MOF-derived nitrogen doped carbon modified g-C3N4 heterostructure composite with enhanced photocatalytic activity for bisphenol A degradation with peroxymonosulfate under visible light irradiation

Abstract

Designing metal-free g-C3N4 based photocatalytic system with efficient photocatalytic activity has received enormous attention in the field of environmental remediation because of its great potential for removing refractory contaminants. Herein, a novel metal organic framework (ZIF-8)-derived nitrogen doped carbon (ZIF-NC) modified g-C3N4 heterostructured composite was synthesized through a facile thermal treatment method. Benefiting from the hierarchical porosity, conductive network, and abundant exposed active sites for peroxymonosulfate (PMS) activation of MOF-derived nitrogen doped carbon, the introduction of MOF-derived nitrogen doped carbon into g-C3N4 not only facilitates the charge separation of g-C3N4 but also greatly accelerates PMS activation to yield high active SO4− radical. The energy band diagrams derived from Mott-Schottky, valence band X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy studies indicate that the formed heterojunction between g-C3N4 and ZIF-NC is Schottky type. The ZIF-NC with lower Fermi level energy can serve as an excellent electron accepter to enable fast electron transfer from the conduction band of g-C3N4 to ZIF-NC and boost the charge separation of g-C3N4. Photoelectrochemical tests combined with multiple spectroscopic techniques further confirm the enhanced charge carrier separation performance of composite. As a result, the as-prepared hybrids displayed remarkably improved photocatalytic activities toward bisphenol A (BPA) degradation in the presence of PMS under visible light irradiation. The apparent rate constant, k, for BPA degradation of the ZIF-NC/g-C3N4 composites with PMS is approximately 8.6 times as high as that of bare g-C3N4. This work provides a promising approach on the rational design of high-performance, cost-effective photocatalysts for environmental remediation.