查找使用阿拉丁产品的科研文献

Photocatalytic depolymerization of lignin to produce high value-added chemicals by carbon quantum dots modified WO3 nanosheets

Zhijie Jiang,Xutang Liu,Wei Zhao,Fei Wang,Mingyu Cui,Linyang Dong,Chong Liang,Dingkai Wang,Shuiyuan Fu

Photocatalysis, a sustainable development strategy, employed to produce value-added chemicals from lignin, has attracted much attention due to its low energy consumption and mild reaction conditions. Carbon quantum dots (CQDs) and tungsten oxide (WO 3 ) composite photocatalysts (CQDs/WO 3 ) were prepared by ultrasonic assisted wet impregnation method in this study. The CQDs/WO 3 nanosheets exhibit good optical properties and satisfactory performance of lignin depolymerization. Characterization results embody that the addition of CQDs significantly changes the morphology of WO 3 . Compared with bulk pure WO 3 , CQDs/WO 3 becomes a nanosheet structure in the size of ∼ 200 nm. Furthermore, CQDs can absorb photogenerated electrons as well as reduce the recombination of photogenerated electrons and holes. The strong oxidizing ability of n -type semiconductor WO 3 enables it to effectively break the typical bonds like C-O or C-C near polar functional groups in lignin. Due to this ingenious design, dealkaline lignin conversion was up to 34.21% as well as the highest yields of vanillin and vanillic acid in the form of lignin were 24.74 mg/g and 8.02 mg/g in 2 h at room temperature, visible light illumination and air atmosphere, respectively. And optimized CQDs/WO 3 also had satisfactory effects on three natural lignin (grass lignin, pine lignin and birch lignin), which proved its universality. Electron spin resonance experiments and mechanism investigation demonstrated that ·O 2 - and ·OH play a weighty role in photocatalytic depolymerization of lignin. This study provides a new gambit for converting lignin to high value-added chemicals (vanillin and vanillic acid) over modified WO 3 .