Construction of magnetically recyclable Fe3O4/hTiO2/g-C3N4 composites for solar photocatalytic degradation of organic pollutants: Study on the performance and mechanism insight

Magnetically separable Fe 3 O 4 /hTiO 2 /g-C 3 N 4 composites were successfully constructed through coating polymethylacrylic acid sacrificial interlayer by the reflux-precipitation polymerization and subsequent TiO 2 outer layer by sol–gel method over magnetic Fe 3 O 4 nanospheres, calcining process and forming composites with g-C 3 N 4 in sequence . The formation mechanism of unique composites was proved by TEM, XPS, VSM, XRD and EDX mapping characterization. Their photocatalytic activity was investigated by the solar photodegradation of organic dyes. The results revealed the photocatalytic performance of Fe 3 O 4 /hTiO 2 /g-C 3 N 4 for degrading methylene blue (95.0 %, 120 min) under simulated sunlight irradiation (Xe lamp, 500 W) was much better than g-C 3 N 4 (71.1 %, 120 min) and Fe 3 O 4 /hTiO 2 (40.3 %, 120 min). The boosted property is presumably ascribed to the synergetic interaction of multiple components and effective separation of the photoproduced electron-hole pairs between g-C 3 N 4 and TiO 2 , which was verified using photocurrent and EIS analysis. On the basis of the scavenging studies of radicals ( h + , •O 2 – and •OH), the mechanism of the boosted photocatalytic performance was put forward. The degradation pathways of methylene blue were also proposed by identifying reaction intermediates produced during photocatalysis. More significantly, the composites presented excellent magnetic responsive property owing to the magnetic Fe 3 O 4 . The superior recyclability was confirmed by cyclical photocatalytic experiments with the help of an external magnet, which is crucial for the sustainable and green application of photocatalysts.