Construction of 2D/2D BCNS/Ti 3 C 2 heterojunction with boron-doped g-C 3 N 4 and Ti 3 C 2 MXene for enhanced photocatalytic water splitting

Graphitic carbon nitride (g-C 3 N 4 ) has attracted great interest in photocatalytic water splitting. However, the poor photogenerated charge carriers transfer and the insufficient driving force for oxygen evolution reaction limit its practical application. In this work, boron-doped g-C 3 N 4 nanosheets (BCNS) have been synthesized by calcining a mixture of g-C 3 N 4 and NaBH 4 . The synthesized BCNS were then combined with Ti 3 C 2 MXene using electrostatic self-assembly to construct a 2D/2D BCNS/Ti 3 C 2 heterojunction. The resultant BCNS retained the original framework of g-C 3 N 4 , while the optimized band structure of BCNS induced prominently enhanced visible light absorption, accelerated charge carriers separation, and the increased driving force for water oxidation compared to pure g-C 3 N 4. Density functional theory further proved that BCNS can enhance the driving force for photocatalytic O 2 evolution. Moreover, the construction of 2D/2D face-to-face BCNS/Ti 3 C 2 heterojunction was carried out to further enhance photocatalytic performance due to the intimate contact interface and the accelerated separation and transfer of photogenerated charge carriers. As a result, the 2D/2D BCNS/Ti 3 C 2 hetrojunction exhibited a dramatically improved photocatalytic water-splitting performance compared to pristine g-C 3 N 4 . This integrated engineering strategy, involving non -metal element doping and 2D/2D heterojunction construction, might provide a unique paradigm for the rational design of efficient photocatalysts for photocatalytic water splitting.