Study On Gas-phase Photocatalytic Performances Of Pt/InVO₄/TiO₂ Under Visible Light Irradiation

InVO₄/TiO₂ photocatalyst was prepared by improved sol-gel method. Pt was subsequently modified onto InVO₄/TiO₂, forming a visible-light-driven photocatalyst of Pt/InVO₄/TiO₂. Photocatalytic activity measurement was investigated under visible light irradiation (λ> 450nm), using ethylene as a model pollutant. Photocatalyts were systematically characterized by FTIR, XRD, HRTEM, PL, BET, TG/DSC, UV-Vis DRS, SPS, FISPS and XPS et al techniques. The photocatalytic activity of Pt/InVO₄/TiO₂, InVO₄/TiO₂ and Pt/TiO₂ were compared under visible light irradiation and photocatalytic mechanism was proposed. Results of HRTEM and XRD preliminarily indicated that InVO₄/TiO₂ photocatalyst is of characteristic heterojunction structure. When the composite content of InVO₄ is up to ca. 0.5%, InVO₄/TiO₂ calcined at 673 K exhibited the highest photocatalytic activity. Terephthalic acid PL probing measurements showed a powerful oxidizing species ( OH) was photoinduced on InVO₄/TiO₂ photocatalyst irradiated by visible light, which is of vial to mineralize organic pollutants. Under visible light irradiation, no ethylene photodegradation was detected on pure TiO₂ while the degradation of ethylene on Pt/InVO₄/TiO₂ was higher at twice than that on Pt/TiO₂ or InVO₄/TiO₂. Modified by Pt and coupled of InVO₄, the band edge of Pt/InVO₄/TiO₂ shifted to visible region range, the transition of TiO₂ crystalline phase, from anatase to rutile, was suppressed efficiently and the specific surface area was increased by 24%. Analysis of XPS showed that binding energy of Ti 2p shifted to a higher energy and Cl 1s shifted to a lower energy. State of O 1s indicated that four type of containing-oxygen species, O2-, Ti-O→PtCl₄, OH-and Oads, were presented on Pt/InVO₄/TiO₂ photocatalyst. This result also made out that a new surface complex, Ti-O→PtCl₄, was formed by the stronger interaction between Pt and TiO2. This work, for the first time, introduced a visible-light-driven InVO₄/TiO₂ photocatalyst, which shows good photocatalytic activity and photostability toward ethylene degradation, and improved photocatalytic activity was then obtained by modification of Pt.