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

Abstract

Magnetically separable Fe3O4/hTiO2/g-C3N4 composites were successfully constructed through coating polymethylacrylic acid sacrificial interlayer by the reflux-precipitation polymerization and subsequent TiO2 outer layer by sol–gel method over magnetic Fe3O4 nanospheres, calcining process and forming composites with g-C3N4 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 Fe3O4/hTiO2/g-C3N4 for degrading methylene blue (95.0 %, 120 min) under simulated sunlight irradiation (Xe lamp, 500 W) was much better than g-C3N4 (71.1 %, 120 min) and Fe3O4/hTiO2 (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-C3N4 and TiO2, which was verified using photocurrent and EIS analysis. On the basis of the scavenging studies of radicals (h+, •O2– 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 Fe3O4. 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.