Study of the tunable structure and two-dimension correlation infrared spectroscopy of Gd/3-methylbenzoic acid with o-phenanthroline, 2,2′-and 4,4′-bipyridines

Enhanced photocatalytic activity of S-doped graphitic carbon nitride hollow microspheres: Synergistic effect, high-concentration antibiotic elimination and antibacterial behavior

For the past few years, graphitic carbon nitride (g-C₃N₄) has been widely used to eliminate environmental pollutants, but limited active site on surface and low separation/migration ability suppress its practical uses. Herein, we adopted a supramolecular self-assembly route followed with S doping to synthesize S-doped g-C₃N₄ with a hollow microsphere composition (SCNHM), where the shell was demonstrated to compose of ultrathin nanosheets. The unique structural characteristics endow the SCNHM with high specific surface area (∼81 m² g^-1) to provide abundant reaction sites and enhanced light-harvesting due to the light-scattering effect of hollow structure. Moreover, the S dopant meliorated the electronic structure to narrow the bandgap and promoted the charge separation/transfer capability. With this synergistic effect, the SCNHM presented greatly improved photocatalytic activity for degrading tetracycline hydrochloride (TC) compared to the CN, SCN and CNHM samples. This photocatalyst could eliminate high-concentration TC (50 mg L^-1) in 18 min, and the 30 min removal efficiencies of 100 mg L^-1 and 200 mg L^-1 reached 92 % and 60 %, which is much better than the reported photocatalysts in literatures (usually ≤ 20 mg L^-1). Additionally, the good photocatalytic durability was confirmed and the degradation pathway of TC was proposed. Furthermore, the SCNHM was proved to meanwhile possess superior performance for inactivating the typical Gram-positive bacterium of Staphylococcus aureus (S. aureus) and the typical Gram-negative bacterium of Escherichia coli (E. coli). Finally, based on determination of band alignment and detection of active species, a plausible photocatalytic mechanism was proposed.

Phenanthroline bridging graphitic carbon nitride framework and Fe (II) ions to promote transfer of photogenerated electrons for selective photocatalytic reduction of Nitrophenols

Nitrophenols (NPs) are widely used in industries and highly toxic to ecological environment and human health. Because aminophenols (APs) are important chemicals, catalytic reduction of NPs via efficient and environment-friendly strategies is of great importance. Herein, we developed a green photocatalysis route to efficiently convert NPs to APs using a Fe (II) modified graphitic carbon nitride (g-C₃N₄) photocatalyst, where phenanthroline units were employed to bridge Fe (II) and carbon nitride framework. The optimized sample P-CN-8-Fe presented significantly improved absorption of visible light, separation of photogenerated charges and carrier transportation in comparison with the pristine g-C₃N₄ and the modified samples of CN-Fe and P-CN-8. Accordingly, the P-CN-8-Fe showed a high conversion (97%) of p-nitrophenol (p-NP) to p-aminophenol (p-AP) under 2 h visible light irradiation, and meanwhile possessed high photocatalytic durability. Its high activity was also demonstrated through photocatalytic reduction of other NPs and nitrobenzene compounds. Finally, a possible mechanism was proposed for the photocatalytic reduction of p-NP by P-CN-8-Fe. This work provides an effective approach to prepare Fe (II) modified g-C₃N₄ through the bridging effect of phenanthroline group, which is a potential visible light driven photocatalyst for reduction of nitrobenzene derivatives.