Nitrogen Co-doped Titanium Dioxide Research Articles

Polylactic acid electrospun membrane loaded with cerium nitrogen co-doped titanium dioxide for visible light-triggered antibacterial photocatalytic therapy.

Wound infection caused by multidrug-resistant bacteria poses a serious threat to antibiotic therapy. Therefore, it is of vital importance to find new methods and modes for antibacterial therapy. The cerium nitrogen co-doped titanium dioxide nanoparticles (N-TiO2, 0.05Ce-N-TiO2, 0.1Ce-N-TiO2, and 0.2Ce-N-TiO2) were synthesized using the hydrothermal method in this study. Subsequently, electrospinning was employed to fabricate polylactic acid (PLA) electrospun membranes loaded with the above-mentioned nanoparticles (PLA-N, PLA-0.05, PLA-0.1, and PLA-0.2). The results indicated that cerium and nitrogen co-doping tetrabutyl titanate enhanced the visible light photocatalytic efficiency of TiO2 nanoparticles and enabled the conversion of ultraviolet light into harmless visible light. The photocatalytic reaction under visible light irradiation induced the generation of ROS, which could effectively inhibit the bacterial growth. The antibacterial assay showed that it was effective in eliminating S. aureus and E. coli and the survival rates of two types of bacteria under 30 min of irradiation were significantly below 20% in the PLA-0.2 experimental group. Moreover, the bactericidal membranes also have excellent biocompatibility performance. This bio-friendly and biodegradable membrane may be applied to skin trauma and infection in future to curb drug-resistant bacteria and provide more alternative options for antimicrobial therapy.

Investigation of antibacterial property of functionalized polypropylene nonwoven fabrics by S–N Co-doped nano-TiO2 films

This study focused on the antibacterial and ultraviolet protection properties of the functionalized polypropylene nonwoven fabrics (PPNWF). Sulfur and nitrogen co-doped titanium dioxide (S–N–TiO2) sol was synthesized by sol–gel method and S–N–TiO2 films were coated on the surface of PPNWF with impregnating method. The tensile strength, mass per unit area, thickness, whiteness, and glossiness of the prepared simples were investigated. The ultraviolet protection properties of the samples were assessed by ultraviolet transmittance spectrum and Ultraviolet Protection Facto. The results show that ultraviolet protection properties, tensile strength, and mass per unit area of the functionalized fabrics increase whereas its whiteness and glossiness decrease. The structural analysis and chemical composition of S–N–TiO2 were made by X-ray diffraction and X-ray photoelectron spectroscopy, which indicate the successful doping of S and N into TiO2. The results of Fourier transform infrared spectrometer and scanning electron microscopy show that S–N–TiO2 nano-films have been well dispersed on the surface of the PPNWF, which is beneficial to the ultraviolet protection property and antibacterial activity of the samples. The antibacterial activities were evaluated by shake flask method. It is found that the S–N–TiO2 nano-films coated PPNWF (S–N–TiO2/PPNWF) exhibit excellent antibacterial activities against both Staphylococcus aureus and Escherichia coli, and the antibacterial rate of 96.8% and 98.4% against Staphylococcus aureus and Escherichia coli, respectively. After 50 cycles of consecutive laundering, the antibacterial rates remain over 85.48% and 84.4% for Staphylococcus aureus and Escherichia coli, respectively. It indicates that the antibacterial performance of the S–N–TiO2/PPNWF fabrics is also durable.

Photocatalytic degradation of glyphosate using Ce/N co-doped TiO2 with oyster shell powder as carrier under the simulated fluorescent lamp

Glyphosate is currently one of the most used organophosphorus herbicides in the world and its accumulation and translocation in soil and wave causes environmental pollution and biological health problems. A new approach to the problem is provided by the preparation of cerium and nitrogen co-doped titanium dioxide composite nano-photocatalysts loaded on modified oyster shell powder (CeNT@Oys) by a simple hydrothermal synthesis. The physicochemical and optoelectronic properties are analyzed using SEM, BET, XRD, Raman, FTIR, UV-vis DRS, XPS characterization techniques and a range of photoelectrochemical techniques. The results show that the addition of modified oyster shell powder increases its specific surface area, while Ce-N-TiO2 is an anatase crystal composed of Ce doped in the form of interstitial and surface, interstitial form of N, and the co-doping of Ce and N elements gives it the property of being excited by visible light. The photocatalytic activity of the different catalysts was evaluated by degrading 50 mg/L glyphosate solution under simulated sunlight. The catalyst was determined to be reusable by five repeated degradation experiments. Based on quenching experiments and the electron paramagnetic resonance tests, the effective active species of glyphosate degraded by the catalyst was determined and the mechanism of glyphosate degradation by photocatalyst was proposed. Finally, the degradation pathway for the photocatalytic degradation of PMG by CeNT@Oys was determined by HPLC-MS/MS determine of the intermediate products.

