Fabrication Of Composite TiO₂Nanotube Array With Noble Metals And The SERS And Gas Sensing Properties

Titania nanotube arrays （TNTA） with high specific surface area,orientation of a high degree of consistency, and outstanding physical andchemical properties were supposed to be widely applications in photocatalyticdegradation, gas, dye sensitized solar cells, humidity sensors, photochromic,and other areas. Titania nanotube array were fabricated by electrochemicalanodization in this paper. Reusable multifunctional surface enhanced Raman（SERS） substrate was obtained on titania nanotube array. Photo enhancedhydrogen sensing, sensing mechanism, and the function of catalyst on titaniananotube array were investigated. And the sensitivity of titania nanotubefabricated on Ti-Au to NO₂is also studied in this paper.In this paper, Ag modified TiO₂nanotube arrays were prepared by meansof Ti-Ag alloy anodization, liquid deposition of Ag before heat treatment ontitania nanotubes and vacuum sputtering of silver after heat treatment. Afterthe comparison of the morphology, it shows that TNTA of the vacuumsputtering of silver after heat treatment with nano-scale silver spherical orrod-like was special and suitable for SERS. And the recyclable anddegradation functions of SERS substrate were tested to R6G molecular. Theresults showed that SERS effect is gradually increasing with the diameterincrease of titania nanotubes. Under UV light irradiation, R6G was quicklydegraded and suitable for reusable substrate. However, with nanotubediameter of50nm, the silver migrated into nanotubes and formed a rod-likestructure when SERS effect is remarkable, and the performance was similarto nanotube with diameter of110nm.Oriented titania nanotube array were fabricated by electrochemicalanodization in a aqueous solution contain of F-irons. The dye of N719and Pdwere modified on the surface of titania nanotube to enhance the hydrogensensitivity, respectively. The sensing properties to hydrogen at room temperature were measured under different irradiation. It was found thatdye-sensitized titanium dioxide nanotube arrays were responded to hydrogenat room temperature under visible light irradiation; and titanium dioxidenanotube arrays were also sensitive to hydrogen at room temperature by Pdmodified. The effects of dye-sensitized, Pd modification, on visible light andsimulated sunlight on hydrogen sensitivity of titania nanotube arrays werediscussed by means of electrochemical impedance spectroscopy （EIS）. It wasalso showed that the equivalent circuit of titania nanotubes was similar to ametal/semiconductor contact model. Activity of O-ion on the surface oftitanium dioxide nanotubes was increased by UV light irradiation, while theactivity of the O-ion in dye-sensitized titanium dioxide nanotube array wasenhanced by visible light. Hydrogen molecules can be decomposed intohydrogen atoms with Pd modified, which was conducive to hydrogen sensingreactions at room temperature.Au modified TiO₂nanotubes array was prepared under differentconditions, and a preliminary test of NO₂Sensing was employed. The resultsshowed that the sensor was sensitive to500ppb of NO₂at room temperature.