S-doped TiO2 Research Articles

Influence of non-metals doping on the structural, electronic, optical, and photocatalytic properties of rutile TiO2 based on density functional theory computations

This study investigates the influence of non-metal doping (C, F, N, and S) on the structural, electronic, and optical properties of rutile TiO2 using Hubbard-corrected density functional theory (DFT) within the Quantum ESPRESSO code. Rutile TiO2 is a promising material for environmental remediation and renewable energy applications. However, it has a large bandgap of 3.03 eV, which confines its use to UV light. By substituting oxygen atoms with a single dopant atom, we aim to shift the absorption edge toward the visible spectrum. Our findings reveal that doping with C, N, and S results in a redshift of the bandgap, while F doping does not exhibit this effect. The imaginary part of the dielectric function indicates shifted absorption edges for C, N, and S-doped TiO2, making them suitable for photocatalytic applications. Additionally, an increased refractive index after doping suggests the presence of excess charge carriers that affect light propagation. This work provides valuable insights for experimentalists exploring non-metal doping influences on rutile TiO2 for photocatalysis.

Photocatalytic oxidative desulfurization of a model fuel using S-doped TiO2/BiVO4 composites: A combination of experimental and theoretical study

In this work, a simultaneous photocatalytic extraction-oxidation system for desulfurization of a model fuel has been investigated. To do this, S-doped TiO2 and S-doped TiO2/BiVO4 photocatalysts were synthesized via sol-gel and hydrothermal methods. Different analyses such as FT-IR, Raman, DRS, XRD, FE-SEM, TEM, BET, EDS, and XPS were used to characterize catalysts. According to the results, the S-doped TiO2/BiVO4 catalyst showed the highest photocatalytic activity for the removal of dibenzothiophene from the model fuel. The reaction was investigated under different conditions such as the catalyst amount, temperature, time, oxidizing value, extracting solvent, and the fuel type. Under optimal conditions, 89.3 % removal of dibenzothiophene was obtained. The catalyst can be recovered up to 3 times without significant reduction in catalytic activity. To evaluate the effect of the TiO2/BiVO4 heterojunction on its photocatalytic activity, DFT calculations were conducted. The obtained results confirmed the greater efficiency of the synthesized composite.

Treating NOx gas Pollution by Visible Light Photocatalytic Reaction of S-doped TiO2 Nanotubes

Treating NOx gas Pollution by Visible Light Photocatalytic Reaction of S-doped TiO2 Nanotubes

Performance analysis of un-doped and doped titania (TiO ) as an electron transport layer (ETL) for perovskite solar cells.

Density functional theory (DFT) calculations are carried out on pure and doped rutile TiO . The bandgap (E ) for pristine, S-doped, Fe-doped, and Fe/S co-doped materials is direct, with values of 2.98 eV, 2.18 eV, 1.58 eV, and 1.40 eV. The effective mass of charge carriers (m*) and ratio of effective masses of holes to effective masses of electrons (R) are also investigated, and it is discovered that Fe/S co-doped materials have the lowest charge carrier recombination rate. The Fe/S co-doped material has the highest . of doped materials shifted into the visible range. Due to the high dopant concentration in Fe and Fe/S-doped cases, the E is lowered to a relatively small value; hence, only pristine and S-doped materials are verified as electron transport layer (ETL). A solar cell device analysis employing pure and S-doped rutile TiO as ETL is completed using DFT-derived parameters in SCAPS-1D modeling software for the first time. For the optimized solar cells, current-voltage (IV) characteristics, quantum efficiency (QE), capacitance-voltage (CV) characteristics, and capacitance-frequency (Cf) characteristics are provided. The aim of the present study is to improve efficiency of perovskite solar cell by doping as well as to improve accuracy of simulation by applying DFT extracted parameters as input. From the analysis, improvement is found in efficiency of doped TiO compared to un-doped TiO . The efficiency of the PSC with S-doped ETL is 1.418% higher than the PSC with un-doped ETL. Quantumwise Automistic Tool Kit (ATK) is used to extract DFT parameters. Using these DFT parameters as input in SCAPS-1D (Solar Cell Capacitance Simulator), solar cells for doped and un-doped material are simulated. The density functional theory (DFT)-based orthogonalized linear combination of atomic orbital (OLCAO) technique is used. Structural optimization is done using the LBFGS (Limited-memory Broyden-Fletcher-Goldfarb-Shanno). PBESol-GGA (Perdew-Burke-Ernzerhof solid-generalized gradient approximation) is applied as exchange correlation for calculating structural parameters, while MGGA-TB09 (meta-generalized gradient approximation-Tran and Blaha) is applied as exchange correlation for calculating optical and electronic properties.

