Dual-functional carbon materials for sustainable Cr(VI)-organic co-decontamination: Structure activity relationship analysis of defect and oxygen content

Based on Cr(VI) reduction, organic pollutants oxidative degradation and the excellent properties of carbon materials, the effectiveness of carbon materials for enhanced simultaneous Cr(VI) reduction and organic pollutants removal was verified. In this work, reduced graphene oxide (rGO) showed high catalytic activity, achieving > 99 % removal of both 10 mg/L 4-methoxyphenol (MOP) and 0.075 mM Cr(VI) within 20 min (k obs of 0.1723 min −1 and 0.1688 min −1 , respectively). To analyze the structure-activity relationship of the carbon materials in the system, a series of rGO derivatives were prepared. The results showed that the redox efficiencies of MOP and Cr(VI) had a significant positive correlation with the defect level of rGO, while the oxygen content was a negative factor for the catalytic performance, demonstrating that the defects were the main sites mediating the redox of MOP and Cr(VI). Furthermore, the O 2 • − , 1 O 2 and electron transfer pathway were identified as the mechanisms of MOP degradation and Cr(VI) reduction, according to quenching, electron spin resonance, salt-bridging and electrochemical oxidation experiments. Ultimately, the stability, broad applicability of simultaneous redox of MOP and Cr(VI) mediated by rGO were confirmed by cycling experiments, degradation experiments in various waters and with different pollutants. This study provides new mechanistic insights for the synergistic treatment of composite pollution using carbon materials.