Nitrogen-sensitized dual phase titanate/titania for visible-light driven phenol degradation

• Published in: Journal of solid state chemistry 2012-12, Vol.196, p.518-527
• Main Authors: Cheng, Yu Hua, Subramaniam, Vishnu P., Gong, Dangguo, Tang, Yuxin, Highfield, James, Pehkonen, Simo O., Pichat, Pierre, Schreyer, Martin K., Chen, Zhong
• Format: Article
• Language: English
• Subjects: ABSORPTION; Charge transfer; Chemistry; CONTROL; Degradation; Doping; Exact sciences and technology; GAS CHROMATOGRAPHY; General and physical chemistry; General, apparatus; GRAIN SIZE; HYDROGEN PEROXIDE; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IRRADIATION; MASS SPECTROSCOPY; NANOSTRUCTURES; NITROGEN; PHENOL; PHOTOCATALYSIS; Photocatalyst; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); SORPTIVE PROPERTIES; SURFACE AREA; Surface chemistry; Surface physical chemistry; SURFACES; SYNTHESIS; Titanate; TITANATES; Titania; Titanium dioxide; TITANIUM OXIDES; TRANSMISSION ELECTRON MICROSCOPY; Triethylamine; VISIBLE RADIATION
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2012.07.011

A dual-phase material (DP-160) comprising hydrated titanate (H2Ti3O7·xH2O) and anatase (TiO2) was synthesized in a low-temperature one-pot process in the presence of triethylamine (TEA) as the N-source. The unique structure exhibits strong visible light absorption. The chromophore is linked to Ti–N bonds derived from both surface sensitization and sub-surface (bulk) doping. From transmission electron microscope (TEM) and textural studies by N2 physisorption, the composite exists as mesoporous particles with a grain size of ∼20nm and mean pore diameter of 3.5nm, responsible for the high surface area (∼180m2/g). DP-160 demonstrated photocatalytic activity in the degradation of phenol under visible light (λ>420nm). The activity of the composite was further enhanced by a small addition (0.001M) of H2O2, which also gave rise to some visible light activity in the control samples. This effect is believed to be associated with the surface peroxo-titanate complex. GC–MS analyses showed that the intermediate products of phenol degradation induced by visible light irradiation of DP-160 did not differ from those obtained by UV (band-gap) irradiation of TiO2. The overall performance of the composite is attributed to efficient excitation via inter-band states (due to N-doping), surface sensitization, improved adsorptive properties of aromatic compounds due to the N-carbonaceous overlayer, and the presence of heterojunctions that are known to promote directional charge transfer in other mixed-phase titanias like Degussa P25. Nitrogen-sensitized dual phase titanate/titania photocatalyst showing extended visible light absorption and efficient photocatalytic degradation of phenol [Display omitted] . ► Low temperature one-pot synthesis of visible light active dual phase photocatalyst. ► The dual phase consists of nanoscale titanate and anatase titania phases. ► The photocatalyst displays high activity in degrading phenol under visible light. ► Mechanisms for the sensitization to visible light are considered.