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TiO2 is one of the most studied semiconductor materials for the photoelectrochemical water splitting to hydrogen production, but it only responds to ultraviolet light. The introduction of organic compound is one of the common means to expand the visible light response of TiO2. In this work, rutile TiO2 nanowire arrays (NWs) were grown on conductive glass by a modified solvothermal method using oleic acid as the key additive. The obtained TiO2 NWs are characterized using x-ray diffraction, x-ray photoelectron spectroscopy, infrared spectroscopy and electrochemical characterization. The results show that the carboxyl groups arising from oleic acid are chemically bonded with the TiO2 NWs in the form of chelating bidentate, which increases the visible light absorption range and active sites of TiO2, and reduces the transfer resistance between the photoelectrode and the electrolyte. The photocurrent density is doubled to 0.17 mA cm−2 at 1.23 V vs. RHE. This work provides a novel idea for the design of metal oxide semiconductor photoanodes by adsorbing organic compounds. [ABSTRACT FROM AUTHOR]

The self-doping of oxygen vacancy and Ti3+ by electrochemical reduction (ER) method has been proved to be an effective means to improve the PEC performance of TiO2. However, the effect of the surface structure on ER treatment remains ambiguous. In this work, three kinds of nanostructured rutile TiO2 (nanowire arrays (TNWs), etched nanowire arrays (E-TNWs) and nanorod arrays (TNRs)) were reduced electrochemically to explore the factors influencing the ER process of rutile TiO2. The experimental results show that alkaline environment (1 M NaOH) is more conducive to the occurrence of ER reaction. And the reduced three kinds of nanostructured TiO2 photoanodes show a significantly higher photocurrent density of about 1.46, 1.65 and 1.45 mA cm−2 at 1.23 V vs. relative hydrogen electrode (RHE), respectively, which are 15, 16 and 1.1 times that of pristine TiO2. The different degrees of photocurrent density enhancement can be ascribed to the different degrees of electrochemical reduction of TiO2 with different crystallinity and exposed crystal facets as well as specific surface area. This study provides new insights into the mechanism of electrochemical reduction method. [ABSTRACT FROM AUTHOR]

The self-doping of oxygen vacancy and Ti3+ by electrochemical reduction (ER) method has been proved to be an effective means to improve the PEC performance of TiO2. However, the effect of the surface structure on ER treatment remains ambiguous. In this work, three kinds of nanostructured rutile TiO2 (nanowire arrays (TNWs), etched nanowire arrays (E-TNWs) and nanorod arrays (TNRs)) were reduced electrochemically to explore the factors influencing the ER process of rutile TiO2. The experimental results show that alkaline environment (1 M NaOH) is more conducive to the occurrence of ER reaction. And the reduced three kinds of nanostructured TiO2 photoanodes show a significantly higher photocurrent density of about 1.46, 1.65 and 1.45 mA cm−2 at 1.23 V vs. relative hydrogen electrode (RHE), respectively, which are 15, 16 and 1.1 times that of pristine TiO2. The different degrees of photocurrent density enhancement can be ascribed to the different degrees of electrochemical reduction of TiO2 with different crystallinity and exposed crystal facets as well as specific surface area. This study provides new insights into the mechanism of electrochemical reduction method. [ABSTRACT FROM AUTHOR]

An efficient Nd: A YAG single-frequency laser was demonstrated using a gradient-doped ceramic non-planar ring oscillator (NPRO). A thermal model of the gradient-doped ceramic NPRO was built to analyze the temperature field and thermal focal length. By employing a gradient-doped gain structure, the thermal distribution within the NPRO can be effectively smoothed to reduce thermal lensing effects. Up to 2.8 W of single-frequency output power at 1064 nm from the gradient-doped ceramic NPRO was obtained, with a slope efficiency of 38%. [ABSTRACT FROM AUTHOR]