Enhanced Photoelectric Property of Mo-C Codoped TiO2 Films Deposited by RF Magnetron Cosputtering

Mo-C codoped TiO2 films were prepared by RF magnetron cosputtering. Ultraviolet-visible spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray Analysis and X-Ray Diffraction were used to study the influences of codoping on energy gap, surface morphology, valence states of elements, ions content and crystal structure, respectively. The concentration of photogenerated carriers was measured by studying photocurrent density, while catalytic property was evaluated by observing degradation rate of methylene blue under visible light. A Mo-doped TiO2 film, whose content of Mo had been optimized in advance, was prepared and later used for subsequent comparisons with codoped samples. The result indicates that Mo-C codoping could curtail the energy gap and shift the absorption edge toward visible range. Under the illumination of visible light, codoped TiO2 films give rise to stronger photocurrent due to smaller band gaps. It is also found that Mo, C codoping results in a porous surface, whose area declines gradually with increasing carbon content. Carbon and Molybdenum doses were delicately optimized. Under the illumination of visible light, sample doped with 9.78at% carbon and 0.36at% Mo presents the strongest photocurrent which is about 8 times larger than undoped TiO2 films, and about 6 times larger than samples doped with Mo only.

Ultrafast one-step synthesis of N and Ti^3＋ codoped TiO2 nanosheets via energetic material deflagration

An energetic-material （NAN3） deflagration method for preparing N- and Ti3＋-codoped TiO2 nanosheets （NT-TiO2） was developed. In this method, N radicals filled the crystal lattice, and Na clusters captured partial O from TiO2. The deflagration process was fast and facile and can be completed within 〈 I s after ignition. The obtained NT-TiO2 exhibited rough surfaces with nanopits and nanoholes. The doping concentration can be regulated by controlling the NaN3 addition. The NT-TiO2 samples showed significant enhancements in the visible-light absorption and photoelectric response. The simultaneously produced N radicals and Na clusters from NaN3 deflagration served as N sources and reduction agents, respectively. Additionally, the high deflagration temperature/ pressure improved the reactivity of N radicals and Na dusters. Thus, the present NaN3 deflagration method was demonstrated as an ultrafast and effective approach to fabricate NT-TiO2 with a visible-light response. The proposed NaN3 deflagration method allows the ultrafast synthesis of new functional materials via the efficient deflagration of energetic materials.

Photocatalytic degradation evaluation of N–Fe codoped aligned TiO2 nanorods based on the effect of annealing temperature

In this paper,a comparative study on the photocatalytic degradation of the Rhodamine B(Rh B)dye as a model compound using N–Fe codoped Ti O2 nanorods under UV and visible-light(λ≥420 nm)irradiations has been performed.Ti O2 photocatalysts were fabricated as aligned nanorod arrays by liquid-phase deposition process,annealed at different temperatures from 400 to 800℃.The effects of annealing temperature on the phase structure,crystallinity,BET surface area,and resulting photocatalytic activity of N–Fe codoped Ti O2 nanorods were also investigated.The degradation studies confirmed that the nanorods annealed at 600℃composed of both anatase(79%)and rutile phases(21%)and offered the highest activity and stability among the series of nanorods,as it degraded 94.8%and 87.2%Rh B in 120 min irradiation under UV and visible-light,respectively.Above 600℃,the photocatalytic performance of nanorods decreased owning to a phase change,decreased surface area and bandgap,and growth of Ti O2 crystallites induced by the annealing temperature.It is hoped that this work could provide precious information on the design of 1 D catalyst materials with more superior photodegradation properties especially under visible-light for the further industrial applications.

Band gap narrowing of TiO_2 by compensated codoping for enhanced photocatalytic activity

In this study, we have performed first-principles screened exchanged hybrid density function theory with the HSE06 function calculations of the C-Mo, C-W, N-Nb and N-Ta codoped anatase TiO2 systems to investigate the effect of codoping on the electronic structure of TiO2. The calculated results demonstrate that （W（s）＋C（s）） codoped TiO2 narrows the band gap significantly, and have little influence on the position of conduction band edges, therefore, enhances the efficiency of the photocatalytic hydrogen generation from water and the photodegradation of organic pollutants. Moreover, the proper oxygen pressure and temperature are two key factors during synthesis which should be carefully under control so that the desired （W（s）＋C（s）） codoped TiO2 can be obtained.