Metal-free graphitic carbon nitride/carbon-dots composites: unveiling mechanochemical synthesis opportunities

Environmentally friendly, metal-free photocatalysts offer a promising alternative to traditional metal-based semiconductors. In this study, we synthesised graphitic carbon nitride (CN) photocatalysts decorated with carbon dots (CDs) using two distinct methods: a hydrothermal approach and a solvent-free mechanochemical extrusion method. The resulting nanocomposites were thoroughly characterised for their physical, chemical, and optical properties and evaluated for photocatalytic activity in the selective oxidation of benzyl alcohol. Results revealed that the synthetic approach significantly impacted the composites' morphological and optical characteristics, affecting their photocatalytic performance. A light-matter interaction modelling study was further conducted to explore the relationship between optical properties and catalytic behaviour, offering valuable insights into the structure-function relationship of these novel photocatalysts. As a result, we present an alternative scheme to traditional synthesis and catalysis methods based on the use of high temperature and pressure conditions, which provides an energetically positive and environmentally friendly approach.