Highly Transparent and Hazy Cellulose Nanopaper Simultaneously with a Self-Cleaning Superhydrophobic Surface

Abstract

Wood-derived sustainable materials like cellulose fibers have received increased attention for replacing nonrenewable substrates in emerging high-tech applications. Herein, for the first time, we fabricated a superhydrophobic (static contact angle = 159.6°, sliding angle = 5.8°), highly transparent (90.2%) and hazy (46.5%) nanopaper made of TEMPO-oxidized cellulose nanofibrils (TOCNF) and polysiloxanes. The original TOCNF nanopaper endowed excellent optical and mechanical properties; the constructed pearl-necklace-like polysiloxanes fibers on the nanopaper surface by further silanization significantly improved water-repellency (70.7% for static contact angle) and toughness (118.7%) of the TOCNF nanopaper. Our proposed novel nanopaper that simultaneously achieved light-management and self-cleaning capabilities not only led to an enhancement (10.43%) in the overall energy conversion efficiency of the solar cell by simply coating but also recovered most of the photovoltaic performance losses due to dust accumulation by a self-cleaning process, indicating its potential application in solar cells. This study on cellulose-based multifunctional substrates provided new insights into the future development of sustainable functional devices.