Heterostructured S-TiO2/g-C3N4 Photocatalysts with High Visible Light Photocatalytic Activity

Novel heterojunctions associating graphitic carbon nitride g-C3N4 and S-doped TiO2 nanoparticles were successfully designed and prepared via a hydrothermal method and used for photocatalytic degradations. The loading in S-TiO2 nanoparticles on g-C3N4 was varied (5, 10 and 20 wt%), and the photocatalysts were characterized by XRD, FT-IR, solid-state UV-visible diffuse reflectance, photoluminescence, XPS, TEM and SEM. The S-TiO2 (5%)/g-C3N4 catalyst exhibits the highest activity for the photocatalytic degradation of the methylene blue (MB) dye under visible light irradiation. The high photocatalytic performance originates from the enhanced separation and transfer of photogenerated charge carriers. The S-TiO2 (5%)/g-C3N4 photocatalyst is stable and can be reused five times without a sharp drop in activity, indicating its high potential for wastewater remediation.

INVESTIGATION OF THE PHOTOCATALYTIC ACTIVITY OF TITANIUM DIOXIDE DOPED WITH S

Titanium dioxide (TiO2) is widely used as a photocatalyst for the purification of industrial wastes. Scientists have attempted to enhance its photocatalytic activity by doping it with metallic and non-metallic elements. Metal dopants can shift TiO2 absorption from ultra violet (UV) to visible light but may reduce photocatalytic efficiency due to recombination centres. Doping TiO2 with non-metals like N, C, S, and F can narrow the energy band gap and improve photocatalytic efficiency. In this work, we studied S-doped TiO2, which combines high photocatalytic activity and structural stability.

Metal-organic framework derived S-doped anatase TiO2@C to store Na+ with high-rate and long-cycle life

The design of a reasonable structure and component regulation are valid methods for enhancing the electrochemical properties of TiO2, which serves as prominent anode in sodium-ion batteries with exceptional structural stability. Herein, the carbon-coated anatase TiO2 doped with S (S-TiO2 @C) was synthesized via a facile metal-organic framework-assisted approach. The S atoms partially substitute oxygen atoms in the lattice, thereby enhancing the capacitive behavior, facilitating charge transfer kinetics, and augmenting the diffusion coefficient of Na+. With exceptionally high porosity and substantial carbon content, the caky S-TiO2 @C electrode manifests superior rate capability of 167.7 mAh g−1 at 5.0 A g−1 and long-cycle life of 239.0 mAh g−1 at 2.0 A g−1 over 4000 cycles. It is foreseeable that the strategy of anionic doping and carbon coating on the metal oxide with porous structure to optimize the sodium storage capability of the electrode will be applied in the future.

Crystalline S-doped TiO2 photoanodes from amorphous titanium oxysulfide (TiOxSy) for photo-oxidation reactions

S-doped TiO2 films were prepared by oxidation annealing of amorphous titanium oxysulfide (TiOxSy) at different temperatures. According to the X-ray diffraction patterns, the films calcined at temperatures of 300–600 °C showed only anatase phase, while the uncalcined sample was amorphous. The chemical composition of synthesized TiOxSy was estimated by X-ray photoelectron spectroscopy (XPS). High-resolution S 2p spectra showed S−2 bonds at 163.47 eV for the amorphous sample. The intensity of this signal decreased after heat treatment. Raman spectroscopy indicated an organization of the material structure with heat treatment of the material. Furthermore, optical characterization revealed that sulfur as dopant into the anatase TiO2 structure, shifted light absorption from ultraviolet to the visible region. Photoeletrochemical studies developed under polychromatic irradiation revealed superior photocurrents for samples calcined at 600 °C, with n-type behavior, adequate for photo-oxidation reactions.

