Phase and morphology changes induced by acid treatment following alkaline reaction of mesoporous anatase: Effect of anions

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• 作者：Yi-Shiue Lin ; Dong-Lin Shieh ; Pei-Yu Chen ; Jong-Liang Lin ; ^{jonglin@mail.ncku.edu.tw}
• 关键词：Anatase ; Titanate ; TiO2-B ; Acid treatment
• 刊名：Materials Chemistry and Physics
• 出版年：2012
• 期刊代码：58_02540584
• 类别：ms
• 出版时间：15 June, 2012
• 卷：134
• 期：2-3
• 页码：1020-1029
• 文件大小：1698 K

摘要

Acid treatment, with aqueous solutions of HCl, HNO₃, H₂SO₄, HNO₃聽+聽NaCl and H₂SO₄聽+聽NaCl, for the amorphous reaction paste resulted from mesoporous anatase particles dispersed in KOH solution at 90聽掳C has been performed. The alkaline reaction paste transforms into hexatitanate after addition of HCl solution (0.1聽M) to a pH value from 6.0 to 12.0, but into TiO₂-B at pH 1.2. Different phase changes are observed when a HNO₃ or H₂SO₄ solution is used. Anatase starts to appear at pH 9.0 for HNO₃ and at 12.0 for H₂SO₄ and persists down to pH 1.2. Besides, in the pH range studied, no other crystal phase is detected. The particle morphology of the TiO₂-B and anatase produced at pH 1.2, using HCl, HNO₃ or H₂SO₄ solution, is nanowire, with a width of 鈭?0聽nm. Although or alone in the pH 1.2 solution favors anatase phase, co-existence Cl^{鈭?/sup> leads to TiO₂-B formation. Cl鈭?/sup> plays a role dominating the formation of hexatitanate, which is then transformed into TiO₂-B. However the particle morphology is affected due to the adsorption of and . The mechanism for the process from hexatitanate to TiO₂-B, not relating to the anion nature, and the anion effect based on the binding manner and strength of the anions to titanium ions are discussed.}