Edge state engineering of nitrogen/phosphorus co-doped graphene nanoribbons towards electron-transfer-based peroxydisulfate activation

The electron transfer-based nonradical advanced oxidation processes (AOPs) exhibit great potential for degrading organic pollutants. However, achieving efficient electron transfer-based nonradical AOPs remains challenging. In this study, we developed the edge-rich and nitrogen/phosphorus (N/P) co-doped graphene nanoribbons by unfolding the multi-walled carbon nanotubes (MWCNTs). The catalysts with the edge-rich structure are capable of efficiently activating the peroxydisulfate (PDS) towards the degradation of carbamazepine (CBZ), a representative pharmaceutical and personal care products (PPCPs). Through adjusting the N/P ratio, the N/P co-doped graphene nanoribbons presented the optimal degradation kinetic constant of 0.452 min−1, compared with 0.0611 min−1 for the intact MWCNTs. Electrochemical characterizations, in situ Raman, galvanic oxidation tests, and quenching experiments confirmed that the N/P co-doped graphene nanoribbons followed an electron transfer-dominated nonradical pathway for pollutant degradation. Density functional theory (DFT) demonstrated that the exposed N/P co-doped edges at the boundary of graphene nanoribbons could elongated OO bond of PDS in facilitating PDS activation. This study provides a new approach to develop the nonradical AOPs-based techniques.