Collaborative Research: Understanding the Synergistic Effect of Graphene Plasmonics and Nanoscale Spatial Confinement on Solar-Driven Water Phase Change

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Water desalination and wastewater treatment rely on the consumption of significant amounts of energy. For distributed water treatment systems, the cost can be ten times higher than that of the centralized plants. The ability to use renewable energy such as solar energy to replace completely, or in part, the energy needed for water treatment may lead to substantial impacts on the sustainability of the global energy and water supply. Efficient solar-thermal energy conversion for vapor generation is an important green technology that could reduce the energy demands of water desalination and wastewater treatment. However, the low vapor evaporation rate remains a challenge for many practical applications. Graphene plasmonics, which refers to the collective electron oscillation in graphene flakes when excited by light, is believed to contribute to the enhanced solar-to-thermal conversion efficiency of graphene nanopetal structures. In this research project, computer modeling and experiments will be combined to understand the synergistic effects of graphene plasmonics and spatial confinement on thermodynamic properties of water and the solar-driven water evaporation rate. The knowledge gained from this study will assist in developing new graphene plasmonic materials for solar thermal evaporation applications. The project will also include significant educational activities, such as outreach programs for local K-12 students and teachers and undergraduate research programs with open-ended design projects.The goal of this research project is to understand how the plasmon resonance-induced local electric field due to extreme light confinement along the unique nanopetal edges either aligns or dis-aligns water molecular dipoles confined between the vertically freestanding graphene flakes in a porous structure. The research project integrates full electromagnetic wave calculations, molecular simulations, and experimental validation. Some of the specific objectives include understanding the fundamental mechanisms governing the influence of graphene plasmonics-induced thermodynamic property change of nano-confined water on vapor evaporation rate. A combination of electromagnetic wave calculations and molecular simulations will be used to model this system. Additionally, the researchers will validate the modeling results through experiments on solar-driven water phase change mediated by anomalous near-infrared plasmons in uniquely synthesized porous graphene nanopetal structures. This project is expected to reveal new mechanisms of graphene plasmon resonance-mediated water phase transition, which may contribute to improving solar-thermal energy conversion technologies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.