Improved photoactivity of TiO2 photoanode of dye-sensitized solar cells by sulfur doping

The photoactivity of the photoanode determines the power conversion efficiency of dye-sensitized solar cells (DSSC). TiO2 has come up as a potential photoanode in DSSC but it has several drawbacks, including large trap density due to lattice defect that influences carrier transport, interfacial charge transfer, and carrier transport. Here we present an effective approach to improve the TiO2 photoanode photoelectrical properties by chalcogenide ion doping, i.e. sulfur (S), that compensates the oxygen vacancy in the TiO2 lattice, enhancing the photoactivity at the visible region, reducing trap density and increasing the photovoltaic process in DSSC device. S doping in the TiO2 lattice was achieved by thiourea treatment. Our result shows that the S doping improves the interfacial charge transfer and reduced the trap density, improving the carrier lifetime and power conversion efficiency. The champion device, S-doped TiO2 with 0.3 M thiourea treatment, produces the DSSC with power conversion efficiency as high as 4.56%, which is two times higher than the DSSC using pristine TiO2. The S doping should find a potential approach for enhancing the photoactivity of the TiO2 photoanode of the DSSC device.

Enhancement in the visible light induced photocatalytic and antibacterial properties of titanium dioxide codoped with cobalt and sulfur

In this study, the sol-gel technique was used to develop Cobalt Sulfur codoped Titanium Dioxide (Co–S codoped TiO2) photocatalysts. For structural analysis of the prepared resultant TiO2 samples, XRD, FTIR, UV–Vis DRS, SEM, HR-TEM and EDX measurements were used to describe the produced photocatalysts. The characterization findings indicate that the synthesized nanoparticles possessed great crystallinity, high purity, and superior optical characteristics. For the methylene blue (MB) degradation process, Co–S codoped TiO2 nanoparticles were tested for their photocatalytic degradation performance. The Co–S codoped TiO2 nanoparticles had improved catalytic activity when compared with pure, Co-doped, S-doped TiO2 and decomposed 93% of MB in 120 min. When compared to pure and doped TiO2, the catalysts of Co–S codoped TiO2 showed a synergistic effect and improved the performance of the catalysts. Furthermore, the antibacterial applications of synthesized Co–S codoped TiO2 nanoparticles was studied against E. coli (Gram negative) and S. aureus (Gram positive) bacteria and exhibited strong antibacterial activity against the selected strains.

Preparation and photocatalytic application of terbium and sulfur co-doped titanium nanomaterials.

Titanium-based nanomaterials co-doped with terbium (Tb) and sulfur (S) were synthesized by sol-gel method via a facile step. Physicochemical properties of the resulting composites were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), X-ray photo-electron spectroscopy (XPS) and UV-Vis diffused reflectance spectroscopy (DRS). Methylene blue (MB) was used as a degradation target for evaluating the photocatalytic performance. The factors which influence the photocatalytic activity were investigated, including calcined temperatures and S doping amount. Tb, S (2 wt%) co-doped TiO2 composite calcined at 500°C exhibited the highest photocatalytic activity with a degradation rate of 72.4% in 3h. The reaction constant was 0.11529, 0.26025, 0.35038 and 0.41462h-1 for undoped TiO2, Tb-doped TiO2, S-doped TiO2 and Tb, S co-doped TiO2, respectively. Importantly, the synergistic effect of terbium and sulfur dopants was profoundly discussed. Furthermore, recycling tests and acute toxicity experiments were carried out to confirm the reusability and biosafety of Tb, S co-doped TiO2.

Enhanced antibacterial activity of visible light activated sulfur-doped TiO2 nanoparticles against Vibrio cholerae

Pure and S-doped TiO2 nanoparticles were synthesized using a facile hydrothermal technique and the influence of sulfur doping on the structural and optical properties of TiO2 are highlighted. The focus of this work is to develop a photocatalyst having enhanced antibacterial activity against Gram negative bacteria. The crystallinity and phase composition of the synthesized nanoparticles were confirmed using X-ray diffraction (XRD) technique which showed that nanoparticles have anatase TiO2 structure which is in good agreement with the Raman studies. In addition, with S-doping crystallite size varied between 17.84 and 33.25 nm. The presence of S in the TiO2 matrix was confirmed by the elemental composition analysis carried out through EDAX measurements. FTIR spectra also revealed a band at 1068.01 cm−1, which is found to be associated with the Ti–O–S bond. UV-Vis measurements showed that the bandgap energy is, in general, decreased with the introduction of S in the TiO2 lattice. TiO2 doped with 40% S content (F-4) showed 71% bacterial growth reduction at concentration of 0.01 μg/mL. The safety of the synthesized nanoparticles was tested in vitro on hepatocellular carcinoma (Huh-7) human cell lines, which suggested that these particles are safe for the treatment of drinking water against Vibrio cholera.

