S-doped TiO2 Research Articles

N-doped, S-doped TiO2nanocatalysts: synthesis, characterization and photocatalytic activity in the presence of sunlight

N doped and S doped nano TiO2catalysts were synthesized by a sol–gel process followed by hydrothermal treatment at low temperature and tested for catalytic activity by natural sunlight photocatalytic degradation of a toxic chemical warfare agent.

A greener approach to synthesize visible light responsive nanoporous S-doped TiO2 with enhanced photocatalytic activity

A visible light responsive nanoporous sulfur doped TiO2 nanophotocatalyst was prepared by a greener approach using ultrasonic irradiation.

Development of high efficient visible light-driven N, S-codoped TiO2 nanowires photocatalysts

One-dimensional (1D) nanowire material (especially nonmetal doped 1D nanowires) synthesized by a facile way is of great significance and greatly desired as it has higher charge carrier mobility and lower carrier recombination rate. N, S-codoped TiO2 nanowires were synthesized using titanium sulfate as a precursor and isopropanol as a protective capping agent by a hydrothermal route. The obtained doped nanowires were characterized by XRD, SEM, HRTEM, SAED, XPS, BET and UV–vis absorption spectrum. The incorporation of N and S into TiO2 NWs can lead to the expansion of its lattice and remarkably lower its electron-transfer resistance. Photocatalytic activity measurement showed that the N, S-codoped TiO2 nanowires with high quantum efficiency revealed the best photocatalytic performance for atrazine degradation under visible light irradiation compared to N, S-codoped TiO2 nanoparticles and S-doped TiO2 nanowires, which was attributed to (i) the synergistic effect of N and S doping in narrowing the band gap, separating electron–hole pairs and increasing the photoinduced electrons, and (ii) extending the anatase-to-rutile transformation temperature above 600°C.

Photocatalytic hydrogen production from methanol aqueous solution under visible-light using Cu/S–TiO2 prepared by electroless plating method

Cu was loaded on the S-doped TiO2 by electroless plating method. The prepared Cu/S–TiO2 exhibited high photocatalytic activity for hydrogen generation, and the yield is up to 7.5mmolh−1g−1cat in methanol solution. Their physical structure and chemical properties were characterized by UV–Vis, XRD, XPS and EXAFS. The copper species were CuO and Cu2O, and the sample showed excellent visible light absorption ability. Comparing with the sample prepared by chemical reducing method, the electroless plated copper on S–TiO2 was highly dispersed, which could facilitate photo-generated charges capture, transfer and separation.

Novel high potential visible-light-active photocatalyst of CNT/Mo, S-codoped TiO2 hetero-nanostructure

The current study deals with synthesize of novel nanophotocatalysts of CNT/Mo,S-codoped TiO2 by reacting between titanium isopropoxide (Ti(OC3H7)4) and CNT in aqueous ammonia and subsequent calcining of hydrolysis of the products. The prepared catalysts were characterized by N2 adsorption–desorption measurements, XRD, SEM, TEM, EDX, FT-IR, and UV–vis DRS spectroscopy. SEM and TEM images exhibited uniform coverage of CNT with anatase TiO2 nanoclusters. It was also demonstrated that the presence of S and Mo within the TiO2 acts as electrons traps and prevents the charge recombination and also enables the TiO2 photocatalyst to be active in visible-light region. Moreover, the CNT/Mo,S-doped TiO2 nanohybrids has been proven to has a excellent photocatalytic performance in photodecomposition of Congored (CR), at which the rate of decomposition reaches 100% in only 20 and 30min under UV and visible-light irradiation, respectively. The enhanced photocatalytic activity was ascribed to the synergetic effects of excellent electrical property of CNT and metal–non-metal codoping. Finally, which to best of our knowledge is done for the first time, we have demonstrated that Mo- and S-doped TiO2 decorated over CNT, or CNT/Mo,S-codoped TiO2, may have high potential applications in photocatalysis and environmental protection with superior catalytic activity under visible-light illumination.

Combination study of DFT calculation and experiment for photocatalytic properties of S-doped anatase TiO2

Although there are many publications about S-doped TiO2, the related mechanism is still not well elucidated. In order to investigate the origin and trend of S substituting for O in TiO2 crystal lattice with proper dopant concentration, a combination of DFT calculation and experiment was used. Bader charge and electronic location function analysis indicate that the largely ionic character between Ti and S bonding in titanium dioxide decreases and there is free electron gas like behavior around S and neighbor Ti for the S-doped anatase TiO2. From DFT calculation, ST2.78 model is found to stabilize the structure of S substitution for lattice O with lower formation energy and its absorbance in visible light increases. Experiment results demonstrate that the sulfur doping results in the shift of the absorption edge for TiO2 to lower energy region, which leads to the nanoparticles active within the wavelength range of 650nm.

