Abstract: Three-dimensional (3D) carbon aerogel with high porosity and lightweight merit has emerged as an important high-performance electromagnetic (EM) absorption material. Despite great progress has been made, most reported 3D carbon aerogels suffer from non-renewability and high cost. Moreover, the randomly distributed porous structure restricts the effective regulation of microwave absorption. Herein, the sustainable shaddock peel cellulose (SPC) was adopted to construct an ultralight and orientated carbon aerogel through a facile bidirectional freezing technique and subsequently thermal treatment process. The resultant carbon aerogel is composed of ordered lamellar layers interconnected by supported bridges, forming a continuous 3D conductive network. Addition of a small amount of graphene oxides (GO) nanosheets in biomass aerogel enhances the interaction of SPC and promotes electron transmission along 3D conductive network. Through tuning the lamellar spacing of aerogel, the as-prepared carbon aerogel achieves a remarkable microwave absorption property with a strong reflection loss (RL) of -63.0 dB and broad effective absorption bandwidth (EAB) of 7.0 GHz under ultralow filler content of 4 wt.%. Moreover, this carbon aerogel also demonstrates excellent thermal insulation property, and is even comparable to commercial products. The present work paves the way for designing low-cost and sustainable biomass-derived carbon aerogel for lightweight and high-performance microwave absorption and infrared stealth function.

Key words: Biomass, Oriented carbon aerogels, Lightweight microwave absorption, Thermal insulation