Faster electron injection and higher interface reactivity in g-C3N4/Fe2O3 nanohybrid for efficient photo-Fenton-like activity toward antibiotics degradation

Two different morphologies of Fe 2 O 3 involving nanodots and nanosheets were deposited on g-C 3 N 4 nanosheets by simple in-situ deposition and impregnation-hydrothermal methods, respectively. Structural effect of Fe 2 O 3 on photo-Fenton-like activity and charge transfer at the interface in these two g-C 3 N 4 /Fe 2 O 3 hybrids were studied. Detail characterizations on charge transfer kinetics revealed that g-C 3 N 4 /nanodot-Fe 2 O 3 structure showed faster electron injection rate and higher injection efficiency (≈0.084 ns −1 and ≈27.5%) than g-C 3 N 4 /nanosheet-Fe 2 O 3 counterpart (≈0.054 ns −1 and ≈19.5%). Stronger intimate junction between g-C 3 N 4 nanosheets and Fe 2 O 3 nanodots was believed to be the reason for faster and more efficient electron injection. In addition, stronger interaction with tetracycline and higher reactivity with H 2 O 2 at the interface were observed for g-C 3 N 4 /nanodot-Fe 2 O 3 compared with g-C 3 N 4 /nanosheet-Fe 2 O 3 . Thereby, under visible light stimulation, g-C 3 N 4 /nanodot-Fe 2 O 3 demonstrated higher photo-Fenton-like tetracycline removal efficiency and rate (≈87% and ≈0.037 min −1 ) than g-C 3 N 4 /nanosheet-Fe 2 O 3 (≈57% and ≈0.016 min −1 ). Furthermore, g-C 3 N 4 /nanodot-Fe 2 O 3 junction can remain robust catalytic performance under various conditions (recycle experiment, real environment, different initial pHs and temperatures, anion coexistence, and other contaminants removal) and possible tetracycline degradation pathways were proposed. This study provided deep insights into structure-activity relationship and electron transfer between g-C 3 N 4 and nanostructured Fe 2 O 3 , which can open a new avenge to develop Fe 2 O 3 -based photo-Fenton catalysts with high efficiencies for antibiotic wastewaters remediation.