Coordination tuning of Fe²⁺ ions concentration in Fe-doped black phosphorus-carbonized cotton fiber (Fe-BP-CCF) composites to regulate photocatalysis and peroxymonosulfate (PMS) activation towards highly efficient degradation of organic pollutants

The present investigation involved the fabrication of Fe2+ ions doped black phosphorous-carbonized cotton fibers (Fe-x-BP-CCF) composites. Various characterization techniques were employed to investigate the structure of the Fe-x-BP-CCF composites. Experiment results indicated that by adjusting the concentration of Fe2+ ions in conjunction with C, N, O, and P elements, the performance of Fe-x-BP-CCF in photocatalysis or PMS activation could be controlled, leading to enhanced degradation of organic dyes and antibiotics. The effectiveness of photocatalysis and PMS activation in degrading Congo red (CR) and methylene blue (MB) dyes, as well as tetracycline (TC) and sulfonamide (SA) antibiotics, was considerably enhanced compared to using only photocatalysis or PMS activation. The reason is credited to the quick separation of photogenerated electron-hole pairs. The Fe-2.0-BP-CCF composite demonstrated a synergistic degradation effect through photocatalysis and PMS activation, requiring only 1 min. In contrast, photodegradation or PMS activation degradation alone necessitated 60 min. Moreover, even with a lower catalyst loading, the Fe-2.0-BP-CCF composite exhibited superior performance, degrading 75.5 % of TC and 71.4 % of SA, surpassing previous research findings. The excellent photocatalysis synergistic with PMS activation properties of Fe-2.0-BP-CCF can be attributed to the ideal amount of Fe2+ ions coordinated with elements C, N, O, and P. This coordination triggers the Fenton-like redox cycle reaction between Fe2+ and Fe3+ ions, which is facilitated by the photogenerated electrons. The resultant reactive radicals of SO4 center dot-, center dot O-2(-) and center dot OH could be produced in the photocatalysis and PMS activation process. In the meantime, the photogenerated holes could stimulate the formation of O-1(2) non-radicals. In addition to offering an efficient environmentally friendly method for wastewater treatment, this study uncovers novel perspectives on the enhancement of PMS activation through photocatalysis.