Boosting visible light response and charge separation by plasmonic Ag and TiO2 modification of Ag3VO4 for degradation of pollutants

The formation of heterojunction structures of semiconductors is one of the most important techniques to increase the photocatalytic efficiency of a photocatalyst. In this paper, Ag/Ag₃VO₄/TiO₂ as a visible light response photocatalyst was prepared easily by a three step process including hydrothermal, precipitation and photoreduction. The Ag/Ag₃VO₄/TiO₂ nanocomposites demonstrated clearly increased visible light absorption and photocatalytic efficiency in degradation of Rhodamine B. The degradation yield of Rhodamine B was detected 97.3% in 45 min under visible light. Compared with Ag₃VO₄, TiO₂ and Ag₃VO₄/TiO₂, Ag/Ag₃VO₄/TiO₂ exhibited the highest efficiency owing to synergetic effect between Ag₃VO₄ and TiO₂ and surface plasmon resonance effect of Ag nanoparticles. So, the Ag/Ag₃VO₄/TiO₂ can be effectively used as an active photocatalyst under visible light and it depicts an ideal potential in elimination organic pollutants.

Tuning of oxygen vacancy-induced electrical conductivity in Ti-doped hematite films and its impact on photoelectrochemical water splitting

Titanium (Ti)-doped hematite (α-Fe₂O₃) films were grown in oxygen-depleted condition by using the spray pyrolysis technique. The impact of post-deposition annealing in oxygen-rich condition on both the conductivity and water splitting efficiency was investigated. The X-ray diffraction pattern revealed that the films are of rhombohedral α-Fe₂O₃ structure and dominantly directed along (012). The as-grown films were found to be highly conductive with electrons as the majority charge carriers (n-type), a carrier concentration of 1.09×10²⁰ cm⁻³, and a resistivity of 5.9×10⁻² Ω-cm. The conductivity of the films were reduced upon post-deposition annealing. The origin of the conductivity was attributed firstly to Ti⁴⁺ substituting Fe³⁺ and secondly to the ionized oxygen vacancies (V_O) in the crystal lattice of hematite. Upon annealing the samples in oxygen-rich condition, V_O slowly depleted and the conductivity reduced. The photocurrent of the as-grown samples was found to be 3.4 mA/cm⁻² at 1.23 V vs. RHE. The solar-to-hydrogen efficiency for the as-grown sample was calculated to be 4.18% at 1.23 V vs. RHE. The photocurrents were found to be significantly stable in aqueous environment. A linear relationship between conductivity and water-splitting efficiency was established.

Ultra-small CeO2 nanoparticles supported on SiO2 for indoor formaldehyde oxidation at low temperature

Ultra-small CeO₂ nanocrystals with a size of 2.5 nm were synthesized for high efficiency HCHO oxidation at low temperature.

Fabrication of Ag/AgBr/Ag3VO4 composites with high visible light photocatalytic performance

Herein, Ag/AgBr/Ag₃VO₄ composites were synthesized by a simple continuous precipitation method. The obtained composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy and photoluminescence spectroscopy (PL). Photocatalytic performance of the composites was assessed by the degradation of methyl orange (MO) and tetracycline hydrochloride (TC) under visible light, and the effects of different nominal mass ratios of AgBr and Ag₃VO₄ on the photocatalytic activity were investigated. The results showed that after 20 min of visible light irradiation (λ > 420 nm), the removal rate of MO in the presence of a 5 : 1 sample reached 98.6%. The EIS and photocurrent results demonstrated that the enhancement of the visible light photocatalytic activity was attributed to the efficient electron–hole pair separation. In addition, the scavenging reactions conducted via the addition of different scavengers confirmed that h⁺ and ·O²⁻ were the main active species in the reaction. The present study offers potential for the degradation of contaminants.

Ag/AgBr/Ag₃VO₄ composites were synthesized by a simple continuous precipitation method, which were used to degrade organic pollutants and found to have excellent photocatalytic properties.

A Facile Synthesis of Visible-Light Driven Rod-on-Rod like α-FeOOH/α-AgVO3 Nanocomposite as Greatly Enhanced Photocatalyst for Degradation of Rhodamine B

In this work, we have synthesized the rod-on-rod–like α-FeOOH/α-AgVO3 nanocomposite photocatalysts with the different amounts of solvothermally synthesized α-FeOOH nanorods via a simple co-precipitation method. The as-synthesized photocatalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, UV−Visible diffuse reflectance spectroscopy, scanning electron microscopy (SEM), element mapping, high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The observed SEM images show that both α-AgVO3 and α-FeOOH exhibits the rod-shaped morphology with nano size. Furthermore, the photocatalytic activities of the obtained photocatalysts were evaluated towards the degradation of Rhodamine B (RhB) under visible-light irradiation. It is demonstrated that the 3 mg α-FeOOH added to the α-FeOOH/α-AgVO3 nanocomposite exhibited an enhanced photocatalytic performance as compared with the pure α-AgVO3 and α-FeOOH. This significant improvement can be attributed to the increased photo-excited electron-hole pair separation efficiency, large portion of visible-light absorption ability and the reduced recombination of the electron-hole pair. The recycling test revealed that the optimized nanocomposite exhibited good photostability and reusability properties. In addition, the believable photodegradation mechanism of RhB using α-FeOOH/α-AgVO3 nanocomposite is proposed. Hence, the developed α-FeOOH/α-AgVO3 nanocomposite is a promising material for the degradation of organic pollutants in an aqueous environment.

Photoelectrochemical properties of Ti-doped hematite nanosheet arrays decorated with CdS nanoparticles

A photoanode comprised of vertically aligned Ti-doped hematite nanosheet arrays decorated with cadmium sulfide nanoparticles was fabricated. The Ti-Fe₂O₃/CdS electrode shows high photoelectrochemical response under visible light irradiation.