Illuminating biomass valorization: the synergy of photocatalysis and ionic liquids for sustainable high-value transformation

The sustainable transformation of biomass into high-value chemicals and fuels represents a key challenge and opportunity in the pursuit of a circular bio-economy. This review highlights the promising synergy between photocatalysis and ionic liquids (ILs) as an innovative strategy for biomass valorization. The unique physicochemical properties of ILs that render them advantageous for biomass dissolution, activation, and selective conversion were outlined. Next, we explore the principles and mechanisms of photocatalysis in the context of biomass substrates, emphasizing its green, light-driven nature and potential for precise control over reaction pathways. Particular attention is given to the bottlenecks in photocatalytic biomass conversion, such as low efficiency, poor selectivity, catalyst instability, and how ILs can address these issues by tuning the reaction environment and interfacial dynamics. The dual role of ILs as both solvent and functional promoter is critically discussed, along with recent advances in IL-photocatalyst system design. Finally, we present a forward-looking perspective on key research directions, including in situ mechanistic studies, development of IL-compatible photocatalysts, establishment of structure-activity relationship models, application of AI and big data in catalyst discovery, and the engineering of next-generation photoreactors. By bridging the fields of green solvents and photocatalysis, this review aims to inspire innovative approaches toward efficient and sustainable biomass valorization.