Efficient utilization of lignocellulosic biomass, which consists of lignin, cellulose, and hemicellulose and is a major renewable resource, is central to green and sustainable chemistry. Polyoxometalates (POMs) have emerged as versatile catalysts for biomass valorization owing to their tunable Brønsted acidity/basicity, redox properties, and unique electron/proton storage capability. This review highlights recent advances in POM-catalyzed lignocellulosic biomass conversion, focusing on lignin depolymerization and the selective conversion of hemicellulose- and cellulose-derived platform compounds, namely furfural (FF) and 5-hydroxymethylfurfural (HMF). We systematically discuss the catalytic roles of different POM families (classical POMs and their cation-modified derivatives, supported POM materials, and structurally novel POM architectures) in lignin depolymerization and examine the selective redox transformations involved in FF and HMF valorization. Moreover, we show how the properties of POM catalysts govern reaction pathways, product selectivity, and reaction mechanisms under thermal, photocatalytic, and electrocatalytic conditions and discuss the challenges and future opportunities for biomass valorization using POM-based catalytic systems.

The structural synthesis and catalytic application of polyoxovanadates (POVs), an important subfamily of polyoxometalates (POMs), have attracted significant attention, owing to their rich coordination chemistry and splendid redox properties. In this review, the advances in the past 10 years in the oxidative transformations catalyzed using all-inorganic POVs, organ functionalized POVs, and POV-based inorganic–organic hybrids have been summarized and are discussed in detail. In particular, we focus on the selective oxidation of organic molecules, including alkanes, alkenes, alcohols, sulfides, sulfur-mustard simulants, and organic dyes. For most oxidative transformations, the active V-peroxo species generated in the presence of hydrogen peroxide or tert-butyl hydroperoxide account for enhanced catalytic activities. In addition, the challenges and prospects in the development of POM-based catalysts are addressed.