State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Box 98, 15 Bei San Huan East Road, 100029, Beijing, China.
Beijing Engineering Center for Hierarchical Catalysts, Beijing University of Chemical Technology, 100029, Beijing, China.
Dalton Trans. 2023 Feb 14;52(7):1950-1961. doi: 10.1039/d2dt03886b.
Aiming at the comprehensive utilization of waste carbon resources and renewable carbon resources, we put forward the photocatalytic coupling process of CO reduction and 5-hydroxymethylfurfural (5-HMF) oxidation mediated by the anionic compound of layered double hydroxides (LDHs). Specifically, a ZnNiFe-LDH was synthesized by co-precipitation method, during which CO was stored between LDH layers in the form of carbonate. Then, a certain amount of metal vacancies were introduced into LDH nanosheets by selectively etching Zn ions. ICP-AES, EPR and XPS showed that the concentration of Zn vacancies gradually increased with the etching time prolonging, which thus optimized the electronic structure of LDH layers. Under the catalysis of the electron-rich metal cations and hydroxyl groups on the layers, the interlayer carbonate was reduced into CO coupled accompanied with the 5-HMF oxidation to 2.5-furandiformaldehyde (DFF). Compared with the unetched ZnNiFe-LDHs, the CO and DFF yields over the LDHs etched for 3 h were increased by 2.84 and 2.82 times under UV-vis irradiation with a density of 500 mW cm. Finally, combined with isotope-labeled CO experiments and FTIR characterization, we revealed the possible coupling mechanism and defect-induced performance enhancement mechanism.
针对废碳资源和可再生碳资源的综合利用，我们提出了由层状双氢氧化物（LDHs）的阴离子化合物介导的 CO 还原和 5-羟甲基糠醛（5-HMF）氧化的光催化偶联过程。具体而言，通过共沉淀法合成了 ZnNiFe-LDH，其中 CO 以碳酸盐的形式储存在 LDH 层之间。然后，通过选择性蚀刻 Zn 离子，在 LDH 纳米片中引入一定量的金属空位。ICP-AES、EPR 和 XPS 表明，随着蚀刻时间的延长，Zn 空位的浓度逐渐增加，从而优化了 LDH 层的电子结构。在富电子金属阳离子和层上羟基的催化作用下，层间碳酸盐被还原为 CO，同时 5-HMF 被氧化为 2.5-糠醛（DFF）。与未蚀刻的 ZnNiFe-LDHs 相比，在 UV-vis 照射下（密度为 500 mW cm），蚀刻 3 h 的 LDHs 的 CO 和 DFF 产率分别提高了 2.84 和 2.82 倍。最后，通过同位素标记 CO 实验和 FTIR 表征，揭示了可能的偶联机制和缺陷诱导的性能增强机制。
