In-situ construction of 2D direct Z-scheme g-C₃N₄/g-C₃N₄ homojunction with high photocatalytic activity

Constructing all-solid-state Z-scheme junction is a very effective strategy to design highly active photocatalysts for solar energy conversion and environmental purification. We herein firstly construct 2D g-C₃N₄/g-C₃N₄ Z-scheme homojunction by using a bottom-up approach, during which the supramolecular complex is initially formed, followed by a facile thermal polycondensation. Based on the active species trapping experiments, Mott–Schottky test and band edge position analysis, the prepared 2D nanosheet g-C₃N₄/g-C₃N₄ homojunctions are found to be Z-scheme type, different from those available reported ones with a type-II energy alignment. Benefiting from the specific 2D morphology with large exposed surface area and Z-scheme junction with efficient separation and high redox abilities of the photoinduced electrons and holes, the obtained 2D g-C₃N₄/g-C₃N₄ homojunctions are much more active than the conventional g-C₃N₄/g-C₃N₄ homojunction (CN-MT) and bulk g-C₃N₄ (CN-M) under visible light irradiation, validating by the high rhodamine degradation rate of 0.833 h⁻¹, which is about 3.9 and 15.4 times higher than that of CN-MT (0.214 h⁻¹) and CN-M (0.054 h⁻¹), respectively. The present work sheds light on design of novel Z-scheme photocatalysts with specific morphology and thus further application in the field of environment or energy.