Narrow Results

${\mathrm{\text{TiO}}}_2$ nanomaterials with different content of ${\mathrm{\text{Ce}}}^{4+}$ ion were synthesized by the chemical method from solutions and demonstrated improved photocatalytic and optical properties with significant redshift compared to pristine ${\mathrm{\text{TiO}}}_2$. According to X-ray phase analysis and transmission electron microscopy, all synthesized materials are characterized by anatase modification, which holds up to $800^{\circ }$C, the particle size for all materials is 12–21 nm. X-ray diffraction spectra revealed that the anatase to rutile phase transition for materials doped with ${\mathrm{\text{Ce}}}^{4+}$ ions begins at a higher temperature of $800^{\circ }$C compared to pristine ${\mathrm{\text{TiO}}}_2$. The influence of synthesis conditions and ${\mathrm{\text{Ce}}}^{4+}$ content (0.1–2 mol.%) on characteristics and photocatalytic activity were investigated. The Ce-doped ${\mathrm{\text{TiO}}}_2$ nanomaterial, containing 0.1% ${\mathrm{\text{Ce}}}^{4+}$ provides an extremely high degree of methylene blue decomposition by 93% within visible light irradiation for 3 h. The stability of the catalyst over four cycles has been shown, which makes it possible to use it in the purification of water resources from dyes or other pollutants.

Reduced graphene oxide (RGO) wrapped TiO₂/Ag ternary nanocomposite was synthesized via a wet chemical method. The synthesized nanocomposite was characterized using UV-Vis spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, Scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD). The average size of RGO wrapped TiO₂ and deposited Ag nanoparticles were 3.2 μm and 48 nm, respectively. Due to the highly facilitated electron transport by the synergistic effect between RGO sheets and Ag nanoparticles, the TiO₂/RGO/Ag nanocomposite exhibited a significant enhancement of photocatalytic activity towards degradation of methylene blue under UV light.

Titanium dioxide (TiO₂) nanoparticles were prepared by resistive heating Ti filament under an oxygen atmosphere. The obtained nanoparticles were confirmed to be a tetragonal crystal TiO₂ and the particle size increased with increasing the oxygen pressure. The NO₂ gas sensing properties of the TiO₂ nanoparticles were investigated. All the sensors made of TiO₂ nanoparticles with different particle sizes exhibited the maximum sensitivities to 1 ppm NO₂ at a relative low operating temperature of 150°C. Comparing with the large particle size of TiO₂ nanoparticles, the ones with the smallest particle size exhibited the highest sensitivity and the best response and recovery characteristic to various NO₂ gas concentrations.

TiO₂-based photoanodes were prepared via thermal oxidation of titanium foils in air at 500–900${}^{\circ }$C. Some of them were pre-treated via etching with HCl prior to oxidation, and others post-treated by means of sensitization with Ag₂S or CdS. XRD analysis revealed that the formation of rutile is observed even at 500${}^{\circ }$C. Etching prior to oxidation removes the Ti passivation layer and facilitates the oxidation process, and lowers the temperature at which the fundamental absorption edge is observed. The highest photocurrent values measured in a photoelectrochemical cell (PEC) were obtained for anodes etched prior to oxidation. Sensitization with CdS or Ag₂S increased photocurrent drastically. It was demonstrated that pre- and post-treated TiO₂-based photoanodes prepared in the process of thermal oxidation offer far better performance in PECs than those which had not been treated.

The dye-sensitized solar cells (DSSCs) have been fabricated by using a series of natural dyes extracted from euonymus japonicus and purple plants. The optical characteristics and chemical structure of dyes were investigated by UV-visible spectroscopy and Fourier infrared spectroscopy. It is found that the absorption of sunlight and bonding performance to TiO₂ electrode of dyes had significantly effects on the conversion efficiency of solar cells. The results show the cells using blueberry as sensitizer achieved best conversion efficiency of 0.218%, attributed to its strong absorption and excellent bonding to the TiO₂ electrode, correspondingly, the short-circuit photocurrent density ($J_{\mathrm{\text{sc}}})$ and open-circuit voltage ($V_{\mathrm{\text{oc}}})$ were 1.3mA/cm² and 430mV, respectively.

