Nanocellulose Paper Semiconductor with a 3D Network Structure and Its Nano–Micro–Macro Trans-Scale Design
Hirotaka Koga, Kazuki Nagashima, Koichi Suematsu, Tsunaki Takahashi, Luting Zhu, Daiki Fukushima, Yintong Huang, Ryo Nakagawa, Jiangyang Liu, Kojiro Uetani, Masaya Nogi, Takeshi Yanagida, and Yuta Nishina
Semiconducting nanomaterials with 3D network structures exhibit various fascinating properties such as electrical conduction, high permeability, and large surface areas, which are beneficial for adsorption, separation, and sensing applications. However, research on these materials is substantially restricted by the limited trans-scalability of their structural design and tunability of electrical conductivity. To overcome this challenge, a pyrolyzed cellulose nanofiber paper (CNP) semiconductor with a 3D network structure is proposed. Its nano–micro–macro trans-scale structural design is achieved by a combination of iodine-mediated morphology-retaining pyrolysis with spatially controlled drying of a cellulose nanofiber dispersion and paper-crafting techniques, such as microembossing, origami, andkirigami. The electrical conduction of this semiconductor is widely and systematically tuned,viathe temperature-controlled progressive pyrolysis of CNP, from insulating (1012Ω cm) to quasimetallic (10–2Ω cm), which considerably exceeds that attained in other previously reported nanomaterials with 3D networks. The pyrolyzed CNP semiconductor provides not only the tailorable functionality for applications ranging from water-vapor-selective sensors to enzymatic biofuel cell electrodes but also the designability of macroscopic device configurations for stretchable and wearable applications. This study provides a pathway to realize structurally and functionally designable semiconducting nanomaterials and all-nanocellulose semiconducting technology for diverse electronics.