Center for Bioinformatics, Simulation and Modeling (CBSM), Faculty of Engineering, Universidad de Talca, 1 Poniente 1141, Talca, Chile.
INFIQC, CONICET, Departamento de Química Teórica y Computacional, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Phys Chem Chem Phys. 2023 Feb 15;25(7):5489-5500. doi: 10.1039/d3cp00064h.
Copper (Cu) nanofluids (NFs) have attracted attention due to their high thermal conductivity, which has conferred a wide variety of applications. However, their high reactivity favors oxidation, corrosion and aggregation, leading them to lose their properties of interest. Copper capped by graphene (Cu@G) core@shell nanoparticles (NPs) have also attracted interest from the medical and industrial sectors because graphene can shield the Cu NPs from undesired phenomena. Additionally, they share some properties that expand the range of applications of Cu NFs. In this work, new Morse potentials are reported to reproduce the behavior of Cu@G NPs through molecular dynamics. Coordination-dependent Morse parameters were fitted for C, H, and Cu based on density functional theory calculations. Then, these parameters were implemented to evaluate the thermal conductivity of Cu@G NFs employing the Green-Kubo formalism, with NPs from 1.5 to 6.1 nm at 100 to 800 K, varying the size, the number of layers and the orientation of the graphene flakes. It was found that Cu@G NFs are stable and have an improved thermal conductivity compared to the Cu NFs, being 3.7 to 18.2 times higher at 300 K with only one graphene layer and above 26.2 times higher for the graphene-trilayered NPs. These values can be higher for temperatures below 300 K. Oppositely, the size, homogeneity and orientations of the graphene flakes did not affect the thermal conductivity of the Cu@G NFs.
铜（Cu）纳米流体（NFs）由于其高导热性而受到关注，这为其提供了广泛的应用。然而，它们的高反应性有利于氧化、腐蚀和聚集，导致它们失去了感兴趣的特性。铜被石墨烯（Cu@G）核壳纳米颗粒（NPs）覆盖也引起了医疗和工业领域的兴趣，因为石墨烯可以防止 Cu NPs 发生不希望出现的现象。此外，它们具有一些共同的特性，扩展了 Cu NFs 的应用范围。在这项工作中，报道了新的 Morse 势能，通过分子动力学来再现 Cu@G NPs 的行为。基于密度泛函理论计算，为 C、H 和 Cu 拟合了依赖于配位的 Morse 参数。然后，使用 Green-Kubo 公式来评估 Cu@G NPs 的导热系数，采用的 NPs 尺寸为 1.5 到 6.1nm，温度为 100 到 800K，变化的因素有尺寸、层数和石墨烯薄片的取向。结果表明，与 Cu NFs 相比，Cu@G NFs 更稳定，导热性能也得到了提高，在 300K 时，仅一层石墨烯的导热系数提高了 3.7 到 18.2 倍，而三层石墨烯的 NPs 的导热系数提高了 26.2 倍以上。在 300K 以下的温度下，这些值可能会更高。相反，石墨烯薄片的尺寸、均匀性和取向对 Cu@G NFs 的导热系数没有影响。
