Nitrogen Co-doped TiO2 Photocatalysts Research Articles

Preparation and Photocatalytic Properties of La, Ce<sup> </sup>and Nonmetal N Co-Doped TiO<sub>2</sub>

TiO2, 1%La/TiO2, 1%Ce/TiO2 and a series of Laand Ce co-doped TiO2 photocatalysts were prepared by sol-gel method. Using sol-gel method combine with hydrothermal method prepared rare earth La, Ce and nitrogen co-doped TiO2 photocatalysts. The microstructure, spectroscopy performance and ion doped form of prepared samples were characterized by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectroscopy techniques and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of doped TiO2 were examined by measuring the photodegradation of methyl orange. The results showed that the products were all anatase TiO2 nano powder, doping Laor Cehinder the growth of TiO2 particle, further more, doping Laand Cetogether hinder the growth of TiO2 particle more effective, doping N broaden the light response range of TiO2 photocatalyst. At the same time, the photocatalytic activity results indicated that the prepared samples showed superior UV light photocatalytic activity, the sample 1% (La:Ce,9:1)-N/TiO2 showed the highest UV-vis photocatalytic activity.

Preparation, characterization and visible light photocatalytic activity of silver, nitrogen co-doped TiO2 photocatalyst

TiO2 photocatalyst codoped with Silver (Ag) and Nitrogen (N) with different Ag doping concentrations is successfully synthesized by hydrothermal method. The as-synthesized samples are characterized through x-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–vis. absorption spectra and x-ray photoelectron spectroscopy (XPS). The photocatalytic response is evaluated by the photodegradation of methylene blue under visible light irradiations. All synthesized samples are composed of pure anatase phase with good crystallinity. The absorption edge of codoped TiO2 is shifted towards visible light region. X-ray photoelectron spectroscopy confirmed the existence of silver and nitrogen in the codoped samples. All the codoped samples demonstrated improved photocatalytic activity compared to pure TiO2. Among the different codoped samples, the one with silver doping concentration of 4 at. % exhibited the highest photoactivity.

Facile Synthesis and Photocatalytic Properities of Mini Nanoparticle CdS Quantum Dots/Boron and Nitrogen Co-Doped TiO<sub>2</sub> Transparent Photocatalyst Emulsion

CdS quantum dots/ Boron and Nitrogen co-doped TiO2 photocatalyst emulsions were synthesized by a complexation-controlled hydrolysis method at room temperature. Boron compounds and Nitrogen compounds were added to TiO2 precursor solution, and CdS quantum dots were attached to TiO2 particles surfaces by using chemical reaction. The hybird composite photocatalysts were characterized by XRD, UV-Vis. Their photocatalytic properties were evaluated through the degradation of acid red 3R dye. The results indicate that when TiO2 emulsion add to Boron ions, Nitrogen ions, and CdS quantum dots, the photocatalytic performance of the emulsion is the best.

Photocatalytic oxidation of propylene on La and N codoped TiO2 nanoparticles

Lanthanum- and nitrogen-codoped TiO2 photocatalysts was synthesized using orthorhombic nanotubes titanic acid as the precursor by a simple impregnation and subsequent calcination method. The morphology, phase structure, and properties of La- and N-codoped TiO2 were well characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectra. The La-/N-codoped TiO2 showed excellent photoactivity of propylene oxidation compared with the single-doped TiO2 and La-/N-codoped P25 TiO2 nanoparticles under visible light irradiation. The origin of the enhancement of the visible light-responsive photocatalytic activity was discussed in detail.

Copper and Nitrogen co-doped TiO2 photocatalyst with enhanced optical absorption and catalytic activity

Cu–N-codoped TiO2 photocatalyst is synthesized by sol–gel method to obtain enhanced optical absorption in the visible region. Optimum concentrations of Cu and N were obtained by maximizing the photocatalytic activity for the monodoped (Cu or N) TiO2. These optimized concentrations were used for synthesizing (Cu, N)–codoped TiO2. The photocatalysts were characterized using XRD, micro-Raman, SEM, XPS, BET surface area analyzer, UV–vis diffuse reflectance spectroscopy and photoluminescence. XPS study suggests the incorporation of Cu2+ into TiO2 lattice, which assists N to substitutionally replace oxygen in codoped TiO2, while maintaining the anatase phase even after doping. N-doping creates minor variation in the energy band gap of TiO2 reducing it upto 3.0eV, while Cu doping was able to narrow the band gap to 2.2eV mainly due to the localized levels of Cu-3d states and shifting of Ti-3d states to lower energy (due to oxygen vacancies) in the band-gap as deduced from XPS data and confirmed by the DFT calculation. In (Cu, N)–codoped TiO2, visible light absorption is higher than the other TiO2 samples, a feature that is mainly attributed to the formation of an isolated intermediate band (IB) occurring due to the strong hybridization between Cu 3d and N 2p orbitals. This IB contributes to visible light absorption by two step optical transition with the first transition from valence band (VB) to IB and the second from IB to conduction band (CB). The dopant species may also act to reduce the charge carrier recombination by acting as the trapping sites for photogenerated charges. (Cu, N)–codoped TiO2 was able to degrade Methylene Blue dye and p-Nitrophenol solution under light irradiation with significantly better rate in comparison to monodoped and undoped TiO2. High photocatalytic activity is attributed to the presence of IB in the energy band gap of TiO2, which creates the synergic effect by higher visible light absorption and lower recombination of photogenerated charges.

