六钛酸钾纳米晶须的水热反应相转变行为

The Phase Transition Behavior of K_2Ti_6O_(13) Nanowhiskers via the Hydrothermal Reaction

以偏钛酸为钛源,与无水碳酸钾混合,利用高温固相法成功制备了六钛酸钾(K2Ti6O13)纳米晶须,并通过不同的水热反应条件考察了K2Ti6O13晶须相转变过程.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)等测试手段表征了K2Ti6O13水热反应过程中的物相转变与形貌变化.结果表明:在不同酸介质水热反应条件下,K2Ti6O13发生相转变,并可控得到锐钛矿相TiO2纳米颗粒、纳米棒及纺锤体金红石TiO2,这种相转变过程可归结为K2Ti6O13风洞结构的溶解-重组机制;在浓NaOH作用下,K2Ti6O13通过剥离与重组作用,向Na2Ti3O7相转变.此外,考察了酸介质水热产物的催化性能,可见光条件下,1mol/LHCl、130℃保温12h得到锐钛矿纳米TiO2颗粒具有优异的光催化性能.

Potassium hexatitanate(K2Ti6O13)nanowhiskers were successfully synthesized via high temperature solid state reaction between metatitanic acid(H2TiO3,a titanium source)and potassium carbonate.The phase transition process was investigated via a facile one-step hydrothermal reaction.The phase and morphology changes of the K2Ti6O13 nanowhisker samples were characterized by a range of methods including powder X-ray diffraction(XRD)and scanning electron microscope(SEM).In HCl solution,nanoparticles or nanorods of anatase and spindle of rutile TiO2 were generated from the K2Ti6O13 via a hydrothermal process based on the 'dissolution-precipitation'theory.In NaOH solution,the K2Ti6O13 was transformed to Na2Ti3O7 based on the cleavage-precipitation mechanism.Furthermore,the photocatalytic activity of the nano-structured TiO2 products was studied by the decomposition of the indigo carmine solution.Compared to the commercially available photocatalyzer P25,the nanoparticles of the anatase TiO2 obtained in 1mol/L HCl at 130 ℃for 12 hshowed better photocatalytic property under the irradiation of visible light.