Nanocellulose from Rice Straw: Structural Color, Radiative Cooling and Sensing Properties of Fluorophore-doped Photonic Films

Irreversible consequences of the climate change caused by increased emission of anthropogenic CO2 drive the need for solutions to lower down the energy consumption for cooling purpose at least in living spaces. Carbon-neutral nanomaterial derived from lignocellulosic biomass remains the most preferred choice for such purposes meeting. In this work, the transreflective properties of nanocellulose extracted from highly abundant agricultural waste, rice straw (Oryza sp. Stems) have been explored. Self-assembly of nanocellulose (NC) generates predominate structural green color by wavelength-selected reflection. Organic fluorophores doped in NC films follow the molecular orientations of nanocellulose. Excited state dynamics of rhodamine B become faster in cellulose nanocrystal films over that in PVA/PVP film indicating crystalline nature of hydroxyl groups present in nanocellulose. The emissive property of intercalating dye, ethidium bromide is quenched owing to aggregation caused quenching. The radiative cooling potential of nanocellulose film has been explored owing to its low solar light absorption and high mid-infrared (MIR) emissivity at atmospheric transmission window (8-13 μm). The temperature of the insulated box is reduced by approx. 6 °C in the presence of NC film under solar simulator illumination. Nanocellulose/PVA electrospun nanofiber is uniform and smooth. Photoluminescent electrospun nanofiber can be utilized for acid-vapor sensing applications.