Theoretical investigation on un-doped and doped TiO2 for solar cell application

Enhancing solar cell efficiency is one of the most challenging and demanding topics for PV researchers. An ab initio study is done here on the structure of crystal, formation energies, electronic structure, the density of states, effective mass, and optical properties of pure and S-doped, Fe-doped, and Fe-/S-doped anatase TiO2. Co-doping causes a significant reduction in the bandgap, suppresses the charge carrier’s recombination rate, and shifted absorption spectra from UV to the visible region. Hence, co-doped anatase TiO2 with Fe and S is more favorable as a buffer layer of the solar cell compared to S-doped and Fe-doped TiO2. The forecasted values of all quantities will benefit researchers to examine these materials for further photovoltaic applications.

Visible light responsive S-Doped TiO2 nanoparticles: synthesis, characterization and photocatalytic degradation of pollutants

Visible light responsive S-Doped TiO2 nanoparticles: synthesis, characterization and photocatalytic degradation of pollutants

Photocatalytic Degradation of 4,4'-Isopropylidenebis(2,6-dibromophenol) on Sulfur-Doped Nano TiO2.

In present work, we examine the photocatalytic properties of S-doped TiO2 (S1, S2) compared to bare TiO2 (S0) in present work. The photocatalytic tests were performed in alkaline aqueous solutions (pH = 10) of three differently substituted phenols (phenol (I), 4,4′-isopropylidenebisphenol (II), and 4,4′-isopropylidenebis(2,6-dibromophenol) (III)). The activity of the catalysts was evaluated by monitoring I, II, III degradation in the reaction mixture. The physicochemical properties (particle size, ζ-potential, Ebg, Eu, E0cb, E0vb, σo, KL) of the catalysts were established, and we demonstrated their influence on degradation reaction kinetics. Substrate degradation rates are consistent with first-order kinetics. The apparent conversion constants of the tested compounds (kapp) in all cases reveal the sulfur-loaded catalyst S2 to show the best photocatalytic activity (for compound I and II S1 and S2 are similarly effective). The different efficiency of photocatalytic degradation I, II and III can be explained by the interactions between the catalyst and the substrate solution. The presence of bromine substituents in the benzene ring additionally allows reduction reactions. The yield of bromide ion release in the degradation reaction III corresponds to the Langmuir constant. The mixed oxidation-reduction degradation mechanism results in higher degradation efficiency. In general, the presence of sulfur atoms in the catalyst network improves the degradation efficiency, but too much sulfur is not desired for the reduction pathway.

Removal of 1-naphthol from Water via Photocatalytic Degradation Over N,S-TiO2/ Silica Sulfuric Acid under visible Light

Background: Naphthol, one of the naphthalene derivatives, is the most significant industrial chemical. It is widely used in the biochemical processes, production of dyes, and pharmaceutical industries. Methods: In the present study, N, S-doped TiO2 thin film immobilized on Silica Sulfuric Acid (SSA) glass Microspheres (MS) was investigated as a novel high efficient photocatalyst. We fabricated N, S-doped TiO2 immobilized on SSA using a simple modified sol-gel process. Its photocatalytic activities were then assessed by 1-naphthol solution in the presence of visible light. The physicochemical properties of photocatalyst were characterized using Energy-Dispersive X-ray (EDX), Scanning Electron Microscope (SEM) images, and X-Ray Diffraction (XRD) pattern. Results: According to the obtained results, the optimal pH, time, concentration, and removal efficiency of 1-naphthol for N, S-doped TiO2 /SSA were 5, 50 min, 25 mg/L, and 92.12%. Conclusion: The present study confirms the usability of the immobilized N, S-doped TiO2 on SSA glass MS as a novel, effective, and efficient technique for treating wastewater containing 1-naphthol under visible light.

