Intercalation-deintercalation engineering of van der Waals stacked MXene films for wearable thermoelectrics and sensing

Integrating materials into heterostructures represents a powerful approach for optimizing interfacial properties and electronic performance. Two-dimensional MXenes, such as Ti₃C₂T_x, are highly promising for thermoelectric applications due to their exceptional electrical conductivity and mechanical flexibility. However, their thermoelectric performance is hindered by a low Seebeck coefficient (∼5 μV K⁻¹). This work developed an organic intercalation–deintercalation strategy to fabricate an all-MXene van der Waals (vdW) stacked Ti₃C₂T_x/Mo₂TiC₂T_x heterostructure film. This approach faciliated effective dispersion, controlled stacking, and precise regulation of interlayer spacing, ensuring robust structural integrity. The resulting heterostructure achieved a tripled Seebeck coefficient (14.7 μV K⁻¹) and a 7-fold enhancement in power factor (16.3 μW m⁻¹ K⁻²), primarily attributed to interfacial effects at metal–semiconductor junctions. Additionally, the film demonstrated outstanding photothermoelectric conversion for efficient heat-to-electricity transformation under light irradiation. Its multifunctional sensing capabilities, including tactile, respiratory, and stress sensing, support diverse applications such as speech assistance, real-time health monitoring, and wearable photothermal management. These findings underscore the potential of innovative vdW stacking strategies in advancing flexible thermoelectric generators, photothermoelectric systems, and multifunctional sensors.