A kinetic study for the degradation of 1,2-dichloroethane by S-doped TiO2 under visible light

Sulfur-doped TiO2 prepared by a sol–gel method to degrade 1,2-dichloroethane (1,2-DCE) under visible light irradiation was investigated. The photocatalytic decomposition rate of 1,2-DCE under visible light condition was expected to increase via doping. Additionally, the physical and chemical properties of the photocatalysts measured by thermo-gravimetric/differential-thermal analysis, X-ray diffraction, UV–Vis spectroscopy, elemental analysis, BET surface analysis, and X-ray photoelectron spectroscopy were obtained for a better understanding of TiO2 particles. The results indicate that S-doped TiO2 are mainly nano-size with an anatase-phase structure, and doping sulfur leads to the formation of Ti–O–S in the TiO2 lattice. The role of S6+ as h+/e− traps promotes photocatalytic activity, and prevents h+/e− recombination. S-doped TiO2 photocatalysts show superior photocatalytic activity compared to that of TiO2. Among all photocatalysts, 10 mol% S/TiO2 exhibits the best decomposition rate of 1,2-DCE. The 10 mol% S-doped TiO2 was, therefore, chosen for the kinetic study. A variety of models were used for best fit of the kinetic data in this study. The results demonstrate that the bimolecular Langmuir–Hinshelwood kinetic model is more feasible than other two to illustrate the photocatalytic reaction of 1,2-DCE.

Aluminum sheet-based S-doped TiO2 for photocatalytic decomposition of toxic organic vapors

S-doped TiO2 (S-TiO2) films were immobilized on flexible low-cost aluminum sheets (S-TiO2-AS) using a sol-gel dipping process and low post-processing temperatures. The photocatalytic degradation of toxic organic vapors using the prepared films was evaluated using a continuous-flow glass tube under visible light exposure. The surface properties of the S-TiO2-AS and TiO2-AS films were examined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and ultraviolet-visible spectroscopy. The photolysis of benzene, toluene, ethyl benzene, and xylene (BTEX) did not occur on the bare AS. In contrast, the photocatalytic degradation efficiencies of the target pollutants using S-TiO2-AS were higher than those obtained using reference TiO2-AS photocatalyst. In particular, the average photocatalytic degradation efficiencies of BTEX using S-TiO2-0.8-AS (S/Ti ratio = 0.8) over a 3-h process were 34%, 78%, 91%, and 94%, respectively, whereas those of TiO2-AS were 2%, 11%, 21%, and 36%, respectively. The photocatalytic decomposition efficiencies of BTEX under visible irradiation using S-TiO2-AS increased with increasing S/Ti ratios from 0.2 to 0.8, but decreased when the ratio further increased to 1.6. Thus, S-TiO2-AS can be prepared using optimal S/Ti ratios. The degradation of BTEX over S-TiO2-AS depended on the air flow rates and initial concentrations of the target chemical. Overall, under optimal conditions, S-TiO2-AS can be effectively applied for the purification of toxic organic vapors.

The Modification of Anatase TiO<sub>2</sub> (001) Surface by N or S Atom: A DFT Investigation

The electronic of S-doped and N-doped anatase TiO2(001) surfaces were investigated using the density functional theory (DFT). Substitutional and interstitial configurations of N and S atoms doped in anatase TiO2(001) surface and sub-surface at different sites were considered and all the formation energies were obtained. The perfect strutures of atoms doping were obstained by formation energies comparisions. The electronic structures of the results indicated that the elemental doping has much more efficient and stable photocatalyst than the pristine one, which narrowed the band gap of TiO2and improved its visible-light response activity.

