Incorporating nitrogen defects into novel few-layer carbon nitride nanosheets for enhanced photocatalytic H₂ production

Carbon nitride nanosheets have shown a great promise for photocatalytic water splitting among numerous photocatalysts due to the versatile advantages. The crucial issues of the weak visible-light absorption and the separation of photo-generated carrier remain a matter of serious concern. Herein, we report a facile calcination-solvothermal-calcination method to prepare nitrogen-deficient carbon nitride nanosheets (DCNS) for the first time, which leads to the simultaneous introduction of nitrogen defects and formation of a fragmented few-layer nanosheet structure. The fragmented few-layer nanosheet structure is known to possess a high specific surface area and abundant interfacial reaction sites, contributing to the rapid consumption of photo-generated carrier. The nitrogen defects are responsible for further boosting the photocatalytic performance by regulating the band structure and optical properties as well as improving the separation efficiency of photo-generated carrier. The optimized DCNS-120 delivers a superior H₂ production rate of 5375 μmol·g⁻¹·h⁻¹, considerably higher than that of bulk carbon nitride (164 μmol·g⁻¹·h⁻¹). We anticipate that this work may pave a new pathway to engineering carbon nitride with a matched structure to achieve the desired efficient photocatalytic H₂ production under visible-light irradiation.