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High-air humidity, especially condensation into droplets under the influence of temperature, can pose a serious threat to air purification filters. This report introduces the use of methyltrimethoxysilane (MTMS) for the silanization hydrophobic modification of cellulose nanofibers (CNFs) and obtains an air filter with super-hydrophobicity (CA = 152.4°) and high-efficiency filtration of particulate matter (PM) through the freeze-drying technology. The antihumidity performance of CNFs filters that undergo hydrophobic modification in high-humidity air is improved. Especially in the case of high-humidity air forming condensed water droplets, the increase in the rate of filtration resistance of the hydrophobically modified CNFs filter is much lower than that of the unmodified filter. In addition, the water-vapor-transmission rate of the hydrophobically modified filter is improved. More importantly, adding MTMS can regulate the porous structure of CNFs filters and improve the filtration performance. The specific surface area and the porosity of the filter are 26.54 m2/g and 99.21%, respectively, and the filtering effects of PM1.0 and PM2.5 reach 99.31 and 99.75%, respectively, while a low-filtration resistance (42 Pa) and a quality factor of up to 0.122 Pa–1 are achieved. This work has improved the application potential of high-performance air-purification devices to remove particulate pollution and may provide useful insights to design next-generation air filters suitable for application in high-air humidity.

Excellent triboelectric charge density and hydrophobicity are achieved on cellulose nanofibrils (CNFs) by employing a simple and environmentally friendly approach to aminosilane modification of a CNF film. The positive charges on the CNF surface obtain gigantic enhancement, and a CNF-based triboelectric nanogenerator (TENG) with enhanced performance and moisture resistance is prepared. The performance of this functional CNF-based TENG can show outstanding output stability when the environmental humidity is 70%. Meanwhile, this TENG can respond to a variety of human activities, including pressing, stretching, bending, and twisting, indicating outstanding flexibility, and it can still be used to monitor the state of human movement in a human sweat environment. This work is expected to provide more insights and possibilities for application of such a functional CNF-based TENG in self-powered wearable electronics.

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