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Light absorption and carrier transfer, are two sequential and complementary steps related to photocatalysis performance, whereas the collective integration of these two aspects into graphitic carbon nitride (g-C3N4) photocatalyst through polycondensation optimization have seldom been achieved. Herein, we report on tailoring the crystalline structure of g-C3N4 by avoiding the formation of incompletely reacted N-rich intermediates and selective breaking the hydrogen bonds between the layers of g-C3N4 simultaneously. The obtained layer plane ordered porous carbon nitride (LOP-CN) material shows efficient photocatalytic H2 generation performance. The highest H2 evolution rate achieved is 53.8 μmol under λ ≥ 400 nm light irradiation, which is 7.4 times higher than that of g-C3N4 prepared by convention thermal polycondensation. The substantially boosted photocatalytic activity is mainly ascribed to the efficient charge separation on long-range atomic order layer plane and the extended visible light harvesting ability. This work highlights the importance of crystalline structure tailoring in improving charge separation and light absorption of g-C3N4 photocatalyst for boosting its photocatalytic H2 evolution activity.

Antibiotics in natural waters have posed serious threats to our ecosystem due to its potent biological toxicity. In the present work, a visible-light-driven PANI/Bi4O5Br2 composite photocatalyst was fabricated and used for the degradation of ciprofloxacin (CIP) and tetracycline (TC) antibiotics under visible light (λ ＞ 420 nm). The PANI/Bi4O5Br2 composite presented a significantly improved ability of CIP and TC photodegradation, which is about 2.2 times and 1.6 times to that of Bi4O5Br2, respectively. The promoted photocatalytic activity results from the interface interaction between PANI and Bi4O5Br2, which contributes to the electron-hole separation. The degradation process of CIP was monitored by mass spectrometry, and a possible degradation pathway was proposed based on the analysis of the product. A microbiological antibacterial experiment was designed, proving that the degraded products of CIP and TC have lower toxicity. Furthermore, long wavelength light irradiated (λ ＞ 550 nm) experiment indicated that the introduction of PANI helps to extend the light absorption region and use the long wavelength light more efficiently, thereby promoting the photocatalytic ability. The optimal composite applied for TC degradation was 0.1% PANI/Bi4O5Br2. Its reaction rate constant was 2.8 times to that of Bi4O5Br2 (λ ＞ 550 nm). Eventually, a possible photocatalytic mechanism over PANI/Bi4O5Br2 composite was proposed.

ZnFe2O4/AgI composites were first prepared successfully with a hydrothermal method, and ZnFe2O4 nanoparticles were uniformly decorated on the surface of AgI particles. The photocatalytic activities of the obtained ZnFe2O4/AgI composites were investigated by the degradation of organic pollutants and the inactivation of bacteria under visible light irradiation. The results showed that the introduction of ZnFe2O4 greatly enhanced the light harvesting ability and improved the separation efficiency of the photogenerated charge carriers, which contributed to the enhanced generation of reactive species and thus promoted the photocatalytic performance. The 5% ZnFe2O4/AgI composite exhibited the optimal photocatalytic disinfection of E. coli (100% removal efficiency in 80 min) as well as the photocatalytic degradation of rhodamine B (RhB) (98.5% removal rate in 40 min). Furthermore, four consecutive cycles also demonstrated the stable photocatalytic activity of the as-prepared ZnFe2O4/AgI composites. In addition, H2O2 was identified as the predominant active species in the photocatalytic inactivation of bacteria. This study indicated that ZnFe2O4/AgI composites are a promising candidate for the treatment of wastewater.