Discoloration of methylene blue at neutral pH by heterogeneous photo-Fenton-like reactions using crystalline and amorphous iron oxides

Different iron oxides were evaluated for the discoloration of methylene blue (MB) at neutral pH by heterogeneous photo-Fenton-like reactions with a UV-LED lamp. Fe3O4, α-Fe2O3, and a-FeOOH catalysts were synthesized and characterized by X-ray diffraction, scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy, and adsorption isotherms of N2. The results show high crystallinity and relatively low surface areas for Fe3O4 and α-Fe2O3, and amorphous structure with high surface area for the case of a-FeOOH. The discoloration of MB by iron oxides as catalysts was studied using UV-Vis spectroscopy. Despite the relative high adsorption of MB for magnetite (12%) compared to the other oxides, it shows a slow discoloration kinetics. Besides, amorphous oxide (named a-FeOOH) shows a higher discoloration kinetics with negligible adsorption capacity. The pseudo first-order kinetic constant values for Fe3O4, α-Fe2O3, and a-FeOOH are 5.31 × 10−3, 6.89 × 10−3, and 13.01 × 10−3 min−1; and the discoloration efficiencies at 120 min were 56, 60, and 82%, respectively. It was testified that low crystallinity iron oxide can be used in the efficient discoloration of MB by photo-Fenton process with a hand UV-A lamp.

Facile synthesis of monodispersed yolk-shelled molybdenum disulfide microspheres with enhanced photocatalytic properties

Monodispersed yolk-shelled MoS₂ microspheres with outstanding photocatalytic properties have been synthesized by the hydrothermal method with the assistance of P123.

The synthesis of multifunctional porous honey comb-like La2O3 thin film for supercapacitor and gas sensor applications

The porous honey comb-like La₂O₃ thin films have been synthesized using one step spray pyrolysis method. The influence of sprayed solution quantity on properties of La₂O₃ thin films is studied using X-ray diffraction, Fourier transform spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, optical absorption and Brunauer-Emmett-Teller techniques. Morphology of La₂O₃ electrode is controlled with sprayed solution quantity. The supercapacitive properties of La₂O₃ thin film electrode are investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance techniques. The La₂O₃ film electrode exhibited the specific capacitance of the 166Fg^-1 with 85% stability for the 3000 cycles. The La₂O₃ film electrode exhibited sensitivity of 68 at 523K for 500ppm CO₂ gas concentration. The possible CO₂ sensing mechanism is discussed.

Gas-sensing and electrical properties of perovskite structure p-type barium-substituted bismuth ferrite

Schematic diagram of the proposed gas-sensing mechanism for the p-type BiFeO₃ based gas sensor: (a) and (c) in air, (b) and (d) in reducing gas, (e) simplified equivalent circuit.