Visible-Light-Induced Selective Oxidation of Amines into Imines over UiO-66-NH2@Au@COF Core–Shell Photocatalysts

• Published in: ACS sustainable chemistry & engineering 2021-09, Vol.9 (37), p.12623-12633
• Main Authors: Zhang, Kaiyue, Xi, Zuoshuai, Wu, Zhenyu, Lu, Guilong, Huang, Xiubing
• Format: Article
• Language: English
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.1c04112

Efficient and stable photocatalysts for selective oxidative coupling of amines to imines are crucial to the conversion of sustainable solar energy to value-added chemical energy. In this work, UiO-66-NH2@Au@COF core–shell nanocomposites with intercalated Au nanoparticles between the UiO-66-NH2 core and the covalent-organic framework (COF) shell have been demonstrated to exhibit enhanced activity and stability for visible-light-driven aerobic selective oxidation of amines to imines. With optimized Au and two-dimensional π-conjugated COF content, the obtained UiO-66-NH2@Au0.5@COF1 photocatalyst exhibited the highest conversion of benzylamine with an imine yield of 66.9% for at least five cycles. It is revealed that the introduction of appropriate Au and COF could not only broaden the visible-light absorption band but also promote the separation of photoinduced charge carriers and enhance the photocatalytic performance. Furthermore, a rational mechanism was explored to elucidate the process of photocatalytic reaction. The intercalated Au nanoparticles with the localized surface plasmon resonance (LSPR) effect act as generators of hot electrons and also transfer channels for the photo-generated electrons from the COF shell to the UiO-66-NH2 core. Importantly, the MOF@metal@COF photocatalysts might provide a promising strategy to construct photocatalysts with desirable activity and stability under visible-light illumination.