Hui Zhao,Cheng Tian,Jian Mei,Shijian Yang,Po Keung Wong
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.
As an important intermediate, imine is widely used in industrial chemistry. The photocatalytic oxidation of amines to form imines is a green and economical method. But it remains a challenge for the efficient transformation under mild conditions. Herein, a Z-scheme carbon nitride (CM)-Fe2O3 heterojunction photocatalyst was synthesized by in-situ preparation of Fe2O3 nanoparticles on two-dimensional CM nanosheets. The as-prepared catalyst exhibited efficient photocatalysis activity in selective oxidation of benzylamine to N-benzylidene benzylamine. Under ambient air and room temperature, the selectivity and conversion rate both can reach 99.9%, and the corresponding turnover frequency value reaches up to 9.99 mmol g−1 h−1, superior to the most of heterogeneous photocatalysts reported in previous literatures. The excellent catalytic activity of the modified CM material may be due to the enhanced absorption of visible light and the improved photogenerated carrier separation and migration rate, and the Z-scheme mechanism also retains the strong oxidation and reduction ability of the composite material. This work will provide a promising and practical method to promote the photocatalytic conversion of solar-driven organics.
In this study, multi-morphological g-C 3 N 4 / Fe 2 O 3 were prepared via hydrothermal supramolecular preorganization for the removal of formaldehyde in simulated indoor environments . We synthesized bulk, spherical and tubular g-C 3 N 4 under hydrothermal conditions and subsequently attached Fe 2 O 3 nanoparticles by impregnation method. Tubular g-C 3 N 4 /Fe 2 O 3 (27.46 m 2 /g) and spherical g-C 3 N 4 /Fe 2 O 3 (33.50 m 2 /g) synthesized through hydrothermal supramolecular preorganization method possessed the higher specific surface area than bulk g-C 3 N 4 /Fe 2 O 3 (11.05 m 2 /g). Among three morphologies of g-C 3 N 4 /Fe 2 O 3 , tubular g-C 3 N 4 /Fe 2 O 3 exhibited the best performance (65%) than bulk (41%) and spherical (59%) and possessed favorable stability. In addition, we explored and optimized the effects of different indoor simulation conditions (formaldehyde concentration, relative humidity, light source power) on the photocatalytic removal of formaldehyde. The mechanism was proposed that g-C 3 N 4 /Fe 2 O 3 formed Z-type heterojunction to promote the separation of photo-generated electrons and holes, further generating hydroxyl radical and superoxide radical to oxidize formaldehyde.
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