Exploring The Magnetic Property And Photocatalytic Performance Of G-C_3N4 And Its Composites

The graphite-like carbon nitride (g-C3N4), one of the most important two-dimensional semiconductors, has attracted considerable attention because of its excellent photocatalysis performance, good thermal and chemical stability, high solar energy usage and specific surface area. So far, the magnetic properties of g-C3N4 has been only reported in theoretical calculation, the origin and tuning of ferromagnetism for g-C3N4 are still in the exploration, which limits its applications in next-generation metal-free spintronics. In this article, we prepared the ultrathin g-C3N4 nanosheets and g-C3N4+Fe3O4 composite material in experimental, we also studied the magnetic properties and photocatalysis performance of the samples in detail. The main conclusions are as follows.1. We chose the urea as a precursor which was heated under different temperatures to get the g-C3N4 nanosheets. The results of magnetic measurement showed that all of the samples exhibit room temperature ferromagnetism (RTFM) after ruling out ferromagnetic element existing in the samples. It means that the RTFM in g-C3N4 nanosheets is intrinsic. We also found that the saturation magnetization and the carbon defect concentration in the samples all decrease with the increase in annealing temperature, revealing its carbon defect related ferromagnetism. Moreover, we further confirmed the defect induced ferromagnetic nature by ab initio calculations. At last, we designed two chemical methods to control the saturation magnetization for the g-C3N4 nanosheets. It is believed that this finding highlights a new promising material toward realistic metal-free spintronic application.2. Basing on the excellent photocatalytic performance of g-C3N4 nanosheets, we prepared g-C3N4+Fe3O4 magnetically separable photocatalysts which can be separated from water easily by a hydrothermal method. These photocatalysts can activate H2O2 to generate reactive oxy-radicals under visible light irradiation, leading to the mineralization of the dye. These photocatalysts have many advantages such as facile fabrication, using sunlight, easily reused and recycled, high catalytic performance, etc. This study indicated a promising approach for the activation of green oxidant (H2O2) by the magnetically separable photocatalysts for environmental remediation.