PH regulated rapid photocatalytic degradation of methylene blue dye via niobium-nitrogen co-doped titanium dioxide nanostructures under sunlight

Niobium and nitrogen co-doped titanium dioxide (Nb-N-TiO2) semiconductor nanostructures were synthesized through a facile sol-gel protocol using titanium tetra iso-propoxide (TTIP), urea and niobium pentoxide as precursors followed by calcination at 450 °C for 4 h. The synthesized nanomaterial (Nb-N-TiO2) was characterized via Fourier Transform Infrared (FTIR) and Raman spectroscopy, UV-Visible (UV-Vis) Spectroscopy, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) technique, Dynamic Light Scattering (DLS) technique and ZETA Potential analysis. The band gap of Nb-N-TiO2 was reduced as compared to TiO2 due to reduced space between valance and conduction band which also reduced the electron-hole (e-, h+) recombination and led to better photocatalytic activity of the Nb-N-TiO2 as confirmed by TAUC plot. Photocatalytic activity of Nb-N-TiO2 was investigated for degradation of methylene blue (MB) dye under sunlight as cheaper light source. Factors like dye concentration, dosage of catalyst, volume of solution time and pH were studied and optimized for MB degradation. Under finally optimized conditions, 97% of 25 ppm MB was degraded just in one minute using 45 mg of photocatalyst. The co-doped nanocatalyst, was re-used for MB degradation upto 4th cycle with its efficiency reduced to 75% which shows a better catalytic role by the catalyst. Degradation products of MB were recognized through electrospray ionization coupled mass spectroscopy (ESI-MS) and liquid chromatography coupled mass spectroscopy (LC-MS) techniques. The catalyst was also applied for MB degradation in tap water sample.

Degradation of cefadroxil by photoelectrocatalytic ozonation under visible-light irradiation and single processes

Here, we investigate the degradation of 20 mg L-1 Cefadroxil (CFX) in water using photoelectrocatalytic ozonation (PECO), and compared against its individual processes. A carbon nitrogen-codoped titanium dioxide (CN-TiO2) anode is synthesized using ethylene glycol and ethylenediamine as carbon and nitrogen source, respectively. The X-ray diffraction (XRD) and Scanning Electronic Microscopy (SEM) analysis conducted to this material indicate a crystalline phase anatase with irregular morphology formed on the electrode surface; while the diffuse reflectance spectroscopy (DRS) shows a shift in the photoanode absorbance towards the visible region, unlike undoped TiO2 structure. This behavior results from the inclusion of Carbon and Nitrogen species on the CN-TiO2 electrode in weight percentages of 14.5 and 1.61 wt%, respectively, according to Energy Dispersive Spectroscopy (EDS) analysis. The Cefadroxil (CFX) abatement is monitored UV–Vis spectroscopy, high-performance liquid chromatography (HPLC), and total organic carbon (TOC). All techniques reveal that the highest CFX removal occurs with PECO (Photoelectrocatalytic Ozonation) process, decreasing TOC by 57.6% (96% degradation by HPLC) after 90 min of treatment. The main by-products formed from oxidation with the PECO, PCO (Photocatalytic Ozonation) and O3 (Ozonation) systems were acid species presumably corresponding to short chain carboxylic acids. Finally, the germination of lettuce sativa is carried out in water contaminated with the drug, and compared with water treated by PECO and PCO processes, showing that PECO process improves germination by 23.5% on the contaminated sample and 7.4% on the sample treated with PCO. These findings confirm that synergism of oxidation techniques could be a tractable way to resolve the problems related to recalcitrant compounds contained in wastewater.

