Magnetron Reactive Sputtering Fabrication of Ta3N5 Nanocolumns For the Photocatalytic and Photoelectrochemical Applications

Abstract

Ta3N5 (band gap approximate 2 1 eV) can effectively absorb the visible light up to 600 nm and other various superior properties which make it promising for photocatalysis However reactive sputtering was not heavily used to make Ta3N5 and a caustic NH3 treatment is often required TaxNy indicates a broad space of phases depending upon the fabrication conditions Making N-rich Ta3N5 using reactive sputtering is full of challenges In this research reactive sputtering was used to directly grow Ta3N5 nanocolumn arrays on an FTO/glass substrate without using caustic NH3 gases In addition no other treatments were adopted such as a seeding layer substrate rotation or a glancing angle strategy thus preventing unnecessary complexity from being incorporated into an existing sputtering system This strategy provides an alternative approach to effectively fabricate nitrides Ta3N5 nanocolumn arrays were obtained by tuning the parameters of the Ar/N2 ratio and the working pressures Various characterization tools such as XRD SEM AES XPS TEM and UV-Vis were used to study the related properties Combining the results of SEM XRD AES and XPS analyses we successfully made the columnar structures of single Ta3N5 phase which was made under the conditions of the flow rates of Ar : N2 = 7 : 15 working pressure of 30 mTorr DC 450W and 600 ℃) The photodegradation performance was measured in an environment with a pH of approximately 10 in which approximately 50 % of methylene blue (5 ppm 10ml) was photodegraded in 150 min under 300 W visible light after dark absorption The photodegradation rate constant k was 0 0059 min-1 which was approximately 2 7 times higher than that of P25 Its stability was also evaluated by a three cycle test

Date of Award	2015 Jul 31
Original language	English
Supervisor	Kao-Shuo Chang (Supervisor)