A recyclable and highly active Co3O4 nanoparticles/titanate nanowire catalyst for organic dyes degradation with peroxymonosulfate

Abstract

In this paper, we reported a recyclable and highly active porous catalyst of titanate nanowires (TNWs) coated with well-distributed Co3O4 nanoparticles (NPs) (Co3O4/TNWs). Sodium ions of TNWs were exchanged with hydrogen ions in the dilute nitric acid, and this protocol was very suitable for capturing cobalt ions. X-ray diffraction (XRD) demonstrated the existence of Co3O4 phase with unique lattice planes, such as (220), (311) and (511). Electron microscopes (FE-SEM and TEM) indicated that the Co3O4 NPs with an average diameter of 22±3nm were coated uniformly on TNWs surface (average diameter: 37±5.5nm), and the Co3O4 NPs mainly exposed their (220) and (222) active planes. XPS analysis confirms the formation of Co3O4 phase by the presence of Co 2p peaks at 780.1eV (2p 3/2) and 795.5eV (2p 1/2). Methylene blue (MB) and other organic dyes (rhodamine B (RhB) and methyl orange (MO)) were chosen as target compounds for catalytic degradation under indoor scattering light. Compared to the original Co3O4/TNWs catalyst, the catalytic efficiency of nanoscaled catalyst with oxone for MB was about 15 times higher, and the MB solution (10mgL−1) was completely degraded within 8min. The catalytic activity of recycled catalyst used in the sixth run still remained very active, and the degradation time for MB was only 16min. The nanosized catalyst also had a high activity for dyes of RhB (10mgL−1) and MO (10mgL−1), as the degradation efficiencies of RhB and MO after 10min of contact time were about 90.2% and 92.6%, respectively.