Photoelectrochemical Performance of S,N-Codoped TiO2 Films Supported on Ti and their Enhanced Photoelectrocatalytic Activity in the Generation of Hydroxyl Radicals

New photoanodes for recalcitrant pollutant degradation should harvest photons from a wide region of the solar spectrum and promote a direct water oxidation reaction towards the hydroxyl radical generation. For this purpose, sulfur, nitrogen-codoped titanium dioxide (S,N-TiO2) films were prepared with different sulfur percentages (1.0, 2.5 and 5.0 at.%) on Ti expanded meshes by sol-gel dip-coating followed by thermal treatment at 400 °C. The morphology, composition, oxidation states of dopants, structural features, optical and semiconducting properties of S,N-TiO2 were used for the materials characterization. While sulfur was found as S4+ or S6+ cations related to surface doping, nitrogen appears as N3− anion occupying substitutional positions in TiO2. This caused an improvement in the photoelectrochemical response of TiO2 related to a decrease of up to 0.25 eV in the optical band gap and the alignments of the TiO2 band structure. S,N-TiO2 films exhibit significantly higher photoelectrocatalytic activity towards ·OH generation under UV–vis light irradiation than the undoped TiO2 films. Using 2.5 at.% S,N-TiO2 film, an increase of 166% in current efficiency was obtained at 0.5 V vs Ag/AgCl, in regard to undoped TiO2 films, together with an enhance of 8.8 times in the initial ·OH generation rate.

Green synthesis of boron and nitrogen co-doped TiO2 with rich B-N motifs as Lewis acid-base couples for the effective artificial CO2 photoreduction under simulated sunlight

Boron and nitrogen co-doped Titanium dioxide (TiO2) nanosheets (BNT) with high surface area of 136.5 m2 g−1 were synthesized using ammonia borane as the green and triple-functional regent, which avoids the harmful and explosive reducing regents commonly used to create surface defects on TiO2. The decomposition of ammonia borane could incorporate reactive Lewis acid-base (B, N) pairs, together with the as-generated H2 to create mesoporous structure and rich oxygen vacancies in pristine TiO2. The BNTs prepared from various ammonia borane loading are evaluated in photoreduction of carbon dioxide (CO2) with steam under simulated sunlight, achieving about 3.5 times higher carbon monoxide (CO) production than pristine TiO2 under the same conditions. Steady state and transient optical measurements indicated BNT with reduced band gap, rich defect states and elevated conduction band position could enhance the light harvesting efficiency and promote the charge transfer at the catalyst/CO2 interface. Density functional theory simulation and in situ FTIR suggest that the Lewis acid-base (B, N) pairs on BNT may very substantially increase the activation of inert CO2 which facilitates their photoreduction with the hydrogen from the water splitting at the surface defects on TiO2. Finally, a reaction mechanism of Lewis acid-base assisted CO2 photoreduction leading to substantially improved performance is proposed.

Effect of Synthesis Conditions of Nitrogen and Platinum Co-Doped Titania Films on the Photocatalytic Performance under Simulated Solar Light

Platinum and nitrogen co-doped titania films of different surface morphologies obtained via a sol-gel process have been tested for tetracycline hydrochloride photocatalytic decomposition under simulated solar light. Titania crystallization to anatase is shown by XRD for all films. A shift of the bandgap edge toward the visible region in absorption spectra and, consequently, a narrowing of the bandgap is observed for some films doped with nitrogen and/or exposed to UV pretreatment. The surface peculiarities of the samples are presented by an SEM and TEM investigation. The surface saturation by Pt and N with a homogeneous distribution of Pt ions on the surface as well as bulk as established by XPS and EDS data can be achieved with a certain synthesis procedure. The influence of the platinum content and of the pretreatment procedure on the state and atomic surface concentration of incorporated nitrogen and platinum is studied by XPS analysis: substitutional and interstitial nitrogen, non-metal containing fragments, Pt0, Pt2+ and Pt4+ ions. The photocatalytic activity of the films is ruled by the presence of Pt2+ ions and N rather than Pt0. The formation of the polycrystalline titania structure and Pt0 nanoparticles (NPs) is confirmed by TEM and electron diffraction images. The mechanism of primary photocatalytic processes is proposed.

