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BSTRACT Graphene foam (GF)—a three-dimensional network of hollow graphene branches—is a highly attractive material for diverse applications. However, to date, the heat dissipation characteristics of GFs have not been characterized. To fill this gap, we synthesized GF devices, subjected them to high temperatures, and investigated their thermal behavior by using infrared microthermography. We find that while the convective area of GF devices is comparable to that of bulk materials (such as metals), the coefficient of convection of these devices is several orders of magnitude higher than that of metals. In addition, the GF devices showed a reproducible thermal behavior, which we attribute to negligible temperature-induced morphological changes (as confirmed by Raman analysis). Taken together, our findings suggest GF as a promising candidate material for advanced cooling applications where efficient heat dissipation is needed, e.g., in electrical circuits.

KEYWORDS convection, graphene foam, heat transfer

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Introduction

The miniaturization of electrically operated devices dramatically promotes their functionality and applicative potential; however, it also substantially increases their power density and subjects them to high electrical heat fluxes [1–5], requiring that they are constantly and effectively cooled [6]. While classical cooling methods [7–9], including convective cooling fins [1, 10–13], are still being used to cool miniaturized electrically operated devices, advanced nano-scale materials offer new frontiers for the thermal management of electrical components and other miniaturized systems, as they provide improved heat dissipation capacities. In this study, we investigate the possible use of one of the most promising nano-materials known today—graphene foam (GF)—as a high-end heat-dissipating material. GF is a relatively new three-dimensional configuration of graphene, arranged as a network of hollow branches [14, 15]. Synthesizing the graphene in a three-dimensional formation yields new properties, such as high mechanical compliance [16] and a unique electromechanical signature [17]. As a result, GF has been integrated into various applications, including reinforcement for composites [18, 19], piezoresistive sensors [20], energy conversion devices [21], and resonators [22]. Thermally, GF composites show enhanced thermal conduction [19, 23] and an excellent ability to store thermal energy [24], while maintaining high mechanical flexibility [19]. Importantly, GF has also demonstrated low interface thermal resistance [25]—a property that strongly encourages its use in cooling applications. However, despite the promising potential of using GF for thermal management, its heat dissipation characteristics have not been investigated. Here, we characterize, for the first time, the heat-convective properties of GF devices subjected to high Address correspondence to [email protected]

temperature loading. We find that, while the convective area of GF is comparable to that of bulk materials, its coefficient of con