Biomass-derived carbonaceous materials (BCMs) have been extensively applied in diverse areas, attributed to their recognized sustainability, low cost, diverse and scalable synthesis routes, and tunable structure and function. Recently, deep eutectic solvents (DESs), a class of novel and green solvents, have emerged as a promising alternative to traditional solvents and processing techniques for the preparation and functionalization of BCMs for various applications. However, there is still a knowledge gap regarding the applications of DESs in the preparation and functionalization of BCMs. Considering these, this review summarizes the emerging applications of DESs in the preparation and functionalization of BCMs, including their use as biomass pretreatment solvents, carbon precursors, soft templates, solvothermal carbonization (STC) media, and post-modification agents. This review also discusses the applications of the resultant BCMs in various fields, such as pollution control, energy storage, and biocatalysis, and highlights the challenges and prospects for using DESs in the preparation and functionalization of BCMs. Overall, the use of designer DESs in the preparation and functionalization of BCMs has the potential to contribute to the development of sustainable and cost-effective technologies for a wide range of applications.
