In situ solvothermal method of C3N5@NH2-MIL-125 composites with enhanced visible-light photocatalytic performance

In order to increase the visible-light photocatalytic performance for the degradation of Rhodamine B (RhB), C3N5@NH2-MIL-125-x (x = 1, 2, 3) were compounded by a typical in situ solvothermal method. XRD, FT-IR, and SEM were employed to investigate the structural characteristics of C3N5@NH2-MIL-125-x which were manifested to be successfully prepared; UV–Visible absorption spectra and photoluminescence spectra of C3N5@NH2-MIL-125-x were carried out to evaluate the photocatalytic activity. The results indicated that the composites of C3N5@NH2-MIL-125-x could boost the visible-light absorption and separation efficiency of photogenerated e−–h+ pairs. Then the photocatalytic degradation experiments and the kinetics properties study for RhB showed C3N5@NH2-MIL-125-3 had the best photocatalytic degradation efficiency up to 93.3% under the visible light. Notably, the recyclability experiments with five cycles and thermal analysis proved C3N5@NH2-MIL-125-3 had a high chemical stability and thermal stability (below 500 °C). Moreover, the active species capture experiments demonstrated –O2− radicals were the primary reactive species, while the OH− radicals and h+ were the subordinate reactive species in the photocatalytic degradation of RhB. In addition, the EIS and TPRs further verified C3N5@NH2-MIL-125-3 possessed a higher separation efficiency of photogenerated e−–h+ pairs. This work provides an effective strategy for compositing NH2-MIL-125 (Ti) and C3N5 toward photocatalytic degradation of the organic pollutants.