Construction of Spindle-Shaped Ti3+ Self-Doped TiO2 Photocatalysts Using Triethanolamine-Aqueous as the Medium and Its Photoelectrochemical Properties

To enhance the utilization efficiency of visible light and reduce the recombination of photogenerated electrons and holes, spindle-shaped TiO2 photocatalysts with different Ti3+ concentrations were fabricated by a simple solvothermal strategy using low-cost, environmentally friendly TiH2 and H2O2 as raw materials and triethanolamine-aqueous as the medium. The photocatalytic activities of the obtained photocatalysts were investigated in the presence of visible light. X-ray diffraction (XRD), Raman spectra, transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectra were applied to characterize the structure, morphologies, and chemical compositions of as-fabricated Ti3+ self-doped TiO2. The concentration of triethanolamine in the mixed solvent plays a significant role on the crystallinity, morphologies, and photocatalytic activities. The electron–hole separation efficiency was found to increase with the increase in the aspect ratio of as-fabricated Ti3+ self-doped TiO2, which was proved by transient photocurrent response and electrochemical impedance spectroscopy.

Using Gd-Enhanced β-NaYF4:Yb,Er Fluorescent Nanorods Coupled to Reduced TiO2 for the NIR-Triggered Photocatalytic Inactivation of Escherichia coli

β-NaYF4:Yb,Er,Gd fluorescent nanorods were successfully coupled to a reduced TiO2 (UCNPs@R-TiO2) nanocomposite and applied to visible-light catalytic sterilization under 980 nm near-infrared (NIR) light illumination. The UCNPs (β-NaYF4:Yb,Er,Gd) absorb the NIR light and emit red and green light. The visible light can be absorbed by the R-TiO2 (Eg = 2.8 eV) for the photocatalytic reaction. About 98.1% of Escherichia coli were effectively killed upon 12 min of NIR light irradiation at a minimum inhibitory concentration (MIC) of 40 μg/mL UCNPs@R-TiO2 nanocomposite. The bactericidal properties were further evaluated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis. We found that the high bactericidal activity was due to the synergistic effect between the UCNPs and R-TiO2. Moreover, the UCNPs show excellent upconversion luminance properties, and the introduction of visible-light-absorbed R-TiO2 nanoparticles (2.8 eV) was conducive to the efficient separation and utilization of photogenerated electron-hole pairs.

β-NaYF4:Yb,Er,Gd nanorods@1T/2H-MoS2 for 980 nm NIR-triggered photocatalytic bactericidal properties

Fabrication of β-NaYF₄:Yb,Er,Gd@1T/2H-MoS₂ nanocomposites for NIR-driven photocatalytic sterilization of Escherichia coli.

A facile synthesis of a highly efficient β-Bi2O3/Bi2O2CO3 heterojunction with enhanced photocatalytic NO oxidation under visible light

Photocatalytic oxidation mechanism of NO on β-Bi₂O₃/Bi₂O₂CO₃.

True Photoreactivity Origin of Ti3+-Doped Anatase TiO2 Crystals with Respectively Dominated Exposed {001}, {101}, and {100} Facets

Combining the advantages of reactive crystal facets and engineering defects is an encouraging way to address the inherent disadvantages of titanium dioxide (TiO₂) nanocrystals. However, revealing the true photoreactivity origin for defective TiO₂ with coexposed or predominant exposed anisotropic facets is still highly challenging. Here, the photoreactivity of TiO₂ nanocrystals with respectively predominant exposed {001}, {101}, and {100} facets before and after Ti³⁺ doping under both ultraviolet and visible light was compared systematically. In detail, the photocatalytic H₂ production for R-TiO₂-001, R-TiO₂-101, and R-TiO₂-100 increased by a factor of 1.34, 2.65, and 3.39 under UV light and a factor of 8.90, 13.47, and 8.72 under visible light. By contrast, the photocatalytic degradation of methyl orange for R-TiO₂-001, R-TiO₂-101, and R-TiO₂-100 increased by a factor of 3.18, 1.42, and 2.17 under UV light and a factor of 4.03, 2.85, and 1.58 under visible light, respectively. The true photocatalytic activity origin for the obtained photoreduction and photo-oxidation ability is attributed to the exposure of more active sites (under-coordinated 5-fold Ti atoms), the facilitated charge transfer among {001}, {101}, and {100} facets, and the Ti³⁺ energy state with variable doping levels to extend the visible light response. This work hopefully provides significant insights into the photoreactivity origin of defective TiO₂ nanocrystals with anisotropic exposed facets.