Preparation and photocatalytic performance of mesoporous g-C3N4/MXene composite with 2D/2D heterostructure

The construction of semiconductor heterojunctions offers a promising route to markedly enhanced photocatalytic performance. A template-based and electrostatic self-assembly strategy was employed to synthesize the mesoporous g-C₃N₄/MXene photocatalyst, integrating melamine-derived g-C₃N₄ with an MXene secondary phase. MXene layers were inserted between g-C₃N₄ layers to construct a special stacked sandwich structure called a 2D/2D heterostructure. The mesoporous g-C₃N₄/MXene composite delivers markedly superior photoelectrochemical performance to bare mesoporous g-C₃N₄. With 10 wt % MXene, the as-prepared g-C₃N₄/MXene attains its maximum BET surface area of 43.19 m²g⁻¹ and simultaneously delivers the highest photocatalytic activity. After 120 min of visible-light irradiation, it degrades 98.6 % of methyl orange and 97.2 % of rhodamine B, while retaining excellent cyclic stability. The construction of a heterojunction between MXene and mesoporous g-C₃N₄ can significantly reduce the band gap of g-C₃N₄, causing a redshift of the UVvis absorption edge, and effectively improve the separation efficiency of photogenerated electron-hole pairs during photoresponse. After cyclic testing, the degradation efficiency showed no significant decline, demonstrating excellent catalytic stability. These findings synthesize an economical, versatile, and efficient mesoporous g-C₃N₄/MXene photocatalyst, which can be used to eliminate pollutants in industrial wastewater streams and improve environmental sustainability.