A comprehensive review of lignin-derived microspheres: Advances in controlled synthesis, functionalization strategies and novel applications

With advancements in green and sustainable material research, lignin has emerged as a key focus for achieving high-value utilization and sustainable development of biomass resources. Lignin-derived microspheres have transitioned from industrial byproducts to highly promising advanced functional materials. This paper presents a comprehensive review of the progress from controlled synthesis to functional applications of lignin-derived microspheres. First, the formation mechanisms of lignin microspheres are systematically discussed, with an emphasis on core preparation techniques, including solvent exchange, anti-solvent precipitation, interfacial polymerization, and electrospray. Strategies for regulating reaction parameters to enable controllable fabrication and performance optimization are thoroughly analyzed. Second, the latest achievements in functional applications are comprehensively reviewed. Benefiting from their modifiable aromatic backbones and porous architectures, lignin-derived microspheres exhibit enormous potential across multiple fields: in energy storage and conversion, their large specific surface area, favorable conductivity, and tunable pore structure confer superior electrochemical performance; in biomedicine, their excellent biocompatibility and biodegradability make them ideal candidates for drug delivery systems; in environmental adsorption and pollution remediation, their high specific surface area and abundant functional groups enable highly efficient removal of various contaminants; and in ultraviolet protection, their strong UV absorption capacity facilitates the development of high-performance UV-shielding materials. Finally, current challenges and future perspectives are outlined, including the development of green and scalable preparation processes, in-depth elucidation of formation mechanisms, and improvement of long-term stability in practical applications. This review aims to provide clear research directions for future studies on the high-value utilization of lignin, promoting technological innovation and industrial translation.