Vanadium and Nitrogen Co-Doped Titanium Dioxide (TiO2) with Enhanced Photocatalytic Performance: Potential in Wastewater Treatment

The vanadium (V) and nitrogen (N) dopants on TiO₂ demonstrated superior photocatalytic performance for the degradation of methylene blue (MB) dye under visible light. The vanadium, V, N-co-doped TiO₂ was synthesized by a modified sol-gel method. It revealed that V and N codoping had a significant effect on the band gap (Eg) of TiO₂, where the pristine TiO₂ possessed a wide band gap (3.18 eV) compared to V-doped TiO₂ (2.89 eV) and N-doped TiO₂ (2.87 eV) while the V, N-co-doped TiO₂ depicted the narrowest band gap (2.65 eV). The greatly increased specific surface area for the V, N-co-doped TiO₂ (103.87 m²/g) as compared to P25 TiO₂ (51.68 m²/g) also contributed to the major improvement in the MB dye degradation efficiency (0.055 min-1). The V, N-co-doped TiO₂ exhibit rapid photocatalytic activity for the degradation of MB with almost 99% of degradation in 120 minutes.

Synthesis and photocatalytic activity of copper and nitrogen co-doped titanium dioxide nanoparticles

Cu–N co-doped TiO2 nanoparticles were synthesized using the sol-gel method at different Cu concentrations (0.1, 0.3, and 0.5 wt%). The synthesized nanoparticles were characterized using X-ray diffractometer (XRD), Fourier transform infrared spectrophotometer (FTIR), field emission scanning electron microscopy and energy dispersive X-ray spectrometer (FESEM/EDS), and UV–vis spectrophotometry (UV–vis). The synthesized spherical nanoparticles were grouped into large clusters. Pure TiO2 nanoparticles exhibited the anatase phase, while Cu–N co-doped TiO2 nanoparticles showed both anatase and rutile phases. In addition, Cu–N co-doped TiO2 nanoparticles showed higher light absorption than pure TiO2 nanoparticles, which affected the photocatalytic efficiency. The photocatalytic degradation of methylene blue (MB) was tested under UV and visible light. Under UV light, pure TiO2 nanoparticles exhibited a maximum photocatalytic efficiency of 88.62% within 90 min. While 0.1 Cu–N co-doped TiO2 nanoparticles tend to be effective in photocatalytic efficiency under visible light, they were able to degrade MB up to 56.33%.

One-pot synthesis of sulfur and nitrogen codoped titanium dioxide nanorod arrays for superior photoelectrochemical water oxidation

Despite its abundant, nontoxicity and photochemical stability, titanium dioxide shows low solar water oxidation performance due to low photogenerated carrier transport and wide optical band gap, which results in substantially low photogenerated carrier density that impair the solar to hydrogen conversion efficiency. Herein, highly enhanced water oxidation performance of high-aspect-ratio TiO2 nanorods doped with dual heteroatoms, sulfur and nitrogen, for photoelectrochemical solar water oxidation is demonstrated. The codoped TiO2 NRs have shown enhanced optical absorption coefficient due to the induced impurities energy states near to the top of the valance band and result in a red shift in the optical absorption edges. Consequently, a 2.82 mAcm−2 photocurrent density at 1.23 V vs. RHE is obtained from the sulfur and nitrogen codoped TiO2 nanorods, and pristine TiO2 nanorods photoanode shows 0.7 mAcm−2. The applied bias photon-to-current conversion efficiency and external quantum efficiency of the codoped TiO2 nanorods are 1.49% and 97.0% at λ = 360 nm and 0.69% and 19.1% at λ = 370 nm for pristine TiO2 nanorods, respectively. Our study offers experimental and theoretical evidence for codoping of sulfur and nitrogen improve the optical and electrical properties of TiO2 for efficient photoelectrochemical solar water oxidation.

Exceedingly high photocatalytic activity of g-C3N4/Gd-N-TiO2 composite with nanoscale heterojunctions

Composite materials, made of graphitic carbon nitride/gadolinium and nitrogen co-doped titanium dioxide (g-C3N4/Gd-N-TiO2), have been successfully prepared by a simple and reproducible in-situ synthetic method. Specific surface area, pore size, particle morphology, crystalline structure, energy band gap, and chemical bonding mode of the materials have been characterized by spectroscopic and electron microscopic means. Photoluminescence measurement and photocatalytic degradation of methyl blue (MB) and antibiotics (gatifloxacin) test show that the composites exhibit significant enhanced photocatalytic activity. Our experimental results indicate that nanoscale heterojunctions are formed in the composites, and these junctions have played a key role in the separation and transportation of photo generated electrons and holes, and hence the effective promotion of the photocatalysis.

