Visible light assisted heterogeneous photo-Fenton-like degradation of Rhodamine B based on the Co-POM/N-TiO2 composites: Catalyst properties, photogenerated carrier transfer and degradation mechanism

Abstract

The water pollution caused by industry emissions makes effluent treatment a serious matter to be settled. The heterogeneous photo-Fenton-like oxidation has been recognized as an effective means to degrade pollutants in water. In this paper, Co-polyoxometalate (POM) was decorated on N-TiO2 to form the hybrid Co-POM/N-TiO2 photo-Fentont-like catalys for the degradation of Rhodamine B (RhB) under visible light irradation. The pseudo first-order kinetic rate constant of RhB degradation in Co-POM/N-TiO2 catalyzed heterogeneous Fenton-like reaction was 9 times higher than those of N-TiO2 catalysts, and the degradation rate can reach to 97.47% within 40 min under visible light irradiation and neutral conditions (at pH=7). Experimental characterizations revealed that the doping efficiently of N into TiO2 not only expanded optical absorption of TiO2 into the visible region, but also was beneficial for the migration of electrons from bulk to surface of TiO2, and further facilitated the charge transfer from TiO2 to Co-POM clusters, resulting in the enhancement in photo-Fenton activity. Our work provides a new idea to construct the transition metal substituted POM/N-TiO2 hybrid catalysts with Fenton-like and visible light photocatalytic activities for the practical application of environmental remediation.