In this paper, novel chestnut-like TiO₂ was successfully synthesized by the hydrothermal method. The presence of chestnut-like structure not only increased the density of active sites with a high accessibility, but also facilitated the diffusion of solvent and products. Then, the chestnut-like TiO₂ based thin films on FTO were successfully prepared by the doctor-blade method. Moreover, the thickness of thin films can be adjusted via different repeated times. After that, in order to further improve its photoelectric properties, the adoption of CdS sensitization with different time interval via chemical bath route was studied. Photoelectrochemical (PEC) measurements showed that CdS/TiO₂ photoelectrode under the optimal condition exhibited minimal resistance and the fastest charge transfer rate. The highest photocurrent density can reach 35.1$\mu$A$\cdot$cm${}^{-2}$, which is almost 5-fold than that of pure chestnut-like TiO₂ (7.6$\mu$A$\cdot$cm${}^{-2}$) based thin films. The enhanced PEC properties could be ascribed to the improvement of light harvesting and the formation of heterostructure to accelerate the separation of photo-generated electron-hole pairs.

Nanostructured thin-film electrode materials are proposed for supercapacitors due to their outstanding performance over bulk materials. In this work, we fabricated a TiO₂ nanotube film over a titanium foil using a top-down approach for supercapacitor electrodes. We noticed that the fabricated nanotubes are uniform and well aligned, confirmed by FESEM; the TiO₂ nanotube parameters were further simulated using COMSOL Multiphysics. Simulations show an areal capacitance of 1.19393 pF/cm² with oxidation and reduction peak currents of 6.18921×10${}^{-15}$ A and −6.0320×10${}^{-15}$ A, respectively, at 10 mV/s scan rate. The as-prepared nanotubes show a poor areal capacitance of 1.0193 F/cm², which is improved to 12.8764 F/cm² at a scan rate of 10 mV/s, that is approximately 12.63 times with oxidation and reduction peak currents of 0.129 mA/cm² and −0.105 mA/cm², respectively, by performing an electrochemical etching. Further, the surface roughness of both as-prepared and etched samples is studied to comment on their surface area changes. The effect of the etched sample is studied, compared and validated with simulation, which reveals that the etched TiO₂ nanotubes thin-film sample shows considerable similarity with the simulation results.

Sludge-derived activated carbon (SDAC) is prepared from sewage sludge and can be used to treat pollutants. SDAC can also be used to dope catalytic materials to improve their pollutant degradation ability. However, there needs to be more research on doping TiO₂ with SDAC. In this study, TiO₂ was doped with SDAC by Ultraviolet light irradiation method under room temperature. The doping process saved a large amount of energy. The TiO₂ doped with SDAC had the ability to degrade dyes under visible light. The results showed that the removal rates of SDAC-doped TiO₂ for methyl orange (MO) and methylene blue (MB) were over 90% and 94% under visible light conditions. After five cycles, the removal rate of MO was 75%, while the removal rate of MB decreased to 45%. Molecular dynamics simulation results showed that the valence band and conduction band of SDAC-doped TiO₂ shifted downward, and three apparent impurity levels appeared near the Fermi level after SDAC doping.

In order to achieve efficient degradation of Rhodamine B (RhB) dye in a short time, Fe and N co-doped TiO₂ photocatalyst (Fe-N-TiO₂) was prepared by sol–gel method and used for photocatalytic activation of peroxymonosulfate (PMS) to degrade RhB. SEM-EDS, XRD, and XPS results showed that Fe-N-TiO₂ was successfully prepared. The results of UV–Vis DRS and EIS showed that compared with pure TiO₂, the modified catalyst showed higher electron transfer efficiency and light absorption ability, which enhanced the electron production ability and activated more PMS to generate free radicals to degrade RhB. The experimental results show that the degradation rate of RhB can reach 85.59% under the PC/PMS system with a PMS concentration of 2.0 mmol L${}^{-1}$, catalyst dosage of 0.5 g L${}^{-1}$ and pH = 3 for 30 min. In addition, the catalyst has good repeatability and stability, and the degradation rate can still be maintained above 70% after 5 times of continuous use. The results of free radical capture experiments showed that the main active substances in the reaction system were $•$OH, SO₄${}^{•-}$, $•$O₂${}^{-}$, and h${}^{+}$, and the possible mechanism of RhB in PC/PMS/Fe-N-TiO₂-0.5% system was proposed, which provided a theoretical basis for dye wastewater treatment.