In situ-growth of Fe2S3 ultrathin layer on CdS nanorod through cation-exchange for efficient photocatalytic degradation of organic pollutants under visible light coupled oxidant activation

A new core-shell structure CdS@Fe2S3 material was synthesized by in situ cation exchange mhod to enhance the degradation of organic pollutants in water under visible light. It is proved that Fe2S3 nanolayer is successfully loaded on CdS nanorods by TEM and UV-Vis spectra and other means. The representative Rhodamine B was selected as the target pollutant and the results of degradation experiment showed that after 60 minutes of exposure to LED visible light with a low energy (25 W), the removal efficiency for this dye could reach 98% in the presence of peroxymonosulfate (PMS) forming free radicals, which displayed a observed kinetic rate constant exceeding 0.62 min−1 that is approximately 5 times higher than the system without PMS addition and 10 times than the system with original CdS as catalyst. The result of inhibition experiments shows that sulfate radical (SO4·-) and singlet oxygen (1O2) play as important roles during the photocatalytic process. A theory for the reduction is proposed. In addition, this core-shell material can be recycled at least four times. Generally, this study can make full use of visible light which can be easily obtained and effectually resolve the organic pollution problems.