Dual defect sites of nitrogen vacancy and cyano group synergistically boost the activation of oxygen molecules for efficient photocatalytic decontamination

Abstract

Solar-driven photodegradation of pharmaceutical and personal care products (PPCPs) is an attractive strategy for environmental remediation but faces poor activity mainly due to the unsatisfied generation rate of active radicals. Herein, we design and synthesize a hierarchical C3N4 tubes containing dual defect sites of nitrogen vacancy and cyano group (Nv/Cy-tCN) via an alkali-assisted strategy. Density functional theory calculations demonstrate that modification of dual defect sites boost the activation of molecular oxygen through the polarization of O-O bonds. Furthermore, the ability to separate carriers and absorb light can be enhanced by the creation of an electron-rich structure in Nv/Cy-tCN. Consequently, the Nv/Cy-tCN shows excellent photo-degradation performance for eleven types of PPCPs, affording a 100% removal rate toward diclofenac within 7 min of natural sunlight irradiation. The Nv/Cy-tCN system exhibited enhanced diclofenac degradation kinetics with a reaction rate constant of 0.055 min−1, which was 12.8 times higher than that of pristine carbon nitride (0.0043 min−1). Importantly, the impacts on real wastewater and the degradation of trace contaminants further support that this photocatalytic system could be effectively used to remediate PPCPs pollution in environmental waterways.