(117h) Repetitive Pool Boiling Runs: A Controlled Process to Form Reduced GO Surfaces from GO with Tunable Surface Chemistry and Morphology

Wettability and wickability of a surface are the key properties that govern a variety of industrial applications. Understanding the effect of aging on the durability of the surfaces and subsequent changes occurring in their molecular structure is vital to maintain functionality. Pool boiling, or two-phase heat transfer is a technique in which maintaining surface properties is critical to maintain the consistent heat dissipation from heater surface. Pool boiling involves a phase change of liquid by absorbing a large amount of latent heat which allows the dissipation of large amount of heat while maintaining low surface temperatures. In the recent years, several carbon nanomaterials-based coatings have been exploited for pool boiling applications due to their high thermal properties. However, the effect of aging on durability of these carbon nanomaterial-based coatings still remain an unexploited field.

Here, we have developed novel graphene oxide-copper (GO-Cu) porous coatings by a multi-step electrodeposition technique owing to higher thermal properties of GO and copper particles. We studied the effect of repetitive pool boiling on changes in molecular structure, surface chemistry, morphology, and wettability of the coatings. We observed the transformation of GO-Cu to reduced-GO-copper (rGO-Cu) coatings with repetitive boiling that led to improved boiling performance. This improvement is attributed to the transition of hydrophilic GO to hydrophobic rGO due to the repetitive pool boiling, and increased surface roughness as a result of hydrophobic surfaces. The durability, robustness and reliability of the GO-Cu coatings was found to be higher than pristine-copper and just-copper coated surfaces. A higher performance demonstrated by GO-Cu coatings indicate their increased sustainability and practicability in numerous engineering applications.