AI 中文总结
研究MXenes材料热导率差异问题，通过非平衡分子动力学模拟Ti3C2Tx，发现立体化学诱导的真空间隙导致热导率差异，指出热导率与原子密度相关，引入大体积表面终止可降低热导率，提出化学驱动设计热传输的途径。
AI 中文摘要
二维MXenes是用于热管理和光谱伪装的有前途的材料，兼具低面外热导率、低红外发射率和机械坚固性。然而，实验测得的面外热导率测量值（0.14 - 0.8 W/mK）有近一个数量级的差异，且模拟存在系统高估，这表明我们对这些材料中热传输的理解存在根本差距。本文认为这些差异源于被忽视的异质表面终止作用。通过对Ti3C2Tx的非平衡分子动力学模拟表明，这种差异源于不同尺寸表面终止共存时相邻层之间由立体化学诱导的真空间隙。即使与均匀终止有微小偏差也会大幅抑制面外热导率，使模拟值与实验定量一致。还表明热导率与原子密度强烈相关，引入大体积表面终止（包括残留水）会将热导率降低到0.3 W/mK，比均匀终止值低一个数量级且低于无序固体预测的最小热导率极限。因此，提出了一种化学驱动的途径来设计MXenes中的热传输。
英文摘要
Two-dimensional MXenes are promising materials for thermal management and spectral camouflage, combining low out-of-plane thermal conductivity with low infrared emissivity and mechanical robustness. Yet the near-order-of-magnitude spread in experimental out-of-plane thermal conductivity measurements (0.14-0.8 W/mK) and the systematic overestimation by simulations point to a fundamental gap in our understanding of heat transport in these materials. Here, we argue these differences originate in the overlooked role of heterogeneous surface terminations. Using Non-Equilibrium Molecular Dynamics simulations of Ti3C2Tx, we show that this discrepancy arises from a stereochemically induced vacuum gap between adjacent layers, formed when surface terminations of different sizes coexist. Even minor deviations from homogeneous terminations drastically suppress out-of-plane thermal conductivity, bringing simulated values into quantitative agreement with experiment. We also show that thermal conductivity scales strongly with the atomic density, and that introducing bulky surface terminations, including residual water, reduces the thermal conductivity to 0.3 W/mK, an order of magnitude below homogeneous termination values and below the minimum thermal conductivity limit predicted for disordered solids. Thus, we propose a chemistry-driven route to engineer thermal transport in MXenes.
Comments21 pages, 3 figures