Synthesis of S doped TiO2 (S-TiO2) to enhance photocatalytic degradation of Ciprofloxacin in aqueous solutions under visible light

In this study, the sol-gel method was successfully used to synthesize S-TiO2 for efficient photocatalytic degradation of Ciprofloxacin solution under visible irradiation. These synthesized materials were characterized by various analytical methods such as XRD, SEM-EDX, FT-IR, and UV diffuse reflectance spectroscopy (DRS). XRD, SEM-EDX, and FT-IR confirmed the successful preparation of these materials. The UV-DSR demonstrated that the material has a lower bandgap in comparison with prime TiO2. The photodegradation results reported that the 0.33S-TiO2 had shown high efficiency in the degradation of Ciprofloxacin in comparison with TiO2. The decomposition of 10 mg/L Ciprofloxacin concentration reached approximately 90% for 150 minutes of visible light irradiation at room temperature at pH = 4.

Time-Dependent Density Functional Theory Calculations of N- and S-Doped TiO2 Nanotube for Water-Splitting Applications.

On the basis of time-dependent density functional theory (TD-DFT) we performed first-principle calculations to predict optical properties and transition states of pristine, N- and S-doped, and N+S-codoped anatase TiO nanotubes of 1 nm-diameter. The host O atoms of the pristine TiO nanotube were substituted by N and S atoms to evaluate the influence of dopants on the photocatalytic properties of hollow titania nanostructures. The charge transition mechanism promoted by dopants positioned in the nanotube wall clearly demonstrates the constructive and destructive contributions to photoabsorption by means of calculated transition contribution maps. Based on the results of our calculations, we predict an increased visible-light-driven photoresponse in N- and S-doped and the N+S-codoped TiO nanotubes, enhancing the efficiency of hydrogen production in water-splitting applications.

Enhanced photocatalytic degradation of Remazol Black under visible light illumination through S doped TiO2 (S-TiO2) nanoparticles: Operational factors and kinetic study

<p>The degradation of Remazol Black (RBB) by S-TiO2 photocatalyst was investigated. X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and UV-vis specular reflectance spectroscopy has been used to characterize S-TiO2. The results suggested that the optical absorption edge of TiO2 was red-shifted by the addition of S dopants and the bandgap energy was 3.02 eV. The sulfur species were found to be evenly dispersed on the TiO2 crystal lattice as cationic sulfur (S6+) which corresponds to the cationic substitution on TiO2. The particle size decreased to 4-14 nm after S doping, which indicates that the addition of S dopants has contributed to an improvement in the photocatalyst surface area. The degradation of RBB was achieved 94% after 120 min visible light irradiation, a remarkable increase compared to bare TiO2 which was only able to degrade 48% of RBB at the same time. Optimization of the pH showed that the optimum pH for RBB degradation was 3.0, and the photocatalyst dose was 0.8 g L-1. Kinetic study showed that S-TiO2 photocatalytic degradation of RBB followed the pseudo-second-order kinetics model. Reducing the bandgap has been found to increase the activity of photodegradation in the visible light region.</p>

S-doped TiO2 spindles wrapped by graphene with high exposed {001} faces and intimate contact

A new composite of intimately contacted S-doped TiO2 spindles/graphene (with S/Ti ratio of 1/3, denoted as S–TiO2@GP) was synthesized via a simple self-developed one-pot vapor-thermal method. As the water needed for the hydrolysis of Titanium (IV) tetraisopropanolate (TIP) was supplied by the etherification reaction of polyols, the hydrolysis rate was largely slowed down, which ensured TiO2 nucleation and growth on the GP surface and achieved close contact. The as-obtained S–TiO2@GP includes TiO2 spindles with six {001}/{010}/{100} facets, proving its high exposure of {001} active facets and potential photocatalytic applications. Its photocatalytic performance was evaluated by degrading methylene blue. Compared to the samples with different S-doping, S–TiO2@GP shows much better photocatalytic performance. This could be attributed to its largely exposed high-active {001} faces, enhanced visible-light-absorption, higher specific surface area and the effective electron-hole separation achieved via photogenerated electron transfer from excited TiO2 to GP, all of which were studied using HRTEM, UV–vis DRS, BET specific surface area, XPS and spin resonance spectra (ESR). ESR results also revealed that both ·O2- and ·OH contribute to the photocatalytic activities. This work provides a promising one-pot method for constructing intimately contacted S-doped TiO2/GP composite with high exposed {001} faces and excellent photocatalytic activities.