Lignin confined in wood as a sensitizer for Cu₂O: Study on photocatalytic performance enhancement

Wood, as a renewable resource, is mainly composed of cellulose, lignin, and hemicellulose. Lignin is spatially confined within the rigid cage-like structure formed by cellulose and hemicellulose, which restricts its rotation and thereby enhances the phosphorescence emission of lignin. To investigate the effect of the phosphorescence emission properties of lignin on photocatalysts, this study employed a demethylation reaction to perform in-situ modification of lignin in wood. Through the chelating effect of demethylated lignin, cuprous oxide (Cu₂O) photocatalysts were anchored on the wood surface via an in-situ synthesis method, forming a stable heterostructure. The design of lignin-sensitized catalysts with lignin spatially confined in wood was verified using the catalytic reduction reaction of 4-aminophenol (4-AP). The results show that the loading of the stable heterostructure and the sensitization effect of spatially confined lignin can increase the photocatalytic efficiency of Cu₂O by 23.08 times, which provides an effective approach for the high-value application of wood.