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

Abstract

Two different morphologies of Fe2O3 involving nanodots and nanosheets were deposited on g-C3N4 nanosheets by simple in-situ deposition and impregnation-hydrothermal methods, respectively. Structural effect of Fe2O3 on photo-Fenton-like activity and charge transfer at the interface in these two g-C3N4/Fe2O3 hybrids were studied. Detail characterizations on charge transfer kinetics revealed that g-C3N4/nanodot-Fe2O3 structure showed faster electron injection rate and higher injection efficiency (≈0.084 ns−1 and ≈27.5%) than g-C3N4/nanosheet-Fe2O3 counterpart (≈0.054 ns−1 and ≈19.5%). Stronger intimate junction between g-C3N4 nanosheets and Fe2O3 nanodots was believed to be the reason for faster and more efficient electron injection. In addition, stronger interaction with tetracycline and higher reactivity with H2O2 at the interface were observed for g-C3N4/nanodot-Fe2O3 compared with g-C3N4/nanosheet-Fe2O3. Thereby, under visible light stimulation, g-C3N4/nanodot-Fe2O3 demonstrated higher photo-Fenton-like tetracycline removal efficiency and rate (≈87% and ≈0.037 min−1) than g-C3N4/nanosheet-Fe2O3 (≈57% and ≈0.016 min−1). Furthermore, g-C3N4/nanodot-Fe2O3 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-C3N4 and nanostructured Fe2O3, which can open a new avenge to develop Fe2O3-based photo-Fenton catalysts with high efficiencies for antibiotic wastewaters remediation.