Owing to insufficient active sites, strongly bound excitons and insufficient optical absorption, polymer semiconductors have only shown mild activity as potential candidates for photocatalysis. A g-C 3 N 4 with improved optical absorption capacity, charge transfer performance and porosity was successfully prepared by a one-step NH 4 Cl-assisted route. Interaction of melamine with NH 4 Cl preparation of Porous g-C 3 N 4 (CN-xy) with active functional groups modified pore wall shown to result in highly crystalline species with a maximum π-π layer stacking distance of heptazine units of 0.321 nm, decreases the optical band gap from 2.80 to 2.13 eV and maximum surface area reached 56.485 m 2 g −1 . The balanced improvement of the multiple defects of g-C 3 N 4 makes the photocatalytic degradation of RhB and the photocatalytic hydrogen production efficiency 4 and 5 times higher than the pristine g-C 3 N 4 , respectively.
Xinyue Zhang,Lin Yuan,Yu Zhang,Xinyu Shu,Renjie Li,Qunfen Deng,Zilong Zhang,Rui Yang
In this work, a modified graphite phase carbon nitride (g-C3N4), used as an efficient photocatalyst, was successfully prepared by employing melamine as a precursor and ammonium chloride as a gas template agent, in conjunction with a two-step calcination strategy to manipulate the polymerization process of melamine. The relevant characterization results indicated that the modified catalyst had loose structure and more active sites, which increased the specific surface area, inhibited the recombination of light-generated electron–hole pairs, and then promoted the generation of active substances. The photocatalytic performance of the catalyst was evaluated using rhodamine B (RhB) as a template under visible light irradiation. The results demonstrated that the secondary calcination temperature significantly influenced the performance of the catalyst. At the optimum secondary calcination temperature (∼650 °C, denoted as 650-CN-2), the reaction rate constant was estimated to be 0.1163 min−1, which was 30.4 and 2.71 times higher than that of pure CN and CN-2, respectively, while achieving a degradation rate of 97% within 30 min. Radical trapping experiments and ESR analysis confirmed that the superoxide free radical (·O2−) serves as the primary active species in photocatalytic degradation. This work not only expanded research ideas for the optimal temperature of the secondary calcination method, but also provided a useful exploration for the efficient synthesis path of catalysts.
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