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.

无金属碳光催化剂在未来可见光驱动的选择性光催化有机合成中具有广阔的前景。然而，从可持续策略设计理想的碳光催化剂以进一步提高光效率和经济性对于便携式工业应用至关重要。在本文中，通过一种简便的水热后处理方法对生物废物进行了简单的水热后处理，报道了一种将水炭微球作为第一种无金属生物炭催化剂的清洁经济策略。所得水碳在可见光照射下对各种胺的选择性氧化偶联反应表现出优异的光催化活性和可重复使用性。实验研究和理论计算表明，表面内置的丰富的含氧官能团可以作为光催化活性位点。特别是，连接到大 π 电子系统的二酚羟基官能团和醌部分是参与光催化活性的主要活性位点。这项研究强调，利用可持续生物废物衍生的水碳材料作为低成本和生态环境的碳催化剂，可能为光驱动的多样化有机转化开辟一条新途径。