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Heat-assisted PbS/TiO 2 thin films with different reaction temperatures were prepared. Microstructure, morphology, optical and photoelectron-chemical properties of the as-synthesized thin films were investigated systematically. For the PbS/TiO 2 thin films with reaction temperature changing from 10 to 95 °C, PbS particles obtained by successive ionic layer adsorption and reaction are galena phase, the mean size of PbS particles decreases firstly and then increases, the coverage of PbS particles on surface increases. At the same time, red shift in the adsorption edges from 416 to 594 nm has been detected, and the optical band gap E g decreases from 3.58 to 2.88 eV. What's more, the intensity of photoluminescence increases firstly and then decreases. The photochemistry measurement suggests that the sample prepared at 60 °C possesses the highest photocurrent in the first test cycle. However, the value of photocurrent decreases immediately with increasing the test cycle. The effect of the reaction temperature on the microstructure, morphology, optical and photoelectron-chemical properties of PbS/TiO 2 thin films have been discussed in detail. [ABSTRACT FROM AUTHOR]

Different surface morphologies of TiO 2 thin films were prepared by hydrothermal synthesis method on Ti substrates through changing reaction time. The microstructure, composition, optical properties and photocatalytic properties of TiO 2 thin films were systematically investigated by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectrometer and ultraviolet-visible spectroscopy. As the reaction time increases, anatase structure and brookite structure of TiO 2 films respectively increases and decreases, corresponding to surface morphology changes from irregular structure to regular geometrical shape structure. These structural changes are accompanied by significant variations of optical properties and photocatalytic properties including a widening of the band gap from 2.86 to 3.19 eV, photocatalytic degradation efficiency from 92.5 to 98.1% and photocatalytic degradation rate from 0.032 to 0.048 min −1 . Among all samples, TiO 2 -1 shows the best photocatalytic properties. Compositional analysis indicates that TiO 2 surface layer contains Ti and O elements, the ratio of Ti:O is 1:2.28 which is close to the atom ratio of TiO 2 . [ABSTRACT FROM AUTHOR]

The novel La-doped FeNiSe 4 /Fe 0.8 Ni 0.2 Se 2 /NF (La-FeNi-Se/NF) heterostructure catalyst was prepared by a facile selenization treatment to La-doped FeNi Prussian blue analogue(PBA) in-situ grown on foam nickel (NF). The optimized La-FeNi-Se-2/NF exhibits superior alkaline OER electrocatalytic activity with a low overpotential 158 mV at 10 mA cm−2, a small Tafel slope 35.6 mV dec−1 and long-time durability. [Display omitted] • A simple and efficient method for preparing La-doped FeNi-Se/NF heterostructure. • The optimized La-FeNi-Se-2/NF exhibits superior alkaline OER electrocatalytic activity. • This performance was superior to most reported FeNi-based OER electrocatalysts. It is of great value to explore non-noble and highly active electrocatalysts for oxygen evolution reaction (OER) to obtain reproducible and clean fuels. In this work, a novel La-doped FeNiSe 4 /Fe 0.8 Ni 0.2 Se 2 /NF (La-FeNi-Se/NF) heterostructure catalyst was prepared by a facile selenization treatment to La-doped FeNi Prussian blue analogue(PBA) in-situ grown on foam nickel (NF). The catalytic performance of La-FeNi-Se/NF was significantly enhanced by the doped La3+. As a result, the optimized La-FeNi-Se-2/NF exhibits superior alkaline OER electrocatalytic activity (overpotential 158 mV at 10 mA cm−2 and Tafel slope 35.6 mV dec−1) than FeNi-Se/NF and Ln-FeNi-Se/NF (Ln = Ce, Gd, Yb), and most reported FeNi-based OER electrocatalysts. The excellent electrocatalytic capability to OER is attributed to the doping FeNi-Se heterostructure with a suitable amount La3+. Also, the unique La-FeNi-Se-2/NF flower-like structure composed of nanograins can produce abundant active sites and enhance charge transfer, thereby further improving the catalytic performance. This work highlights an effective chemical and engineering method to prepare efficient electrochemical catalysts. [ABSTRACT FROM AUTHOR]

TiO 2 nanotubes arrays (TiO 2 -NTAs) layers were successfully formed by electrochemical anodization on a titanium (Ti) surface in fluorine-containing electrolytes under different processing voltages and annealing temperatures. The formed TiO 2 -NTAs layers annealed at different temperatures were compared in terms of their morphologies, structures and band gaps. Their wetting abilities, photo-induced hydrophilicities and photocatalytic performances were also evaluated. It was found the sample anodized at 40 V for 2 h have the most uniform surface morphology. The TiO 2 -NTAs structures annealed at 600 °C for 2 h in air show multiphase crystallinity and have the narrowest band gap (2.89 eV). These structures have noticeable nanowires on the top of the nanotubes. Their photocatalytic activity, tested by degradation of aqueous methylene orange solutions under UV light illumination for 2 h, is the highest among all samples (degradation efficiency was 89.05%). Specimens annealed at 200, 400 and 800 °C show light-induced hydrophilicity. However, small contact angle change was observed when samples were annealed at 600 °C. [ABSTRACT FROM AUTHOR]