Boosting interlayer charge transfer in polymeric carbon nitride by Mo ions for efficient photocatalytic H2 evolution

Abstract

Tuning the band structure by doping metal elements is an effective way to boost charge transfer and thus improve the photocatalytic activity of polymeric carbon nitride (CN). Herein, Mo-doped carbon nitride (Mo–CN) was prepared by calcining melamine, cyanuric acid and sodium molybdate at elevated temperature. Under visible light at λ ≥ 420 nm, the optimal hydrogen production rate of 3Mo–CN reaches 16.7 μmol h⁻¹, about eight times that of pristine CN. Experimental results demonstrate that Mo doping reduces the band gap, increases the specific surface area, extends the visible light harvesting range, and enhances the separation and transfer of photogenerated carriers. Theoretical simulation verifies that the intercalated Mo acts as a bridging channel for interlayer charge transfer, increases the intramolecular electron transition distance (D_ct) and charge transfer quantity, and enhances the localization of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). All these factors are interwoven to contribute to the enhanced photocatalytic performance of polymeric carbon nitride.