Recent progress in single atom catalysts for biomass conversion

Biomass, as an emerging environmental and renewable resource derived from various green sources, is increasingly being recognized for its inherent structural characteristics that are conducive to the production of high-value chemicals. The complicated structure and oxygen-rich nature of biomass and its derivatives necessitate high-value targeted conversion, typically involving liquid-phase hydrogenation or the addition of acidic or basic environments. These processes impose stringent requirements on the efficiency and durability of the catalysts. Recently, the innovation of single atom catalysts (SACs) with individual catalytic sites dispersed on various supports has demonstrated high catalytic efficiency and good selectivity. Owing to their high atomic utilization and cost-efficiency, SACs have emerged as one of the most promising heterogeneous catalysts. This review summarizes current progress on the catalytic conversion of biomass mediated by SACs. Significant emphasis is placed on the unique active sites and reaction mechanisms of SACs in various kinds of catalytic methods (thermocatalysis, electrocatalysis, photocatalysis). In order to facilitate comparison, the various reactions are categorized according to the type of raw material (cellulose, hemicellulose, lignin, etc.). Especially, the developing strategies for preparing SACs are summarized to better satisfy industrial requirements. Finally, we provide an anticipatory outlook of future developments in this field, focusing on biomass utilization and advanced catalytic systems.