An in vivo study on the photo-enhanced toxicities of S-doped TiO2 nanoparticles to zebrafish embryos (Danio rerio) in terms of malformation, mortality, rheotaxis dysfunction, and DNA damage

The role of light on the acute toxicities of S-doped and Sigma TiO2 nanoparticles in zebrafish was studied. Metrics included mortality for both, and rheotaxis dysfunction and DNA damage for S-doped only. It was found that the acute toxicity of S-TiO2 nanoparticles was enhanced by simulated sunlight (SSL) irradiation (96-h LC50 of 116.56 ppm) and exceeded that of Sigma TiO2, which was essentially non-toxic. Behavioral disorder, in terms of rheotaxis, was significantly increased by treatment with S-TiO2 nanoparticles under SSL irradiation. In order to further understand its toxicity mechanism, we investigated hair cells in neuromasts of the posterior lateral line (PLL) using DASPEI staining. Significant hair cell damage was observed in the treated larvae. The Comet assay was employed to investigate the DNA damage, which might be responsible for the loss of hair cells. Production of the superoxide anion (), a major ROS generated by TiO2 nanoparticles, was assayed and used to postulate causative factors to account for these damages. Oxidative effects were most severe in the liver, heart, intestine, pancreatic duct, and pancreatic islet – results consistent with our earlier findings in the investigation of embryonic malformation. TEM micrographs, used to further investigate the fate of S-TiO2 nanoparticles at the cellular level, suggested receptor-mediated autophagy and vacuolization. Our findings validate the benefit of using the transparent zebrafish embryo as an in vivo model for evaluating photo-induced nanotoxicity. These results highlight the importance of conducting a systematic risk assessment in connection with the use of doped TiO2 nanoparticles in aquatic ecosystems.

Evaluation of nanostructured S-doped TiO2 thin films and their photoelectrochemical application as photoanode for corrosion protection of 304 stainless steel

Undoped and S-doped TiO2 thin films were prepared on titanium substrate through a sol–gel method. The photoelectrochemical behavior of S-doped TiO2 thin film (as photoanode) was studied. The effect of Sulfur doping on structural, optical and morphological properties of TiO2 was studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), FT-IR, UV–ViS and FE-SEM. Superiority of the S-doped TiO2 film was shown through taking advantage of linear sweep voltametry measurement, open-circuit potential of 304 stainless steel as well as potetiodynamic polarization technique. Results showed that S-doped TiO2 thin film is an efficient photoanode with long term stability (several hours).

Enhancing the photocatalytic degradation of salicylic acid by using molecular imprinted S-doped TiO2 under simulated solar light

Molecular imprinted polymer coated S-doped TiO2 (MIP/S-TiO2) nanocomposites were successfully synthesized by a surface molecular imprinting technique using p-phenylenediamine as the functional monomer and salicylic acid as the template molecule. The structure and properties of the catalysts were characterized by X-ray diffraction, scanning electron microscopy, and UV–vis diffuse reflectance spectra. Compared with TiO2 nanoparticles, the absorption edge of MIP/S-TiO2 nanocomposites was enhanced over the whole range of visible region. Moreover, MIP/S-TiO2 nanocomposites showed higher adsorption capacity for salicylic acid than for S-TiO2 nanoparticles. The rate constant for the photodegradation of salicylic acid over MIP/S-TiO2 nanocomposites was 1.7 times that of salicylic acid over S-TiO2 nanoparticles, which was attributed to the molecular recognition ability of MIP/S-TiO2 nanocomposites for the target molecules.

Photoelectrochemical Characteristics of N-and S-doped TiO2 with Coumarin

Photoelectrochemical Characteristics of N-and S-doped TiO2 with Coumarin

High quality sulfur-doped titanium dioxide nanocatalysts with visible light photocatalytic activity from non-hydrolytic thermolysis synthesis

A non-hydrolytic route for monodisperse S-doped TiO2 nanocatalysts with enhanced visible light activation is demonstrated.

Core-Shell Nanostructured “Black” Rutile Titania as Excellent Catalyst for Hydrogen Production Enhanced by Sulfur Doping

Modification of rutile titanium dioxide (TiO2) for hydrogen generation and water cleaning is a grand challenge due to the chemical inertness of rutile, while such inertness is a desired merit for its stability in photoelectrochemical applications. Herein, we report an innovative two-step method to prepare a core-shell nanostructured S-doped rutile TiO2 (R'-TiO2-S). This modified black rutile TiO2 sample exhibits remarkably enhanced absorption in visible and near-infrared regions and efficient charge separation and transport. As a result, the unique sulfide surface (TiO(2-x):S) boosts the photocatalytic water cleaning and water splitting with a steady solar hydrogen production rate of 0.258 mmol h(-1) g(-1). The black titania is also an excellent photoelectrochemical electrode exhibiting a high solar-to-hydrogen conversion efficiency of 1.67%. The sulfided surface shell is proved to be an effective strategy for enhancing solar light absorption and photoelectric conversion.