Facile Synthesis and Photocatalytic Properities of PbS Quantum Dots/Boron and Nitrogen Co-Doped TiO<sub>2</sub> Transparent Photocatalyst Emulsion

PbS quantum dots/ Boron and Nitrogen co-doped TiO2 photocatalyst emulsions were synthesized by a complexation-controlled hydrolysis method at room temperature. Boron compounds and Nitrogen compounds were added to TiO2 precursor solution, and PbS quantum dots were attached to TiO2 particles surfaces by using chemical reaction. The hybird composite photocatalysts were characterized by nanoparticle size analyzer. Their photocatalytic properties were evaluated through the degradation of acid red 3R dye. The results indicate that when TiO2 emulsion added to Boron ions, Nitrogen ions, and PbS quantum dots, the reflux time is 15 min, the photocatalytic performance of the emulsion is the best.

Degradation of Methylene Blue by Titania Doped with Transition Metal and Nitrogen

For introduction of low energy consuming system in photocatalytic oxidation process, transition metal and nitrogen doped TiO2 were synthesized with urea and nitrate salt of 4-periodic transition metal elements and their photoactivation characteristics was investigated. In order to find out the photochemical characteristics of produced TiO2, we have conducted the methylene blue dye decomposition experiment by setting BLB Lamp as a light source. Photocatalyst of nitrogen doped TiO2 showed higher photoactive effects than pure TiO2 but transition metal and nitrogen co-doped TiO2 photocatalyst showed lower photocatalytic effects than only transition metal doped TiO2.

Preparation and properties of sliver and nitrogen co-doped TiO2 photocatalyst

TiO2 photocatalysts co-doped with different content of Ag and N were prepared by sol–gel method combined with microwave chemical method. The samples were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), ultraviolet–visible diffuse reflectance spectrum (UV–vis) and photo-luminescence emission spectrum (PL). The photocatalytic activity was investigated by photocatalytic degradation of methylene blue (MB) under irradiation of fluorescent lamp. The results indicate that Ag and N co-doping can restrain the increase of grain size, broaden the absorption spectrum to visible light region, and inhibit the recombination of the photo-generated electron–hole pairs. Moreover, the photocatalytic activity of Ag–N–TiO2 in MB degradation is remarkable improved. The degradation rate of the sample with Ag:TiO2=0.05at%, N:TiO2=18.50wt% in 5h is 93.44%, which is much higher than that of Degussa P25 (39.40%).

Preparation and Characterization of Ce/N-Codoped TiO2 Particles for Production of H2 by Photocatalytic Splitting Water Under Visible Light

Cerium and nitrogen codoped TiO2 photocatalysts were successfully prepared by sol–gel method. The results showed that Ce doped in TiO2 could prevent phase transition of anatase to rutile and inhibit the growth of crystallite. In addition, Ce and N codoped in TiO2 enhanced the lattice distortion. N–Ti bond and N–Ti–O bond were formed in codoped titania, which narrowed the energy gap and extended the absorption edge to the visible light range, and the synergistic effects of the Ce and N codoped samples made the red shift more distinct. The results showed that the rate of hydrogen production was the best for the sample prepared under the conditions of the content of Ce doped for 0.6% (molar ratio) and calcination temperature of photocatalyst preparation at 500 °C. Cerium and nitrogen codoped TiO2 photocatalysts were successfully prepared by sol–gel method, and codoped TiO2 photocatalytic activity in the visible light is improved obviously.

Preparation of Nb2O5 and N co-doped TiO2 photocatalysts and their enhanced photocatalytic activities under visible light

Niobium pentaoxide (Nb2O5) and nitrogen co-doped TiO2 photocatalysts were prepared by mechanical alloying with Nb2O5, TiO2 and urea as raw materials. The pure TiO2 powders of Degussa P25 were chosen as precursor. Chemical and physical properties of the Nb2O5 and N co-doped TiO2 photocatalysts were investigated, including XRD patterns, XPS spectra, DRS spectra, FT-IR spectra and N2 adsorption-desorption isotherms. Experiments on photodegradation of methylene blue (MB) and sulfosalicylic acid (SSA) under visible light were carried out to evaluate the photoactivities of the prepared samples, and the chemical oxygen demand (COD) analysis was also conducted as a comparison.