Enhancement of the visible light photocatalytic performance of C-doped TiO2 by loading with V2O5

V₂O₅ was loaded on the surface of C-doped TiO₂ (C-TiO₂) by incipient wetness impregnation in order to enhance the visible light photocatalytic performance. The physicochemical properties of the C-TiO₂/V₂O₅ composite were characterized by XRD, Raman, TEM, XPS, UV–vis diffuse reflectance spectra, and PL in detail. The result indicated that a heterojunction between C-TiO₂ and V₂O₅ was formed and the separation of excited electron–hole pairs on C-TiO₂/V₂O₅ is greatly promoted. Thus, this composite photocatalyst exhibited enhanced visible light photocatalytic activity in degradation of gas-phase toluene compared with the pristine C-TiO₂.     

The Synthesis and Photocatalytic Properties of Nitrogen Doped TiO<Subscript>2</Subscript> Films Prepared Using the AC-PLD Method

Synthesis of N doped TiO₂ films were conducted by the atmospheric controlled pulsed laser deposition (AC-PLD) method to generate visible light active photocatalytic films. In this method, the anion doped TiO₂ films were synthesized on a quartz substrate by the irradiation of a pulsed Nd:YAG laser on a TiO₂ target in the presence of gaseous nitrogen containing reagents at reduced pressure. For nitrogen doping, the use of CH₃CN was found to be more effective than the use of NH₃. The visible light absorption properties of the films were very sensitive to the CH₃CN partial pressure during ablation. When using CH₃CN, nitrogen and an equal quantity of carbon was uniformly doped into the TiO₂ films. The resultant films showed better catalytic performance than those which were either un-doped or doped using NH₃. The formation of nitrogen doped TiO₂ is discussed by relating experimental results to thermodynamic considerations. It is also suggested that stronger reducing agents such as carbon are required for doping nitrogen into TiO₂ films.     

An investigation of the performance of catalytic aerogel filters

Gas permeable, photoactive and crack-free titania–silica aerogels of high titanium content (i.e., up to Ti/Si = 1) were prepared by two-steps acid–base catalyzed method involving an acid-catalyzed prehydrolysis of silicon alkoxide followed by a base-catalyzed hydrolysis/condensation reactions with a chelated titania precursor. The prepared titania–silica aerogels displayed good mechanical strength (>30 kN m⁻²), large surface area (>550 m²/g), mesoporous structure (8–11 nm) and good gas permeation. The porous aerogels trap and filter airborne particulates and the titania–silica aerogel have a fair performance for aerosol (65%) and bioaerosol (94%) filtrations. The photoactive anatase nano-TiO₂ crystallized within the aerogel displays an order of magnitude higher reaction rate for UVA photooxidation of trichloroethylene compared to commercial Degussa P25 TiO₂. The bactericidal activity of the titania–silica aerogel for Bacillus subtilis cells under UVA was also six orders of magnitude better.     

Fe3O4 coupled BiOCl: A highly efficient magnetic photocatalyst

The magnetic photocatalyst, Fe₃O₄/BiOCl nanocomposite, was prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution TEM (HRTEM), physical property measurement system (PPMS). It was found that Fe₃O₄/BiOCl was an effective photocatalyst to degrade the organic dyes. Compared with the conventional core–shell magnetic photocatalysts, such as Fe₃O₄/TiO₂ system which dramatically lost their intrinsically photocatalytic activity due to the introduction of the magnetic core, the as-synthesized Fe₃O₄/BiOCl reserved as high photocatalytic activity as that of BiOCl. The high catalytic activity possibly involved in a coupled structure and the special interfaces, that is, the probability of combination of the carriers could be reduced in this system. Moreover, the superparamagnetic Fe₃O₄/BiOCl can be not only easily recycled but also fluidized by applying an external magnetic field.     

Realizing efficient photocatalytic water splitting over Mg-modified BaNbO2N under visible light illumination

With a light absorption up to 740 nm, BaNbO₂N is promising for solar water splitting but normally owns a low activity due to a high defect concentration. Here, Mg is adopted as a dopant to modify the BaNbO₂N. The presence of Mg not only reduces the defect concentration and enhances surface hydrophilicity but also tunes the bandgap as well as the band edge positions. These modifications greatly promote the charge separation and transfer of BaNbO₂N, boosting the photocatalytic activities for O₂-evolution reactions. An apparent quantum efficiency of 1.65 % at 420 ± 20 nm has been attained for Mg modified BaNbO₂N. Overall water splitting at a stable gas-evolution rate (∼ 2.0 μmol·h⁻¹ for H₂ and ∼ 1.0 μmol·h⁻¹ for O₂) has been realized by integrating Mg-modified BaNbO₂N into a Z-scheme system. These findings justify Mg as an effective dopant to modulate the photocatalytic behavior of Nb-based perovskite oxynitrides.     

Selective coordination activation regulating the selectivity for photocatalytic hydrogenation of α, β-unsaturated aldehyde over Pd/MIL-100(FeaCub)

Here, the mixed metal nodes MOFs, Pd/MIL-100(Fe_aCu_b), were constructed as photocatalysts for hydrogenation of α, β-unsaturated aldehyde (UAL) under visible light. 1 wt% Pd/MIL-100(Fe_0.81Cu_0.19) can convert a range of UAL to saturated aldehydes (SAL) with a high efficiency (≈ 100 %) and selectivity (≈ 98 %). The results of XPS and in situ DRIFTS reveal that UAL can be selectively activated via a coordination of -CC- on Cu²⁺ sites, determining the high selectivity of the photocatalytic reaction. The mixed metal nodes and Pd clusters can improve the transformation and separation of photogenerated electrons-holes. EPR result suggests that photogenerated carriers can facilitate the generation of H·on Pd/MIL-100(Fe_0.81Cu_0.19), enhancing the catalytic activity. A possible mechanism is proposed for elucidating the catalytic processes at the molecular level. This work provides a valuable strategy for tailoring the selectivity of photocatalytic hydrogenation via selective coordination activation.