Oxygen Deficient TiO2−x with Dual Reaction Sites for Activation of H2O2 to Degrade Organic Pollutants

Abstract

The present study reports the development of a novel defective TiO2−x catalyst with oxygen vacancy (OV) which carries dual types of reaction sites for H2O2 activation. The performance of this catalyst on the degradation of organic pollutants was evaluated using organic dyes [such as methyl orange, methylene blue, and rhodamine B (RhB)] as model pollutants. The defects in TiO2−x exhibited a wide pH working window (pH 2–9) for RhB degradation which is wider than that of traditional Fenton systems. Furthermore, this catalyst retained its high catalytic activity even after five cycles. It was confirmed that the surface OV and Ti3+ of TiO2−x served as the active sites for H2O2 activation while the oxygen vacancy promoted adsorption of the organic pollutants, thus enhancing the Fenton-like catalytic performance. The results are applicable to Fenton catalysts via surface engineering and can stimulate new opportunities for the optimization of defect-type Fenton catalysts. This study, reports the defect of TiO2−x oxygen vacancy (OV) catalyst with oxygen vacancy (OV) which carries dual types of reaction sites for H2O2 activation. The performance of this catalyst on the degradation of organic pollutants was evaluated using organic dyes [such as methyl orange, methylene blue, and rhodamine B (RhB)] as model pollutants. The defects in TiO2−x exhibited a wide pH working window (pH 2–9) for RhB degradation which is wider than that of traditional Fenton systems. Figure shows the schematic of the reaction mechanism. First, H2O2 adsorbs on the TiO2−x surfaces; consequently, the OV and Ti3+ serve as the “Fenton-catalytic” center for H2O2 activation to produce ·OH radicals on the TiO2−x surface. Meanwhile, OV on TiO2−x surface is beneficial for the adsorbed organic pollutants. Because of the generated hydroxyl radical on the TiO2−x surface is very close to the adsorbed pollutant. As a result, the rapid reaction of in situ generated hydroxyl radical with the adsorbed organic pollutants on the TiO2−x surface giving rise to excellent Fenton-like catalytic performance. The proposed overall Fenton-like reaction mechanism on oxygen deficient TiO2−x catalyst.