Hierarchical TiO2 Structures Derived from F− Mediated Oriented Assembly as Triple-functional Photoanode Material for Improved Performances in CdS/CdSe Sensitized Solar Cells

Hydrodynamic performance assessment of photocatalytic reactor with baffles and roughness in the flow path: A modelling approach with experimental validation

Purification of wastewater is essential for human being as well as for the flora and fauna, and sustainable environment. Photocatalytic reactor with TiO2 coated layer can be used to degrade the pollutants but without proper pollutant mass transfer in the reactive surface, photocatalytic reactor decreases its effectiveness. The baffles and rough surface in the flow path can improve the fluid mixing to enhance pollutant mass transfer to improve the reactor's performance. In this study, a computational fluid dynamics (CFD) model has been developed to investigate the effect of four top baffles and three rough surfaces (semi-circular, triangle, and rectangle) on pressure drops, mass transfer and the hydrodynamic performance of the reactor. The experimental investigation was carried out using Formic Acid (FA) as pollutant in feed water for model validation. The simulated result varies only within 5% with the experimental data of FA concentration versus feed flow rate and fluid velocity. The model was run at fluid velocity of 0.15 m/s and 0.5 m/s (Reynolds number of 2150 (laminar flow) and 7500 (turbulent flow), respectively. The simulation result shows that the addition of baffles and roughness on the reactive surfaces increases the turbulent kinetic energy (minimum increase 8%) and consequently increases the mass transfer (maximum increase 37%) of the pollutant. The highest wall shear was observed to be 40 Pa when both square and triangular elements were used as roughness elements at turbulent flow condition. The results also shows that the highest pressure-drop of 8 kPa was found when the square roughness element was used at turbulent flow condition. Overall, the photocatalytic reactor performance is significantly enhanced by the application of combined baffles and roughness elements in the reactive surface.

Robust α-Fe2O3@TiO2 Core–Shell Structures With Tunable Buffer Chambers for High-Performance Lithium Storage

α-Fe2O3 has high potential energy storage capacity and can serve as a green and low-cost anode material for lithium-ion batteries. However, α-Fe2O3 suffers large volume expansion and pulverization. Based on DFT calculations, TiO2 can effectively maintain the integrity of the crystal structure during the discharge/charge process. Well-defined cubic α-Fe2O3 is coated with a TiO2 layer using the hydrothermal method with the assistance of oxalic acid surface treatment, and then α-Fe2O3@TiO2 with tunable buffer chambers is obtained by altering the hydrochloric acid etching time. With the joint efforts of the buffer chamber and the robust structure of the TiO2 layer, α-Fe2O3@TiO2 alleviates the expansion of α-Fe2O3 during the discharge/charge process. The optimized sample (FT-1h) achieves good cycling performance. The reversible specific capacity remains at 893.7 mA h g-1, and the Coulombic efficiency still reaches up to 98.47% after 150 cycles at a current density of 100 mA g−1. Furthermore, the reversible specific capacity can return to 555.5 mA h g−1 at 100 mA g−1 after cycling at a high current density. Hence, the buffer chamber and the robust TiO2 layer can effectively improve the cycling stability and rate performance of α-Fe2O3.

Improved adsorption and degradation performance by S-doping of (001)-TiO2

In this work, sulfur-doped (S-doped) TiO₂ with the (001) face exposed was synthesized by thermal chemical vapor deposition at 180 or 250 °C using S/Ti molar ratios R _S/Ti of 0, 0.5, 1, 2, 3, 4 and 5. The S-doped samples synthesized at 250 °C exhibit a significantly improved photocatalytic performance. More precisely, S-doping has the following effects on the material: (1) S can adopt different chemical states in the samples. Specifically, it exists in the form of S^2- replacing O^2- at a ratio of R _S/Ti = 1 and also in the form of S⁶⁺ replacing Ti⁴⁺ at R _S/Ti ≥ 2. As a result, S-doping causes a lattice distortion, because the ionic radii of S^2- and S⁶⁺ differ from that of the O^2- and Ti⁴⁺ ions. (2) S-doping increases the adsorption coefficient A _e for methylene blue (MB) from 0.9% to 68.5% due to the synergistic effects of the oxygen vacancies, increased number of surface chemical adsorption centers as a result of SO₄ ^2- adsorption on the TiO₂ surface and the larger pore size. (3) S-doping increases the MB degradation rate from 6.9 × 10^-2 min^-1 to 18.2 × 10^-2 min^-1 due to an increase in the amount of •OH and •O^2- radicals.

Combined photoanodes of TiO2 nanoparticles and {001}-faceted TiO2 nanosheets for quantum dot-sensitized solar cells

A key point for constructing quantum dot-sensitized solar cells (QDSSCs) with high efficiency is to improve the utilization of sunlight.

N/Ti3+-codoped triphasic TiO2/g-C3N4 heterojunctions as visible-light photocatalysts for the degradation of organic contaminants

N/Ti³⁺-codoped triphasic TiO₂/g-C₃N₄ heterojunctions were successfully prepared by a one-step in situ hydrothermal method, and they demonstrated considerably enhanced photocatalytic performance.