0D/1D Co3O4 quantum dots/surface hydroxylated g-C3N4 nanofibers heterojunction with enhanced photocatalytic removal of pharmaceuticals and personal care products

Abstract

Graphitic carbon nitride (g-C3N4) is a promising candidate for photocatalytic degradation of emerging environmental contaminants, pharmaceuticals and personal care products (PPCPs). To improve the photodegradation performance of pure g-C3N4, the construction of different heterostructures, surface modification and morphology engineering could be considered. However, the surface of g-C3N4 is usually difficult to modify due to fewer functional groups on its surface. In this work, surface hydroxylated g-C3N4 nanofibers were prepared by NaOH treatment (NTCN), and then went through an in-situ growth method to obtain 0D/1D Co3O4-NTCN nanocomposites. Hydrolysis can effectively modify the surface of g-C3N4 to make it rich in hydroxyl and reduce the number of amino groups, which is conducive to photocatalytic activity. Surface hydroxylation of NTCN was confirmed by FTIR and XPS. Structurally, Co3O4-NTCN has a unique 0D / 1D structure, which has not been reported much on photocatalysts based on carbon nitride, providing a large surface area and short diffusion distances and resulting in more exposure to the light and the effective transfer of interfacial photogenerated charge from the interior to the surface. The photodegradation ratio of TC, DCF and MT can reach 97.3% TC, 88.9% and 63.2% within 60 min respectively. DFT calculation is used to illustrate the band structure and separation and migration of photoinduced charges of Co3O4-NTCN composites. Radicals trapping test demonstrate O2⋅− and ⋅OH are the major radicals, and a possible Z-scheme mechanism is proposed.