Cellulose aerogels have great prospects for noise reduction applications due to their sustainable value and superior 3D interconnected porous structures. The drying principle is a crucial factor in the preparation process for developing high-performance aerogels, particularly with respect to achieving high acoustic absorption properties. In this study, multifunctional cellulose nanocrystal (CNC) aerogels were conveniently prepared using two distinct freeze-drying principles: refrigerator conventional freezing (RCF) and liquid nitrogen unidirectional freezing (LnUF). The results indicate that the rapid RCF process resulted in a denser CNC aerogel structure with disordered larger pores, causing a stronger compressive performance (Young’s modulus of 40 kPa). On the contrary, the LnUF process constructed ordered structures of CNC aerogels with a lower bulk density (0.03 g/cm³) and smaller apertures, resulting in better thermal stability, higher diffuse reflection across visible light, and especially increased acoustic absorption performance at low–mid frequencies (600–3000 Hz). Moreover, the dissipation mechanism of sound energy in the fabricated CNC aerogels is predicted by a designed porous media model. This work not only paves the way for optimizing the performance of aerogels through structure control, but also provides a new perspective for developing sustainable and efficient acoustic absorptive materials for a wide range of applications.

Bio-based materials with excellent acoustic absorption properties are in great demand in architecture, interior, and human settlement applications for efficient noise control. In this study, crayfish shells, a form of kitchen waste, are utilized as the primary material to produce ultralight and multifunctional chitin aerogels, which effectively eliminate noise. Different replacement solvents and freezing rates were employed to regulate the porous structures of chitin aerogels, and their resulting acoustic absorption performance was investigated. Results demonstrate that employing deionized water as the replacement solvent and utilizing a common-freeze mode (frozen via refrigerator at −26 °C) can produce chitin aerogels with larger porosity (96.26%) and apertures, as well as thicker pore walls. This results in superior broadband acoustic absorption performance (with a maximum absorption coefficient reaching 0.99) and higher Young's modulus (28 kPa). Conversely, chitin aerogels solvent-exchanged with tert-butyl alcohol or subjected to quick-freeze mode (frozen via liquid nitrogen) exhibit smaller porosity (92.32% and 94.84%) and apertures, thereby possessing stronger diffuse reflection of visible light (average reflectance of 94.30% and 88.18%), and enhanced low-frequency (500 to 1600 Hz) acoustic absorption properties. Additionally, the acoustic absorption mechanism of fabricated chitin aerogels was predicted using a simple three-parameter analysis Johnson–Champoux–Allard–Lafarge (JCAL) model. This study presents a novel approach to developing multifunctional biomass materials with excellent acoustic absorption properties, which could have a wide range of potential applications.

Wood is a sustainable material with big sound absorption potential based on its natural porous characteristics. However, the acoustic absorption performance of wood is greatly limited by the low permeability of wood structures. In this study, we prepared a new type of cellulose wood (CW) using a two-step delignification process on a natural basswood matrix followed by supercritical CO₂ drying. The as-prepared CW exhibited a high air permeability of 33.78 Darcys (increase of 496.82%) and superior porous characteristics compared to the natural basswood, resulting in a significant improvement in the acoustic absorption performance with an increased average absorption of 106.25% and maximum absorption of 126.32%. The dissipation of sound energy in the structure of CW is well predicted by a designed porous media model. Moreover, a high specific stiffness of 2.14 × 10⁵ m² s⁻² and a diffuse reflectance of 97.02% across the visible light were demonstrated for the CW as well. Such a fascinating multifunctional wood-derived material may provide new insights into the development of efficient and sustainable acoustic absorbers for various applications.

Uniaxial strain (6–12%) makes 2D β-AuTe a stable photocatalyst with high carrier mobility and UV-VIS absorption for acidic H ₂ O splitting with 20.07% STH efficiency. Our study also proposes strain as a simpler way of designing new photocatalysts.