Simultaneous Nitrogen Doping Research Articles

Ionic-liquid-assisted synthesis of high-visible-light-activated N–B–F-tri-doped mesoporous TiO2 via a microwave route

A facile and green method was developed for the simultaneous doping of nitrogen, boron, and fluorine in TiO2 by H2TiO3 via a microwave-assisted route. The ionic liquid (IL) [BMIm]BF4 serves not only as microwave absorbent but also as a dopant. The IL also shows the ability to self-assemble under microwave irradiation, which causes it to act as an inhibitor for the growth of the TiO2 particles. The N–B–F-tri-doped TiO2 obtained exhibits large specific surface area, small crystal size, and a mesoporous structure, and the mechanism for the formation of the N–B–F-tri-doped TiO2 was proposed. The prepared materials exhibit excellent visible light photocatalytic activity in the degradation of organic pollutants, including methyl orange, rhodamine B, Orange G, and reactive red X, which is attributed to the presence of a Ti–B–N structure on the TiO2 surface, inducing a narrow band gap of 2.78eV, and the synergistic effects of N, B, and F, which improve the separation efficiency of the photo-generated electron/hole pairs. The results obtained may provide a new sight for the application of ILs in the microwave-assisted preparation of nanomaterials.

Fast and low-temperature reduction of graphene oxide films using ammonia plasma

Reduced graphene oxide (rGO) has been produced using an ammonia (NH3) plasma reduction method. Simultaneous nitrogen doping during the reduction process enabled a rapid and low-temperature restoration of the electrical properties of the rGO. The chemical, structural, and electrical properties of the rGO films were analyzed using x-ray photoelectron spectroscopy, Raman spectroscopy, atomic force microscopy, and conductivity measurements. The oxygen functional groups were efficiently removed, and simultaneous nitrogen doping (6%) was carried out. In addition, the surface of the rGO film was flattened. Consequently, the rGO films exhibited electrical properties comparable to those prepared via other reduction methods.

Novel preparation of nitrogen-doped graphene in various forms with aqueous ammonia under mild conditions

Nitrogen-doped graphene (N-G), in the form of a stable dispersion, a strong hydrogel and a macroporous aerogel, was synthesized by simultaneous nitrogen doping and reduction of graphene oxide with aqueous ammonia under mild conditions. The N content and thermal stability of the resultant samples proved to be high.

Simultaneous Nitrogen Doping and Reduction of Graphene Oxide

We developed a simple chemical method to obtain bulk quantities of N-doped, reduced graphene oxide (GO) sheets through thermal annealing of GO in ammonia. X-ray photoelectron spectroscopy (XPS) study of GO sheets annealed at various reaction temperatures reveals that N-doping occurs at a temperature as low as 300 degrees C, while the highest doping level of approximately 5% N is achieved at 500 degrees C. N-doping is accompanied by the reduction of GO with decreases in oxygen levels from approximately 28% in as-made GO down to approximately 2% in 1100 degrees C NH(3) reacted GO. XPS analysis of the N binding configurations of doped GO finds pyridinic N in the doped samples, with increased quaternary N (N that replaced the carbon atoms in the graphene plane) in GO annealed at higher temperatures (> or = 900 degrees C). Oxygen groups in GO were found responsible for reactions with NH(3) and C-N bond formation. Prereduced GO with fewer oxygen groups by thermal annealing in H(2) exhibits greatly reduced reactivity with NH(3) and a lower N-doping level. Electrical measurements of individual GO sheet devices demonstrate that GO annealed in NH(3) exhibits higher conductivity than those annealed in H(2), suggesting more effective reduction of GO by annealing in NH(3) than in H(2), consistent with XPS data. The N-doped reduced GO shows clearly n-type electron doping behavior with the Dirac point (DP) at negative gate voltages in three terminal devices. Our method could lead to the synthesis of bulk amounts of N-doped, reduced GO sheets useful for various practical applications.

Metal ion induced room temperature phase transformation and stimulated infrared spectroscopy on TiO 2-based surfaces

Raman and infrared spectroscopy are used to demonstrate (1) the high spin metal ion induced room temperature transformation of anatase to rutile TiO 2 and (2) the phenomena of stimulated IR spectroscopy induced by simultaneous nitrogen doping and high spin metal ion seeding of a TiO 2 nanocolloid lattice.