119Sn Mössbauer and Ferromagnetic Studies on Hierarchical Tin- and Nitrogen-Codoped TiO2 Microspheres with Efficient Photocatalytic Performance

Hierarchical tin-doped titania (ST) and tin- and nitrogen-codoped titania (SNT) microspheres were prepared by a hydrothermal method and nitriding treatment, in particular, SNT-enhanced visible light photocatalytic activity for the degradation of rhodamine B in aqueous solution and room-temperature ferromagnetism (RTFM). We initiated the photovoltaic study of ST and SNT microspheres to confirm the photovoltaic properties of perovskite solar cell (PSC) applications. The SNT microspheres exhibited relatively large saturation magnetization and high photocatalytic activity. To clarify the enhancement of the photoactivity, the prepared samples were characterized by 119Sn Mossbauer spectrometry under external magnetic fields. The broadened peaks of ST and SNT microspheres were decomposed into a doublet and a sextet under an external magnetic field because the samples showed weak ferromagnetism, although these samples are composed of nonmagnetic components. It is noteworthy that ST and SNT microspheres exhibits o...

THERMALLY OXIDIZED C, N CO-DOPED ANATASE-TiO2 COATINGS ON STAINLESS STEEL FOR TRIBOLOGICAL PROPERTIES

Ti ( C , N ) coatings were prepared on stainless steel (SS) substrates by plasma surface alloying technique. Carbon–nitrogen co-doped titanium dioxide ( C - N - TiO 2) coatings were fabricated by oxidative of the Ti ( C , N ) coatings in air. The prepared C - N - TiO 2 coatings were characterized by SEM, XPS and XRD. Results reveal that the SS substrates were entirely shielded by the C - N - TiO 2 coatings. The C - N - TiO 2 coatings are anatase in structure as characterized by X-ray diffraction. The tribological behavior of the coatings was tested with ball-on-disc sliding wear and compared with substrate. Such a C - N - TiO 2 coatings showed good adhesion with the substrate and tribological properties of the SS in terms of much reduced friction coefficient and increased wear resistance.

Molybdenum and Nitrogen Co-Doped Titanium Dioxide Nanotube Arrays with Enhanced Visible Light Photocatalytic Activity

Molybdenum and nitrogen co-doped $TiO_2$ nanotube arrays (TNAs) were prepared by anodizing in association with hydrothermal treatment. As-prepared Mo and N co-doped TNAs were characterized by field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and ultraviolet-visible light diffuse reflection spectroscopy. Besides, the photocatalytic activity of Mo and N co-doped TNAs for the degradation of methylene blue (denoted as MB) under visible light irradiation was evaluated. It was found that N in co-doped TNAs coexists in the forms of N-Ti-O and N-O-Ti, while Mo exists as $Mo^{6+}$ by substituting Ti in the lattice of $TiO_2$. In the meantime, Mo and N co-doping extends the absorption of TNAs into the whole visible light region and results in remarkably enhanced photocatalytic activity for the degradation of MB under visible light irradiation. This could be attributed to the synergetic effect between Mo-doping and N-doping. Namely, Mo and N passivated co-doping produces new states in TNAs, thereby narrowing the bandgap and decreasing the recombination rate of electrons and holes. As a result, the visible light absorption and photocatalytic activity of TNAs is greatly increased. Furthermore, Mo ions with multiple valences in all co-doped samples could act as trapping sites to effectively decrease the recombination rate of electrons and holes, which also contribute to improved photocatalytic activity of Mo and N co-doped TNAs. Keywords: TiO2 Nanotube Arrays, Mo, N, Co-Doping, Photocatalytic Activity.

Purification of BTEX at Indoor Air Levels Using Carbon and Nitrogen Co-Doped Titania under Different Conditions

