Structural characterization of graphene-coated copper substrate prepared by scalable In-Situ spray coating using xylene dispersion

Abstract

Introduction. Graphene exhibits exceptional thermal conductivity, hydrophobicity, mechanical strength, and electron transport properties, which render it a candidate material for advanced thermal management and heat transfer applications. However, conventional deposition techniques, such as chemical vapor deposition (CVD), are often expensive, technologically complex, and difficult to scale for large-area engineering applications. The present study is focused on the development of a simple, cost-effective, and scalable in-situ spray-coating technique for depositing graphene onto copper substrates using a xylene-based dispersion system. Materials and methods. A stable sprayable graphene dispersion was prepared from graphene synthesized using the modified Hummers method and dispersed in a mixture of xylene, isopropanol, epoxy binder, and suspension agents. The coating was deposited onto copper substrates under controlled conditions. Structural and surface characterization of the graphene-coated copper substrate was performed using X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The graphene layer thickness and interlayer spacing were estimated using Bragg's law and the Scherrer equation. Results and Discussion. XRD analysis confirmed the formation of few-layer graphene with an interlayer spacing of 3.37 Å and an estimated thickness corresponding to approximately 5–6 graphene layers. Raman spectroscopy revealed the characteristic D, G, and 2D bands, confirming successful graphene deposition on the copper substrate. The ID/IG ratio decreased from 2.1 for the as-received graphene powder to 0.85 after coating deposition, indicating preferential deposition of better-dispersed graphene sheets. FTIR analysis suggested Cu–O–C interfacial interactions between graphene and copper. SEM observations revealed uniformly distributed wrinkled graphene sheets forming interconnected conductive pathways across the substrate surface. The crystallographic structure of copper remained unchanged after coating, and no secondary phases were detected. Conclusions. The developed xylene-assisted spray-coating process provides a practical and scalable route for depositing graphene on copper substrates. The resulting coating exhibited an interlayer spacing of 3.37 Å, approximately 5–6 graphene layers, characteristic graphene Raman signatures, and a uniform surface morphology. These findings demonstrate the potential of graphene-coated copper substrates for advanced thermal management systems, including condensers, evaporators, phase-change heat exchangers, and high-performance heat-transfer surfaces.