All-Mxene Thermoelectric Nanogenerator

MXenes have been widely investigated in energy storage, electromagnetic interference shielding, sensing, electronic, and photonic applications. Some MXenes have been predicted to have outstanding thermoelectric (TE) properties, but relevant explorations are very limited. Herein, the TE performance of Mo2TiC2Tx and Nb2CTx MXenes are carefully controlled into n- and p-type, respectively, by organic molecule intercalation and thermal treatment. Optimized Mo2TiC2Tx and Nb2CTx MXenes show thermoelectric power factor (PF) of 13.26 and 11.06 µW m-1 K-2 at room temperature, respectively. Combing Ti3C2Tx MXene as a contact electrode owing to its high electrical conductivity (up to 8000 S cm-1 in this study), we have successfully designed and fabricated all-MXene flexible and integrated TE nanogenerators. The MXene TE nanogenerator was fabricated using 20 p-n units and could produce an output voltage and power of 35.3 mV and 33.9 nW, respectively, under a temperature difference of 30 °C. Although this performance is below classical thermoelectric materials, it is comparable to other solution-processed 2D materials, being developed for nanogenerators applications.