Biowaste-derived hydrochar microspheres: Realizing metal-free visible-light photocatalytic oxidation of amines

• Published in: Journal of catalysis Vol. 404; pp. 149 - 162
• Main Authors: Su, Feng, Peng, Haoyu, Yin, Hui, Luo, Chao, Zhu, Lixia, Zhong, Wenzhou, Mao, Liqiu, Yin, Dulin
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2021
• Subjects: Biowaste; Imine; Metal-free; Photocatalytic synthesis, Hydrochar; Biowaste; Metal-free; Photocatalytic synthesis, Hydrochar; Imine
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/j.jcat.2021.09.019

[Display omitted] •Using sustainable biowastes to prepare low-cost biochar photocatalysts.•Biochar photocatalysts shows superior responsiveness in oxidation of amine.•Diphenolic groups and pyrene core are the dominant photo-catalytic sites.•Biochar photocatalysts can be at least seven runs (90 % imine yields). Metal-free carbon photocatalysts hold great promise in future visible-light-driven selective photocatalytic organic synthesis. However, designing ideal carbon photocatalysts from sustainable strategies to further improve the photo-efficiency and economic nature is crucial for portable industrial applications. Herein, a clean and economic strategy to fabricate hydrochar microspheres as the first metal-free biochar potocatalysts is reported by a facile hydrothermal post-treatment approach from biowaste. The obtained hydrochars present excellent photocatalytic activity and reusability toward the selective oxidative coupling reactions of various amines under visible-light irradiation. Experimental studies and theoretical calculation revealed that the abundant oxygenated functional groups built-in on the surface could function as photocatalytic active sites. In particular, the diphenolic hydroxyl functional groups and quinone moieties attached to the large π-electronic-system were the main active sites involved in the photocatalytic activity. This research highlights that the utilization of sustainable biowaste-derived hydrochar materials as a low-cost and eco-environmental carbocatalysts, may open up a new avenue for light-driven diverse organic transformations.