Recent advances in the potential applications of hollow kapok fiber-based functional materials

Kapok fiber (KF) belongs to a type of seed fibers collected from the fruits of Ceiba pentandra tree. From sustainable biomass resource, KF is a naturally abundant cellulose fiber with good economic value, excellent biocompatibility and biodegradability. Especially, KF has inherent thin-walled large lumen and hydrophobic–oleophilic surface, which makes KF receive increasing attention in recent years as the starting material for fabrication of different types of functional materials. Among them, KF can be blended with, filled in, grafted by, coated with other components, or carbonized via pyrolysis or hydrothermal, and then is currently focused on by many researchers for adapting to different applications. In this review, we present the structural characteristics of KF, KF-based functional materials and their potential applications, especially in fields related to the environment and energy, such as oil sorbents, adsorbents for heavy metals and dyes, sound absorption materials, electrode materials of supercapacitors, photocatalysis and catalysis materials, and so forth.