Carbon fragments incorporated carbon nitride for selective activation of peroxymonosulfate into singlet oxygen towards water decontamination

The metal-free nature of carbon nitride endows it the advantages of low cost and less secondary pollution when uses in peroxymonosulfate (PMS)-based advanced oxidation processes. However, practical applications call for continued efforts on developing modification protocols to achieve higher catalytic efficiency while breaking its dependence on visible light. Herein, a one-step carbon fragments doping method was developed to synthesis a series modified carbon nitride. The obtained catalyst DCNs showed high efficiency on non-photocatalytic activation of PMS for organic pollutant removal. Characterization results proved that carbon fragments were incorporated into the skeleton of carbon nitride during the thermal treatment process. Along with the rise of doping amount, the system efficiency on pollutant removal increased first then decreased. The dominant reactive species was identified as singlet oxygen, which was deduced to originate from the electron loss process of HSO5- at the carbon sites on DCN. Density functional theory calculations suggest that appropriate doping of carbon fragments on carbon nitride improves the adsorption energy and charge transfer efficiency of PMS on the catalyst surface, thereby elevating the catalytic efficiency on pollutant removal. In addition, as a non-radical species dominated process, the DCN catalyst well resisted the interference from water matrices to degrade pollutants in high efficiency. At the same time, DCN had good reusability, exhibiting considerable prospects for practical applications.