MXene-functionalized SWCNT/polyurethane nanocomposite for flexible thermoelectric module

Single-walled carbon nanotubes (SWCNT) are efficient materials for thermoelectric modules owing to their high electrical conductivity and appreciable Seebeck coefficient, which facilitate the fabrication of flexible energy-harvesting devices. SWCNT were functionalized with an exfoliated MXene structure using noncovalent bonding, which enhanced their thermoelectric properties. MXene was combined with SWCNT via vacuum filtration to fabricate free-standing films with SWCNT contents ranging from 2 to 100 wt%. The resulting composite films exhibited p-type thermoelectric behavior. The composite containing 50 wt% SWCNT and 50 wt% MXene exhibited the highest Seebeck coefficient (35.26 µV K^-1) and electrical conductivity (46 498 S m^-1) with a power factor of 57.8 µW m^-1 K^-2. These values were higher than those of pure SWCNT, which showed a Seebeck coefficient of 28.93 µV K^-1, a power factor of 27.1 µW m^-1 K^-2, and an electrical conductivity of 32 362 S m^-1, respectively. The optimized 50 wt% SWCNT/MXene composition was subsequently used to form a polyurethane nanocomposite using a co-solvent technique. The disulfide chain-extended polyurethane served as the polymer matrix, promoting uniform dispersion of the fillers in the thermoelectric module. The fabricated module provided an average Seebeck coefficient of ∼197.49 µV K^-1 over a temperature difference ranging from 24.30 to 47.50 K. The fabricated six-leg thermoelectric module generated a maximum power output of 0.95 µW. This modification is advantageous for flexible thermoelectric applications.