To date, carbon and nitrogen co-doped photocatalysts (CN-TiO2) for environmental application focused mainly on the aqueous phase to investigate the decomposition of water pollutants. Accordingly, the present study explored the photocatalytic performance of CN-TiO2 photocatalysts for the purification of indoor-level gas-phase aromatic species under different operational conditions. The characteristics of prepared photocatalysts were investigated using X-ray diffraction, scanning emission microscope, diffuse reflectance UV-VIS-NIR analysis, and Fourier transform infrared (FTIR) analysis. In most cases, the decomposition efficiency for the target compounds exhibited a decreasing trend as input concentration (IC) increased. Specifically, the average decomposition efficiencies for benzene, toluene, ethyl benzene, and xylene (BTEX) over a 3-h process decreased from 29% to close to zero, 80 to 5%, 95 to 19%, and 99 to 32%, respectively, as the IC increased from 0.1 to 2.0 ppm. The decomposition efficiencies obtained from the CN-TiO2 photocatalytic system were higher than those of the TiO2 system. As relative humidity (RH) increased from 20 to 95%, the decomposition efficiencies for BTEX decreased from 39 to 5%, 97 to 59%, 100 to 87%, and 100 to 92%, respectively. In addition, as the stream flow rates (SFRs) decreased from 3.0 to 1.0 L min-1, the average efficiencies for BTEX increased from 0 to 58%, 63 to 100%, 69 to 100%, and 68 to 100%, respectively. Taken together, these findings suggest that three (IC, RH, and SFR) should be considered for better BTEX decomposition efficiencies when applying CN-TiO2 photocatalytic technology to purification of indoor air BTEX.

Effect of carbon and nitrogen co-doping on characteristics and sonocatalytic activity of TiO2 nanotubes catalyst for degradation of Rhodamine B in water

Carbon and nitrogen co-doped titanium dioxide nanotubes (CN co-doped TiO2 NTs) catalysts were successfully synthesized using a hydrothermal method at N:Ti molar ratios between 0.1 and 1.0. Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscope (XPS), UV–Vis diffuse reflectance spectroscope (UV–Vis DRS) and surface area analyzer were used to characterize the synthesized catalysts. Urea doping at N:Ti=0.3 led to the highest sonocatalytic activity with an apparent-first-order rate constant of 0.0226min−1 as compared to 0.0098min−1 for the un-doped TiO2 NTs. The high performance was associated with the synergistic effects between the doped C and N atoms, higher surface area and lower band gap energy. It was also ascribed to the creation of surface oxygen vacancies due to the formation of Ti3+ species and better crystallinity of anatase phase as compared to the un-doped TiO2 NTs. Most of the nitrogen atoms were bonded to oxygen atoms in the interstitial sites (TiON and TiNO), but only minority of them could substitute the sites of oxygen atoms (NTiO). C atoms evidently presented in the form of TiC and a complex carbonate species on the catalyst surface.

Enhancing the visible light absorption via combinational doping of TiO 2 with nitrogen (N) and chromium (Cr)

Chromium and nitrogen co-doped titanium dioxide photocatalysts were prepared by the solvothermal method. The samples were characterized by UV–vis diffuse reflectance spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). The particle size of the codoped titania is narrowed to about 9 nm calculated from the XRD data. Doping of chromium and nitrogen ions effectively improves the visible absorption range with an optimal doping concentration of 2 at% and 10 at% (Ti:N or Ti:Cr) for nitrogen and chromium element, respectively. The main reason comes from the narrowed intrinsic band gap (∼1.8 eV) depended on the justly co-doping content. Meanwhile, the simple codoped models with different concentration of chromium were built and the corresponding electronic structures were calculated by the DFT method. Theoretical results show that the band gap is decreased with by increasing the doped concentration of chromium, which reveals well the changing trend of the experimental results of band gaps.

Preparation of cerium and nitrogen co-doped titania hollow spheres with enhanced visible light photocatalytic performance

N,Ce-codoped titania hollow spheres were prepared using carbon spheres as template and using N,Ce-codoped titania nanoparticles as building blocks. The N,Ce-codoped titania nanoparticles were synthesized at low temperature. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectrum (DRS). The effect of N and Ce content on the physical structure and photocatalytic properties of the as-prepared hollow sphere samples was investigated. The mechanism of photocatalytic degradation of dyes under visible light irradiation was also discussed.

Facile preparation of visible-light-sensitive sulfur–nitrogen-codoped titanium dioxide

S–N-codoped TiO2 powders have been synthesized through a facile one-step sol–gel method by using tetrabutyltitanate and thiourea as precursors. The S–N-codoped TiO2 treated at 500 °C showed the highest photocatalytic activity for degrading methylene blue under visible light irradiation. XRD, XPS and UV–vis studies revealed that the high visible-light photocatalytic activity of the doped TiO2 may originate from the synergetic effect of sulfur and nitrogen codoping into TiO2.