Interfacial charge dominating major active species and degradation pathways: An example of carbon based photocatalyst

In this work, the chlorine-doped and undoped hydrothermal carbonation carbon (Cl-HTCC, HTCC) photocatalysts were used to study the correlation of their interfacial charge and photocatalytic performance. For degradation of aromatic dye, rhodamine B (RhB), Cl-HTCC manifests much better photocatalytic performance compared with that of undoped HTCC. Besides the slightly enhanced charge transfer brought, the Cl-HTCC showed more negatively interfacial charge and thus a stronger adsorption of positively charged RhB. This made the photogenerated holes (h⁺) directly react with the adsorbed RhB, which does not require the h⁺ to produce hydroxyl radical (OH) and reduce its lost during the transformation, thus enhanced the performance of Cl-HTCC. While for undoped HTCC, it showed a weaker adsorption of RhB, and the photogenerated h⁺ firstly reacted with H₂O molecules to produce OH. Then, the OH can attack the RhB. Besides, the intermediates and the degradation pathways are also evaluated here via UPLC-MS. Results show that the interfacial charge also dominated the degradation pathways. This work provides a novel metal-free photocatalyst for environmental remediation and will inspire further efforts to enhance the photocatalytic performance by concerning interfacial conditions.