Nanosheet-Stacked g-C3N4 Tubes with Carbon Vacancies for Enhanced Photocatalytic H2 Evolution

Abstract

Graphitic carbon nitride (g-C₃N₄) is a photocatalyst that has been extensively investigated. Unfortunately, g-C₃N₄ suffers from the challenges of insufficient light absorption and rapid complexation of photogenerated charges. Modification methods such as defect engineering and nanostructure reconstruction can improve photocatalytic performance. This is because modification can improve carrier separation efficiency, increase active sites and increase light absorption, etc. Here, we demonstrate a simple approach to fabricate nanosheet-stacked g-C₃N₄ (M-CN₆₀₀) tubes with carbon vacancies (V_Cs) and used for photocatalytic water splitting to hydrogen production. M-CN₆₀₀ was prepared by the thermal polymerization of precursors. These precursors were obtained through the melem induced by methanesulfonic acid. Due to the nano effect, the obtained M-CN₆₀₀ exhibits a significantly higher specific surface area (105.2 m² g^–1) and pore volume (0.391 cm³ g^–1) compared to pristine g-C₃N₄ (B-CN). This creates more reaction sites, which improve the performance of photocatalytic H₂ production. The nanosheet-stacked structure reduces the transport distance of photogenerated carriers to the material surface. In addition, M-CN₆₀₀ possesses more negative conduction band positions with stronger photocatalytic reduction ability. Moreover, due to the presence of V_Cs in the catalyst, the separation of photogenerated electron and hole pairs is accelerated. Under visible light (λ > 420 nm), the obtained M-CN₆₀₀ exhibits excellent photocatalytic H₂ evolution performance, which is 21.5-fold higher than that of B-CN. This work provides a method for preparation of nanostructured g-C₃N₄ with efficient photocatalytic performance.