Two-dimensional MXene materials with high electrotonic conductivity, good chemical stability, and unique laminar structure show great potential in the field of electrochemistry. In contrast to the widely concerned electrical properties, studies on the thermal properties of MXene materials are very limited. This paper presents a comprehensive analysis of the thermal properties of Ti3C2Tx MXene thin film. Thermal diffusivity and thermal conductivity of Ti3C2Tx films are characterized by the transient electro-thermal technique. The experimental results show a 16% enhancement in thermal conductivity when the temperature is increased from 307 K to 352 K. The phonon transport contributes substantially to thermal conductivity compared with electron transport. Molecular dynamic simulation is employed to further investigate the role of phonon thermal transport of Ti3C2 layer. It is found that the combined effect of specific heat capacity, stacking structure and internal stress states is responsible for the thermal transport performance of Ti3C2Tx MXene thin film.
20 May 2022 in International Journal of Hydrogen Energy
This work reports the dynamic behaviors of graphene aerogel (GA) microfibers during and after continuous wave (CW) laser photoreduction. The reduction results in one‐order of magnitude increase in the electrical conductivity. The experimental results reveal the exact mechanisms of photoreduction as it occurs: immediate photochemical removal of oxygen functional groups causing a sharp decrease in electrical resistance and subsequent laser heating that facilitates thermal rearrangement of GO sheets towards more graphene‐like domains. X‐ray and Raman spectroscopy analysis confirm that photoreduction removes virtually all oxygen and nitrogen containing functional groups. Interestingly, a dynamic period immediately following the end of laser exposure shows a slow, gradual increase in electrical resistance, suggesting that a proportion of the electrical conductivity enhancement from photoreduction is not permanent. A two‐part experiment monitoring the resistance changes in real‐time before and after photoreduction is conducted to investigate this critical period. The thermal diffusivity evolution of the microfiber is tracked and shows an improvement of 277 % after all photoreduction experiments. A strong linear coherency between thermal diffusivity and electrical conductivity is also uncovered. This is the first known work to explore both the dynamic electrical and thermal evolution of a GO‐based aerogel during and after photoreduction.
The surface and grain boundary scattering impact on the electrical and thermal conduction in the thin metallic films coated on organic substrates has not been studied thoroughly. In this work, we study heat and electron transport in the 6.4 nm thin Au films supported by polyimide (PI) substrate using the transient electro-thermal technique. Thermal and electrical conductivities of 6.4 nm thin Au film are much smaller than bulk value. The thermal and electrical conductivities of 6.4 nm Au film deposited on the PI fiber are reduced by 59.3% and 76.8% in the comparison with the value of bulk Au. For PI film, the reduction of thermal and electrical conductivities is 47.9% and 46.3%. Lorenz numbers of 6.4 nm Au film supported by PI fiber and PI film are 4.51 × 10−8 WΩK−2 and 2.12 × 10−8 WΩK−2, respectively. The thermal conductivities of PI fiber and PI film are 0.87 Wm−1K−1 and 0.44 Wm−1K−1. The results reveal that PI is a suitable substrate material in the flexible electronic devices field.