A bio-inspired MXene/quaternary chitosan membrane with a “brick-and-mortar” structure towards high-performance photothermal conversion

Abstract

MXenes (Ti₃C₂T_x) as two-dimensional nanomaterials have demonstrated great potential in energy storage, electromagnetic interference shielding and catalysis. However, the mechanical fragility of MXenes and their vulnerability to oxidation in a water–oxygen environment severely limit their practical application. Herein, inspired by the “brick and mortar” structure of natural nacre, a flexible MXene/quaternary chitosan (QCS) membrane with high mechanical robustness, outstanding antioxidant activity, and tailored electronic conductivity was developed for efficient photothermal conversion. The intercalation and confinement of positively charged QCS molecular chains between MXene nanosheets largely enhance the mechanical strength of MXene/QCS membranes by improving the interfacial interaction. Arising from the electrostatic interaction and hydrogen bonding between MXene nanosheets and QCS molecular chains, MXene/QCS membranes simultaneously possess a high tensile strength of 50.93 MPa and a Young's modulus of 4.4 GPa. The electronic conductivity can be easily tailored by controlling the MXene-QCS weight ratio, achieving a maximum value of 128 S m⁻¹. Interestingly, the antioxidant nature of QCS contributes to an outstanding radical scavenging capacity of over 80%. More importantly, the developed MXene/QCS membrane demonstrates efficient photothermal conversion with the rate of the temperature increase up to 1.5 °C min⁻¹ under simulated sunlight irradiation, showing great potential in the fields of photothermal therapy and solar steam generation.