Synthesis of nitrogen and sulfur Co-doped carbon with special hollow sphere structure for enhanced catalytic oxidation

In this study, a facile atmospheric pressure chemical vapor deposition (CVD) method is used for the synthesis of nitrogen and sulfur co-doped hollow carbon sphere (NSC). Nano-CaCO 3 is used as template for the formation of hollow and highly hierarchical porous carbon structure. The doped percentages of N and S can be easily regulated by changing the ratio of N and S precursors and the deposition temperature. The obtained NSC is highly active for the catalytic oxidation of organic pollutants with peroxymonosulfate (PMS) as oxidant, and the reaction rate constant is 4.5 and 32.7 times faster than the single N or S doped samples, respectively. The PMS activation mechanism is comprehensively investigated by electron paramagnetic resonance (EPR) and radical quenching tests. Superoxide intermediate (O 2 •− ) and singlet oxygen ( 1 O 2 ) play the dominant role for phenol degradation. Moreover, with the introduction of secondary doped S atoms, more O 2 •− are generated for organics degradation. The excellent catalytic activity of NSC should be resulted from the optimized N and S doping percentages and large specific surface area (SSA). The synthesis strategy in this study provides a facile and low-cost synthetic method for heteroatom doped carbon materials and would expand the application of metal-free materials in the environmental remediation field.