Symposium SF03: Emerging Thermal Materials—From Nanoscale Heat Transport, Devices and Applications, to Theories

M. Cynthia Hipwell, Texas A&M University

Tunable Thermal Conductance of Termination-Engineered MXenes through Intercalation

Written by Atif Javaid

MXenes are new class of layered two-dimensional (2D) materials that are made from selective etching of transition metal carbides and nitrides with general formula Mn+1AXn in hydrofluoric acid (HF) or HF-forming etchants. These are relatively newly discovered materials (discovered in 2011) and are widely used in energy harvesting, haptic displays, conformal/wearable electronics, battery envelopes, electromagnetic interference shielding, and thermal management. There are approximately 200 experimental demonstrations and approximately 2000 theoretical predictions of MXenes. The tunable thermal conductivity requirements include on-demand modulation, high modulation ratio, response time, reversibility, and low temperature heptics, especially for soft robotics. The monolayer MXenes have demonstrated an order of magnitude change in thermal conductivity by changing surface termination from -F to -O due to increased phonon scattering rate and reduced phonon mean free path. Cynthia Hipwell and her research team, at the Texas A&M University, characterized thermal transport performance of MXene nanosheet stacks and large-area free-standing multi-layer MXene sheets and explored the correlation between surface functionalization and thermal transport. They reported reduction in through plane conductance with increase in thickness of MXenes and experimentally demonstrated predicted dependence of MXene thermal conductivity on surface termination.