New functionalization approach synthesis of Sulfur doped, Nitrogen doped and Co-doped porous carbon: Superior metal-free Carbocatalyst for the catalytic oxidation of aqueous organics pollutants

Abstract

New green synthesis methods of novel commercially applicable carbocatalysts suitable for the catalytic oxidation of organic pollutants, remain a challenge. Herein, Nitrogen doped (N-PC), Sulfur doped (S-PC) and Co-doped (N, S-PC) porous carbon, were synthesized via a new facile environmentally functionalization approach followed by pyrolysis. Thus, Almond Shell (AS) as Bio-sourced material was used for porous carbon (PC) preparation as support. Thereafter, the introduction of Melamine, Diphenyl Disulfide and Thiourea on the PC matrix with high -COCl− and -CCl− groups facilitated the surface functionalization, and allowed us the introduction of high N and S heteroatoms contents in the PC networks surface. It was found that the optimized carbocatalysts could effectively activate PS, and exhibited excellent catalytic performances for the organic pollutants degradation, with an exceptionally low activation energy and fast kinetic reaction. Based on a systematic comparison, it was found that the N-PC exhibited the superior catalytic activity for activating the PS and degrading various organic pollutants. Such superior catalytic activity of the N-PC Carbocatalyst resulted from its high surface area, its low defect degree with the higher content of Graphitic-N. In addition, all experimental and theoretical investigations demonstrated the critical role of graphitic–N for the PS activation. It is expected that the doping process by N will significantly break the chemical inertness of the PC network and will make the N-PC surface more positively charged accelerating hence its interaction with the negatively charged S2O82−. Furthermore, the 1O2 was found to be the predominant reactive oxygen species (ROS) as assessed by radical scavenging tests and EPR experiments. The carbocatalysts were not easily influenced by the water aqueous phase, which give us more obvious advantages over the PS activation.