TEMPO-oxidized cellulose nanofibers for enhanced mechanical and oxidation stability

MXenes, two-dimensional (2D) metal carbides, and nitrides exhibit exceptional electrical conductivity, hydrophilicity, and tunable surface properties, making them highly attractive for applications in energy storage, catalysis, and sensing. However, MXenes (e.g., Ti₃C₂T_x) suffer from mechanical brittleness and poor oxidation stability, limiting their applicability and long-term durability. In this study, we present a composite integrating MXene with TEMPO-oxidized cellulose nanofibers (TOCN) derived from tunicate and tannic acid (TA). TOCN possesses high mechanical strength due to the high crystallinity of tunicate, while carboxyl groups introduced by TEMPO-mediated oxidation facilitate improved interfacial bonding with MXene layers. TA, a natural polyphenol with excellent oxidation resistance, further integrates MXene and TOCN by strong hydrogen bonding. The fabricated MXene/TA/TOCN composite demonstrated significantly improved mechanical strength of 98.3 MPa and oxidation resistance while maintaining good electrical conductivity (81.4 S/cm). This synergistic integration of TA and TOCN highlights the potential of MXene/TA/TOCN for energy storage devices and flexible electronic applications.

Graphical abstract

We integrated tannic acid (TA) and TEMPO-oxidized cellulose nanofibers (TOCN) with MXene to overcome its inherent poor oxidative stability and durability. The resulting MXene/TA/TOCN composite demonstrated enhanced stability in an acidic solution and under ultrasonication, highlighting our approach to address its critical limitations