Fabrication and photocatalytic properties of cationic and anionic S-doped TiO2 nanofibers by electrospinning

In present work, S-doped TiO2 nanofibers, with several hundred nanometers in diameter, have been prepared via electrospinning technique using thiourea and CS2 as the sulfur precursors (denoted as UTF and CTF, respectively). The results revealed that sulfur atoms were successfully incorporated into the bulk phase of TiO2 nanofibers. Cationic doping was found with the substitution of Ti4+ by S6+ and TiOS bonds were formed in the UTF sample, but anionic doping was obtained in the CTF sample and OTiS bonds were produced via the S2− substituted for O2−. Meanwhile, evidence showed that chemisorbed SO42− groups were present on the surface of both S-doped samples. Furthermore, S-doping could effectively inhibit the growth of crystalline grain size and obviously increase light absorbance in visible region. The photocatalytic activity of obtained nanofibers was analyzed for the degradation of organic pollutants by visible-light irradiation, and the photocatalytic mechanism was investigated by employing several scavengers for active species. Results showed that photoinduced holes (h+) and chemisorbed hydroxyls (OHads−) on catalyst surface played a vital role in the photocatalysis of UTF system, but photoinduced holes (h+) and electrons (e−) had the nearly equal importance in CTF system.

Synthesis of Cu/S-TiO2 photocatalysts for hydrogen generation

S-doped TiO2 was modified by Cu with methods of electroless plating, wet impregnation and chemical reduction respectively. The chemical properties of the prepared Cu/S-TiO2 were characterised by ultraviolet visible absorption spectrum (UV-Vis), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy analysis (XPS) techniques. The results showed that copper species loaded by electroless copper plating and wet impregnation method were Cu2O/CuO, while Cu was detected in the sample prepared by chemical reduction method. The Cu/S-TiO2 prepared by electroless plating method showed excellent visible light absorption ability, and the catalyst exhibited the highest photocatalytic activity for hydrogen generation in methanol solution under simulated sunlight (420–500 nm).

Dielectric and photocatalytic properties of sulfur doped TiO2 nanoparticles prepared by ball milling

Sulfur (S) doped commercial TiO2 P-25 has been achieved by changing the amount of thiourea using ball milling technique. The results of XRD clearly reveal biphasial anatase and rutile mixtures for all prepared samples and doping of S does not change the morphology of the TiO2. The optical absorption edge of S-doped TiO2 was red shifted with indirect bandgap energy of 2.8eV. The dielectric studies confirm that the dielectric constant of TiO2 increases after doping, however it becomes more conductive. Newly designed S-doped TiO2 photocatalysts exhibited excellent photocatalytic performance for the degradation of methylene blue (MB) under visible light. The overall photocatalytic activity of 0.11at.% S-doped TiO2 was significantly 3-times higher than that of commercial TiO2 P-25 and complete degradation of MB has taken place after 90min of irradiation under visible light while only 35% dye degraded when the reaction has been carried out in the presence of undoped TiO2.

Anionic or Cationic S-Doping in Bulk Anatase TiO2: Insights on Optical Absorption from First Principles Calculations

Using first principles calculations, we investigate the structural, electronic, optical, and energetic properties of S-doped anatase TiO2 bulk systems. To ensure accurate band gap predictions, we use the HSE06 exchange correlation functional, and the absorption spectra are obtained with density functional perturbation (DFPT) theory by employing HSE06. Various oxidation states (anionic and cationic) of sulfur are considered depending on the location in bulk TiO2: in interstitial position or in substitution for either oxygen or titanium atoms. Among the explored structures, two anionic and one cationic configurations induce an improved optical absorption response in the visible region as observed experimentally. Moreover, we undertake a thermodynamic analysis as a function of the chemical potential of oxygen and considering three relevant sulfur chemical doping agents (S2, H2S, and thiourea). It highlights that cationic configurations (S4+ and S6+) are strongly stabilized in a wide range of oxygen chemical ...

Research on Photocatalytic Degradation Kinetics of S-Doped TiO<sub>2</sub> to Phenol

S-doped TiO2 nanomaterials were prepared via hydrothermal synthesis method using tetrabutyl titanate. Kinetics of S-doped TiO2 catalyzing phenol was researched by analysising the influence of initial phenol concentration, initial phenol pH value on photochemical catalysis speed. The results indicated that the value of K decreased with the rising of phenol concentration. The influence of initial solution pH was exsiting an optimal value. When pH value was 4, photocatalytic rate was maxium, corresponding K was 0.17983 min-1.