Multimodality of Structural, Electrical, and Gravimetric Responses of Intercalated MXenes to Water
ES Muckley and M Naguib and HW Wang and L Vlcek and NC Osti and RL Sacci and XH Sang and RR Unocic and Y Xie and M Tyagi and E Mamontov and KL Page and PRC Kent and J Nanda and IN Ivanov, ACS NANO, 11, 11118-11126 (2017).
Understanding of structural, electrical, and gravimetric peculiarities of water vapor interaction with ion-intercalated MXenes led to design of a multimodal humidity sensor. Neutron scattering coupled to molecular dynamics and ab initio calculations showed that a small amount of hydration results in a significant increase in the spacing between MXene layers in the presence of K and Mg intercalants between the layers. Films of K- and Mg-intercalated MXenes exhibited relative humidity (RH) detection thresholds of 40.8% RH and showed monotonic RH response in the 0-85% RH range. We found that MXene gravimetric response to water is 10 times faster than their electrical response, suggesting that H2O induced swelling/contraction of channels between MXene sheets results in trapping of H2O molecules that act as charge-depleting dopants. The results demonstrate the use of MXenes as humidity sensors and infer potential impact of water on structural and electrical performance of MXene-based devices.
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