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Lignin, as a renewable and environmentally friendly resource, serves as the primary source of aromatic compounds in nature. Harnessing lignin for high-value applications is essential for addressing energy and environmental challenges, and thus it is crucial to develop high-performance lignin-based materials through advanced materials technologies. Among various lignin-based materials, hydrogels and adhesives have garnered significant attention due to their simple preparation methods and excellent properties. This review summarizes recent advancements in the preparation strategies, structural features, functional attributes, and applications of lignin-based hydrogels and adhesives. First, the structural characteristics and utilization methods of lignin are analyzed based on its source. Then, the preparation methods of lignin-based hydrogels are detailed, offering an in-depth comparison of the advantages and disadvantages of physical and chemical crosslinking methods. The functional attributes of lignin-based hydrogels and their applications in fields such as flexible sensing and energy storage are thoroughly reviewed. Additionally, this review discusses the preparation methods of lignin-based adhesives and their ongoing development for wood bonding applications. Finally, future directions for the development of lignin-based hydrogels and adhesives are explored. This review provides fundamental knowledge on the preparation, application, and development of lignin-based hydrogels and adhesives, offering valuable insights for the efficient conversion and utilization of lignin. [ABSTRACT FROM AUTHOR]

Lignin, characterized by its amorphous, heavily polymerized structure, is a primary natural source of aromatic compounds, yet its complex constitution poses considerable challenges in its transformation and utilization. Therefore, the selective cleavage of C-C bonds represents a critical and challenging step in lignin degradation, essential for the production of high-value aromatic compounds. In this study, we report a simple electrocatalytic approach for lignin valorization via C-C bond cleavage by developing a nonmetallic electrocatalyst of carbon-based materials. It is found that the hydrophilicity and hydrophobicity of the electrocatalyst have a significant effect on the degradation process. Under mild conditions, the hydrophilic carbon paper exhibits 100% substrate conversion, yielding 97% benzaldehyde and 96% quinone with ionic liquid electrolytes. The mechanism study shows that the carbon catalyst with higher surface defects favors electron transfer in the oxidative cleavage process of C-C bonds. These results signify a substantial advancement in lignin degradation, offering an environmentally friendly, metal-free electrochemical route., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Co-published by Zhejiang University and American Chemical Society.)