Zinc oxide hollow spheres decorated with cerium dioxide. The role of morphology in the photoactivity of semiconducting oxides

The photochemical activity of the recently proposed CeO2-ZnO photocatalytic material active under visible light has been improved by means of significant modifications of its morphology. A polymeric templating agent (Pluronic) has been used in the synthesis obtaining a particle morphology based on hollow spheres that is better defined in the case of high template concentration. The charge separation ability and the light-induced surface electron transfer under irradiation with visible polychromatic light in various ranges of frequency has been investigated by Electron Paramagnetic Resonance. The reactivity of the photogenerated holes has been monitored by the spin trapping technique in the presence of DMPO. The hollow spheres morphology achieved through the synthesis here reported leads to systems with a higher photoactivity under visible irradiation than the same system displaying the classic platelets morphology. A parallel increase of the photocatalytic activity of this novel system in pollution remediation reactions is therefore predictable.

Preparation and Photocatalysis of CuO/Bentonite Based on Adsorption and Photocatalytic Activity

A CuO/bentonite composite photocatalyst was prepared to fully utilize the adsorption capacity of bentonite and the photocatalytic activity of CuO. CuO and bentonite were chosen as a photocatalyst due to the excellent optical property of CuO and large specific surface area of bentonite, together with their high stability and low production cost. The sample was characterized by XRD, SEM, and BET. The effects of several factors on degradation process were investigated such as dosage of H2O2, irradiation time, pH of the solution, and dosage of catalyst. The optimum conditions for decolorization of methylene blue solution by CuO/bentonite were determined. Under optimal conditions, the decolorization efficiency of methylene blue by a 1.4% CuO/bentonite (400 °C) composite photocatalyst under visible irradiation at 240 min reached 96.98%. The degradation process follow edpseudo-second-order kinetics. The photocatalytic mechanism is discussed in detail. This composite structure provides a new solution to the cycle and aggregation of the photocatalyst in water.

Synergy of Single Atoms Pd and Oxygen Vacancies on In2O3 for Highly Selective C1 Oxygenates Production from Methane under Visible Light

Methane (CH4) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues on both conversion and selectivity. Herein, under visible irradiation (420 nm), the synergy of palladium (Pd) atom cocatalyst and oxygen vacancies (OVs) on In2O3 nanorods enabled superior photocatalytic CH4 activation by O2. The optimised catalyst reached ca. 100 µmol·h− 1 of C1 oxygenates, with a selectivity of primary products (CH3OH and CH3OOH) up to 82.5 %. Mechanism investigation elucidated that such superior photocatalysis was induced by the dedicated function of Pd single atoms and oxygen vacancies on boosting hole and electron transfer pathway, respectively. O2 was proven to be the only oxygen source for CH3OH production, while H2O acted as the promoter for efficient CH4 activation through ·OH production and facilitated product desorption as indicated by DFT modelling. This work thus provides new understandings on simultaneous regulation of activity and selectivity by the significant synergy of single atom cocatalysts and oxygen vacancies.

Structural and Optical Properties of Bi12NiO19 Sillenite Crystals: Application for the Removal of Basic Blue 41 from Wastewater

This article covers the structural and optical property analysis of the sillenite Bi12NiO19 (BNO) in order to characterize a new catalyst that could be used for environmental applications. BNO crystals were produced by the combustion method using Polyvinylpyrrolidone as a combustion reagent. Different approaches were used to characterize the resulting catalyst. Starting with X-ray diffraction (XRD), the structure was refined from XRD data using the Rietveld method and then the structural form of this sillenite was illustrated for the first time. This catalyst has a space group of I23 with a lattice parameter of a = 10.24 Å. In addition, the special surface area (SSA) of BNO was determined by the Brunauer-Emmett-Teller (BET) method. It was found in the range between 14.56 and 20.56 cm2·g−1. Then, the morphology of the nanoparticles was visualized by Scanning Electron Microscope (SEM). For the optical properties of BNO, UV-VIS diffusion reflectance spectroscopy (DRS) was used, and a 2.1 eV optical bandgap was discovered. This sillenite′s narrow bandgap makes it an effective catalyst for environmental applications. The photocatalytic performance of the synthesized Bi12NiO19 was examined for the degradation of Basic blue 41. The degradation efficiency of BB41 achieved 98% within just 180 min at pH ~9 and with a catalyst dose of 1 g/L under visible irradiation. The relevant reaction mechanism and pathways were also proposed in this work.

Studi dan Aplikasi Elektroda FeTiO3-TiO2/Ti untuk Degradasi Reactive Blue 160 dengan Metode Fotoelektrokatalisis

The manufacture of titanium dioxide (TiO2) electrodes is made by anodizing method and coated with ilmenite (FeTiO3) through a dip-coating technique. The ilmenite (FeTiO3) coated TiO2/Ti plate electrode was developed for the degradation of the reactive blue 160 dye under photoelectrocatalytic UV and Visible light irradiation. The performance of FeTiO3-TiO2 / Ti composites degrades reactive blue 160 under UV irradiation and is visible photoelectrocatalytically compared to TiO2. The results of XRD characterization of TiO2 crystals in the form of anatase at 2θ, namely 35.1 ° (110), and the substitution of Fe dopant on TiO2 in the form of anatase and rutile crystals. FTIR data indicated the presence of Fe-O bonds at wave numbers <700 nm. SEM-EDX results showed a thin layer of FeTiO3 was formed, indicating that the dip-coating method was effective in the coating process. The performance of the FeTiO3-TiO2 / Ti electrode has the highest activity against the oxidation process under visible light than the TiO2/Ti electrode. The results of degradation of reactive blue 160 dye with a concentration of 0.5 ppm by photoelectrocatalytic showed that the TiO2 / Ti and FeTiO3-TiO2/Ti electrodes were active in visible irradiation with degradation rate constants of 48% and 69%. Keywords: Electrodes, ilmenite, TiO2 / Ti, degradation, reactive blue 160, photoelectrocatalysis

Synthesis of g-C3N4/InVO4 materials as novel photocatalysts for degradation of antibiotics under visible light

Novel g-C3N4/InVO4 materials were synthesized by a fabricated via hydrothermal and heating methods. The physicochemical properties of the photocatalysts were investigated by X-ray diffraction (XRD), infrared spectroscopy (IR), Photoluminescence spectroscopy (PL), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS) and Energy dispersive X-ray spectroscopy (EDX). The photocatalytic performances were evaluated by degradation of tetracycline (TC). The g-C3N4/InVO4 composite at a weight ratio of 10 % exhibited the most excellent photocatalytic activity for TC degradation under visible irradiation which was more active than that of pure components.