Synthesis of sol–gel Na2Zr x Ti6−x O13 (0≤x≤1) materials and their performance in photocatalytic degradation of organic dyes

Abstract

In this work we present the synthesis and characterization of four compositions of the solid solution with the general formula Na2Zr x Ti6−x O13 (0≤x≤1) which was prepared by a sol-gel method. The main goal of this work is to evaluate the influence of the incorporation of different amounts of zirconium into the binary phase Na2Ti6O13 on two properties: the textural surface and E g values. This titanate phase crystallizes in a monoclinic unit cell and is built into an octahedral TiO6 framework forming a rectangular tunnel structure. Additionally, we have compared their photocatalytic performances in degradation of organic dyes under visible light. The heat-treated sol-gel samples were characterized by X-ray powder diffraction, N2 physisorption, thermal analysis, UV and FT-IR spectroscopy. According to the X-ray powder diffraction results, the new ternary tunnel compound Na2ZrTi5O13 was obtained as a single phase at 800°C. The cell parameters for the two end-member phases of that solid solution were refined to confirm that Zr ion was incorporated into the structural framework. This ternary compound had an E g value of about 2.9 eV. The activity of all heat-treated Na2ZrTi5O13 samples was tested in the photocatalytic degradation of methylene blue and Rhodamine B under visible light. The Na2ZrTi5O13 calcined at 400°C showed the best performance with 95% of photodegradation of methylene blue and a half time t 1/2 of 15 min.