Effect of synergy between oxygen vacancies and graphene oxide on performance of TiO2 for photocatalytic NO removal under visible light

Abstract

• The composite photocatalyst B-TiO 2 -xGO was prepared by sol–gel and calcination methods. • 2D honeycomb GO improve the separation of the photogenerated charge carriers and absorption of H 2 O 2 . • Photo-activity of B-TiO 2 -3GO was 1.5-fold for NO removal than bare B-TiO 2. • The synergy between oxygen vacancies and graphene oxide was explored and demonstrated in detail. It is important to find an effective way to enhance the photocatalytic NO removal efficiency of black-TiO 2 . In this work, we used a simple hydrothermal method to synthesize the black TiO 2 -GO composite. One of the black TiO 2 -GO composites, B-TiO 2 -3GO (black TiO 2 -GO composites with graphene content of 3 wt%), exhibits remarkably high activity toward the photocatalytic removal of NO, with a NO conversion rate of 50.4% which is greater than that of pure black TiO 2 (33.9%). The experimental results revealed that the TiO 2 -GO nanocomposite photocatalyst has the high absorption ability from large surface area and well mobility of charge carriers, which can enhance its photocatalytic activity. What’s more, the UV–vis (DRS)spectra, XPS and NO-TPD-MS indicated that the synergy between H 2 O 2 , oxygen vacancies and GO. Finally, a possible photocatalytic NO removal mechanism over the B-TiO 2 -GO composite is also presented based on the results of the band structures, the free radical capture experiments and electron spin resonance (ESR) tests. This work would provide a strategy to design HNO 3 /H 2 O 2 -resistant deNOx photocatalyst in the pollutant purification field.